19 results on '"Alessandro Paggi"'
Search Results
2. Detection of X-Ray Polarization from the Blazar 1ES 1959+650 with the Imaging X-Ray Polarimetry Explorer
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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
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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.
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- 2024
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3. The IXPE View of GRB 221009A
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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
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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.
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- 2023
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4. Optical Spectroscopic Observations of Gamma-Ray Blazar Candidates. XII. Follow-up Observations from SOAR, Blanco, NTT, and OAN-SPM
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Abigail García-Pérez, Harold A. Peña-Herazo, Francesco Massaro, Vahram Chavushyan, Raffaele D’abrusco, Nicola Masetti, Marco Landoni, Fabio La Franca, Víctor M. Patiño-Álvarez, Raúl A. Amaya-Almazán, Dan Milisavljevic, Alessandro Paggi, Federica Ricci, Elena Jiménez-Bailón, and Howard A. Smith
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Optical identification ,Blazars ,BL Lacertae objects ,Flat-spectrum radio quasars ,Astronomy ,QB1-991 - Abstract
Roughly one third of the sources in the Fermi-LAT catalogs are listed as unidentified/unassociated γ -ray sources (UGS), i.e., they lack a low-energy counterpart. In addition, there is a growing population of blazars of uncertain type (BCUs). Spectroscopic observations are crucial to confirm the blazar nature of the UGSs candidate counterparts and BCUs. Hence, in 2013 we started an optical spectroscopic campaign to carry out the identifications and classifications. In this paper, as a continuation of the campaign we report the spectra of 39 sources: the sample comprises 37 sources classified as BCUs, one source classified as a BL Lac in the Fourth Source Catalog of the Fermi-LAT (4FGL), and one source classified as UGS. We classify 19 of the sources in the sample as BL Lacs, 13 as blazars with nonnegligible host-galaxy emission, six as Flat Spectrum Radio Quasars, and one as a normal elliptical galaxy. The source listed as BL Lac in the 4FGL seems to be a blazar with nonnegligible host-galaxy emission in our observations, most likely due to an ongoing quiescent state. We classified the UGS source as a BL Lac. Six out of the 39 sources were previously reported in the campaign; in general, both the classifications and redshifts are in agreement, except for one of them with no redshift reported before. Altogether, we provided reliable redshift estimates to 21 out of the 39 sources. Finally, we describe the statistics of the data collected in our campaign so far.
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- 2023
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5. Powerful Yet Lonely: Is 3C 297 a High-redshift Fossil Group?
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Valentina Missaglia, Juan P. Madrid, Mischa Schirmer, Francesco Massaro, Alberto Rodríguez-Ardila, Carlos J. Donzelli, Martell Valencia, Alessandro Paggi, Ralph P. Kraft, Chiara Stuardi, and Belinda J. Wilkes
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Active galactic nuclei ,Brightest cluster galaxies ,Galaxy clusters ,Intracluster medium ,Astrophysics ,QB460-466 - Abstract
The environment of the high-redshift ( z = 1.408), powerful radio-loud galaxy 3C 297 has several distinctive features of a galaxy cluster. Among them, a characteristic halo of hot gas revealed by Chandra X-ray observations. In addition, a radio map obtained with the Very Large Array shows a bright hotspot in the northwestern direction, created by the interaction of the active galactic nucleus (AGN) jet arising from 3C 297 with its environment. In the X-ray images, emission cospatial with the northwestern radio lobe is detected, and peaks at the position of the radio hotspot. The extended, complex X-ray emission observed with our new Chandra data is largely unrelated to its radio structure. Despite having attributes of a galaxy cluster, no companion galaxies have been identified from 39 new spectra of neighboring targets of 3C 297 obtained with the Gemini Multi-Object Spectrograph. None of the 19 galaxies for which a redshift was determined lies at the same distance as 3C 297. The optical spectral analysis of the new Gemini spectrum of 3C 297 reveals an isolated Type II radio-loud AGN. We also detected line broadening in [O ii ] λ 3728 with a FWHM about 1700 km s ^−1 and possible line shifts of up to 500–600 km s ^−1 . We postulate that the host galaxy of 3C 297 is a fossil group, in which most of the stellar mass has merged into a single object, leaving behind an X-ray halo.
