Author: "A Possenti" / Topic: astrophysics - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"A Possenti"' showing total 519 results

Start Over Author "A Possenti" Topic astrophysics

519 results on '"A Possenti"'

1. An IXPE-led X-Ray Spectropolarimetric Campaign on the Soft State of Cygnus X-1: X-Ray Polarimetric Evidence for Strong Gravitational Lensing

Author: James F. Steiner, Edward Nathan, Kun Hu, Henric Krawczynski, Michal Dovčiak, Alexandra Veledina, Fabio Muleri, Jiri Svoboda, Kevin Alabarta, Maxime Parra, Yash Bhargava, Giorgio Matt, Juri Poutanen, Pierre-Olivier Petrucci, Allyn F. Tennant, M. Cristina Baglio, Luca Baldini, Samuel Barnier, Sudip Bhattacharyya, Stefano Bianchi, Maimouna Brigitte, Mauricio Cabezas, Floriane Cangemi, Fiamma Capitanio, Jacob Casey, Nicole Rodriguez Cavero, Simone Castellano, Elisabetta Cavazzuti, Sohee Chun, Eugene Churazov, Enrico Costa, Niccolò Di Lalla, Alessandro Di Marco, Elise Egron, Melissa Ewing, Sergio Fabiani, Javier A. García, David A. Green, Victoria Grinberg, Petr Hadrava, Adam Ingram, Philip Kaaret, Fabian Kislat, Takao Kitaguchi, Vadim Kravtsov, Brankica Kubátová, Fabio La Monaca, Luca Latronico, Vladislav Loktev, Christian Malacaria, Frédéric Marin, Andrea Marinucci, Olga Maryeva, Guglielmo Mastroserio, Tsunefumi Mizuno, Michela Negro, Nicola Omodei, Jakub Podgorný, John Rankin, Ajay Ratheesh, Lauren Rhodes, David M. Russell, Miroslav Šlechta, Paolo Soffitta, Sean Spooner, Valery Suleimanov, Francesco Tombesi, Sergei A. Trushkin, Martin C. Weisskopf, Silvia Zane, Andrzej A. Zdziarski, Sixuan Zhang, Wenda Zhang, Menglei Zhou, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Wayne H. Baumgartner, Ronaldo Bellazzini, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Immacolata Donnarumma, Victor Doroshenko, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Riccardo Ferrazzoli, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Jeffery J. Kolodziejczak, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Ikuyuki Mitsuishi, Chi-Yung Ng, Stephen L. O’Dell, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Nicholas E. Thomas, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Kinwah Wu, and Fei Xie
Subjects: Accretion, Polarimetry, X-ray astronomy, Stellar mass black holes, Astrophysics, QB460-466
Abstract: We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May–June. Companion multiwavelength data during the campaign are likewise shown. The 2–8 keV X-rays exhibit a net polarization degree PD = 1.99% ± 0.13% (68% confidence). The polarization signal is found to increase with energy across the Imaging X-ray Polarimetry Explorer’s (IXPE) 2–8 keV bandpass. The polarized X-rays exhibit an energy-independent polarization angle of PA = −25.°7 ± 1.°8 east of north (68% confidence). This is consistent with being aligned to Cyg X-1’s au-scale compact radio jet and its parsec-scale radio lobes. In comparison to earlier hard-state observations, the soft state exhibits a factor of 2 lower polarization degree but a similar trend with energy and a similar (also energy-independent) position angle. When scaling by the natural unit of the disk temperature, we find the appearance of a consistent trend line in the polarization degree between the soft and hard states. Our favored polarimetric model indicates that Cyg X-1’s spin is likely high ( a _* ≳ 0.96). The substantial X-ray polarization in Cyg X-1's soft state is most readily explained as resulting from a large portion of X-rays emitted from the disk returning and reflecting off the disk surface, generating a high polarization degree and a polarization direction parallel to the black hole spin axis and radio jet. In IXPE’s bandpass, the polarization signal is dominated by the returning reflection emission. This constitutes polarimetric evidence for strong gravitational lensing of X-rays close to the black hole.
Published: 2024
Full Text: View/download PDF

2. Highly Significant Detection of X-Ray Polarization from the Brightest Accreting Neutron Star Sco X-1

Author: Fabio La Monaca, Alessandro Di Marco, Juri Poutanen, Matteo Bachetti, Sara Elisa Motta, Alessandro Papitto, Maura Pilia, Fei Xie, Stefano Bianchi, Anna Bobrikova, Enrico Costa, Wei Deng, Ming-Yu Ge, Giulia Illiano, Shu-Mei Jia, Henric Krawczynski, Eleonora Veronica Lai, Kuan Liu, Guglielmo Mastroserio, Fabio Muleri, John Rankin, Paolo Soffitta, Alexandra Veledina, Filippo Ambrosino, Melania Del Santo, Wei Chen, Javier A. Garcia, Philip Kaaret, Thomas D. Russell, Wen-Hao Wei, Shuang-Nan Zhang, Chao Zuo, Zaven Arzoumanian, Massimo Cocchi, Andrea Gnarini, Ruben Farinelli, Keith Gendreau, Francesco Ursini, Martin C. Weisskopf, Silvia Zane, Iván Agudo, Lucio A. Antonelli, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Michela Negro, Chi-Yung Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Kinwah Wu, and IXPE Collaboration
Subjects: Polarimetry, Spectropolarimetry, Neutron stars, Accretion, Stellar accretion disks, Low-mass x-ray binary stars, Astrophysics, QB460-466
Abstract: The Imaging X-ray Polarimetry Explorer measured with high significance the X-ray polarization of the brightest Z-source, Sco X-1, resulting in the nominal 2–8 keV energy band in a polarization degree of 1.0% ± 0.2% and a polarization angle of 8° ± 6° at a 90% confidence level. This observation was strictly simultaneous with observations performed by NICER, NuSTAR, and Insight-HXMT, which allowed for a precise characterization of its broadband spectrum from soft to hard X-rays. The source has been observed mainly in its soft state, with short periods of flaring. We also observed low-frequency quasiperiodic oscillations. From a spectropolarimetric analysis, we associate a polarization to the accretion disk at
Published: 2024
Full Text: View/download PDF

3. Discovery of a Shock-compressed Magnetic Field in the Northwestern Rim of the Young Supernova Remnant RX J1713.7–3946 with X-Ray Polarimetry

Author: Riccardo Ferrazzoli, Dmitry Prokhorov, Niccolò Bucciantini, Patrick Slane, Jacco Vink, Martina Cardillo, Yi-Jung Yang, Stefano Silvestri, Ping Zhou, Enrico Costa, Nicola Omodei, C.-Y. Ng, Paolo Soffitta, Martin C. Weisskopf, Luca Baldini, Alessandro Di Marco, Victor Doroshenko, Jeremy Heyl, Philip Kaaret, Dawoon E. Kim, Frédéric Marin, Tsunefumi Mizuno, Melissa Pesce-Rollins, Carmelo Sgrò, Douglas A. Swartz, Toru Tamagawa, Fei Xie, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Immacolata Donnarumma, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Fabio Muleri, Michela Negro, Stephen L. O’Dell, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Juri Poutanen, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Gloria Spandre, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Kinwah Wu, and Silvia Zane
Subjects: X-ray astronomy, Polarimetry, Supernova remnants, Astrophysics, QB460-466
Abstract: Supernova remnants (SNRs) provide insights into cosmic-ray acceleration and magnetic field dynamics at shock fronts. Recent X-ray polarimetric measurements by the Imaging X-ray Polarimetry Explorer (IXPE) have revealed radial magnetic fields near particle acceleration sites in young SNRs, including Cassiopeia A, Tycho, and SN 1006. We present here the spatially resolved IXPE X-ray polarimetric observation of the northwestern rim of SNR RX J1713.7–3946. For the first time, our analysis shows that the magnetic field in the particle acceleration sites of this SNR is oriented tangentially with respect to the shock front. Because of the lack of precise Faraday rotation measurements in the radio band, this was not possible before. The average measured polarization degree (PD) of the synchrotron emission is 12.5% ± 3.3%, lower than the one measured by IXPE in SN 1006, comparable to the Tycho one, but notably higher than the one in Cassiopeia A. On subparsec scales, localized patches within RX J1713.7–3946 display a PD of up to 41.5% ± 9.5%. These results are compatible with a shock-compressed magnetic field. However, in order to explain the observed PD, either the presence of a radial net magnetic field upstream of the shock or partial reisotropization of the turbulence downstream by radial magnetohydrodynamical instabilities can be invoked. From comparison of PD and magnetic field distribution with γ -rays and ^12 CO data, our results provide new inputs in favor of a leptonic origin of the γ -ray emission.
Published: 2024
Full Text: View/download PDF

4. X-Ray Polarization of the Eastern Lobe of SS 433

Author: Philip Kaaret, Riccardo Ferrazzoli, Stefano Silvestri, Michela Negro, Alberto Manfreda, Kinwah Wu, Enrico Costa, Paolo Soffitta, Samar Safi-Harb, Juri Poutanen, Alexandra Veledina, Alessandro Di Marco, Patrick Slane, Stefano Bianchi, Adam Ingram, Roger W. Romani, Nicolò Cibrario, Brydyn Mac Intyre, Romana Mikus̆incová, Ajay Ratheesh, James F. Steiner, Jiri Svoboda, Stefano Tugliani, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Javier A. García, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, Chi-Yung Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Oliver J. Roberts, Carmelo Sgrò, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Fei Xie, and Silvia Zane
Subjects: High mass x-ray binary stars, Jets, High energy astrophysics, Supernova remnants, Astrophysical black holes, Astrophysics, QB460-466
Abstract: How astrophysical systems translate the kinetic energy of bulk motion into the acceleration of particles to very high energies is a pressing question. SS 433 is a microquasar that emits TeV γ -rays indicating the presence of high-energy particles. A region of hard X-ray emission in the eastern lobe of SS 433 was recently identified as an acceleration site. We observed this region with the Imaging X-ray Polarimetry Explorer and measured a polarization degree in the range 38%–77%. The high polarization degree indicates the magnetic field has a well-ordered component if the X-rays are due to synchrotron emission. The polarization angle is in the range −12° to +10° (east of north), which indicates that the magnetic field is parallel to the jet. Magnetic fields parallel to the bulk flow have also been found in supernova remnants and the jets of powerful radio galaxies. This may be caused by interaction of the flow with the ambient medium.
Published: 2024
Full Text: View/download PDF

5. X-Ray Polarized View of the Accretion Geometry in the X-Ray Binary Circinus X-1

Author: John Rankin, Fabio La Monaca, Alessandro Di Marco, Juri Poutanen, Anna Bobrikova, Vadim Kravtsov, Fabio Muleri, Maura Pilia, Alexandra Veledina, Rob Fender, Philip Kaaret, Dawoon E. Kim, Andrea Marinucci, Herman L. Marshall, Alessandro Papitto, Allyn F. Tennant, Sergey S. Tsygankov, Martin C. Weisskopf, Kinwah Wu, Silvia Zane, Filippo Ambrosino, Ruben Farinelli, Andrea Gnarini, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Alan P. Marscher, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Michela Negro, Chi-Yung Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Roberto Turolla, Jacco Vink, and Fei Xie
Subjects: X-ray binary stars, Polarimetry, X-ray astronomy, X-ray sources, Astrophysics, QB460-466
Abstract: Cir X-1 is a neutron star X-ray binary characterized by strong variations in flux during its eccentric ∼16.6 day orbit. There are also strong variations in the spectral state, and it has historically shown both atoll and Z state properties. We observed the source with the Imaging X-ray Polarimetry Explorer during two orbital segments, 6 days apart, for a total of 263 ks. We find an X-ray polarization degree in these segments of 1.6% ± 0.3% and 1.4% ± 0.3% at polarization angles of 37° ± 5° and −12° ± 7°, respectively. Thus, we observed a rotation of the polarization angle by 49° ± 8° along the orbit. Because variations of accretion flow, and then of the hardness ratio, are expected during the orbit, we also studied the polarization binned in hardness ratio and found the polarization angle differing by 67° ± 11° between the lowest and highest values of the hardness ratio. We discuss possible interpretations of this result that could indicate a possible misalignment between the symmetry axes of the accretion disk and the Comptonizing region caused by the misalignment of the neutron star’s angular momentum with respect to the orbital one.
Published: 2024
Full Text: View/download PDF

6. X-Ray and Multiwavelength Polarization of Mrk 501 from 2022 to 2023

Author: Chien-Ting J. Chen, Ioannis Liodakis, Riccardo Middei, Dawoon E. Kim, Laura Di Gesu, Alessandro Di Marco, Steven R. Ehlert, Manel Errando, Michela Negro, Svetlana G. Jorstad, Alan P. Marscher, Kinwah Wu, Iván Agudo, Juri Poutanen, Tsunefumi Mizuno, Pouya M. Kouch, Elina Lindfors, George A. Borman, Tatiana S. Grishina, Evgenia N. Kopatskaya, Elena G. Larionova, Daria A. Morozova, Sergey S. Savchenko, Ivan S. Troitsky, Yulia V. Troitskaya, Andrey A. Vasilyev, Alexey V. Zhovtan, Francisco José Aceituno, Giacomo Bonnoli, Víctor Casanova, Juan Escudero, Beatriz Agís-González, César Husillos, Jorge Otero Santos, Alfredo Sota, Vilppu Piirola, Ioannis Myserlis, Emmanouil Angelakis, Alexander Kraus, Mark Gurwell, Garrett Keating, Ramprasad Rao, Sincheol Kang, Sang-Sung Lee, Sang-Hyun Kim, Whee Yeon Cheong, Hyeon-Woo Jeong, Chanwoo Song, Andrei V. Berdyugin, Masato Kagitani, Vadim Kravtsov, Anagha P. Nitindala, Takeshi Sakanoi, Ryo Imazawa, Mahito Sasada, Yasushi Fukazawa, Koji S. Kawabata, Makoto Uemura, Tatsuya Nakaoka, Hiroshi Akitaya, Carolina Casadio, Albrecht Sievers, Lucio Angelo Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccoló Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Niccoló Di Lalla, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Philip Kaaret, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Fabio Muleri, C.-Y. Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel Lawrence Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgró, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Fei Xie, and Silvia Zane
Subjects: Blazars, Active galaxies, Black holes, Relativistic jets, Spectropolarimetry, Polarimetry, Astrophysics, QB460-466
Abstract: We present multiwavelength polarization measurements of the luminous blazar Mrk 501 over a 14 month period. The 2–8 keV X-ray polarization was measured with the Imaging X-ray Polarimetry Explorer (IXPE) with six 100 ks observations spanning from 2022 March to 2023 April. Each IXPE observation was accompanied by simultaneous X-ray data from NuSTAR, Swift/XRT, and/or XMM-Newton. Complementary optical–infrared polarization measurements were also available in the B , V , R , I , and J bands, as were radio polarization measurements from 4.85 GHz to 225.5 GHz. Among the first five IXPE observations, we did not find significant variability in the X-ray polarization degree and angle with IXPE. However, the most recent sixth observation found an elevated polarization degree at >3 σ above the average of the other five observations. The optical and radio measurements show no apparent correlations with the X-ray polarization properties. Throughout the six IXPE observations, the X-ray polarization degree remained higher than, or similar to, the R -band optical polarization degree, which remained higher than the radio value. This is consistent with the energy-stratified shock scenario proposed to explain the first two IXPE observations, in which the polarized X-ray, optical, and radio emission arises from different regions.
Published: 2024
Full Text: View/download PDF