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- 2022
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6. OPTICAL SPECTROSCOPIC OBSERVATIONS OF GAMMA-RAY BLAZAR CANDIDATES. VI. FURTHER OBSERVATIONS FROM TNG, WHT, OAN, SOAR, AND MAGELLAN TELESCOPES
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M. Kagaya, Víctor M. Patiño-Álvarez, Marco Landoni, Francesco Massaro, Federica Ricci, Laura Chomiuk, Hideaki Katagiri, Raffaele D'Abrusco, V. H. Chavushyan, N. Masetti, F. La Franca, Dan Milisavljevic, Jay Strader, Elena Jiménez-Bailón, Howard A. Smith, Gino Tosti, C. C. Cheung, N. Álvarez Crespo, Alessandro Paggi, Álvarez Crespo, N., Massaro, F., Milisavljevic, D., Landoni, M., Chavushyan, V., Patiño Álvarez, V., Masetti, N., Jiménez Bailón, E., Strader, J., Chomiuk, L., Katagiri, H., Kagaya, M., Cheung, C. C., Paggi, A., D'Abrusco, R., Ricci, Federica, LA FRANCA, Fabio, Smith, Howard A., Tosti, G., ITA, USA, and RICCI, FEDERICA
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ACTIVE GALACTIC NUCLEI ,RADIO-SOURCES ,Active galactic nucleus ,SAMPLE ,010504 meteorology & atmospheric sciences ,active [Galaxies] ,Young stellar object ,Astrophysics::High Energy Astrophysical Phenomena ,Population ,galaxies: active ,Astrophysics ,Astrophysics::Cosmology and Extragalactic Astrophysics ,01 natural sciences ,MHZ ,BL Lacertae objects: general ,quasars: general ,radiation mechanisms: non-thermal ,GHZ ,0103 physical sciences ,Emission spectrum ,Blazar ,education ,SOURCE CATALOG ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,0105 earth and related environmental sciences ,Physics ,education.field_of_study ,non-thermal [Radiation mechanisms] ,general [BL Lacertae objects] ,Gamma ray ,Quasar ,Astronomy and Astrophysics ,general [Quasars] ,COUNTERPARTS ,Space and Planetary Science ,ALL-SKY SURVEY ,OBJECTS ,Astrophysics - High Energy Astrophysical Phenomena ,EMISSION ,Fermi Gamma-ray Space Telescope - Abstract
Indexación: Web of Science Blazars, one of the most extreme classes of active galaxies, constitute so far the largest known population of.-ray sources, and their number is continuously growing in the Fermi catalogs. However, in the latest release of the Fermi catalog there is still a large fraction of sources that are classified as blazar candidates of uncertain type (BCUs) for which optical spectroscopic observations are necessary to confirm their nature and their associations. In addition, about one-third of the gamma-ray point sources listed in the Third Fermi-LAT Source Catalog (3FGL) are still unassociated and lacking an assigned lower-energy counterpart. Since 2012 we have been carrying out an optical spectroscopic campaign to observe blazar candidates to confirm their nature. In this paper, the sixth of the series, we present optical spectroscopic observations for 30 gamma-ray blazar candidates from different observing programs we carried out with the Telescopio Nazionale Galileo, William Herschel Telescope, Observatorio Astronomico Nacional, Southern Astrophysical Research Telescope, and Magellan. Telescopes. We found that 21 out of 30 sources investigated are BL Lac objects, while the remaining targets are classified as flat-spectrum radio quasars showing the typical broad emission lines of normal quasi-stellar objects. We conclude that our selection of gamma-ray blazar. candidates based on their multifrequency properties continues to be a successful way to discover potential low-energy counterparts of the Fermi. unidentified gamma-ray sources and to confirm the nature of BCUs. http://iopscience.iop.org/article/10.3847/0004-6256/151/4/95/meta
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- 2016
7. XMM-NewtonandSwiftobservations of High Frequency Peaked BL Lacs in the TeV era
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Francesco Massaro, Alfonso Cavaliere, Martin Elvis, and Alessandro Paggi
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Physics ,Swift ,History ,Astrophysics::High Energy Astrophysical Phenomena ,Spectral density ,Astronomy ,Astrophysics ,Curvature ,Lower energy ,Synchrotron ,Spectral line ,Computer Science Applications ,Education ,Luminosity ,law.invention ,Physics and Astronomy (all) ,Acceleration ,law ,computer ,computer.programming_language - Abstract