7. Analysis of Crab X-Ray Polarization Using Deeper Imaging X-Ray Polarimetry Explorer Observations

Author: Josephine Wong, Tsunefumi Mizuno, Niccoló Bucciantini, Roger W. Romani, Yi-Jung Yang, Kuan Liu, Wei Deng, Kazuho Goya, Fei Xie, Maura Pilia, Philip Kaaret, Martin C. Weisskopf, Stefano Silvestri, C.-Y. Ng, Chien-Ting Chen, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccoló Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Fabio Muleri, Michela Negro, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel Lawrence Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Andrea Possenti, Juri Poutanen, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Carmelo Sgró, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey Tsygankov, Roberto Turolla, Jacco Vink, Kinwah Wu, and Silvia Zane
Subjects: Pulsar wind nebulae, Pulsars, Polarimetry, X-ray astronomy, Astrophysics, QB460-466
Abstract: We present Crab X-ray polarization measurements using Imaging X-Ray Polarimetry Explorer (IXPE) data with a total exposure of 300 ks, three times more than the initial 2022 discovery paper. Polarization is detected in three times more pulsar phase bins, revealing an S-shaped +40° polarization angle sweep in the main pulse and >1 σ departures from the OPTIMA optical polarization in both pulses, suggesting different radiation mechanisms or sites for the polarized emission at the two wavebands. Our polarization map of the inner nebula reveals a toroidal magnetic field, as seen in prior IXPE analyses. Along the southern jet, the magnetic field orientation relative to the jet axis changes from perpendicular to parallel and the polarization degree decreases by ∼6%. These observations may be explained by kink instabilities along the jet or a collision with a dense, jet-deflecting medium at the tip. Using spectropolarimetric analysis, we find asymmetric polarization in the four quadrants of the inner nebula, as expected for a toroidal field geometry, and a spatial correlation between polarization degree and photon index.
Published: 2024
Full Text: View/download PDF

8. Gravitational Self-lensing of Fast Radio Bursts in Neutron Star Magnetospheres. I. The Model

Author: Simone Dall’Osso, Riccardo La Placa, Luigi Stella, Pavel Bakala, and Andrea Possenti
Subjects: Radio transient sources, Gravitational lensing, Magnetars, Radio pulsars, Astrophysics, QB460-466
Abstract: Fast radio bursts (FRBs) are cosmological subsecond bursts of coherent radio emission, whose source is still unknown. To date, the Galactic magnetar SGR 1935 + 2154 is the only astrophysical object known to emit radio bursts akin to FRBs, albeit less powerful, supporting suggestions that FRBs originate from magnetars. Many remarkable properties of FRBs—e.g., the dichotomy between repeaters and one-off sources, and their power-law energy distributions (with typical index ∼2–3)—are not well understood yet. Moreover, the huge radio power released by the most active repeaters is challenging even for the magnetic energy reservoir of magnetars. Here, we assume that FRBs originate from corotating hotspots anchored in neutron star (NS) magnetospheres and occasionally get amplified by large factors via gravitational self-lensing in the strong NS field. We evaluate the probability of amplification and show that: (i) a power-law energy distribution of events ∝ E ^−(2−3) is generally expected; (ii) all FRB sources may be regarded as repeating, their appearance as one-off sources or repeaters being determined by the critical dependence of the amplification probability on the emission geometry and source orientation relative to Earth; and (iii) the most active repeaters, in particular, correspond to extremely rare and finely tuned orientations (∼1 in 10 ^6 ), leading to large probabilities of amplification that make their bursts frequently detectable. At the same time, their power release appears enhanced, typically by factors ≳10, easing their energy budget problem.
Published: 2024
Full Text: View/download PDF

9. Timing of Millisecond Pulsars in NGC 6752. III. On the Presence of Nonluminous Matter in the Cluster’s Core

Author: A. Corongiu, A. Ridolfi, F. Abbate, M. Bailes, A. Possenti, M. Geyer, R. N. Manchester, M. Kramer, P. C. C. Freire, M. Burgay, S. Buchner, and F. Camilo
Subjects: Millisecond pulsars, Pulsars, Globular star clusters, Astrophysics, QB460-466
Abstract: Millisecond pulsars are subject to accelerations in globular clusters (GCs) that manifest themselves in both the first and second spin period time derivatives, and can be used to explore the mass distribution of the potentials they inhabit. Here we report on over 20 yr of pulsar timing observations of five millisecond radio pulsars in the core of the core-collapse GC NGC 6752 with the Parkes (Murriyang) and MeerKAT radio telescopes, which have allowed us to measure the proper motions, positions, and first and second time derivatives of the pulsars. The pulsar timing parameters indicate that all the pulsars in the core experience accelerations and jerks that can be explained only if an amount of nonluminous mass of at least 2.56 × 10 ^3 M _⊙ is present in the core of NGC 6752. On the other hand, our studies highly disfavor the presence of an intermediate-mass black hole at the center of the cluster, with a mass equal to or greater than ∼3000 M _⊙ .
Published: 2024
Full Text: View/download PDF

10. Observations of Low and Intermediate Spectral Peak Blazars with the Imaging X-Ray Polarimetry Explorer

Author: Herman L. Marshall, Ioannis Liodakis, Alan P. Marscher, Niccolò Di Lalla, Svetlana G. Jorstad, Dawoon E. Kim, Riccardo Middei, Michela Negro, Nicola Omodei, Abel L. Peirson, Matteo Perri, Simonetta Puccetti, Marco Laurenti, Iván Agudo, Giacomo Bonnoli, Andrei V. Berdyugin, Elisabetta Cavazzuti, Nicole Rodriguez Cavero, Immacolata Donnarumma, Laura Di Gesu, Jenni Jormanainen, Henric Krawczynski, Elina Lindfors, Greg Madjeski, Frédéric Marin, Francesco Massaro, Luigi Pacciani, Juri Poutanen, Fabrizio Tavecchio, Pouya M. Kouch, Francisco José Aceituno, Maria I. Bernardos, Víctor Casanova, Maya García-Comas, Beatriz Agís-González, César Husillos, Alessandro Marchini, Alfredo Sota, Dmitry Blinov, Ioakeim G. Bourbah, Sebastian Kielhmann, Evangelos Kontopodis, Nikos Mandarakas, Stylianos Romanopoulos, Raphael Skalidis, Anna Vervelaki, George A. Borman, Evgenia N. Kopatskaya, Elena G. Larionova, Daria A. Morozova, Sergey S. Savchenko, Andrey A. Vasilyev, Alexey V. Zhovtan, Carolina Casadio, Juan Escudero, Joana Kramer, Ioannis Myserlis, Efthalia Trainou, Ryo Imazawa, Mahito Sasada, Yasushi Fukazawa, Koji S. Kawabata, Makoto Uemura, Tsunefumi Mizuno, Tatsuya Nakaoka, Hiroshi Akitaya, Joseph R. Masiero, Dimitri Mawet, Georgia V. Panopoulou, Samaporn Tinyanont, Masato Kagitani, Vadim Kravtsov, Takeshi Sakanoi, Matthew Dattolo, Mark Gurwell, Garrett Keating, Ramprasad Rao, Whee Yeon Cheong, Hyeon-Woo Jeong, Sincheol Kang, Sang-Hyun Kim, Sang-Sung Lee, Emmanouil Angelakis, Alexander Kraus, Antonio Hales, Seiji Kameno, Ruediger Kneissl, Hugo Messias, Hiroshi Nagai, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Chen-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Alessandro Di Marco, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Philip Kaaret, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Fabio La Monaca, Luca Latronico, Simone Maldera, Alberto Manfreda, Andrea Marinucci, Giorgio Matt, Ikuyuki Mitsuishi, Fabio Muleri, C.-Y. Ng, Stephen L. O’Dell, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, Fei Xie, and Silvia Zane
Subjects: X-ray astronomy, Polarimetry, Spectropolarimetry, Radio loud quasars, X-ray quasars, Blazars, Astrophysics, QB460-466
Abstract: We present X-ray polarimetry observations from the Imaging X-ray Polarimetry Explorer (IXPE) of three low spectral peak and one intermediate spectral peak blazars, namely 3C 273, 3C 279, 3C 454.3, and S5 0716+714. For none of these objects was IXPE able to detect X-ray polarization at the 3 σ level. However, we placed upper limits on the polarization degree at ∼10%–30%. The undetected polarizations favor models where the X-ray band is dominated by unpolarized photons upscattered by relativistic electrons in the jets of blazars, although hadronic models are not completely eliminated. We discuss the X-ray polarization upper limits in the context of our contemporaneous multiwavelength polarization campaigns.
Published: 2024
Full Text: View/download PDF

11. The NANOGrav 15 yr Data Set: Chromatic Gaussian Process Noise Models for Six Pulsars

Author: Bjorn Larsen, Chiara M. F. Mingarelli, Jeffrey S. Hazboun, Aurélien Chalumeau, Deborah C. Good, Joseph Simon, Gabriella Agazie, Akash Anumarlapudi, Anne M. Archibald, Zaven Arzoumanian, Paul T. Baker, Paul R. Brook, H. Thankful Cromartie, Kathryn Crowter, Megan E. DeCesar, Paul B. Demorest, Timothy Dolch, Elizabeth C. Ferrara, William Fiore, Emmanuel Fonseca, Gabriel E. Freedman, Nate Garver-Daniels, Peter A. Gentile, Joseph Glaser, Ross J. Jennings, Megan L. Jones, David L. Kaplan, Matthew Kerr, Michael T. Lam, Duncan R. Lorimer, Jing Luo, Ryan S. Lynch, Alexander McEwen, Maura A. McLaughlin, Natasha McMann, Bradley W. Meyers, Cherry Ng, David J. Nice, Timothy T. Pennucci, Benetge B. P. Perera, Nihan S. Pol, Henri A. Radovan, Scott M. Ransom, Paul S. Ray, Ann Schmiedekamp, Carl Schmiedekamp, Brent J. Shapiro-Albert, Ingrid H. Stairs, Kevin Stovall, Abhimanyu Susobhanan, Joseph K. Swiggum, Haley M. Wahl, David J. Champion, Ismaël Cognard, Lucas Guillemot, Huanchen Hu, Michael J. Keith, Kuo Liu, James W. McKee, Aditya Parthasarathy, Delphine Perrodin, Andrea Possenti, Golam M. Shaifullah, and Gilles Theureau
Subjects: Millisecond pulsars, Gravitational wave astronomy, Gravitational wave detectors, Pulsar timing method, Interstellar medium, Astronomy data analysis, Astrophysics, QB460-466
Abstract: Pulsar timing arrays (PTAs) are designed to detect low-frequency gravitational waves (GWs). GWs induce achromatic signals in PTA data, meaning that the timing delays do not depend on radio frequency. However, pulse arrival times are also affected by radio-frequency-dependent “chromatic” noise from sources such as dispersion measure (DM) and scattering delay variations. Furthermore, the characterization of GW signals may be influenced by the choice of chromatic noise model for each pulsar. To better understand this effect, we assess if and how different chromatic noise models affect the achromatic noise properties in each pulsar. The models we compare include existing DM models used by the North American Nanohertz Observatory for Gravitational waves (NANOGrav) and noise models used for the European PTA Data Release 2 (EPTA DR2). We perform this comparison using a subsample of six pulsars from the NANOGrav 15 yr data set, selecting the same six pulsars as from the EPTA DR2 six-pulsar data set. We find that the choice of chromatic noise model noticeably affects the achromatic noise properties of several pulsars. This is most dramatic for PSR J1713+0747, where the amplitude of its achromatic red noise lowers from ${\mathrm{log}}_{10}{A}_{\mathrm{RN}}=-{14.1}_{-0.1}^{+0.1}$ to $-{14.7}_{-0.5}^{+0.3}$ , and the spectral index broadens from ${\gamma }_{\mathrm{RN}}={2.6}_{-0.4}^{+0.5}$ to ${\gamma }_{\mathrm{RN}}={3.5}_{-0.9}^{+1.2}$ . We also compare each pulsar's noise properties with those inferred from the EPTA DR2, using the same models. From the discrepancies, we identify potential areas where the noise models could be improved. These results highlight the potential for custom chromatic noise models to improve PTA sensitivity to GWs.
Published: 2024
Full Text: View/download PDF

12. Tracking the X-Ray Polarization of the Black Hole Transient Swift J1727.8–1613 during a State Transition

Author: Adam Ingram, Niek Bollemeijer, Alexandra Veledina, Michal Dovčiak, Juri Poutanen, Elise Egron, Thomas D. Russell, Sergei A. Trushkin, Michela Negro, Ajay Ratheesh, Fiamma Capitanio, Riley Connors, Joseph Neilsen, Alexander Kraus, Maria Noemi Iacolina, Alberto Pellizzoni, Maura Pilia, Francesco Carotenuto, Giorgio Matt, Guglielmo Mastroserio, Philip Kaaret, Stefano Bianchi, Javier A. García, Matteo Bachetti, Kinwah Wu, Enrico Costa, Melissa Ewing, Vadim Kravtsov, Henric Krawczynski, Vladislav Loktev, Andrea Marinucci, Lorenzo Marra, Romana Mikušincová, Edward Nathan, Maxime Parra, Pierre-Olivier Petrucci, Simona Righini, Paolo Soffitta, James F. Steiner, Jiří Svoboda, Francesco Tombesi, Stefano Tugliani, Francesco Ursini, Yi-Jung Yang, Silvia Zane, Wenda Zhang, Iván Agudo, Lucio A. Antonelli, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Victor Doroshenko, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, Chi-Yung Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Fei Xie, and IXPE Collaboration
Subjects: Accretion, X-ray astronomy, Low-mass x-ray binary stars, Polarimetry, Astrophysical black holes, Astrophysics, QB460-466
Abstract: We report on an observational campaign on the bright black hole (BH) X-ray binary Swift J1727.8–1613 centered around five observations by the Imaging X-ray Polarimetry Explorer. These observations track for the first time the evolution of the X-ray polarization of a BH X-ray binary across a hard to soft state transition. The 2–8 keV polarization degree decreased from ∼4% to ∼3% across the five observations, but the polarization angle remained oriented in the north–south direction throughout. Based on observations with the Australia Telescope Compact Array, we find that the intrinsic 7.25 GHz radio polarization aligns with the X-ray polarization. Assuming the radio polarization aligns with the jet direction (which can be tested in the future with higher-spatial-resolution images of the jet), our results imply that the X-ray corona is extended in the disk plane, rather than along the jet axis, for the entire hard intermediate state. This in turn implies that the long (≳10 ms) soft lags that we measure with the Neutron star Interior Composition ExploreR are dominated by processes other than pure light-crossing delays. Moreover, we find that the evolution of the soft lag amplitude with spectral state does not follow the trend seen for other sources, implying that Swift J1727.8–1613 is a member of a hitherto undersampled subpopulation.
Published: 2024
Full Text: View/download PDF