Most of TeV detected extragalactic sources are BL Lac objects. They belong to the subclass of high frequency peaked BL Lacs (HBLs) exhibiting their spectral energy distributions with a lower energy peak in the X-ray band,interpreted as synchrotron emission. The X-ray spectra are generally curved, and well described in terms of a log-parabolic shape. In a previous investigation of TeV HBLs (TBLs) we found two correlations between their spectral parameters: (1) The synchrotron peak luminosity Lp increases with its peak energy Ep, (2) the curvature parameter b decreases as Ep increases. The first is consistent with the synchrotron scenario, while the second is expected with statistical/stochastic acceleration mechanisms for the emitting particles. Here, we present an extensive X-ray analysis of a sample of HBLs observed with XMM Newton and SWIFT but undetected at TeV energies (UBLs), to compare their spectral behavior with that of TBLs. We investigate the distributions of their spectral parameters, providing an interpretation of both the Ep and b distributions in terms of systematic and stochastic acceleration processes. We also compare the X-ray spectral behavior of UBLs with that in gamma-rays and propose a criterion to select the best HBLs candidates for future TeV observations.
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- 2012
8. The Power form BL Lacs
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Alessandro Paggi
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Physics ,History ,Active galactic nucleus ,Accretion (meteorology) ,Astrophysics::High Energy Astrophysical Phenomena ,Strong gravity ,Astronomy ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,Computer Science Applications ,Education ,Magnetic field ,Black hole ,Physics and Astronomy (all) ,Lorentz factor ,symbols.namesake ,symbols ,Relativistic quantum chemistry ,Blazar ,Astrophysics::Galaxy Astrophysics - Abstract
Blazars are among the brightest Active Galactic Nuclei (AGNs) observed with inferred (isotropic) luminosities up to Liso ~ 1047 erg s−1. Emission from these sources is widely held to originate from a relativistic jet closely aligned to the observer line of sight, with bulk Lorentz factor Γ ~ 10 ÷ 20. Taking into account related relativistic effects the intrinsic jet powers are actually much lower, L ~ Γ−2Liao. A physical reference is provided by the power extractable from a central rotating Kerr Hole spun up by past accretion via the electromagnetic interaction with the magnetic field of the accretion disc, the Blandford-Znajek (BZ) mechanism. The limiting power reads LBZ ~ 2 × 1045 (MBH/109 M⊙) erg s−1 in an equilibrium magnetic field B ~ 104 G. We study in particular gas-poor BL Lacs, which show no evidence of current accretion or well developed accretion disk, and can therefore provide a simple benchmark for this model. A study of several such BL Lacs across the entire electromagnetic spectrum allows robust estimates of the source parameters and energetics, showing that these sources comply with the BZ limit or just exceed it, within the uncertainties on black hole (BH) masses estimation. In particular, powerful BL Lacs like 0716+714 close to the BZ limit appear to be constrained in the evolution of their flaring activity. It is therefore exciting to look for sources sharply exceeding the BZ limit. If any, they could involve orbits plunging into the BH horizon in a region with very intense magnetic field B > 104 G and dominated by strong gravity effects.
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- 2011
9. Two New Catalogs of Blazar Candidates in the WISE Infrared Sky.
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Raffaele D’Abrusco, Nuria Álvarez Crespo, Francesco Massaro, Riccardo Campana, Vahram Chavushyan, Marco Landoni, Fabio La Franca, Nicola Masetti, Dan Milisavljevic, Alessandro Paggi, Federica Ricci, and Howard A. Smith
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- 2019
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10. Chandra Early-type Galaxy Atlas.
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Dong-Woo Kim, Craig Anderson, Douglas Burke, Raffaele D’Abrusco, Giuseppina Fabbiano, Antonella Fruscione, Jennifer Lauer, Michael McCollough, Douglas Morgan, Amy Mossman, Ewan O’Sullivan, Alessandro Paggi, Saeqa Vrtilek, and Ginevra Trinchieri
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- 2019
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11. CHEERS Results from NGC 3393. III. Chandra X-Ray Spectroscopy of the Narrow Line Region.