13. Comparing Recent Pulsar Timing Array Results on the Nanohertz Stochastic Gravitational-wave Background

Author: G. Agazie, J. Antoniadis, A. Anumarlapudi, A. M. Archibald, P. Arumugam, S. Arumugam, Z. Arzoumanian, J. Askew, S. Babak, M. Bagchi, M. Bailes, A.-S. Bak Nielsen, P. T. Baker, C. G. Bassa, A. Bathula, B. Bécsy, A. Berthereau, N. D. R. Bhat, L. Blecha, M. Bonetti, E. Bortolas, A. Brazier, P. R. Brook, M. Burgay, S. Burke-Spolaor, R. Burnette, R. N. Caballero, A. Cameron, R. Case, A. Chalumeau, D. J. Champion, S. Chanlaridis, M. Charisi, S. Chatterjee, K. Chatziioannou, B. D. Cheeseboro, S. Chen, Z.-C. Chen, I. Cognard, T. Cohen, W. A. Coles, J. M. Cordes, N. J. Cornish, F. Crawford, H. T. Cromartie, K. Crowter, M. Curyło, C. J. Cutler, S. Dai, S. Dandapat, D. Deb, M. E. DeCesar, D. DeGan, P. B. Demorest, H. Deng, S. Desai, G. Desvignes, L. Dey, N. Dhanda-Batra, V. Di Marco, T. Dolch, B. Drachler, C. Dwivedi, J. A. Ellis, M. Falxa, Y. Feng, R. D. Ferdman, E. C. Ferrara, W. Fiore, E. Fonseca, A. Franchini, G. E. Freedman, J. R. Gair, N. Garver-Daniels, P. A. Gentile, K. A. Gersbach, J. Glaser, D. C. Good, B. Goncharov, A. Gopakumar, E. Graikou, J.-M. Griessmeier, L. Guillemot, K. Gültekin, Y. J. Guo, Y. Gupta, K. Grunthal, J. S. Hazboun, S. Hisano, G. B. Hobbs, S. Hourihane, H. Hu, F. Iraci, K. Islo, D. Izquierdo-Villalba, J. Jang, J. Jawor, G. H. Janssen, R. J. Jennings, A. Jessner, A. D. Johnson, M. L. Jones, B. C. Joshi, A. R. Kaiser, D. L. Kaplan, A. Kapur, F. Kareem, R. Karuppusamy, E. F. Keane, M. J. Keith, L. Z. Kelley, M. Kerr, J. S. Key, D. Kharbanda, T. Kikunaga, T. C. Klein, N. Kolhe, M. Kramer, M. A. Krishnakumar, A. Kulkarni, N. Laal, K. Lackeos, M. T. Lam, W. G. Lamb, B. B. Larsen, T. J. W. Lazio, K. J. Lee, Y. Levin, N. Lewandowska, T. B. Littenberg, K. Liu, T. Liu, Y. Liu, A. Lommen, D. R. Lorimer, M. E. Lower, J. Luo, R. Luo, R. S. Lynch, A. G. Lyne, C.-P. Ma, Y. Maan, D. R. Madison, R. A. Main, R. N. Manchester, R. Mandow, M. A. Mattson, A. McEwen, J. W. McKee, M. A. McLaughlin, N. McMann, B. W. Meyers, P. M. Meyers, M. B. Mickaliger, M. Miles, C. M. F. Mingarelli, A. Mitridate, P. Natarajan, R. S. Nathan, C. Ng, D. J. Nice, I. C. Niţu, K. Nobleson, S. K. Ocker, K. D. Olum, S. Osłowski, A. K. Paladi, A. Parthasarathy, T. T. Pennucci, B. B. P. Perera, D. Perrodin, A. Petiteau, P. Petrov, N. S. Pol, N. K. Porayko, A. Possenti, T. Prabu, H. Quelquejay Leclere, H. A. Radovan, P. Rana, S. M. Ransom, P. S. Ray, D. J. Reardon, A. F. Rogers, J. D. Romano, C. J. Russell, A. Samajdar, S. A. Sanidas, S. C. Sardesai, A. Schmiedekamp, C. Schmiedekamp, K. Schmitz, L. Schult, A. Sesana, G. Shaifullah, R. M. Shannon, B. J. Shapiro-Albert, X. Siemens, J. Simon, J. Singha, M. S. Siwek, L. Speri, R. Spiewak, A. Srivastava, I. H. Stairs, B. W. Stappers, D. R. Stinebring, K. Stovall, J. P. Sun, M. Surnis, S. C. Susarla, A. Susobhanan, J. K. Swiggum, K. Takahashi, P. Tarafdar, J. Taylor, S. R. Taylor, G. Theureau, E. Thrane, N. Thyagarajan, C. Tiburzi, L. Toomey, J. E. Turner, C. Unal, M. Vallisneri, E. van der Wateren, R. van Haasteren, A. Vecchio, V. Venkatraman Krishnan, J. P. W. Verbiest, S. J. Vigeland, H. M. Wahl, S. Wang, Q. Wang, C. A. Witt, J. Wang, L. Wang, K. E. Wayt, Z. Wu, O. Young, L. Zhang, S. Zhang, X.-J. Zhu, A. Zic, and The International Pulsar Timing Array Collaboration
Subjects: Gravitational waves, Pulsars, Astrophysics, QB460-466
Abstract: The Australian, Chinese, European, Indian, and North American pulsar timing array (PTA) collaborations recently reported, at varying levels, evidence for the presence of a nanohertz gravitational-wave background (GWB). Given that each PTA made different choices in modeling their data, we perform a comparison of the GWB and individual pulsar noise parameters across the results reported from the PTAs that constitute the International Pulsar Timing Array (IPTA). We show that despite making different modeling choices, there is no significant difference in the GWB parameters that are measured by the different PTAs, agreeing within 1 σ . The pulsar noise parameters are also consistent between different PTAs for the majority of the pulsars included in these analyses. We bridge the differences in modeling choices by adopting a standardized noise model for all pulsars and PTAs, finding that under this model there is a reduction in the tension in the pulsar noise parameters. As part of this reanalysis, we “extended” each PTA’s data set by adding extra pulsars that were not timed by that PTA. Under these extensions, we find better constraints on the GWB amplitude and a higher signal-to-noise ratio for the Hellings–Downs correlations. These extensions serve as a prelude to the benefits offered by a full combination of data across all pulsars in the IPTA, i.e., the IPTA’s Data Release 3, which will involve not just adding in additional pulsars but also including data from all three PTAs where any given pulsar is timed by more than a single PTA.
Published: 2024
Full Text: View/download PDF

14. An X-Ray and Radio View of the 2022 Reactivation of the Magnetar SGR J1935+2154

Author: A. Y. Ibrahim, A. Borghese, F. Coti Zelati, E. Parent, A. Marino, O. S. Ould-Boukattine, N. Rea, S. Ascenzi, D. P. Pacholski, S. Mereghetti, G. L. Israel, A. Tiengo, A. Possenti, M. Burgay, R. Turolla, S. Zane, P. Esposito, D. Götz, S. Campana, F. Kirsten, M. P. Gawroński, and J. W. T. Hessels
Subjects: Neutron stars, Magnetars, Astrophysics, QB460-466
Abstract: Recently, the Galactic magnetar SGR J1935+2154 has garnered attention due to its emission of an extremely luminous radio burst, reminiscent of fast radio bursts (FRBs). SGR J1935+2154 is one of the most active magnetars, displaying flaring events nearly every year, including outbursts as well as short and intermediate bursts. Here, we present our results on the properties of the persistent and bursting X-ray emission from SGR J1935+2154 during the initial weeks following its outburst on 2022 October 10. The source was observed with XMM-Newton and NuSTAR (quasi-)simultaneously during two epochs, separated by ∼5 days. The persistent emission spectrum is well described by an absorbed blackbody plus power-law model up to an energy of ∼25 keV. No significant changes were observed in the blackbody temperature ( kT _BB ∼ 0.4 keV) and emitting radius ( R _BB ∼ 1.9 km) between the two epochs. However, we observed a slight variation in the power-law parameters. Moreover, we detected X-ray pulsations in all the data sets and derived a spin-period derivative of $\dot{P}=5.52(5)\times {10}^{-11}$ s s ^−1 . This is 3.8 times larger than the value measured after the first recorded outburst in 2014. Additionally, we performed quasi-simultaneous radio observations using three 25–32 m class radio telescopes for a total of 92.5 hr to search for FRB-like radio bursts and pulsed emission. However, our analysis did not reveal any radio bursts or periodic emission.
Published: 2024
Full Text: View/download PDF

15. X-Ray Polarization of the Black Hole X-Ray Binary 4U 1630–47 Challenges the Standard Thin Accretion Disk Scenario

Author: Ajay Ratheesh, Michal Dovčiak, Henric Krawczynski, Jakub Podgorný, Lorenzo Marra, Alexandra Veledina, Valery F. Suleimanov, Nicole Rodriguez Cavero, James F. Steiner, Jiří Svoboda, Andrea Marinucci, Stefano Bianchi, Michela Negro, Giorgio Matt, Francesco Tombesi, Juri Poutanen, Adam Ingram, Roberto Taverna, Andrew West, Vladimir Karas, Francesco Ursini, Paolo Soffitta, Fiamma Capitanio, Domenico Viscolo, Alberto Manfreda, Fabio Muleri, Maxime Parra, Banafsheh Beheshtipour, Sohee Chun, Nicolò Cibrario, Niccolò Di Lalla, Sergio Fabiani, Kun Hu, Philip Kaaret, Vladislav Loktev, Romana Mikušincová, Tsunefumi Mizuno, Nicola Omodei, Pierre-Olivier Petrucci, Simonetta Puccetti, John Rankin, Silvia Zane, Sixuan Zhang, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Alessandro Di Marco, Immacolata Donnarumma, Victor Doroshenko, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Frédéric Marin, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Ikuyuki Mitsuishi, Stephen C.-Y. Ng, Stephen L. O’Dell, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Maura Pilia, Andrea Possenti, Brian D. Ramsey, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, and Fei Xie
Subjects: Polarimetry, X-ray astronomy, Stellar mass black holes, Accretion, Astrophysics, QB460-466
Abstract: A large energy-dependent X-ray polarization degree is detected by the Imaging X-ray Polarimetry Explorer (IXPE) in the high-soft emission state of the black hole X-ray binary 4U 1630–47. The highly significant detection (at ≈50 σ confidence level) of an unexpectedly high polarization, rising from ∼6% at 2 keV to ∼10% at 8 keV, cannot be easily reconciled with standard models of thin accretion disks. In this work, we compare the predictions of different theoretical models with the IXPE data and conclude that the observed polarization properties are compatible with a scenario in which matter accretes onto the black hole through a thin disk covered by a partially ionized atmosphere flowing away at mildly relativistic velocities.
Published: 2024
Full Text: View/download PDF

16. X-Ray Polarimetry of the Dipping Accreting Neutron Star 4U 1624–49

Author: M. Lynne Saade, Philip Kaaret, Andrea Gnarini, Juri Poutanen, Francesco Ursini, Stefano Bianchi, Anna Bobrikova, Fabio La Monaca, Alessandro Di Marco, Fiamma Capitanio, Alexandra Veledina, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. García, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, Michela Negro, Chi-Yung Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, Fei Xie, and Silvia Zane
Subjects: X-ray binary stars, Neutron stars, X-ray astronomy, Polarimetry, Astrophysics, QB460-466
Abstract: We present the first X-ray polarimetric study of the dipping accreting neutron star 4U 1624−49 with the Imaging X-ray Polarimetry Explorer. We report a detection of polarization in the nondip time intervals with a confidence level of 99.99%. We find an average polarization degree (PD) of 3.1% ± 0.7% and a polarization angle of 81° ± 6° east of north in the 2–8 keV band. We report an upper limit on the PD of 22% during the X-ray dips with 95% confidence. The PD increases with energy, reaching from 3.0% ± 0.9% in the 4–6 keV band to 6% ± 2% in the 6–8 keV band. This indicates the polarization likely arises from Comptonization. The high PD observed is unlikely to be produced by Comptonization in the boundary layer or spreading layer alone. It can be produced by the addition of an extended geometrically thin slab corona covering part of the accretion disk, as assumed in previous models of dippers, and/or a reflection component from the accretion disk.
Published: 2024
Full Text: View/download PDF

17. Detection of X-Ray Polarization from the Blazar 1ES 1959+650 with the Imaging X-Ray Polarimetry Explorer

Author: Manel Errando, Ioannis Liodakis, Alan P. Marscher, Herman L. Marshall, Riccardo Middei, Michela Negro, Abel Lawrence Peirson, Matteo Perri, Simonetta Puccetti, Pazit L. Rabinowitz, Iván Agudo, Svetlana G. Jorstad, Sergey S. Savchenko, Dmitry Blinov, Ioakeim G. Bourbah, Sebastian Kiehlmann, Evangelos Kontopodis, Nikos Mandarakas, Stylianos Romanopoulos, Raphael Skalidis, Anna Vervelaki, Francisco José Aceituno, Maria I. Bernardos, Giacomo Bonnoli, Víctor Casanova, Beatriz Agís-González, César Husillos, Alessandro Marchini, Alfredo Sota, Pouya M. Kouch, Elina Lindfors, Carolina Casadio, Juan Escudero, Ioannis Myserlis, Ryo Imazawa, Mahito Sasada, Yasushi Fukazawa, Koji S. Kawabata, Makoto Uemura, Tsunefumi Mizuno, Tatsuya Nakaoka, Hiroshi Akitaya, Mark Gurwell, Garrett K. Keating, Ramprasad Rao, Adam Ingram, Francesco Massaro, Lucio Angelo Antonelli, Raffaella Bonino, Elisabetta Cavazzuti, Chien-Ting Chen, Nicolò Cibrario, Stefano Ciprini, Alessandra De Rosa, Laura Di Gesu, Federico Di Pierro, Immacolata Donnarumma, Steven R. Ehlert, Francesco Fenu, Ephraim Gau, Vladimir Karas, Dawoon E. Kim, Henric Krawczynski, Marco Laurenti, Lindsey Lisalda, Rubén López-Coto, Grzegorz Madejski, Frédéric Marin, Andrea Marinucci, Ikuyuki Mitsuishi, Fabio Muleri, Luigi Pacciani, Alessandro Paggi, Pierre-Olivier Petrucci, Nicole Rodriguez Cavero, Roger W. Romani, Fabrizio Tavecchio, Stefano Tugliani, Kinwah Wu, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Enrico Costa, Ettore Del Monte, Niccolò Di Lalla, Alessandro Di Marco, Victor Doroshenko, Michal Dovčiak, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Philip Kaaret, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Fabio La Monaca, Luca Latronico, Simone Maldera, Alberto Manfreda, Giorgio Matt, C.-Y. Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Melissa Pesce-Rollins, Maura Pilia, Andrea Possenti, Juri Poutanen, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Carmelo Sgrò, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Fei Xie, and Silvia Zane
Subjects: Relativistic jets, X-ray active galactic nuclei, Active galactic nuclei, Blazars, Polarimetry, Spectropolarimetry, Astrophysics, QB460-466
Abstract: Observations of linear polarization in the 2–8 keV energy range with the Imaging X-ray Polarimetry Explorer (IXPE) explore the magnetic field geometry and dynamics of the regions generating nonthermal radiation in relativistic jets of blazars. These jets, particularly in blazars whose spectral energy distribution peaks at X-ray energies, emit X-rays via synchrotron radiation from high-energy particles within the jet. IXPE observations of the X-ray-selected BL Lac–type blazar 1ES 1959+650 on 2022 May 3–4 showed a significant linear polarization degree of Π _x = 8.0% ± 2.3% at an electric-vector position angle ψ _x = 123° ± 8°. However, on 2022 June 9–12, only an upper limit of Π _x ≤ 5.1% could be derived (at the 99% confidence level). The degree of optical polarization at that time, Π _O ∼ 5%, is comparable to the X-ray measurement. We investigate possible scenarios for these findings, including temporal and geometrical depolarization effects. Unlike some other X-ray-selected BL Lac objects, there is no significant chromatic dependence of the measured polarization in 1ES 1959+650, and its low X-ray polarization may be attributed to turbulence in the jet flow with dynamical timescales shorter than 1 day.
Published: 2024
Full Text: View/download PDF

18. First Detection of Polarization in X-Rays for PSR B0540-69 and Its Nebula

Author: Fei Xie, Josephine Wong, Fabio La Monaca, Roger W. Romani, Jeremy Heyl, Philip Kaaret, Alessandro Di Marco, Niccolò Bucciantini, Kuan Liu, Chi-Yung Ng, Niccolò Di Lalla, Martin C. Weisskopf, Enrico Costa, Paolo Soffitta, Fabio Muleri, Matteo Bachetti, Maura Pilia, John Rankin, Sergio Fabiani, Iván Agudo, Lucio A. Antonelli, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Michela Negro, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Andrea Possenti, Juri Poutanen, Simonetta Puccetti, Brian D. Ramsey, Ajay Ratheesh, Oliver J. Roberts, Carmelo Sgrò, Patrick Slane, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Kinwah Wu, Silvia Zane, IXPE Collaboration, Zorawar Wadiasingh, Wynn C. G. Ho, Alice K. Harding, Keith C. Gendreau, and Zaven Arzoumanian
Subjects: Pulsars, Pulsar wind nebulae, Polarimetry, Astrophysics, QB460-466
Abstract: We report on X-ray polarization measurements of the extragalactic Crab-like PSR B0540-69 and its Pulsar Wind Nebula (PWN) in the Large Magellanic Cloud, using a ∼850 ks Imaging X-ray Polarimetry Explorer (IXPE) exposure. The PWN is unresolved by IXPE. No statistically significant polarization is detected for the image-averaged data, giving a 99% confidence polarization upper limit (MDP _99 ) of 5.3% in the 2–8 keV energy range. However, a phase-resolved analysis detects polarization for both the nebula and pulsar in the 4–6 keV energy range. For the PWN defined as the off-pulse phases, the polarization degree (PD) of (24.5 ± 5.3)% and polarization angle (PA) of (78.1 ± 6.2)° is detected at 4.6 σ significance level, consistent with the PA observed in the optical band. In a single on-pulse window, a hint of polarization is measured at 3.8 σ with PD of (50.0 ± 13.1)% and PA of (6.2 ± 7.4)°. A “simultaneous” PSR/PWN analysis finds two bins at the edges of the pulse exceeding 3 σ PD significance, with PD of (68 ± 20)% and (62 ± 20)%; intervening bins at 2–3 σ significance have lower PD, hinting at additional polarization structure.
Published: 2024
Full Text: View/download PDF

19. Discovery of X-Ray Polarization from the Black Hole Transient Swift J1727.8−1613

Author: Alexandra Veledina, Fabio Muleri, Michal Dovčiak, Juri Poutanen, Ajay Ratheesh, Fiamma Capitanio, Giorgio Matt, Paolo Soffitta, Allyn F. Tennant, Michela Negro, Philip Kaaret, Enrico Costa, Adam Ingram, Jiří Svoboda, Henric Krawczynski, Stefano Bianchi, James F. Steiner, Javier A. García, Vadim Kravtsov, Anagha P. Nitindala, Melissa Ewing, Guglielmo Mastroserio, Andrea Marinucci, Francesco Ursini, Francesco Tombesi, Sergey S. Tsygankov, Yi-Jung Yang, Martin C. Weisskopf, Sergei A. Trushkin, Elise Egron, Maria Noemi Iacolina, Maura Pilia, Lorenzo Marra, Romana Mikušincová, Edward Nathan, Maxime Parra, Pierre-Olivier Petrucci, Jakub Podgorný, Stefano Tugliani, Silvia Zane, Wenda Zhang, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Victor Doroshenko, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Chi-Yung Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Nicholas E. Thomas, Alessio Trois, Roberto Turolla, Jacco Vink, Kinwah Wu, and Fei Xie
Subjects: Accretion, X-ray astronomy, Low-mass x-ray binary stars, Polarimetry, Astrophysical black holes, Astrophysics, QB460-466
Abstract: We report the first detection of the X-ray polarization of the bright transient Swift J1727.8−1613 with the Imaging X-ray Polarimetry Explorer. The observation was performed at the beginning of the 2023 discovery outburst, when the source resided in the bright hard state. We find a time- and energy-averaged polarization degree of 4.1% ± 0.2% and a polarization angle of 2.°2 ± 1.°3 (errors at 68% confidence level; this translates to ∼20 σ significance of the polarization detection). This finding suggests that the hot corona emitting the bulk of the detected X-rays is elongated, rather than spherical. The X-ray polarization angle is consistent with that found in submillimeter wavelengths. Since the submillimeter polarization was found to be aligned with the jet direction in other X-ray binaries, this indicates that the corona is elongated orthogonal to the jet.
Published: 2023
Full Text: View/download PDF

20. The First X-Ray Polarization Observation of the Black Hole X-Ray Binary 4U 1630–47 in the Steep Power-law State

Author: Nicole Rodriguez Cavero, Lorenzo Marra, Henric Krawczynski, Michal Dovčiak, Stefano Bianchi, James F. Steiner, Jiri Svoboda, Fiamma Capitanio, Giorgio Matt, Michela Negro, Adam Ingram, Alexandra Veledina, Roberto Taverna, Vladimir Karas, Francesco Ursini, Jakub Podgorný, Ajay Ratheesh, Valery Suleimanov, Romana Mikušincová, Silvia Zane, Philip Kaaret, Fabio Muleri, Juri Poutanen, Christian Malacaria, Pierre-Olivier Petrucci, Ephraim Gau, Kun Hu, Sohee Chun, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Victor Doroshenko, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. García, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Chi-Yung Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Gloria Spandre, Paolo Soffitta, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, and Fei Xie
Subjects: X-ray astronomy, Polarimetry, Stellar mass black holes, High energy astrophysics, Astrophysics, QB460-466
Abstract: The Imaging X-ray Polarimetry Explorer (IXPE) observed the black hole X-ray binary 4U 1630–47 in the steep power-law (or very high) state. The observations reveal a linear polarization degree of the 2–8 keV X-rays of 6.8% ± 0.2% at a position angle of 21.°3 ± 0.°9 east of north (all errors at 1 σ confidence level). Whereas the polarization degree increases with energy, the polarization angle stays constant within the accuracy of our measurements. We compare the polarization of the source in the steep power-law state with the previous IXPE measurement of the source in the high soft state. We find that, even though the source flux and spectral shape are significantly different between the high soft state and the steep power-law state, their polarization signatures are similar. Assuming that the polarization of both the thermal and power-law emission components are constant over time, we estimate the power-law component polarization to be 6.8%–7.0% and note that the polarization angle of the thermal and power-law components must be approximately aligned. We discuss the implications for the origin of the power-law component and the properties of the emitting plasma.
Published: 2023
Full Text: View/download PDF

21. IXPE and Multiwavelength Observations of Blazar PG 1553+113 Reveal an Orphan Optical Polarization Swing

Author: Riccardo Middei, Matteo Perri, Simonetta Puccetti, Ioannis Liodakis, Laura Di Gesu, Alan P. Marscher, Nicole Rodriguez Cavero, Fabrizio Tavecchio, Immacolata Donnarumma, Marco Laurenti, Svetlana G. Jorstad, Iván Agudo, Herman L. Marshall, Luigi Pacciani, Dawoon E. Kim, Francisco José Aceituno, Giacomo Bonnoli, Víctor Casanova, Beatriz Agís-González, Alfredo Sota, Carolina Casadio, Juan Escudero, Ioannis Myserlis, Albrecht Sievers, Pouya M. Kouch, Elina Lindfors, Mark Gurwell, Garrett K. Keating, Ramprasad Rao, Sincheol Kang, Sang-Sung Lee, Sang-Hyun Kim, Whee Yeon Cheong, Hyeon-Woo Jeong, Emmanouil Angelakis, Alexander Kraus, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Niccolò Di Lalla, Alessandro Di Marco, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. García, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Philip Kaaret, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, Michela Negro, Chi-Yung Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Juri Poutanen, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, Fei Xie, and Silvia Zane
Subjects: BL Lacertae objects, Spectropolarimetry, Polarimetry, Active galactic nuclei, Jets, X-ray active galactic nuclei, Astrophysics, QB460-466
Abstract: The lower-energy peak of the spectral energy distribution of blazars has commonly been ascribed to synchrotron radiation from relativistic particles in the jets. Despite the consensus regarding jet emission processes, the particle acceleration mechanism is still debated. Here, we present the first X-ray polarization observations of PG 1553+113, a high-synchrotron-peak blazar observed by the Imaging X-ray Polarimetry Explorer (IXPE). We detect an X-ray polarization degree of (10 ± 2)% along an electric-vector position angle of ψ _X = 86° ± 8°. At the same time, the radio and optical polarization degrees are lower by a factor of ∼3. During our IXPE pointing, we observed the first orphan optical polarization swing of the IXPE era, as the optical angle of PG 1553+113 underwent a smooth monotonic rotation by about 125°, with a rate of ∼17° day ^–1 . We do not find evidence of a similar rotation in either radio or X-rays, which suggests that the X-ray and optically emitting regions are separate or, at most, partially cospatial. Our spectropolarimetric results provide further evidence that the steady-state X-ray emission in blazars originates in a shock-accelerated and energy-stratified electron population.
Published: 2023
Full Text: View/download PDF

22. First Detection of X-Ray Polarization from the Accreting Neutron Star 4U 1820−303

Author: Alessandro Di Marco, Fabio La Monaca, Juri Poutanen, Thomas D. Russell, Alessio Anitra, Ruben Farinelli, Guglielmo Mastroserio, Fabio Muleri, Fei Xie, Matteo Bachetti, Luciano Burderi, Francesco Carotenuto, Melania Del Santo, Tiziana Di Salvo, Michal Dovčiak, Andrea Gnarini, Rosario Iaria, Jari J. E. Kajava, Kuan Liu, Riccardo Middei, Stephen L. O’Dell, Maura Pilia, John Rankin, Andrea Sanna, Jakob van den Eijnden, Martin C. Weisskopf, Anna Bobrikova, Fiamma Capitanio, Enrico Costa, Philip Kaaret, Alessio Marino, Paolo Soffitta, Francesco Ursini, Filippo Ambrosino, Massimo Cocchi, Sergio Fabiani, Herman L. Marshall, Giorgio Matt, Sara Elisa Motta, Alessandro Papitto, Luigi Stella, Antonella Tarana, Silvia Zane, Iván Agudo, Lucio A. Antonelli, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Immacolata Donnarumma, Victor Doroshenko, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Francesco Massaro, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Michela Negro, Chi-Yung Ng, Nicola Omodei, Chiara Oppedisano, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Kinwah Wu, and IXPE Collaboration
Subjects: Low-mass x-ray binary stars, Neutron stars, Polarimetry, Spectropolarimetry, Stellar accretion disks, Astrophysics, QB460-466
Abstract: This paper reports the first detection of polarization in the X-rays for atoll-source 4U 1820−303, obtained with the Imaging X-ray Polarimetry Explorer (IXPE) at 99.999% confidence level (CL). Simultaneous polarimetric measurements were also performed in the radio with the Australia Telescope Compact Array. The IXPE observations of 4U 1820−303 were coordinated with Swift X-ray Telescope, Neutron Star Interior Composition Explorer, and Nuclear Spectroscopic Telescope Array aiming to obtain an accurate X-ray spectral model covering a broad energy interval. The source shows a significant polarization above 4 keV, with a polarization degree of 2.0% ± 0.5% and a polarization angle of −55° ± 7° in the 4–7 keV energy range, and a polarization degree of 10% ± 2% and a polarization angle of −67° ± 7° in the 7–8 keV energy bin. This polarization also shows a clear energy trend with polarization degree increasing with energy and a hint for a position-angle change of ≃90° at 96% CL around 4 keV. The spectro-polarimetric fit indicates that the accretion disk is polarized orthogonally to the hard spectral component, which is presumably produced in the boundary/spreading layer. We do not detect linear polarization from the radio counterpart, with a 3 σ upper limit of 50% at 7.25 GHz.
Published: 2023
Full Text: View/download PDF