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W. Peter Maksym, Giuseppina Fabbiano, Martin Elvis, Margarita Karovska, Alessandro Paggi, John Raymond, Junfeng Wang, Thaisa Storchi-Bergmann, and Guido Risaliti
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ACTIVE galactic nuclei ,GALAXIES ,COMPTON scattering ,PHOTOIONIZATION - Abstract
We present spatially resolved Chandra narrow-band imaging and imaging spectroscopy of NGC 3393. This galaxy hosts a Compton-thick Seyfert 2 active galactic nucleus (AGN) with sub-kpc bipolar outflows that are strongly interacting with the circumnuclear gas. We identify narrow-band excess emission associated with the Ne ix 0.905 keV transition (with likely contributions due to intermediate-state iron emission) that points to strong shocks driven by AGN feedback. Imaging spectroscopy resolves outflow-interstellar medium (ISM) interaction sites and the surrounding ISM at ∼100 pc scales, and suggests the presence of a hot AGN wind above the plane at radii beyond the shock sites. The cross-cone shows evidence for reprocessing of photoionization that has passed through gaps in the torus, and also for collisionally excited plasma that may be powered by a shock-confined equatorial outflow. Deep X-ray observations at subarcsecond resolution (such as may be performed very efficiently by Lynx, which would also energetically resolve the complex line emission) are necessary to eliminate model degeneracies and reduce uncertainties in local feedback properties. [ABSTRACT FROM AUTHOR]
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- 2019
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12. 3C 17: The BCG of a Galaxy Cluster at z = 0.22.
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Juan P. Madrid, Carlos J. Donzelli, Alberto Rodríguez-Ardila, Alessandro Paggi, Francesco Massaro, and Mischa Schirmer
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- 2018
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13. Disturbed Fossil Group Galaxy NGC 1132.
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Dong-Woo Kim, Craig Anderson, Doug Burke, Giuseppina Fabbiano, Antonella Fruscione, Jen Lauer, Michael McCollough, Doug Morgan, Amy Mossman, Ewan O’Sullivan, Alessandro Paggi, Saeqa Vrtilek, and Ginevra Trinchieri
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CLASSIFICATION of galaxies ,SIMULATION methods & models ,SHOCK waves ,GALACTIC dynamics ,GALAXY mergers - Abstract
We have analyzed the Chandra archival data of NGC 1132, a well-known fossil group, i.e., a system expected to be old and relaxed long after the giant elliptical galaxy assembly. Instead, the Chandra data reveal that the hot gas morphology is disturbed and asymmetrical, with a cold front following a possible bow shock. We discuss possible origins of the disturbed hot halo, including sloshing by a nearby object, merger, ram pressure by external hotter gas, and nuclear outburst. We consider that the first two mechanisms are likely explanations for the disturbed hot halo, with a slight preference for a minor merger with a low impact parameter because of the match with simulations and previous optical observations. In this case, NGC 1132 may be a rare example of unusual late mergers seen in recent simulations. Regardless of the origin of the disturbed hot halo, the paradigm of the fossil system needs to be reconsidered. [ABSTRACT FROM AUTHOR]
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- 2018
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14. Constraining the Physical State of the Hot Gas Halos in NGC 4649 and NGC 5846.