23. X-Ray Polarization of BL Lacertae in Outburst

Author: Abel L. Peirson, Michela Negro, Ioannis Liodakis, Riccardo Middei, Dawoon E. Kim, Alan P. Marscher, Herman L. Marshall, Luigi Pacciani, Roger W. Romani, Kinwah Wu, Alessandro Di Marco, Niccoló Di Lalla, Nicola Omodei, Svetlana G. Jorstad, Iván Agudo, Pouya M. Kouch, Elina Lindfors, Francisco José Aceituno, Maria I. Bernardos, Giacomo Bonnoli, Víctor Casanova, Maya García-Comas, Beatriz Agís-González, César Husillos, Alessandro Marchini, Alfredo Sota, Carolina Casadio, Juan Escudero, Ioannis Myserlis, Albrecht Sievers, Mark Gurwell, Ramprasad Rao, Ryo Imazawa, Mahito Sasada, Yasushi Fukazawa, Koji S. Kawabata, Makoto Uemura, Tsunefumi Mizuno, Tatsuya Nakaoka, Hiroshi Akitaya, Yeon Cheong, Hyeon-Woo Jeong, Sincheol Kang, Sang-Hyun Kim, Sang-Sung Lee, Emmanouil Angelakis, Alexander Kraus, Nicoló Cibrario, Immacolata Donnarumma, Juri Poutanen, Fabrizio Tavecchio, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccoló Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Philip Kaaret, Vladimir Karas, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Grzegorz Madejski, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Fabio Muleri, C.-Y. Ng, Stephen L. O’Dell, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Carmelo Sgró, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Fei Xie, and Silvia Zane
Subjects: Astrophysical black holes, Black hole physics, Supermassive black holes, Active galactic nuclei, Active galaxies, Jets, Astrophysics, QB460-466
Abstract: We report the first >99% confidence detection of X-ray polarization in BL Lacertae. During a recent X-ray/ γ -ray outburst, a 287 ks observation (2022 November 27–30) was taken using the Imaging X-ray Polarimetry Explorer (IXPE), together with contemporaneous multiwavelength observations from the Neil Gehrels Swift observatory and XMM-Newton in soft X-rays (0.3–10 keV), NuSTAR in hard X-rays (3–70 keV), and optical polarization from the Calar Alto and Perkins Telescope observatories. Our contemporaneous X-ray data suggest that the IXPE energy band is at the crossover between the low- and high-frequency blazar emission humps. The source displays significant variability during the observation, and we measure polarization in three separate time bins. Contemporaneous X-ray spectra allow us to determine the relative contribution from each emission hump. We find >99% confidence X-ray polarization ${{\rm{\Pi }}}_{2\mbox{--}4\mathrm{keV}}={21.7}_{-7.9}^{+5.6} \% $ and electric vector polarization angle ψ _2–4keV = −28.°7 ± 8.°7 in the time bin with highest estimated synchrotron flux contribution. We discuss possible implications of our observations, including previous IXPE BL Lacertae pointings, tentatively concluding that synchrotron self-Compton emission dominates over hadronic emission processes during the observed epochs.
Published: 2023
Full Text: View/download PDF

24. IXPE Observations of the Quintessential Wind-accreting X-Ray Pulsar Vela X-1

Author: Sofia V. Forsblom, Juri Poutanen, Sergey S. Tsygankov, Matteo Bachetti, Alessandro Di Marco, Victor Doroshenko, Jeremy Heyl, Fabio La Monaca, Christian Malacaria, Herman L. Marshall, Fabio Muleri, Alexander A. Mushtukov, Maura Pilia, Daniele Rogantini, Valery F. Suleimanov, Roberto Taverna, Fei Xie, Iván Agudo, Lucio A. Antonelli, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Immacolata Donnarumma, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana G. Jorstad, Philip Kaaret, Vladimir Karas, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Michela Negro, Chi-Yung Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Paolo Soffitta, Gloria Spandre, Rashid A. Sunyaev, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, Silvia Zane, and IXPE Collaboration
Subjects: Pulsars, Starlight polarization, Neutron stars, High mass x-ray binary stars, Magnetic fields, Accretion, Astrophysics, QB460-466
Abstract: The radiation from accreting X-ray pulsars was expected to be highly polarized, with some estimates for the polarization degree of up to 80%. However, phase-resolved and energy-resolved polarimetry of X-ray pulsars is required in order to test different models and to shed light on the emission processes and the geometry of the emission region. Here we present the first results of the observations of the accreting X-ray pulsar Vela X-1 performed with the Imaging X-ray Polarimetry Explorer. Vela X-1 is considered to be the archetypal example of a wind-accreting, high-mass X-ray binary system, consisting of a highly magnetized neutron star accreting matter from its supergiant stellar companion. The spectropolarimetric analysis of the phase-averaged data for Vela X-1 reveals a polarization degree (PD) of 2.3% ± 0.4% at the polarization angle (PA) of −47.°3 ± 5.°4. A low PD is consistent with the results obtained for other X-ray pulsars and is likely related to the inverse temperature structure of the neutron star atmosphere. The energy-resolved analysis shows the PD above 5 keV reaching 6%–10% and a ∼90° difference in the PA compared to the data in the 2–3 keV range. The phase-resolved spectropolarimetric analysis finds a PD in the range 0%–9% with the PA varying between −80° and 40°.
Published: 2023
Full Text: View/download PDF

25. The IXPE View of GRB 221009A

Author: Michela Negro, Niccolò Di Lalla, Nicola Omodei, Péter Veres, Stefano Silvestri, Alberto Manfreda, Eric Burns, Luca Baldini, Enrico Costa, Steven R. Ehlert, Jamie A. Kennea, Ioannis Liodakis, Herman L. Marshall, Sandro Mereghetti, Riccardo Middei, Fabio Muleri, Stephen L. O’Dell, Oliver J. Roberts, Roger W. Romani, Carmelo Sgró, Masanobu Terashima, Andrea Tiengo, Domenico Viscolo, Alessandro Di Marco, Fabio La Monaca, Luca Latronico, Giorgio Matt, Matteo Perri, Simonetta Puccetti, Juri Poutanen, Ajay Ratheesh, Daniele Rogantini, Patrick Slane, Paolo Soffitta, Elina Lindfors, Kari Nilsson, Anni Kasikov, Alan P. Marscher, Fabrizio Tavecchio, Nicoló Cibrario, Shuichi Gunji, Christian Malacaria, Alessandro Paggi, Yi-Jung Yang, Silvia Zane, Martin C. Weisskopf, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Immacolata Donnarumma, Victor Doroshenko, Michal Dovc̆iak, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Philip Kaaret, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Simone Maldera, Frédéric Marin, Andrea Marinucci, Ikuyuki Mitsuishi, Tsunefumi Mizuno, C.-Y. Ng, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Brian D. Ramsey, John Rankin, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Kinwah Wu, and Fei Xie
Subjects: Gamma-ray bursts, Polarimetry, X-ray astronomy, Astrophysics, QB460-466
Abstract: We present the IXPE observation of GRB 221009A, which includes upper limits on the linear polarization degree of both prompt and afterglow emission in the soft X-ray energy band. GRB 221009A is an exceptionally bright gamma-ray burst (GRB) that reached Earth on 2022 October 9 after traveling through the dust of the Milky Way. The Imaging X-ray Polarimetry Explorer (IXPE) pointed at GRB 221009A on October 11 to observe, for the first time, the 2–8 keV X-ray polarization of a GRB afterglow. We set an upper limit to the polarization degree of the afterglow emission of 13.8% at a 99% confidence level. This result provides constraints on the jet opening angle and the viewing angle of the GRB, or alternatively, other properties of the emission region. Additionally, IXPE captured halo-rings of dust-scattered photons that are echoes of the GRB prompt emission. The 99% confidence level upper limit to the prompt polarization degree depends on the background model assumption, and it ranges between ∼55% and ∼82%. This single IXPE pointing provides both the first assessment of X-ray polarization of a GRB afterglow and the first GRB study with polarization observations of both the prompt and afterglow phases.
Published: 2023
Full Text: View/download PDF

26. A Strong X-Ray Polarization Signal from the Magnetar 1RXS J170849.0-400910

Author: Silvia Zane, Roberto Taverna, Denis González–Caniulef, Fabio Muleri, Roberto Turolla, Jeremy Heyl, Keisuke Uchiyama, Mason Ng, Toru Tamagawa, Ilaria Caiazzo, Niccolò Di Lalla, Herman L. Marshall, Matteo Bachetti, Fabio La Monaca, Ephraim Gau, Alessandro Di Marco, Luca Baldini, Michela Negro, Nicola Omodei, John Rankin, Giorgio Matt, George G. Pavlov, Takao Kitaguchi, Henric Krawczynski, Fabian Kislat, Ruth Kelly, Iván Agudo, Lucio A. Antonelli, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chieng-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana G. Jorstad, Philip Kaaret, Vladimir Karas, Jeffery J. Kolodziejczak, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Francesco Massaro, Ikuyuki Mitsuishi, Tsunefumi Mizuno, C.-Y. Ng, Stephen L. O’Dell, Chiara Oppedisano, Alessandro Papitto, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Juri Poutanen, Simonetta Puccetti, Brian D. Ramsey, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgró, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Fabrizio Tavecchio, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, and Fei Xie
Subjects: Polarimetry, Magnetars, Astrophysics, QB460-466
Abstract: Magnetars are the most strongly magnetized neutron stars, and one of the most promising targets for X-ray polarimetric measurements. We present here the first Imaging X-ray Polarimetry Explorer observation of the magnetar 1RXS J170849.0-400910, jointly analyzed with a new Swift observation and archival NICER data. The total (energy- and phase-integrated) emission in the 2–8 keV energy range is linerarly polarized, at a ∼35% level. The phase-averaged polarization signal shows a marked increase with energy, ranging from ∼20% at 2–3 keV up to ∼80% at 6–8 keV, while the polarization angle remains constant. This indicates that radiation is mostly polarized in a single direction. The spectrum is well reproduced by a combination of either two thermal (blackbody) components or a blackbody and a power law. Both the polarization degree and angle also show a variation with the spin phase, and the former is almost anticorrelated with the source counts in the 2–8 and 2–4 keV bands. We discuss the possible implications and interpretations, based on a joint analysis of the spectral, polarization, and pulsation properties of the source. A scenario in which the surface temperature is not homogeneous, with a hotter cap covered by a gaseous atmosphere and a warmer region in a condensed state, provides a satisfactory description of both the phase- and energy-dependent spectro-polarimetric data. The (comparatively) small size of the two emitting regions, required to explain the observed pulsations, does not allow to reach a robust conclusion about the presence of vacuum birefringence effects.
Published: 2023
Full Text: View/download PDF

27. Missing for 20 yr: MeerKAT Redetects the Elusive Binary Pulsar M30B

Author: Vishnu Balakrishnan, Paulo C. C. Freire, S. M. Ransom, Alessandro Ridolfi, E. D. Barr, W. Chen, Vivek Venkatraman Krishnan, D. Champion, M. Kramer, T. Gautam, Prajwal V. Padmanabh, Yunpeng Men, F. Abbate, B. W. Stappers, I. Stairs, E. Keane, and A. Possenti
Subjects: Radio pulsars, Globular star clusters, Astrophysics, QB460-466
Abstract: PSR J2140−2311B is a 13 ms pulsar discovered in 2001 in a 7.8 hr Green Bank Telescope observation of the core-collapsed globular cluster M30 and predicted to be in a highly eccentric binary orbit. This pulsar has eluded detection since then; therefore, its precise orbital parameters have remained a mystery until now. In this work, we present the confirmation of this pulsar using observations taken with the UHF receivers of the MeerKAT telescope as part of the TRAPUM Large Survey Project. Taking advantage of the beamforming capability of our backends, we have localized it, placing it 1.′2(1) from the cluster center. Our observations have enabled the determination of its orbit: It is highly eccentric ( e = 0.879) with an orbital period of 6.2 days. We also measured the rate of periastron advance, $\dot{\omega }=0.078\pm 0.002\,\deg \,{\mathrm{yr}}^{-1}$ . Assuming that this effect is fully relativistic, general relativity provides an estimate of the total mass of the system, M _TOT = 2.53 ± 0.08 M _⊙ , consistent with the lightest double neutron star systems known. Combining this with the mass function of the system gives the pulsar and companion masses of m _p < 1.43 M _⊙ and m _c > 1.10 M _⊙ , respectively. The massive, undetected companion could either be a massive white dwarf or a neutron star. M30B likely formed as a result of a secondary exchange encounter. Future timing observations will allow the determination of a phase-coherent timing solution, vastly improving our uncertainty in $\dot{\omega }$ and likely enabling the detection of additional relativistic effects, which will determine m _p and m _c .
Published: 2023
Full Text: View/download PDF

28. X-Ray Polarization Observations of BL Lacertae

Author: Riccardo Middei, Ioannis Liodakis, Matteo Perri, Simonetta Puccetti, Elisabetta Cavazzuti, Laura Di Gesu, Steven R. Ehlert, Grzegorz Madejski, Alan P. Marscher, Herman L. Marshall, Fabio Muleri, Michela Negro, Svetlana G. Jorstad, Beatriz Agís-González, Iván Agudo, Giacomo Bonnoli, Maria I. Bernardos, Víctor Casanova, Maya García-Comas, César Husillos, Alessandro Marchini, Alfredo Sota, Pouya M. Kouch, Elina Lindfors, George A. Borman, Evgenia N. Kopatskaya, Elena G. Larionova, Daria A. Morozova, Sergey S. Savchenko, Andrey A. Vasilyev, Alexey V. Zhovtan, Carolina Casadio, Juan Escudero, Ioannis Myserlis, Antonio Hales, Seiji Kameno, Ruediger Kneissl, Hugo Messias, Hiroshi Nagai, Dmitry Blinov, Ioakeim G. Bourbah, Sebastian Kiehlmann, Evangelos Kontopodis, Nikos Mandarakas, Stylianos Romanopoulos, Raphael Skalidis, Anna Vervelaki, Joseph R. Masiero, Dimitri Mawet, Maxwell A. Millar-Blanchaer, Georgia V. Panopoulou, Samaporn Tinyanont, Andrei V. Berdyugin, Masato Kagitani, Vadim Kravtsov, Takeshi Sakanoi, Ryo Imazawa, Mahito Sasada, Yasushi Fukazawa, Koji S. Kawabata, Makoto Uemura, Tsunefumi Mizuno, Tatsuya Nakaoka, Hiroshi Akitaya, Mark Gurwell, Ramprasad Rao, Niccoló Di Lalla, Nicoló Cibrario, Immacolata Donnarumma, Dawoon E. Kim, Nicola Omodei, Luigi Pacciani, Juri Poutanen, Fabrizio Tavecchio, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccoló Bucciantini, Fiamma Capitanio, Simone Castellano, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Alessandro Di Marco, Victor Doroshenko, Michal Dovčiak, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Vladimir Karas, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, C.-Y. Ng, Stephen L. O’Dell, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Roger W. Romani, Carmelo Sgró, Patrick Slane, Paolo Soffitta, Gloria Spandre, Toru Tamagawa, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, Fei Xie, and Silvia Zane
Subjects: Relativistic jets, X-ray active galactic nuclei, Active galactic nuclei, Blazars, Spectropolarimetry, Astrophysics, QB460-466
Abstract: Blazars are a class of jet-dominated active galactic nuclei with a typical double-humped spectral energy distribution. It is of common consensus that the synchrotron emission is responsible for the low frequency peak, while the origin of the high frequency hump is still debated. The analysis of X-rays and their polarization can provide a valuable tool to understand the physical mechanisms responsible for the origin of high-energy emission of blazars. We report the first observations of BL Lacertae (BL Lac) performed with the Imaging X-ray Polarimetry Explorer, from which an upper limit to the polarization degree Π _X < 12.6% was found in the 2–8 keV band. We contemporaneously measured the polarization in radio, infrared, and optical wavelengths. Our multiwavelength polarization analysis disfavors a significant contribution of proton-synchrotron radiation to the X-ray emission at these epochs. Instead, it supports a leptonic origin for the X-ray emission in BL Lac.
Published: 2022
Full Text: View/download PDF