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Alessandro Paggi, Dong-Woo Kim, Craig Anderson, Doug Burke, Raffaele D’Abrusco, Giuseppina Fabbiano, Antonella Fruscione, Tara Gokas, Jen Lauer, Michael McCollough, Doug Morgan, Amy Mossman, Ewan O’Sullivan, Ginevra Trinchieri, Saeqa Vrtilek, Silvia Pellegrini, Aaron J. Romanowsky, and Jean Brodie
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INTERSTELLAR medium , *HYDROSTATIC equilibrium , *GRAVITATION , *DARK matter , *STAR formation - Abstract
We present results of a joint Chandra/XMM-Newton analysis of the early-type galaxies NGC 4649 and NGC 5846 aimed at investigating differences between mass profiles derived from X-ray data and those from optical data, to probe the state of the hot interstellar medium (ISM) in these galaxies. If the hot ISM is at a given radius in hydrostatic equilibrium (HE), the X-ray data can be used to measure the total enclosed mass of the galaxy. Differences from optically derived mass distributions therefore yield information about departures from HE in the hot halos. The X-ray mass profiles in different angular sectors of NGC 4649 are generally smooth with no significant azimuthal asymmetries within 12 kpc. Extrapolation of these profiles beyond this scale yields results consistent with the optical estimate. However, in the central region ( kpc) the X-ray data underpredict the enclosed mass, when compared with the optical mass profiles. Consistent with previous results, we estimate a nonthermal pressure component accounting for 30% of the gas pressure, likely linked to nuclear activity. In NGC 5846 the X-ray mass profiles show significant azimuthal asymmetries, especially in the NE direction. Comparison with optical mass profiles in this direction suggests significant departures from HE, consistent with bulk gas compression and decompression due to sloshing on ∼15 kpc scales; this effect disappears in the NW direction, where the emission is smooth and extended. In this sector we find consistent X-ray and optical mass profiles, suggesting that the hot halo is not responding to strong nongravitational forces. [ABSTRACT FROM AUTHOR]
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- 2017
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15. CHEERS Results from NGC 3393. II. Investigating the Extended Narrow-line Region Using Deep Chandra Observations and Hubble Space Telescope Narrow-line Imaging.
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W. Peter Maksym, Giuseppina Fabbiano, Martin Elvis, Margarita Karovska, Alessandro Paggi, John Raymond, Junfeng Wang, and Thaisa Storchi-Bergmann
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ACTIVE galactic nuclei ,INTERSTELLAR medium ,RADIO observations of artificial satellites - Abstract
The CHandra Extended Emission Line Region Survey (CHEERS) is an X-ray study of nearby active galactic nuclei (AGNs) designed to take full advantage of Chandra's unique angular resolution by spatially resolving feedback signatures and effects. In the second paper of a series on CHEERS target NGC 3393, we examine deep high-resolution Chandra images and compare them with Hubble Space Telescope narrow-line images of [O iii], [S ii], and Hα, as well as previously unpublished mid-ultraviolet (MUV) images. The X-rays provide unprecedented evidence that the S-shaped arms that envelope the nuclear radio outflows extend only ≲0.″2 (≲50 pc) across. The high-resolution multiwavelength data suggest that the extended narrow-line region is a complex multiphase structure in the circumnuclear interstellar medium (ISM). Its ionization structure is highly stratified with respect to outflow-driven bubbles in the bicone and varies dramatically on scales of ∼10 pc. Multiple findings show likely contributions from shocks to the feedback in regions where radio outflows from the AGN most directly influence the ISM. These findings include Hα evidence for gas compression and extended MUV emission and are in agreement with existing STIS kinematics. Extended filamentary structure in the X-rays and optical suggests the presence of an undetected plasma component, whose existence could be tested with deeper radio observations. [ABSTRACT FROM AUTHOR]
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- 2017
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16. X-Ray Emission from the Nuclear Region of Arp 220.
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Alessandro Paggi, Giuseppina Fabbiano, Guido Risaliti, Junfeng Wang, Margarita Karovska, Martin Elvis, W. Peter Maksym, Jonathan McDowell, and Jay Gallagher
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SPECTRUM analysis , *STARBURSTS , *INFRARED radiation , *X-ray emission spectroscopy , *HEAT - Abstract
We present an imaging and spectral analysis of the nuclear region of the ultraluminous infrared galaxy merger of Arp 220, using deep Chandra-ACIS observations summing up to . Narrowband imaging with subpixel resolution of the innermost nuclear region reveals two distinct Fe–K emitting sources, coincident with the infrared and radio nuclear clusters. These sources are separated by 1′ (∼380 pc). The X-ray emission is extended and elongated in the eastern (E) nucleus, like the disk emission observed in millimeter radio images, suggesting a starburst dominance in this region. We estimate an Fe–K equivalent width of for both sources and observe 2–10 keV luminosities of (western, W) and (E). In the 6–7 keV band the emission from these regions is dominated by the 6.7 keV Fe xxv line, suggesting a contribution from collisionally ionized gas. The thermal energy content of this gas is consistent with the kinetic energy injection in the interstellar medium by SNe II. However, nuclear winds from a hidden active galactic nucleus (AGN) () cannot be excluded. The upper limits on the neutral Fe–Kα flux of the nuclear regions correspond to the intrinsic AGN 2–10 keV luminosities of (W) and (E). For typical AGN spectral energy distributions the bolometric luminosities are (W) and (E), and black hole masses of (W) and (E) are evaluated for Eddington limited AGNs with a standard 10% efficiency. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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17. MAPPING SEYFERT AND LINER EXCITATION MODES IN THE INNER KPC OF NGC 3393.
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W. Peter Maksym, Giuseppina Fabbiano, Martin Elvis, Margarita Karovska, Alessandro Paggi, John Raymond, Junfeng Wang, and Thaisa Storchi-Bergmann
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ACTIVE galactic nuclei ,SEYFERT galaxies ,SUPERMASSIVE black holes ,STAR formation ,PHOTOIONIZATION - Abstract
We mapped the extended narrowline region (ENLR) of NGC 3393 on scales of ( kpc) from the nucleus using emission line images of Hαλ6563, [O iii], and [S ii], taken with the Hubble Space Telescope as part of the CHandra survey of Extended Emission line Regions in nearby Seyfert galaxies (CHEERS). By mapping these lines onto a spatially resolved Baldwin–Phillips–Terlevich diagram, we investigate the impact of feedback from a Compton-thick active galactic nucleus on its circumnuclear ISM. We find that the expected Seyfert-like emission within the ionization bicone ( 770 pc). We also find a new, figure-8-shaped low ionization emission line region (LINER) cocoon enveloping the bicone and defining a sharp ( pc) transition between higher and lower-ionization zones. These data illustrate the morphological dependence of ionization states of the ENLR relative to bicone and host gas geometries. [ABSTRACT FROM AUTHOR]
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- 2016
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18. HIDDEN ACTIVE GALACTIC NUCLEI IN EARLY-TYPE GALAXIES.
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Alessandro Paggi, Giuseppina Fabbiano, Francesca Civano, Silvia Pellegrini, Martin Elvis, and Dong-Woo Kim
- Subjects
- *
TIDAL stripping (Astrophysics) , *GALACTIC nuclei , *ASTRONOMY , *ELECTROMAGNETIC waves ,UNIVERSE - Abstract
We present a stacking analysis of the complete sample of early-type galaxies (ETGs) in the Chandra COSMOS (C-COSMOS) survey, to explore the nature of the X-ray luminosity in the redshift and stellar luminosity ranges and . Using established scaling relations, we subtract the contribution of X-ray binary populations to estimate the combined emission of hot ISM and active galactic nuclei (AGNs). To discriminate between the relative importance of these two components, we (1) compare our results with the relation observed in the local universe for hot gaseous halos emission in ETGs, and (2) evaluate the spectral signature of each stacked bin. We find two regimes where the non-stellar X-ray emission is hard, consistent with AGN emission. First, there is evidence of hard, absorbed X-ray emission in stacked bins including relatively high z (∼1.2) ETGs with average high X-ray luminosity (). These luminosities are consistent with the presence of highly absorbed “hidden” AGNs in these ETGs, which are not visible in their optical–IR spectra and spectral energy distributions. Second, confirming the early indication from our C-COSMOS study of X-ray detected ETGs, we find significantly enhanced X-ray luminosity in lower stellar mass ETGs (), relative to the local relation. The stacked spectra of these ETGs also suggest X-ray emission harder than expected from gaseous hot halos. This emission is consistent with inefficient accretion onto . [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
19. A COMPREHENSIVE STATISTICAL DESCRIPTION OF RADIO-THROUGH-γ-RAY SPECTRAL ENERGY DISTRIBUTIONS OF ALL KNOWN BLAZARS.
- Author
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Peiyuan Mao, C. Megan Urry, Francesco Massaro, Alessandro Paggi, Joe Cauteruccio, and Soren R. Künzel
- Published
- 2016
- Full Text
- View/download PDF
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