29. First X-Ray Polarization Measurement Confirms the Low Black Hole Spin in LMC X-3

Author: Jiří Svoboda, Michal Dovčiak, James F. Steiner, Fabio Muleri, Adam Ingram, Anastasiya Yilmaz, Nicole Rodriguez Cavero, Lorenzo Marra, Juri Poutanen, Alexandra Veledina, Mehrnoosh Rahbardar Mojaver, Stefano Bianchi, Javier A. García, Philip Kaaret, Henric Krawczynski, Giorgio Matt, Jakub Podgorný, Martin C. Weisskopf, Fabian Kislat, Pierre-Olivier Petrucci, Maimouna Brigitte, Michal Bursa, Sergio Fabiani, Kun Hu, Sohee Chun, Guglielmo Mastroserio, Romana Mikus̆incová, Ajay Ratheesh, Roger W. Romani, Paolo Soffitta, Francesco Ursini, Silvia Zane, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Victor Doroshenko, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Riccardo Ferrazzoli, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimír Karas, Takao Kitaguchi, Jeffery J. Kolodziejczak, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Michela Negro, Chi-Yung Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Oliver J. Roberts, Carmelo Sgrò, Patrick Slane, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Kinwah Wu, and Fei Xie
Subjects: X-ray binary stars, X-ray observatories, Accretion, Astrophysical black holes, Black hole physics, Spectropolarimetry, Astrophysics, QB460-466
Abstract: X-ray polarization is a powerful tool to investigate the geometry of accreting material around black holes, allowing independent measurements of the black hole spin and orientation of the innermost parts of the accretion disk. We perform X-ray spectropolarimetric analysis of an X-ray binary system in the Large Magellanic Cloud, LMC X-3, that hosts a stellar-mass black hole, known to be persistently accreting since its discovery. We report the first detection of the X-ray polarization in LMC X-3 with the Imaging X-ray Polarimetry Explorer, and find the average polarization degree (PD) of 3.2% ± 0.6% and a constant polarization angle of −42° ± 6° over the 2–8 keV range. Using accompanying spectroscopic observations by NICER, NuSTAR, and the Neil Gehrels Swift observatories, we confirm previous measurements of the black hole spin via the X-ray continuum method, a ≈ 0.2. From polarization analysis only, we found consistent results with low black hole spin, with an upper limit of a < 0.7 at a 90% confidence level. A slight increase in the PD with energy, similar to other black hole X-ray binaries in the soft state, is suggested from the data but with a low statistical significance.
Published: 2023
Full Text: View/download PDF

30. X-Ray Polarization of the BL Lacertae Type Blazar 1ES 0229+200

Author: Steven R. Ehlert, Ioannis Liodakis, Riccardo Middei, Alan P. Marscher, Fabrizio Tavecchio, Iván Agudo, Pouya M. Kouch, Elina Lindfors, Kari Nilsson, Ioannis Myserlis, Mark Gurwell, Ramprasad Rao, Francisco José Aceituno, Giacomo Bonnoli, Víctor Casanova, Beatriz Agís-González, Juan Escudero, César Husillos, Jorge Otero Santos, Alfredo Sota, Emmanouil Angelakis, Alexander Kraus, Garrett K. Keating, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccoló Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccoló Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Philip Kaaret, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, Michela Negro, C.-Y. Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Juri Poutanen, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgró, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, Fei Xie, and Silvia Zane
Subjects: Polarimetry, X-ray quasars, Radio galaxies, Astrophysics, QB460-466
Abstract: We present polarization measurements in the 2–8 keV band from blazar 1ES 0229+200, the first extreme high synchrotron peaked source to be observed by the Imaging X-ray Polarimetry Explorer (IXPE). Combining two exposures separated by about two weeks, we find the degree of polarization to be Π _X = 17.9% ± 2.8% at an electric-vector position angle ψ _X = 25.°0 ± 4.°6 using a spectro-polarimetric fit from joint IXPE and XMM-Newton observations. There is no evidence for the polarization degree or angle varying significantly with energy or time on both short timescales (hours) or longer timescales (days). The contemporaneous polarization degree at optical wavelengths was >7× lower, making 1ES 0229+200 the most strongly chromatic blazar yet observed. This high X-ray polarization compared to the optical provides further support that X-ray emission in high-peaked blazars originates in shock-accelerated, energy-stratified electron populations, but is in tension with many recent modeling efforts attempting to reproduce the spectral energy distribution of 1ES 0229+200, which attribute the extremely high energy synchrotron and Compton peaks to Fermi acceleration in the vicinity of strongly turbulent magnetic fields.
Published: 2023
Full Text: View/download PDF

31. The Third Fermi Large Area Telescope Catalog of Gamma-Ray Pulsars

Author: D. A. Smith, S. Abdollahi, M. Ajello, M. Bailes, L. Baldini, J. Ballet, M. G. Baring, C. Bassa, J. Becerra Gonzalez, R. Bellazzini, A. Berretta, B. Bhattacharyya, E. Bissaldi, R. Bonino, E. Bottacini, J. Bregeon, P. Bruel, M. Burgay, T. H. Burnett, R. A. Cameron, F. Camilo, R. Caputo, P. A. Caraveo, E. Cavazzuti, G. Chiaro, S. Ciprini, C. J. Clark, I. Cognard, A. Corongiu, P. Cristarella Orestano, M. Crnogorcevic, A. Cuoco, S. Cutini, F. D’Ammando, A. de Angelis, M. E. DeCesar, S. De Gaetano, R. de Menezes, J. Deneva, F. de Palma, N. Di Lalla, F. Dirirsa, L. Di Venere, A. Domínguez, D. Dumora, S. J. Fegan, E. C. Ferrara, A. Fiori, H. Fleischhack, C. Flynn, A. Franckowiak, P. C. C. Freire, Y. Fukazawa, P. Fusco, G. Galanti, V. Gammaldi, F. Gargano, D. Gasparrini, F. Giacchino, N. Giglietto, F. Giordano, M. Giroletti, D. Green, I. A. Grenier, L. Guillemot, S. Guiriec, M. Gustafsson, A. K. Harding, E. Hays, J. W. Hewitt, D. Horan, X. Hou, F. Jankowski, R. P. Johnson, T. J. Johnson, S. Johnston, J. Kataoka, M. J. Keith, M. Kerr, M. Kramer, M. Kuss, L. Latronico, S.-H. Lee, D. Li, J. Li, B. Limyansky, F. Longo, F. Loparco, L. Lorusso, M. N. Lovellette, M. Lower, P. Lubrano, A. G. Lyne, Y. Maan, S. Maldera, R. N. Manchester, A. Manfreda, M. Marelli, G. Martí-Devesa, M. N. Mazziotta, J. E. McEnery, I. Mereu, P. F. Michelson, M. Mickaliger, W. Mitthumsiri, T. Mizuno, A. A. Moiseev, M. E. Monzani, A. Morselli, M. Negro, R. Nemmen, L. Nieder, E. Nuss, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, M. Palatiello, D. Paneque, G. Panzarini, A. Parthasarathy, M. Persic, M. Pesce-Rollins, R. Pillera, H. Poon, T. A. Porter, A. Possenti, G. Principe, S. Rainò, R. Rando, S. M. Ransom, P. S. Ray, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, N. Renault-Tinacci, R. W. Romani, M. Sánchez-Conde, P. M. Saz Parkinson, L. Scotton, D. Serini, C. Sgrò, R. Shannon, V. Sharma, Z. Shen, E. J. Siskind, G. Spandre, P. Spinelli, B. W. Stappers, T. E. Stephens, D. J. Suson, S. Tabassum, H. Tajima, D. Tak, G. Theureau, D. J. Thompson, O. Tibolla, D. F. Torres, J. Valverde, C. Venter, Z. Wadiasingh, N. Wang, P. Wang, P. Weltevrede, K. Wood, J. Yan, G. Zaharijas, C. Zhang, and W. Zhu
Subjects: Binary pulsars, Millisecond pulsars, Pulsar timing method, Rotation powered pulsars, Pulsars, Gamma-rays, Astrophysics, QB460-466
Abstract: We present 294 pulsars found in GeV data from the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. Another 33 millisecond pulsars (MSPs) discovered in deep radio searches of LAT sources will likely reveal pulsations once phase-connected rotation ephemerides are achieved. A further dozen optical and/or X-ray binary systems colocated with LAT sources also likely harbor gamma-ray MSPs. This catalog thus reports roughly 340 gamma-ray pulsars and candidates, 10% of all known pulsars, compared to ≤11 known before Fermi. Half of the gamma-ray pulsars are young. Of these, the half that are undetected in radio have a broader Galactic latitude distribution than the young radio-loud pulsars. The others are MSPs, with six undetected in radio. Overall, ≥236 are bright enough above 50 MeV to fit the pulse profile, the energy spectrum, or both. For the common two-peaked profiles, the gamma-ray peak closest to the magnetic pole crossing generally has a softer spectrum. The spectral energy distributions tend to narrow as the spindown power $\dot{E}$ decreases to its observed minimum near 10 ^33 erg s ^−1 , approaching the shape for synchrotron radiation from monoenergetic electrons. We calculate gamma-ray luminosities when distances are available. Our all-sky gamma-ray sensitivity map is useful for population syntheses. The electronic catalog version provides gamma-ray pulsar ephemerides, properties, and fit results to guide and be compared with modeling results.
Published: 2023
Full Text: View/download PDF

32. Magnetic Structures and Turbulence in SN 1006 Revealed with Imaging X-Ray Polarimetry

Author: Ping Zhou, Dmitry Prokhorov, Riccardo Ferrazzoli, Yi-Jung Yang, Patrick Slane, Jacco Vink, Stefano Silvestri, Niccolò Bucciantini, Estela Reynoso, David Moffett, Paolo Soffitta, Doug Swartz, Philip Kaaret, Luca Baldini, Enrico Costa, C.-Y. Ng, Dawoon E. Kim, Victor Doroshenko, Steven R. Ehlert, Jeremy Heyl, Frédéric Marin, Tsunefumi Mizuno, Melissa Pesce-Rollins, Carmelo Sgrò, Toru Tamagawa, Martin C. Weisskopf, Fei Xie, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Michal Dovčiak, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana G. Jorstad, Fabian Kislat, Vladimir Karas, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Giorgio Matt, Ikuyuki Mitsuishi, Fabio Muleri, Michela Negro, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Juri Poutanen, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver Roberts, Roger W. Romani, Gloria Spandre, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Kinwah Wu, and Silvia Zane
Subjects: Supernova remnants, Polarimetry, X-ray astronomy, Shocks, Cosmic rays, Astrophysics, QB460-466
Abstract: Young supernova remnants strongly modify the surrounding magnetic fields, which in turn play an essential role in accelerating cosmic rays (CRs). The X-ray polarization measurements probe magnetic field morphology and turbulence at the immediate acceleration site. We report the X-ray polarization distribution in the northeastern shell of SN 1006 from a 1 Ms observation with the Imaging X-ray Polarimetry Explorer. We found an average polarization degree of 22.4% ± 3.5% and an average polarization angle of −45.°4 ± 4.°5 (measured on the plane of the sky from north to east). The X-ray polarization angle distribution reveals that the magnetic fields immediately behind the shock in the northeastern shell of SN 1006 are nearly parallel to the shock normal or radially distributed, similar to that in the radio observations, and consistent with the quasi-parallel CR acceleration scenario. The X-ray emission is marginally more polarized than that in the radio band. The X-ray polarization degree of SN 1006 is much larger than that in Cas A and Tycho, together with the relatively tenuous and smooth ambient medium of the remnant, favoring that CR-induced instabilities set the magnetic turbulence in SN 1006, and CR acceleration is environment-dependent.
Published: 2023
Full Text: View/download PDF

33. The Polarized Cosmic Hand: IXPE Observations of PSR B1509−58/MSH 15−52

Author: Roger W. Romani, Josephine Wong, Niccoló Di Lalla, Nicola Omodei, Fei Xie, C.-Y. Ng, Riccardo Ferrazzoli, Alessandro Di Marco, Niccoló Bucciantini, Maura Pilia, Patrick Slane, Martin C. Weisskopf, Simon Johnston, Marta Burgay, Deng Wei, Yi-Jung Yang, Shumeng Zhang, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Nicoló Cibrario, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Ioannis Liodakis, Philip Kaaret, Vladimir Karas, Dawoon E. Kim, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Grzegorz Madejski, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Giorgio Matt, Riccardo Middei, Ikuyuki Mitsuishi, Tsunefumi Mizuno, Fabio Muleri, Michela Negro, Stephen L. O’Dell, Chiara Oppedisano, Luigi Pacciani, Alessandro Papitto, George G. Pavlov, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Andrea Possenti, Juri Poutanen, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Carmelo Sgró, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey Tsygankov, Roberto Turolla, Jacco Vink, Kinwah Wu, and Silvia Zane
Subjects: Pulsar wind nebulae, Rotation powered pulsars, Polarimetry, Astrophysics, QB460-466
Abstract: We describe IXPE polarization observations of the pulsar wind nebula (PWN) MSH 15−5 ^2 , the “Cosmic Hand.” We find X-ray polarization across the PWN, with B -field vectors generally aligned with filamentary X-ray structures. High-significance polarization is seen in arcs surrounding the pulsar and toward the end of the “jet,” with polarization degree PD > 70%, thus approaching the maximum allowed synchrotron value. In contrast, the base of the jet has lower polarization, indicating a complex magnetic field at significant angle to the jet axis. We also detect significant polarization from PSR B1509−58 itself. Although only the central pulse phase bin of the pulse has high individual significance, flanking bins provide lower-significance detections and, in conjunction with the X-ray image and radio polarization, can be used to constrain rotating vector model solutions for the pulsar geometry.
Published: 2023
Full Text: View/download PDF

34. IXPE and XMM-Newton Observations of the Soft Gamma Repeater SGR 1806–20

Author: Roberto Turolla, Roberto Taverna, Gian Luca Israel, Fabio Muleri, Silvia Zane, Matteo Bachetti, Jeremy Heyl, Alessandro Di Marco, Ephraim Gau, Henric Krawczynski, Mason Ng, Andrea Possenti, Juri Poutanen, Luca Baldini, Giorgio Matt, Michela Negro, Iván Agudo, Lucio A. Antonelli, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chieng-Ting Chen, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana G. Jorstad, Philip Kaaret, Vladimir Karas, Fabian Kislat, Takao Kitaguchi, Jeffery J. Kolodziejczak, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Francesco Massaro, Ikuyuki Mitsuishi, Tsunefumi Mizuno, C.-Y. Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver J. Roberts, Roger W. Romani, Carmelo Sgró, Patrick Slane, Paolo Soffitta, Gloria Spandre, Douglas A. Swartz, Toru Tamagawa, Fabrizio Tavecchio, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Jacco Vink, Martin C. Weisskopf, Kinwah Wu, and Fei Xie
Subjects: Neutron stars, Magnetars, Polarimetry, X-ray sources, Astrophysics, QB460-466
Abstract: Recent observations with the Imaging X-ray Polarimetry Explorer (IXPE) of two anomalous X-ray pulsars provided evidence that X-ray emission from magnetar sources is strongly polarized. Here we report on the joint IXPE and XMM-Newton observations of the soft γ -repeater SGR 1806–20. The spectral and timing properties of SGR 1806–20 derived from XMM-Newton data are in broad agreement with previous measurements; however, we found the source at an all-time low persistent flux level. No significant polarization was measured apart from the 4–5 keV energy range, where a probable detection with PD = 31.6% ± 10.5% and $\mathrm{PA}=-17\buildrel{\circ}\over{.} {6}_{-15\buildrel{\circ}\over{.} 0}^{+15\buildrel{\circ}\over{.} 5}$ was obtained. The resulting polarization signal, together with the upper limits we derive at lower and higher energies (2–4 and 5–8 keV, respectively), is compatible with a picture in which thermal radiation from the condensed star surface is reprocessed by resonant Compton scattering in the magnetosphere, similar to what was proposed for the bright magnetar 4U 0142+61.
Published: 2023
Full Text: View/download PDF

35. A Young White Dwarf Orbiting PSR J1835−3259B in the Bulge Globular Cluster NGC 6652

Author: Jianxing Chen, Mario Cadelano, Cristina Pallanca, Francesco R. Ferraro, Barbara Lanzoni, Alina G. Istrate, Marta Burgay, Paulo C. C. Freire, Tasha Gautam, Andrea Possenti, and Alessandro Ridolfi
Subjects: Millisecond pulsars, Binary pulsars, Globular star clusters, HST photometry, Neutron stars, White dwarf stars, Astrophysics, QB460-466
Abstract: We report on the discovery of the companion star to the millisecond pulsar PSR J1835−3259B in the Galactic globular cluster NGC 6652. Taking advantage of deep photometric archival observations acquired through the Hubble Space Telescope in near-UV and optical bands, we identified a bright and blue object at a position compatible with that of the radio pulsar. The companion is located along the helium-core white dwarf cooling sequence, and the comparison with binary evolution models provides a mass of 0.17 ± 0.02 M _⊙ , a surface temperature of 11,500 ± 1900 K, and a very young cooling age of only 200 ± 100 Myr. The mass and the age of the companion are compatible with a progenitor star of about 0.87 M _⊙ , which started transferring mass to the primary during its evolution along the subgiant branch and stopped during the early red giant branch phase. Combining together the pulsar mass function and the companion mass, we found that this system is observed at an almost edge-on orbit and hosts a neutron star with a mass of 1.44 ± 0.06 M _⊙ , thus suggesting a highly nonconservative mass accretion phase. The young age of the WD companion is consistent with the scenario of a powerful, relatively young MSP indicated by the earlier detection of gamma-rays from this system.
Published: 2023
Full Text: View/download PDF

36. Deep X-Ray and Radio Observations of the First Outburst of the Young Magnetar Swift J1818.0−1607

Author: A. Y. Ibrahim, A. Borghese, N. Rea, F. Coti Zelati, E. Parent, T. D. Russell, S. Ascenzi, R. Sathyaprakash, D. Götz, S. Mereghetti, M. Topinka, M. Rigoselli, V. Savchenko, S. Campana, G. L. Israel, A. Tiengo, R. Perna, R. Turolla, S. Zane, P. Esposito, G. A. Rodríguez Castillo, V. Graber, A. Possenti, C. Dehman, M. Ronchi, and S. Loru
Subjects: Neutron stars, Magnetars, Astrophysics, QB460-466
Abstract: Swift J1818.0−1607 is a radio-loud magnetar with a spin period of 1.36 s and a dipolar magnetic field strength of B ∼ 3 × 10 ^14 G, which is very young compared to the Galactic pulsar population. We report here on the long-term X-ray monitoring campaign of this young magnetar using XMM-Newton, NuSTAR, and Swift from the activation of its first outburst in 2020 March until 2021 October, as well as INTEGRAL upper limits on its hard X-ray emission. The 1–10 keV magnetar spectrum is well modeled by an absorbed blackbody with a temperature of kT _BB ∼ 1.1 keV and apparent reduction in the radius of the emitting region from ∼0.6 to ∼0.2 km. We also confirm the bright diffuse X-ray emission around the source extending between ∼50″ and ∼110″. A timing analysis revealed large torque variability, with an average spin-down rate $\dot{\nu }\,\sim $ −2.3 × 10 ^−11 Hz ^2 that appears to decrease in magnitude over time. We also observed Swift J1818.0−1607 with the Karl G. Jansky Very Large Array on 2021 March 22. We detected the radio counterpart to Swift J1818 measuring a flux density of S _v = 4.38 ± 0.05 mJy at 3 GHz and a half-ringlike structure of bright diffuse radio emission located at ∼90″ to the west of the magnetar. We tentatively suggest that the diffuse X-ray emission is due to a dust-scattering halo and that the radio structure may be associated with the supernova remnant of this young pulsar, based on its morphology.
Published: 2023
Full Text: View/download PDF

37. Polarization Properties of the Weakly Magnetized Neutron Star X-Ray Binary GS 1826–238 in the High Soft State

Author: Fiamma Capitanio, Sergio Fabiani, Andrea Gnarini, Francesco Ursini, Carlo Ferrigno, Giorgio Matt, Juri Poutanen, Massimo Cocchi, Romana Mikusincova, Ruben Farinelli, Stefano Bianchi, Jari J. E. Kajava, Fabio Muleri, Celia Sanchez-Fernandez, Paolo Soffitta, Kinwah Wu, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Luca Baldini, Wayne H. Baumgartner, Ronaldo Bellazzini, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Niccolò Bucciantini, Simone Castellano, Elisabetta Cavazzuti, Stefano Ciprini, Enrico Costa, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Niccolò Di Lalla, Alessandro Di Marco, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Riccardo Ferrazzoli, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Jeremy Heyl, Wataru Iwakiri, Svetlana G. Jorstad, Vladimir Karas, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Frédéric Marin, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Ikuyuki Mitsuishi, Tsunefumi Mizuno, C.-Y. Ng, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Melissa Pesce-Rollins, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Roger W. Romani, Carmelo Sgrò, Patrick Slane, Gloria Spandre, Toru Tamagawa, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Jacco Vink, Martin C. Weisskopf, Fei Xie, and Silvia Zane
Subjects: Low-mass x-ray binary stars, X-ray astronomy, X-ray binary stars, Astrophysics, QB460-466
Abstract: The launch of the Imaging X-ray Polarimetry Explorer (IXPE) on 2021 December 9 has opened a new window in X-ray astronomy. We report here the results of the first IXPE observation of a weakly magnetized neutron star, GS 1826−238, performed on 2022 March 29–31 when the source was in a high soft state. An upper limit (99.73% confidence level) of 1.3% for the linear polarization degree is obtained over the IXPE 2–8 keV energy range. Coordinated INTEGRAL and NICER observations were carried out simultaneously with IXPE. The spectral parameters obtained from the fits to the broadband spectrum were used as inputs for Monte Carlo simulations considering different possible geometries of the X-ray emitting region. Comparing the IXPE upper limit with these simulations, we can put constraints on the geometry and inclination angle of GS 1826–238.
Published: 2023
Full Text: View/download PDF

38. X-Ray Polarimetry Reveals the Magnetic-field Topology on Sub-parsec Scales in Tycho’s Supernova Remnant

Author: Riccardo Ferrazzoli, Patrick Slane, Dmitry Prokhorov, Ping Zhou, Jacco Vink, Niccolò Bucciantini, Enrico Costa, Niccolò Di Lalla, Alessandro Di Marco, Paolo Soffitta, Martin C. Weisskopf, Kazunori Asakura, Luca Baldini, Jeremy Heyl, Philip E. Kaaret, Frédéric Marin, Tsunefumi Mizuno, C.-Y. Ng, Melissa Pesce-Rollins, Stefano Silvestri, Carmelo Sgrò, Douglas A. Swartz, Toru Tamagawa, Yi-Jung Yang, Iván Agudo, Lucio A. Antonelli, Matteo Bachetti, Wayne H. Baumgartner, Ronaldo Bellazzini, Stefano Bianchi, Stephen D. Bongiorno, Raffaella Bonino, Alessandro Brez, Fiamma Capitanio, Simone Castellano, Elisabetta Cavazzuti, Chien-Ting Chen, Stefano Ciprini, Alessandra De Rosa, Ettore Del Monte, Laura Di Gesu, Immacolata Donnarumma, Victor Doroshenko, Michal Dovčiak, Steven R. Ehlert, Teruaki Enoto, Yuri Evangelista, Sergio Fabiani, Javier A. Garcia, Shuichi Gunji, Kiyoshi Hayashida, Wataru Iwakiri, Svetlana G. Jorstad, Fabian Kislat, Vladimir Karas, Takao Kitaguchi, Jeffery J. Kolodziejczak, Henric Krawczynski, Fabio La Monaca, Luca Latronico, Ioannis Liodakis, Simone Maldera, Alberto Manfreda, Andrea Marinucci, Alan P. Marscher, Herman L. Marshall, Giorgio Matt, Ikuyuki Mitsuishi, Fabio Muleri, Michela Negro, Stephen L. O’Dell, Nicola Omodei, Chiara Oppedisano, Alessandro Papitto, George G. Pavlov, Abel L. Peirson, Matteo Perri, Pierre-Olivier Petrucci, Maura Pilia, Andrea Possenti, Juri Poutanen, Simonetta Puccetti, Brian D. Ramsey, John Rankin, Ajay Ratheesh, Oliver Roberts, Roger W. Romani, Gloria Spandre, Fabrizio Tavecchio, Roberto Taverna, Yuzuru Tawara, Allyn F. Tennant, Nicholas E. Thomas, Francesco Tombesi, Alessio Trois, Sergey S. Tsygankov, Roberto Turolla, Kinwah Wu, Fei Xie, and Silvia Zane
Subjects: Supernova remnants, Polarimetry, X-ray astronomy, Astrophysics, QB460-466
Abstract: Supernova remnants are commonly considered to produce most of the Galactic cosmic rays via diffusive shock acceleration. However, many questions regarding the physical conditions at shock fronts, such as the magnetic-field morphology close to the particle acceleration sites, remain open. Here we report the detection of a localized polarization signal from some synchrotron X-ray emitting regions of Tycho’s supernova remnant made by the Imaging X-ray Polarimetry Explorer. The derived degree of polarization of the X-ray synchrotron emission is 9% ± 2% averaged over the whole remnant, and 12% ± 2% at the rim, higher than the value of polarization of 7%–8% observed in the radio band. In the west region, the degree of polarization is 23% ± 4%. The degree of X-ray polarization in Tycho is higher than for Cassiopeia A, suggesting a more ordered magnetic field or a larger maximum turbulence scale. The measured tangential direction of polarization corresponds to the radial magnetic field, and is consistent with that observed in the radio band. These results are compatible with the expectation of turbulence produced by an anisotropic cascade of a radial magnetic field near the shock, where we derive a magnetic-field amplification factor of 3.4 ± 0.3. The fact that this value is significantly smaller than those expected from acceleration models is indicative of highly anisotropic magnetic-field turbulence, or that the emitting electrons either favor regions of lower turbulence, or accumulate close to where the orientation of the magnetic field is preferentially radially oriented due to hydrodynamical instabilities.
Published: 2023
Full Text: View/download PDF

39. PSR J1753-2240: A mildly recycled pulsar in an eccentric binary system

Author: Keith, M. J., Kramer, M., Lyne, A. G., Eatough, R. P., Stairs, I. H., Possenti, A., Camilo, F., and Manchester, R. N.
Subjects: Astrophysics
Abstract: We report the discovery of PSR J1753-2240 in the Parkes Multibeam Pulsar Survey database. This 95-ms pulsar is in an eccentric binary system with a 13.6-day orbital period. Period derivative measurements imply a characteristic age in excess of 1 Gyr, suggesting that the pulsar has undergone an episode of accretion-induced spin-up. The eccentricity and spin period are indicative of the companion being a second neutron star, so that the system is similar to that of PSR J1811-1736, although other companion types cannot be ruled out at this time. The companion mass is constrained by geometry to lie above 0.48 solar masses, although long-term timing observations will give additional constraints. If the companion is a white dwarf or main sequence star, optical observations may yield a direct detection of the companion. If the system is indeed one of the few known double neutron star systems, it would lie significantly far from the recently proposed spin-period/eccentricity relationship., Comment: For publication in MNRAS. 6 pages, 3 figures
Published: 2008
Full Text: View/download PDF

40. High-Resolution Timing Observations of Spin-Powered Pulsars with the AGILE Gamma-Ray Telescope

Author: Pellizzoni, A., Pilia, M., Possenti, A., Fornari, F., Caraveo, P., Del Monte, E., Mereghetti, S., Tavani, M., Argan, A., Trois, A., Burgay, M., Chen, A., Cognard, I., Costa, E., D'Amico, N., Esposito, P., Evangelista, Y., Feroci, M., Fuschino, F., Giuliani, A., Halpern, J., Hobbs, G., Hotan, A., Johnston, S., Kramer, M., Longo, F., Manchester, R. N., Marisaldi, M., Palfreyman, J., Weltevrede, P., Barbiellini, G., Boffelli, F., Bulgarelli, A., Cattaneo, P. W., Cocco, V., D'Ammando, F., De Paris, G., Di Cocco, G., Donnarumma, I., Fiorini, M., Froysland, T., Galli, M., Gianotti, F., Harding, A., Labanti, C., Lapshov, I., Lazzarotto, F., Lipari, P., Mauri, F., Morselli, A., Pacciani, L., Perotti, F., Picozza, P., Prest, M., Pucella, G., Rapisarda, M., Rappoldi, A., Soffitta, P., Trifoglio, M., Vallazza, E., Vercellone, S., Vittorini, V., Zambra, A., Zanello, D., Pittori, C., Verrecchia, F., Preger, B., Santolamazza, P., Giommi, P., and Salotti, L.
Subjects: Astrophysics
Abstract: AGILE is a small gamma-ray astronomy satellite mission of the Italian Space Agency dedicated to high-energy astrophysics launched in 2007 April. Its 1 microsecond absolute time tagging capability coupled with a good sensitivity in the 30 MeV-30 GeV range, with simultaneous X-ray monitoring in the 18-60 keV band, makes it perfectly suited for the study of gamma-ray pulsars following up on the CGRO/EGRET heritage. In this paper we present the first AGILE timing results on the known gamma-ray pulsars Vela, Crab, Geminga and B 1706-44. The data were collected from 2007 July to 2008 April, exploiting the mission Science Verification Phase, the Instrument Timing Calibration and the early Observing Pointing Program. Thanks to its large field of view, AGILE collected a large number of gamma-ray photons from these pulsars (about 10,000 pulsed counts for Vela) in only few months of observations. The coupling of AGILE timing capabilities, simultaneous radio/X-ray monitoring and new tools aimed at precise photon phasing, exploiting also timing noise correction, unveiled new interesting features at sub-millisecond level in the pulsars' high-energy light-curves., Comment: Accepted for publication in The Astrophysical Journal. 14 pages in emulate-apj style, 2 tables, 9 figures (1 color). Replacement corrected Figure 6
Published: 2008
Full Text: View/download PDF

41. Relativistic Spin Precession in the Double Pulsar

Author: Breton, Rene P., Kaspi, Victoria M., Kramer, Michael, McLaughlin, Maura A., Lyutikov, Maxim, Ransom, Scott M., Stairs, Ingrid H., Ferdman, Robert D., Camilo, Fernando, and Possenti, Andrea
Subjects: Astrophysics, General Relativity and Quantum Cosmology
Abstract: The double pulsar PSR J0737-3039A/B consists of two neutron stars in a highly relativistic orbit that displays a roughly 30-second eclipse when pulsar A passes behind pulsar B. Describing this eclipse of pulsar A as due to absorption occurring in the magnetosphere of pulsar B, we successfully use a simple geometric model to characterize the observed changing eclipse morphology and to measure the relativistic precession of pulsar B's spin axis around the total orbital angular momentum. This provides a test of general relativity and alternative theories of gravity in the strong-field regime. Our measured relativistic spin precession rate of 4.77 (+0.66,-0.65) degrees per year (68% confidence level) is consistent with that predicted by general relativity within an uncertainty of 13%., Comment: 28 pages, 6 figures, 1 table, 2 movies
Published: 2008
Full Text: View/download PDF

42. PSR J1410-6132: A young, energetic pulsar associated with EGRET source 3EG J1410-6147

Author: O'Brien, J. T., Johnston, S., Kramer, M., Lyne, A. G., Bailes, M., Possenti, A., Burgay, M., Lorimer, D. R., McLaughlin, M. A., Hobbs, G., Parent, D., and Guillemot, L.
Subjects: Astrophysics
Abstract: We present the discovery of PSR J1410-6132, a 50-ms pulsar found during a high-frequency survey of the Galactic plane, using a 7-beam 6.3-GHz receiver on the 64-m Parkes radio telescope. The pulsar lies within the error box of the unidentified EGRET source 3EG J1410-6147, has a characteristic age of 26 kyr and a spin-down energy of 10^37 erg s^-1. It has a very high dispersion measure of 960+/-10 cm^-3 pc and the largest rotation measure of any pulsar, RM=+2400 +/- 30 rad m^-2. The pulsar is very scatter-broadened at frequencies of 1.4 GHz and below, making pulsed emission almost impossible to detect. Assuming a distance of 15 kpc, the pulsar's spin-down energy and a gamma-ray efficiency factor of ~10 per cent is sufficient to power the gamma-ray source. We therefore believe we have identified the nature of 3EG J1410-6147. This new discovery suggests that deep targeted high-frequency surveys of inner-galaxy EGRET sources could uncover further young, energetic pulsars., Comment: Accepted for publication in MNRAS
Published: 2008
Full Text: View/download PDF

43. A puzzling millisecond pulsar companion in NGC 6266

Author: Cocozza, G., Ferraro, F. R., Possenti, A., Beccari, G., Lanzoni, B., Ranson, S., Rood, R. T., and D'Amico, N.
Subjects: Astrophysics
Abstract: We report on the optical identification of the companion to the eclipsing millisecond pulsar PSR J1701$-$3006B in the globular cluster NGC 6266. A relatively bright star with an anomalous red colour and an optical variability ($\sim$ 0.2 mag) that nicely correlates with the orbital period of the pulsar ($\sim$ 0.144 days) has been found nearly coincident with the pulsar nominal position. This star is also found to lie within the error box position of an X-ray source detected by Chandra observations, thus supporting the hypothesis that some interaction is occurring between the pulsar wind and the gas streaming off the companion. Although the shape of the optical light curve is suggestive of a tidally deformed star which has nearly completely filled its Roche lobe, the luminosity ($\sim 1.9 L_\odot$) and the surface temperature ($\sim 6000$ K) of the star, deduced from the observed magnitude and colours, would imply a stellar radius significantly larger than the Roche lobe radius. Possible explanations for this apparent inconsistency are discussed., Comment: 11 pages, 3 figures, ApJL accepted
Published: 2008
Full Text: View/download PDF

44. The very soft X-ray spectrum of the Double Pulsar System J0737-3039

Author: Possenti, A., Rea, N., McLaughlin, M. A., Camilo, F., Kramer, M., Burgay, M., Joshi, B. C., and Lyne, A. G.
Subjects: Astrophysics
Abstract: We present the results of an 80 ks Chandra ACIS-S observation of the double pulsar system J0737-3039. Furthermore, we report on spectral, spatial and timing analysis of the combined X-ray observations performed so far for this system. Fitting a total of ~1100 photons, we show that the X-ray spectrum of the J0737-3039 system is very soft, and not satisfactorily modeled by a simple blackbody or an atmospheric model. However, it is not possible yet to discriminate between a predominantly non-thermal and a predominantly thermal origin for the X-ray emission. Adopting a simple power-law emission model, the photon index (Gamma=3.7) and the implied conversion efficiency of the rotational energy of PSR J0737-3039A into X-ray emission (4.1x10^-4, for a distance to the source of 500 pc) are compatible with the X-ray photons being emitted in the magnetosphere of PSR J0737-3039A. This hypothesis is also supported by the absence of detectable X-ray orbital modulation (up to ~20%) or any X-ray nebular emission and it is in agreement with the high (~75%) X-ray pulsed fraction of PSR J0737-3039A. A two blackbody or a Comptonized blackbody model also reproduce the data, and the upper limit to the value of the hydrogen column density N_H <10^20 cm^-2, is in better agreement (with respect to the power-law model) with the Galactic N_H in that direction and at that distance. For the two blackbody model the implied emission radii and temperatures are also compatible with those seen in other recycled pulsars, calling for the bulk of the X-ray photons being originated from heated regions at the surface of pulsar A. On the other hand, in the Comptonized blackbody model, the electron temperature seems to be significantly smaller than in other similar objects., Comment: 12 pages. Accepted for publication in ApJ
Published: 2008
Full Text: View/download PDF

45. The double pulsar: evolutionary constraints from the system geometry

Author: Ferdman, R. D., Stairs, I. H., Kramer, M., Manchester, R. N., Lyne, A. G., Breton, R. P., McLaughlin, M. A., Possenti, A., and Burgay, M.
Subjects: Astrophysics
Abstract: The double pulsar system PSR J0737-3039A/B is a highly relativistic double neutron star (DNS) binary, with a 2.4-hour orbital period. The low mass of the second-formed NS, as well the low system eccentricity and proper motion, point to a different evolutionary scenario compared to other known DNS systems. We describe analysis of the pulse profile shape over 6 years of observations, and present the resulting constraints on the system geometry. We find the recycled pulsar in this system, PSR J0737-3039A, to have a low misalignment between its spin and orbital angular momentum axes, with a 68.3% upper limit of 6.1 degrees, assuming emission from both magnetic poles. This tight constraint lends credence to the idea that the supernova that formed the second pulsar was relatively symmetric, possibly involving electron-capture onto an O-Ne-Mg core., Comment: 5 page, 2 figures; To appear in the conference proceedings "40 Years of Pulsars: Millisecond Pulsars, Magnetars, and More", August 12-17, 2007, at McGill University, Montreal, Canada. Version with full-resolution figures can be found at http://www.phas.ubc.ca/~ferdman/ferdman.0737_geo.full.ps.gz; typos corrected, some rewording, and references added
Published: 2007
Full Text: View/download PDF

46. Transient Phenomena in Anomalous X-ray Pulsars

Author: Israel, GianLuca, Bernardini, Federico, Burgay, Marta, Rea, Nanda, Possenti, Andrea, Dall'Osso, Simone, and Stella, and Luigi
Subjects: Astrophysics
Abstract: In 2003 a previously unpulsed Einstein and ROSAT source cataloged as soft and dim (Lx of few 10^33 ergs) thermal emitting object, namely XTE J1810-197, was identified as the first unambiguous transient Anomalous X-ray Pulsar. Two years later this source was also found to be a bright highly polarized transient radio pulsar, a unique property among both AXPs and radio pulsars. In September 2006 the Swift Burst Alert Telescope (BAT) detected an intense burst from the candidate AXP CXOU J164710.2-455216, which entered in an outburst state reaching a peak emission of at least a factor of 300 higher than quiescence. Here, we briefly outline the recent results concerning the outburst phenomena observed in these two AXPs. In particular, XTE J1810-197 has probed to be a unique laboratory to monitor the timing and spectral properties of a cooling/fading AXP, while new important information have been inferred from X-ray and radio band simultaneous observations. CXOU J164710.2-455216 has been monitored in X-rays and radio bands since the very beginning of its outbursting state allowing us to cover the first phases of the outburst and to study the timing and spectral behavior during the first months., Comment: 5 pages, 3 figures, proceedings of the conference "40 Years of Pulsars, Millisecond Pulsars, Magnetars and More", Montreal, August 12-17 2007. To be published by AIPC
Published: 2007
Full Text: View/download PDF

47. A Search for Pulsed and Bursty Radio Emission from X-ray Dim Isolated Neutron Stars

Author: Kondratiev, V. I., Burgay, M., Possenti, A., McLaughlin, M. A., Lorimer, D. R., Turolla, R., Popov, S., and Zane, S.
Subjects: Astrophysics
Abstract: We have carried out a search for radio emission from six X-ray dim isolated neutron stars (XDINSs) observed with the Robert C. Byrd Green Bank Radio Telescope (GBT) at 820 MHz. No bursty or pulsed radio emission was found down to a 4sigma significance level. The corresponding flux limit is 0.01-0.04 mJy depending on the integration time for the particular source and pulse duty cycle of 2%. These are the most sensitive limits yet on radio emission from these objects., Comment: 3 pages, 3 figures, to be appeared in the Proceedings of the conference "40 Years of Pulsars: Millisecond Pulsars, Magnetars, and More" held on August 12-17, 2007, McGill University, Montreal, Canada
Published: 2007
Full Text: View/download PDF

48. Discovery of Pulsations and a Possible Spectral Feature in the X-ray Emission from Rotating Radio Transient J1819-1458

Author: McLaughlin, M. A., Rea, N., Gaensler, B. M., Chatterjee, S., Camilo, F., Kramer, M., Lorimer, D. R., Lyne, A. G., Israel, G. L., and Possenti, A.
Subjects: Astrophysics
Abstract: PSR J1819-1458 is a rotating radio transient (RRAT) source with an inferred surface dipole magnetic field strength of 5e13 G and a 4.26-s spin period. We present XMM-Newton observations of the X-ray counterpart of this source, CXOU J181939.1-145804, in which we identify pulsations and a possible spectral feature. The X-ray pulsations are at the period predicted by the radio ephemeris, providing an unambiguous identification with the radio source and confirmation of its neutron star nature. The X-ray pulse has a 0.3-5 keV pulsed fraction of 34% and is aligned with the expected phase of the radio pulse. The X-ray spectrum is fit well by an absorbed blackbody with kT = 0.14 keV with the addition of an absorption feature at 1 keV, with total absorbed flux of 1.5e-13 ergs/cm^2/s (0.3-5 keV). This absorption feature is well modeled by a Gaussian or resonant cyclotron scattering model, but its significance is dependent on the choice of continuum model. We find no evidence for any X-ray bursts or aperiodic variability on timescales of 6 ms to the duration of the observation and can place the most stringent limit to date of < 3e-9 ergs/cm^2/s on the absorbed 0.3-5 keV flux of any bursts., Comment: 5 figures, accepted by ApJ
Published: 2007
Full Text: View/download PDF

49. Millisecond pulsars around intermediate-mass black holes in globular clusters

Author: Devecchi, B., Colpi, M., Mapelli, M., and Possenti, A.
Subjects: Astrophysics
Abstract: We study the process of dynamical capture of a millisecond pulsar (MSP) by a single or binary IMBH, simulating various types of single-binary and binary-binary encounters. It is found that [IMBH,MSP] binaries form over cosmic time in a cluster, via encounters of wide--orbit binary MSPs off the single IMBH, and at a lower pace, via interactions of (binary or single) MSPs with the IMBH orbited by a typical cluster star. The formation of an [IMBH,MSP] system is strongly inhibited if the IMBH is orbited by a stellar mass black hole. The [IMBH,MSP] binaries that form are relatively short-lived, $\lsim 10^{8-9}$ yr, since their orbits decay via emission of gravitational waves. The detection of an [IMBH,MSP] system has a low probability of occurrence, when inferred from the current sample of MSPs in GCs. If next generation radio telescopes, like SKA, will detect an order of magnitude larger population of MSP in GCs, at least one [IMBH,MSP] is expected. Therefore, a complete search for low-luminosity MSPs in the GCs of the Milky Way with SKA will have the potential of testing the hypothesis that IMBHs of order $100 \msun$ are commonly hosted in GCs., Comment: 14 pages, 11 figures, 4 tables, to be published in MNRAS
Published: 2007
Full Text: View/download PDF

50. Age constraints in the double pulsar system J0737-3039

Author: Lorimer, D. R., Freire, P. C. C., Stairs, I. H., Kramer, M., McLaughlin, M. A., Burgay, M., Thorsett, S. E., Dewey, R. J., Lyne, A. G., Manchester, R. N., D'Amico, N., Possenti, A., and Joshi, B. C.
Subjects: Astrophysics
Abstract: We investigate the age constraints that can be placed on the double pulsar system using models for the spin-down of the first-born 22.7-ms pulsar A and the 2.77-s pulsar B with characteristic ages of 210 and 50 Myr respectively. Standard models assuming dipolar spin-down of both pulsars suggest that the time since the formation of B is ~50 Myr, i.e. close to B's characteristic age. However, adopting models which account for the impact of A's relativistic wind on B's spin-down we find that the formation of B took place either 80 or 180 Myr ago, depending the interaction mechanism. Formation 80 Myr ago, closer to B's characteristic age, would result in the contribution from J0737-3039 to the inferred coalescence rates for double neutron star binaries increasing by 40%. The 180 Myr age is closer to A's characteristic age and would be consistent with the most recent estimates of the coalescence rate. The new age constraints do not significantly impact recent estimates of the kick velocity, tilt angle between pre and post-supernova orbital planes or pre-supernova mass of B's progenitor., Comment: 5 pages, 2 figures, 1 table, accepted for publication by MNRAS
Published: 2007
Full Text: View/download PDF

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Language

Publication Type

Journal

Database

Publisher

519 results on '"A Possenti"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources