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Start Over Author "Cikota, A" Journal monthly notices of the royal astronomical society
27 results on '"Cikota, A"'

1. Linear spectropolarimetry of 35 Type Ia Supernovae with VLT/FORS: An analysis of the Si ii line polarization

Author

Cikota, Aleksandar, Patat, Ferdinando, Wang, Lifan, Wheeler, J Craig, Bulla, Mattia, Baade, Dietrich, Höflich, Peter, Cikota, Stefan, Clocchiatti, Alejandro, Maund, Justyn R, Stevance, Heloise F, and Yang, Yi

Subjects
Astronomical Sciences, Physical Sciences, supernovae: general, polarization, astro-ph.HE, astro-ph.SR, Astronomical and Space Sciences, Astronomy & Astrophysics, Astronomical sciences, Particle and high energy physics, Space sciences
Abstract

Spectropolarimetry enables us to measure the geometry and chemical structure of the ejecta in supernova explosions, which is fundamental for the understanding of their explosion mechanism(s) and progenitor systems. We collected archival data of 35 Type Ia supernovae (SNe Ia), observed with Focal Reducer and Low-Dispersion Spectrograph (FORS) on the Very Large Telescope at 127 epochs in total. We examined the polarization of the Si II λ6355 Å line (pSi II) as a function of time, which is seen to peak at a range of various polarization degrees and epochs relative to maximum brightness. We reproduced the m15–pSi II relationship identified in a previous study, and show that subluminous and transitional objects display polarization values below the m15–pSi II relationship for normal SNe Ia. We found a statistically significant linear relationship between the polarization of the Si II λ6355 Å line before maximum brightness and the Si II line velocity and suggest that this, along with the m15–pSi II relationship, may be explained in the context of a delayed-detonation model. In contrast, we compared our observations to numerical predictions in the m15–vSi II plane and found a dichotomy in the polarization properties between Chandrasekhar and sub-Chandrasekhar mass explosions, which supports the possibility of two distinct explosion mechanisms. A subsample of SNe displays evolution of loops in the q–u plane that suggests a more complex Si structure with depth. This insight, which could not be gleaned from total flux spectra, presents a new constraint on explosion models. Finally, we compared our statistical sample of the Si II polarization to quantitative predictions of the polarization levels for the double-detonation, delayed-detonation, and violent-merger models.

Published
2019

2. The shape of SN 1993J re-analysed

Author

Stevance, HF, Baade, D, Bruten, JR, Cikota, A, Clocchiatti, A, Hines, DC, Höflich, P, Maund, JR, Patat, F, Vallely, PJ, and Wheeler, JC

Subjects
techniques: polarimetric, supernovae: general, supernovae: individual: SN 1993J, astro-ph.SR, astro-ph.GA, Astronomical and Space Sciences, Astronomy & Astrophysics
Abstract

SN 1993J is one of the best-studied Type IIb supernovae. Spectropolarimetric data analyses were published over two decades ago at a time when the field of supernova spectropolarimetry was in its infancy. Here, we present a new analysis of the spectropolarimetric data of SN 1993J and an improved estimate of its interstellar polarization (ISP) as well as a critical review of ISP removal techniques employed in the field. The polarization of SN 1993J is found to show significant alignment on the q − u plane, suggesting the presence of a dominant axis and therefore of continuum polarization. We also see strong line polarization features, including H β, He I λ5876, H α, He I λ6678, He I λ7065, and high velocity (HV) components of He I λ5876 and H α. SN 1993J is therefore the second example of a stripped-envelope supernova, alongside iPTF13bvn, with prominent HV helium polarization features, and the first to show a likely HV H α contribution. Overall, we determine that the observed features can be interpreted as the superposition of anisotropically distributed line forming regions over ellipsoidal ejecta. We cannot exclude the possibility of an off-axis energy source within the ejecta. These data demonstrate the rich structures that are inaccessible if solely considering the flux spectra but can be probed by spectropolarimetric observations. In future studies, the new ISP corrected data can be used in conjunction with 3D radiative transfer models to better map the geometry of the ejecta of SN 1993J.

Published
2020

3. The 3D shape of Type IIb SN 2011hs

Author

Stevance, HF, Maund, JR, Baade, D, Bruten, J, Cikota, A, Höflich, P, Wang, L, Wheeler, JC, Clocchiatti, A, Spyromilio, J, Patat, F, Yang, Y, and Crowther, P

Subjects
techniques: polarimetric, supernovae: general, supernovae: individual: SN 2011hs, astro-ph.SR, Astronomical and Space Sciences, Astronomy & Astrophysics
Abstract

We observed seven epochs of spectropolarimetry in optical wavelengths for the Type IIb SN 2011hs, ranging from-3 to +40 d with respect to V-band maximum. A high degree of interstellar polarization was detected (up to ∼3 per cent), with a peak lying blueward of 4500 Å. Similar behaviours have been seen in some Type Ia supernovae (SNe), but had never been observed in a Type IIb. We find that it is most likely the result of a relative enhancement of small silicate grains in the vicinity of the SN. Significant intrinsic continuum polarization was recovered at-3 and +2 d (p = 0.55 ± 0.12 per cent and 0.75 ± 0.11 per cent, respectively). We discuss the change of the polarization angle across spectral lines and in the continuum as diagnostics for the 3D structure of the ejecta. We see a gradual rotation by about-50° in the continuum polarization angle between-2 and +18 d after V-band maximum. A similar rotation in He i λ5876, Hα and the Ca ii infrared triplet seems to indicate a strong influence of the global geometry on the line polarization features. The differences in the evolution of their respective loops on the Stokes q-u plane suggest that line specific geometries are also being probed. Possible interpretations are discussed and placed in the context of literature. We find that the spectropolarimetry of SN 2011hs is most similar to that of SN 2011dh, albeit with notable differences.

Published
2019

4. Multiwavelength study of the gravitationally lensed blazar QSO B0218+357 between 2016 and 2020

Author

V A Acciari, S Ansoldi, L A Antonelli, A Arbet Engels, M Artero, K Asano, D Baack, A Babić, A Baquero, U Barres de Almeida, J A Barrio, I Batković, J Becerra González, W Bednarek, L Bellizzi, E Bernardini, M Bernardos, A Berti, J Besenrieder, W Bhattacharyya, C Bigongiari, A Biland, O Blanch, G Bonnoli, Ž Bošnjak, G Busetto, R Carosi, G Ceribella, M Cerruti, Y Chai, A Chilingarian, S Cikota, S M Colak, E Colombo, J L Contreras, J Cortina, S Covino, G D’Amico, V D’Elia, P Da Vela, F Dazzi, A De Angelis, B De Lotto, M Delfino, J Delgado, C Delgado Mendez, D Depaoli, F Di Pierro, L Di Venere, E Do Souto Espiñeira, D Dominis Prester, A Donini, D Dorner, M Doro, D Elsaesser, V Fallah Ramazani, A Fattorini, G Ferrara, M V Fonseca, L Font, C Fruck, S Fukami, R J García López, M Garczarczyk, S Gasparyan, M Gaug, N Giglietto, F Giordano, P Gliwny, N Godinović, J G Green, D Green, D Hadasch, A Hahn, L Heckmann, J Herrera, J Hoang, D Hrupec, M Hütten, T Inada, S Inoue, K Ishio, Y Iwamura, I Jiménez, J Jormanainen, L Jouvin, Y Kajiwara, M Karjalainen, D Kerszberg, Y Kobayashi, H Kubo, J Kushida, A Lamastra, D Lelas, F Leone, E Lindfors, S Lombardi, F Longo, R López-Coto, M López-Moya, A López-Oramas, S Loporchio, B Machado de Oliveira Fraga, C Maggio, P Majumdar, M Makariev, M Mallamaci, G Maneva, M Manganaro, K Mannheim, L Maraschi, M Mariotti, M Martínez, D Mazin, S Menchiari, S Mender, S Mićanović, D Miceli, T Miener, M Minev, J M Miranda, R Mirzoyan, E Molina, A Moralejo, D Morcuende, V Moreno, E Moretti, V Neustroev, C Nigro, K Nilsson, K Nishijima, K Noda, S Nozaki, Y Ohtani, T Oka, J Otero-Santos, S Paiano, M Palatiello, D Paneque, R Paoletti, J M Paredes, L Pavletić, P Peñil, C Perennes, M Persic, P G Prada Moroni, E Prandini, C Priyadarshi, I Puljak, W Rhode, M Ribó, J Rico, C Righi, A Rugliancich, L Saha, N Sahakyan, T Saito, S Sakurai, K Satalecka, F G Saturni, B Schleicher, K Schmidt, T Schweizer, J Sitarek, I Šnidarić, D Sobczynska, A Spolon, A Stamerra, D Strom, M Strzys, Y Suda, T Surić, M Takahashi, F Tavecchio, P Temnikov, T Terzić, M Teshima, L Tosti, S Truzzi, A Tutone, S Ubach, J van Scherpenberg, G Vanzo, M Vazquez Acosta, S Ventura, V Verguilov, C F Vigorito, V Vitale, I Vovk, M Will, C Wunderlich, D Zarić, F de Palma, F D’Ammando, A Barnacka, D K Sahu, M Hodges, T Hovatta, S Kiehlmann, W Max-Moerbeck, A C S Readhead, R Reeves, T J Pearson, A Lähteenmäki, I Björklund, M Tornikoski, J Tammi, S Suutarinen, K Hada, and K Niinuma

Published
2021
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5. MAGIC detection of GRB 201216C at z = 1.1

Author

Abe, H, primary, Abe, S, additional, Acciari, V A, additional, Agudo, I, additional, Aniello, T, additional, Ansoldi, S, additional, Antonelli, L A, additional, Engels, A Arbet, additional, Arcaro, C, additional, Artero, M, additional, Asano, K, additional, Baack, D, additional, Babić, A, additional, Baquero, A, additional, de Almeida, U Barres, additional, Barrio, J A, additional, Batković, I, additional, Baxter, J, additional, González, J Becerra, additional, Bednarek, W, additional, Bernardini, E, additional, Bernete, J, additional, Berti, A, additional, Besenrieder, J, additional, Bigongiari, C, additional, Biland, A, additional, Blanch, O, additional, Bonnoli, G, additional, Bošnjak, Ž, additional, Burelli, I, additional, Busetto, G, additional, Campoy-Ordaz, A, additional, Carosi, A, additional, Carosi, R, additional, Carretero-Castrillo, M, additional, Castro-Tirado, A J, additional, Ceribella, G, additional, Chai, Y, additional, Cifuentes, A, additional, Cikota, S, additional, Colombo, E, additional, Contreras, J L, additional, Cortina, J, additional, Covino, S, additional, D’Amico, G, additional, D’Elia, V, additional, Da Vela, P, additional, Dazzi, F, additional, De Angelis, A, additional, De Lotto, B, additional, Del Popolo, A, additional, Delfino, M, additional, Delgado, J, additional, Mendez, C Delgado, additional, Depaoli, D, additional, Di Pierro, F, additional, Di Venere, L, additional, Prester, D Dominis, additional, Donini, A, additional, Dorner, D, additional, Doro, M, additional, Elsaesser, D, additional, Emery, G, additional, Escudero, J, additional, Fari na, L, additional, Fattorini, A, additional, Foffano, L, additional, Font, L, additional, Fukami, S, additional, Fukazawa, Y, additional, López, R J García, additional, Garczarczyk, M, additional, Gasparyan, S, additional, Gaug, M, additional, Paiva, J G Giesbrecht, additional, Giglietto, N, additional, Giordano, F, additional, Gliwny, P, additional, Godinović, N, additional, Grau, R, additional, Green, D, additional, Green, J G, additional, Hadasch, D, additional, Hahn, A, additional, Hassan, T, additional, Heckmann, L, additional, Herrera, J, additional, Hrupec, D, additional, Hütten, M, additional, Imazawa, R, additional, Inada, T, additional, Iotov, R, additional, Ishio, K, additional, Martínez, I Jiménez, additional, Jormanainen, J, additional, Kerszberg, D, additional, Kluge, G W, additional, Kobayashi, Y, additional, Kouch, P M, additional, Kubo, H, additional, Kushida, J, additional, Lezáun, M Láinez, additional, Lamastra, A, additional, Leone, F, additional, Lindfors, E, additional, Linhoff, L, additional, Lombardi, S, additional, Longo, F, additional, López-Coto, R, additional, López-Moya, M, additional, López-Oramas, A, additional, Loporchio, S, additional, Lorini, A, additional, Lyard, E, additional, de Oliveira Fraga, B Machado, additional, Majumdar, P, additional, Makariev, M, additional, Maneva, G, additional, Mang, N, additional, Manganaro, M, additional, Mangano, S, additional, Mannheim, K, additional, Mariotti, M, additional, Martínez, M, additional, Mas-Aguilar, A, additional, Mazin, D, additional, Menchiari, S, additional, Mender, S, additional, Mićanović, S, additional, Miceli, D, additional, Miener, T, additional, Miranda, J M, additional, Mirzoyan, R, additional, González, M Molero, additional, Molina, E, additional, Mondal, H A, additional, Moralejo, A, additional, Morcuende, D, additional, Nanci, C, additional, Nava, L, additional, Neustroev, V, additional, Rosillo, M Nievas, additional, Nigro, C, additional, Nikolić, L, additional, Nilsson, K, additional, Nishijima, K, additional, Ekoume, T Njoh, additional, Noda, K, additional, Nozaki, S, additional, Ohtani, Y, additional, Okumura, A, additional, Otero-Santos, J, additional, Paiano, S, additional, Palatiello, M, additional, Paneque, D, additional, Paoletti, R, additional, Paredes, J M, additional, Pavletić, L, additional, Pavlović, D, additional, Persic, M, additional, Pihet, M, additional, Pirola, G, additional, Podobnik, F, additional, Moroni, P G Prada, additional, Prandini, E, additional, Principe, G, additional, Priyadarshi, C, additional, Rhode, W, additional, Ribó, M, additional, Rico, J, additional, Righi, C, additional, Sahakyan, N, additional, Saito, T, additional, Satalecka, K, additional, Saturni, F G, additional, Schleicher, B, additional, Schmidt, K, additional, Schmuckermaier, F, additional, Schubert, J L, additional, Schweizer, T, additional, Sciaccaluga, A, additional, Sitarek, J, additional, Sliusar, V, additional, Sobczynska, D, additional, Spolon, A, additional, Stamerra, A, additional, Strišković, J, additional, Strom, D, additional, Strzys, M, additional, Suda, Y, additional, Suutarinen, S, additional, Tajima, H, additional, Takahashi, M, additional, Takeishi, R, additional, Tavecchio, F, additional, Temnikov, P, additional, Terauchi, K, additional, Terzić, T, additional, Teshima, M, additional, Tosti, L, additional, Truzzi, S, additional, Tutone, A, additional, Ubach, S, additional, van Scherpenberg, J, additional, Acosta, M Vazquez, additional, Ventura, S, additional, Verguilov, V, additional, Viale, I, additional, Vigorito, C F, additional, Vitale, V, additional, Vovk, I, additional, Walter, R, additional, Will, M, additional, Yamamoto, T, additional, Gomboc, A, additional, Jordana-Mitjans, N, additional, Melandri, A, additional, Mundell, C G, additional, Shrestha, M, additional, and Steele, I A, additional

Published
2023
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6. Multiwavelength Variability and Correlation Studies of Mrk 421 During Historically Low X-ray and Y-ray Activity in 2015–2016

Author

Janeth Valverde Quispe, V. A. Acciari, S. Ansoldi, L. A. Antonelli, K. Asano, A. Babic, B. Banerjee, A. Baquero, U.BarresdeAlmeida, J. A. Barrio, J. Becerra Gonzalez, W. Bednarek, L. Bellizzi, E. Bernardini, M. Bernardos, A. Berti, J. Besenrieder, W. Bhattacharyya, C. Bigongiari, O. Blanch, G. Bonnoli, Z. Bosnjak, G. Busetto, R. Carosi, G. Ceribella, M. Cerruti, Y. Chai, A. Chilingarian, S. Cikota, S. M. Colak, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, G. D’Amico, V. D’Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, C. Delgado Mendez, D. Depaoli, T. Di Girolamo, F. Di Pierro, L. Di Venere, E. Do Souto Espineira, D. Dominis Prester, A. Donini, M. Doro, V. Fallah Ramazani, A. Fattorini, G. Ferrara, L. Foffano, M. V. Fonseca, L. Font, C. Fruck, S. Fukami, R. J. Garcıa Lopez, M. Garczarczyk, S. Gasparyan, M. Gaug, N. Giglietto, F. Giordano, P. Gliwny, N. Godinovic, J. G. Green, D. Green, D. Hadasch, A. Hahn, L. Heckmann, J. Herrera, J. Hoang, D. Hrupec, M. Hutten, T. Inada, S. Inoue, K. Ishio, Y. Iwamura, J. Jormanainen, L. Jouvin, Y. Kajiwara, M. Karjalainen, D. Kerszberg, Y. Kobayashi, H. Kubo, J. Kushida, A. Lamastra, D. Lelas, F. Leone, E. Lindfors, S. Lombardi, F. Longo, M. Lopez, R. Lopez-Coto, A. Lopez-Oramas, S. Loporchio, B. Machado de Oliveira Fraga, C. Maggio, P. Majumdar, M. Makariev, M. Mallamaci, G. Maneva, M. Manganaro, L. Maraschi, M. Mariotti, M. Martınez, D. Mazin, S. Mender, S. Micanovic, D. Miceli, T. Miener, M. Minev, J. M. Miranda, R. Mirzoyan, E. Molina, A. Moralejo, D. Morcuende, V. Moreno, E. Moretti, P. Munar-Adrover, V. Neustroev, C. Nigro, K. Nilsson, D. Ninci, K. Nishijima, K. Noda, S. Nozaki, Y. Ohtani, T. Oka, J. Otero-Santos, M. Palatiello, D. Paneque, R. Paoletti, J. M. Paredes, L. Pavletic, P. P enil, C. Perennes, M. Persic, P. G . Prada Moroni, E. Prandini, C. Priyadarshi, I. Puljak, W. Rhode, M. Ribo, J. Rico, C. Righi, A. Rugliancich, L. Saha, N. Sahakyan, T. Saito, S. Sakurai, K. Satalecka, B. Schleicher, K. Schmidt, T. Schweizer, J. Sitarek, I. Snidaric, D. Sobczynska, A. Spolon, A. Stamerra, D. Strom, M. Strzys, Y. Suda, T. Suric, M. Takahashi, F. Tavecchio, P. Temnikov, T. Terzic, M. Teshima, N. Torres-Alba, L. Tosti, S. Truzzi, J. van Scherpenberg, G. Vanzo, M. Vazquez Acosta, S. Ventura, V. Verguilov, C. F. Vigorito, V. Vitale, I. Vovk, M. Will, D. Zaric, A. Arbet-Engels, D. Baack, M. Balbo, M. Beck, N. Biederbeck, A. Biland, T. Bretz, K. Bruegge, J. Buss, D. Dorner, D. Elsaesser, D. Hildebrand, R. Iotov, M. Klinger, K. Mannheim, D. Neise, A. Neronov, M. Noethe, A. Paravac, V. Sliusar, F. Theissen, R. Walter, J. Valverde, D. Horan, M. Giroletti, M. Perri, F. Verrecchia, C. Leto, A. C. Sadun, J. W. Moody, M. Joner, A. P. Marscher, S. G. Jorstad, A. Lahteenmaki, M. Tornikoski, V. Ramakrishnan, E. Jarvela, R. J. C. Vera, S. Righini, and A.Y.Lien

Subjects
Astronomy
Abstract

We report a characterization of the multiband flux variability and correlations of the nearby (z=0.031) blazar Markarian 421(Mrk 421) using data from Mets ̈ahovi, Swift, Fermi-LAT, MAGIC, FACT, and other collaborations and instruments from 2014November till 2016 June. Mrk 421 did not show any prominent flaring activity, but exhibited periods of historically low activity above 1 TeV (F>1TeV<1.7×10−12ph cm−2s−1) and in the 2–10 keV (X-ray) band (F2−10 keV<3.6×10−11erg cm−2s−1),during which the Swift-BAT data suggest an additional spectral component beyond the regular synchrotron emission. The highest flux variability occurs in X-rays and very high-energy (E>0.1 TeV)γ-rays, which, despite the low activity, show a significant positive correlation with no time lag. The HRkeV and HRTeV show the harder-when-brighter trend observed in many blazars, but the trend flattens at the highest fluxes, which suggests a change in the processes dominating the blazar variability. Enlarging our dataset with data from years 2007 to 2014, we measured a positive correlation between the optical and the GeV emission over a range of about 60 d centred at time lag zero, and a positive correlation between the optical/GeV and the radio emission over a range of about 60 d centred at a time lag of 43+9−6d. This observation is consistent with the radio-bright zone being located about 0.2 parsec downstream from the optical/GeV emission regions of the jet. The flux distributions are better described with a lognormal function in most of the energy bands probed, indicating that the variability in Mrk 421 is likely produced by a multiplicative process.

Published
2020
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7. The core normal Type Ia supernova 2019np – an overall spherical explosion with an aspherical surface layer and an aspherical 56Ni core

Author

Hoeflich, Peter, primary, Yang, Yi, additional, Baade, Dietrich, additional, Cikota, Aleksandar, additional, Maund, Justyn R, additional, Mishra, Divya, additional, Patat, Ferdinando, additional, Patra, Kishore C, additional, Wang, Lifan, additional, Wheeler, J Craig, additional, Filippenko, Alexei V, additional, Gal-Yam, Avishay, additional, and Schulze, Steven, additional

Published
2023
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8. The interaction of supernova 2018evt with a substantial amount of circumstellar matter – An SN 1997cy-like event

Author

Yang, Yi, primary, Baade, Dietrich, additional, Hoeflich, Peter, additional, Wang, Lifan, additional, Cikota, Aleksandar, additional, Chen, Ting-Wan, additional, Burke, Jamison, additional, Hiramatsu, Daichi, additional, Pellegrino, Craig, additional, Howell, D Andrew, additional, McCully, Curtis, additional, Valenti, Stefano, additional, Schulze, Steve, additional, Gal-Yam, Avishay, additional, Wang, Lingzhi, additional, Filippenko, Alexei V, additional, Maeda, Keiichi, additional, Bulla, Mattia, additional, Yao, Yuhan, additional, Maund, Justyn R, additional, Patat, Ferdinando, additional, Spyromilio, Jason, additional, Wheeler, J Craig, additional, Rau, Arne, additional, Hu, Lei, additional, Li, Wenxiong, additional, Andrews, Jennifer E, additional, Galbany, Llúis, additional, Sand, David J, additional, Shahbandeh, Melissa, additional, Hsiao, Eric Y, additional, and Wang, Xiaofeng, additional

Published
2022
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9. The shape of SN 1993J re-analysed

Author

John C Wheeler, Patrick J. Vallely, Alejandro Clocchiatti, P. Höflich, J. Bruten, Heloise F. Stevance, Dean C. Hines, Aleksandar Cikota, Dietrich Baade, Justyn R. Maund, and Ferdinando Patat

Subjects
Physics, 010308 nuclear & particles physics, FOS: Physical sciences, chemistry.chemical_element, Astronomy and Astrophysics, Astrophysics, Polarization (waves), Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Spectral line, Supernova, Superposition principle, Astrophysics - Solar and Stellar Astrophysics, chemistry, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Radiative transfer, Astrophysics::Solar and Stellar Astrophysics, Energy source, Ejecta, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Helium
Abstract

SN 1993J is one of the best studied Type IIb supernovae. Spectropolarimetric data analyses were published over two decades ago at a time when the field of supernova spectropolarimetry was in its infancy. Here we present a new analysis of the spectropolarimetric data of SN 1993J and an improved estimate of its interstellar polarization (ISP) as well as a critical review of ISP removal techniques employed in the field. The polarization of SN 1993J is found to show significant alignment on the $q-u$ plane, suggesting the presence of a dominant axis and therefore of continuum polarization. We also see strong line polarization features, including $\mathrm{H\beta}$, He\,{\sc i} $\lambda 5876$, $\mathrm{H\alpha}$, He\,{\sc i} $\lambda 6678$, He\,{\sc i} $\lambda 7065$, and high velocity (HV) components of He\,{\sc i} $\lambda 5876$ and $\mathrm{H\alpha}$. SN 1993J is therefore the second example of a stripped envelope supernova, alongside iPTF13bvn, with prominent HV helium polarization features, and the first to show a likely HV \halpha contribution. Overall, we determine that the observed features can be interpreted as the superposition of anisotropically distributed line forming regions over ellipsoidal ejecta. We cannot exclude the possibility of an off-axis energy source within the ejecta. These data demonstrate the rich structures that are inaccessible if solely considering the flux spectra but can be probed by spectropolarimetric observations. In future studies, the new ISP corrected data can be used in conjunction with 3D radiative transfer models to better map the geometry of the ejecta of SN 1993J., Comment: 18 pages, 12 figures, Accepted for publication in MNRAS

Published
2020
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10. The core normal Type Ia supernova 2019np – an overall spherical explosion with an aspherical surface layer and an aspherical 56Ni core.

Author

Hoeflich, Peter, (杨轶), Yi Yang, Baade, Dietrich, Cikota, Aleksandar, Maund, Justyn R, Mishra, Divya, Patat, Ferdinando, Patra, Kishore C, Wang, Lifan, Wheeler, J Craig, Filippenko, Alexei V, Gal-Yam, Avishay, and Schulze, Steven

Subjects
TYPE I supernovae, OCCULTATIONS (Astronomy), EXPLOSIONS
Abstract

Optical spectropolarimetry of the normal thermonuclear supernova (SN) 2019np from −14.5 to +14.5 d relative to B -band maximum detected an intrinsic continuum polarization (p cont) of 0.21 ± 0.09 per cent at the first epoch. Between days −11.5 and  +0.5, p cont remained ∼0 and by day +14.5 was again significant at 0.19 ± 0.10 per cent. Not considering the first epoch, the dominant axis of |${\rm Si\, {\small II}}$|  λ6355 was roughly constant staying close the continuum until both rotated in opposite directions on day  +14.5. Detailed radiation-hydrodynamical simulations produce a very steep density slope in the outermost ejecta so that the low first-epoch p cont ≈ 0.2 per cent nevertheless suggests a separate structure with an axis ratio ∼2 in the outer carbon-rich (3.5–4) × 10−3 M⊙. Large-amplitude fluctuations in the polarization profiles and a flocculent appearance of the polar diagram for the |${\rm Ca\, {\small II}}$|  near-infrared triplet (NIR3) may be related by a common origin. The temporal evolution of the polarization spectra agrees with an off-centre delayed detonation. The late-time increase in polarization and the possible change in position angle are also consistent with an aspherical 56Ni core. The p cont and the absorptions due to |${\rm Si\, {\small II}}$| λ6355 and |${\rm Ca\, {\small II}}$|  NIR3 form in the same region of the extended photosphere, with an interplay between line occultation and thermalization producing p. Small-scale polarization features may be due to small-scale structures, but many could be related to atomic patterns of the quasi-continuum; they hardly have an equivalent in the total-flux spectra. We compare SN 2019np to other SNe and develop future objectives and strategies for SN Ia spectropolarimetry. [ABSTRACT FROM AUTHOR]

Published
2023
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11. An intermittent extreme BL Lac: MWL study of 1ES 2344+514 in anenhanced state

Author

A Acciari, Magic Collaboration V., Ansoldi, S., A Antonelli, L., Arbet&nbsp, A, Engels, Babić, A., Banerjee, B., Barres&nbsp, U, Almeida, Nbsp, A Barrio, J., Becerra&nbsp, J, González, Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Blanch, O., Bonnoli, G., Bošnjak, Ž, Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingaryan, A., Cikota, S., M Colak, S., Colin, U., Colombo, E., L Contreras, J., Cortina, J., Covino, S., Elia do Souto Espiñeira, Da&nbsp, P, Vela, Dazzi, F., De&nbsp, Angelis, B, Lotto, Delfino, M., Delgado, J., Depaoli, D., Di&nbsp, F, Pierro, L, Venere, Do&nbsp, E, Espiñeira, Souto Nbsp, Dominis&nbsp, D, Prester, Donini, A., Doro, M., Elsaesser, D., Fallah&nbsp, V, Ramazani, Fattorini, A., Ferrara, G., Foffano, L., V Fonseca, M., Font, L., Fruck, C., Fukami, S., García Nbsp, J., R, López, Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Godinović, N., Gliwny, P., Green, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Hütten, M., Inada, T., Inoue, S., Ishio, K., Iwamura, Y., Jouvin, L., Kajiwara, Y., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., López, M., López-Coto, R., López-Oramas, A., Loporchio, S., Machado&nbsp, Oliveira&nbsp, de&nbsp, Fraga, Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Maraschi, L., Mariotti, M., Martínez, M., Mazin, D., Mender, S., Mićanović, S., Miceli, D., Miener, T., Minev, M., M Miranda, J., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogués, L., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., M Paredes, J., Pavletić, L., Peñil, P., Peresano, M., Persic, M., Prada Nbsp, G., Moroni, Prandini, E., Puljak, I., Ribó, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Schleicher, B., Schmidt, K., Schweizer, T., Sitarek, J., Šnidarić, I., Sobczynska, D., Spolon, A., Stamerra, A., Strom, D., Strzys, M., Suda, Y., Surić, T., Takahashi, M., Tavecchio, F., Temnikov, P., Terzić, T., Teshima, M., Torres-Albà, N., Tosti, L., van&nbsp, Scherpenberg, Vanzo, G., Vazquez&nbsp, M, Acosta, Ventura, S., Verguilov, V., F Vigorito, C., Vitale, V., Vovk, I., Will, M., Zarić, D., D Baack, Fact Collaboration, Balbo, M., Beck, M., Biederbeck, N., Biland, A., Blank, M., Bretz, T., Bruegge, K., Bulinski, M., Buss, J., Doerr, M., Dorner, D., Hildebrand, D., Iotov, R., Klinger, M., Mannheim, K., Achim&nbsp, S, Mueller, Neise, D., Neronov, A., Nöthe, M., Paravac, A., Rhode, W., Sedlaczek, K., Shukla, A., Sliusar, V., Tani, L., Theissen, F., Walter, R., Acosta Nbsp, J., Mwl, Collaborators, Pulido, V Filippenko, A., Hovatta, T., Kiehlmann, S., M Larionov, V., Max-Moerbeck, W., M Raiteri, C., S Readhead, A. C., Šegon, M., Villata, M., Zheng, W., German Research Foundation, Swiss National Science Foundation, Ministerio de Ciencia, Innovación y Universidades (España), Department of Atomic Energy (India), Japan Society for the Promotion of Science, Academy of Finland, Croatian Science Foundation, University of Rijeka, Ministerio de Economía y Competitividad (España), Acciari, V. A., Ansoldi, S., Antonelli, L. A., Arbet Engels, A., Babic, A., Banerjee, B., Barres de Almeida, U., Barrio, J. A., Becerra Gonzalez, J., Bednarek, W., Bellizzi, L., Bernardini, E., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Blanch, O., Bonnoli, G., Bosnjak, Z., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingaryan, A., Cikota, S., Colak, S. M., Colin, U., Colombo, E., Contrera, J. L., Cortina, J., Covino, S., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Depaoli, D., Di Pierro, F., Di Venere, L., Do Souto Espineira, E., Dominis Prester, D., Donini, A., Doro, M., Elsaesser, D., Fallah Ramazani, V., Fattorini, A., Ferrara, G., Foffano, L., Fonsec, M. V., Font, L., Fruck, C., Fukami, S., Garcia Lopez, R. J., Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Godinovic, N., Gliwny, P., Green, D., Hadasch, D., Hahn, A., Herrera, J., Hoang, J., Hrupec, D., Hutten, M., Inada, T., Inoue, S., Ishio, K., Iwamura, Y., Jouvin, L., Kajiwara, Y., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., Lopez, M., Lopez-Coto, R., Lopez-Oramas, A., Loporchio, S., Machado de Oliveira Fraga, B., Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Maraschi, L., Mariotti, M., Martinez, M., Mazin, D., Mender, S., Micanovic, S., Miceli, D., Miener, T., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Munar-Adrover, P., Neustroev, V., Nigro, C., Nilsson, K., Ninci, D., Nishijima, K., Noda, K., Nogues, L., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Parede, J. M., Pavletic, L., Penil, P., Peresano, M., Persic, M., Prada Moroni, P. G., Prandini, E., Puljak, I., Ribo, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Schleicher, B., Schmidt, K., Schweizer, T., Sitarek, J., Snidaric, I., Sobczynska, D., Spolon, A., Stamerra, A., Strom, D., Strzys, M., Suda, Y., Suric, T., Takahashi, M., Tavecchio, F., Temnikov, P., Terzic, T., Teshima, M., Torres-Alba, N., Tosti, L., Van Scherpenberg, J., Vanzo, G., Vazquez Acosta, M., Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Zaric, D., Baack, D., Balbo, M., Beck, M., Biederbeck, N., Biland, A., Blank, M., Bretz, T., Bruegge, K., Bulinski, M., Buss, J., Doerr, M., Dorner, D., Hildebrand, D., Iotov, R., Klinger, M., Mannheim, K., Achim Mueller, S., Neise, D., Neronov, A., Nothe, M., Paravac, A., Rhode, W., Sedlaczek, K., Shukla, A., Sliusar, V., Tani, L., Theissen, F., Walter, R., Acosta Pulido, J., Filippenko, A. V., Hovatta, T., Kiehlmann, S., Larionov, V. M., Max-Moerbeck, W., Raiteri, C. M., Readhead, A. C. S., Segon, M., Villata, M., Zheng, W., Metsähovi Radio Observatory, Aalto-yliopisto, and Aalto University

Subjects
Flux, OBSERVATORY SUPERNOVA SEARCH, Astrophysics, 7. Clean energy, 01 natural sciences, law.invention, law, MAGIC (telescope), 010303 astronomy & astrophysics, BL Lacertae objects: individual: 1ES 2344+514 – galaxies: active –gamma-rays: galaxies, individuals: 1Es 2344+514 [BL Lacertae objects], High Energy Astrophysical Phenomena (astro-ph.HE), astro-ph.HE, Physics, BL Lacertae objects: Individual: 1ES 2344+514, BL Lacertae objects: individuals: 1Es 2344+514, Galaxies: active, GALAXIES, active [galaxies], SPECTRAL VARIABILITY, Spectral energy distribution, Electrónica, OBJECTS, Electricidad, Astrophysics - High Energy Astrophysical Phenomena, Flare, BL Lac object, Gamma-rays: galaxies, Astrophysics and Astronomy, TELESCOPE, Astrophysics::High Energy Astrophysical Phenomena, MODELS, FOS: Physical sciences, CONNECTION, Telescope, 0103 physical sciences, Galaxies: Active, Gamma-rays: Galaxies, 010308 nuclear & particles physics, active, BL Lacertae objects: individual: 1ES 2344+514, gamma-rays: galaxies, Astrophysics - High Energy Astrophysical Phenomena [galaxies], Astronomy and Astrophysics, Light curve, individual: 1ES 2344+514 [BL Lacertae objects], Crab Nebula, galaxies [gamma-rays], Space and Planetary Science, DISCOVERY, RADIATION, ddc:520, galaxies: active, GAMMA-RAY EMISSION
Abstract

Extreme High-frequency BL~Lacs (EHBL) feature their synchrotron peak of the broadband spectral energy distribution (SED) at $\nu_{\rm s} \geq $10$^{17}$\,Hz. The BL~Lac object 1ES~2344+514 was included in the EHBL family because of its impressive shift of the synchrotron peak in 1996. During the following years, the source appeared to be in a low state without showing any extreme behaviours. In August 2016, 1ES~2344+514 was detected with the ground-based $\gamma$-ray telescope FACT during a high $\gamma$-ray state, triggering multi-wavelength (MWL) observations. We studied the MWL light curves of 1ES~2344+514 during the 2016 flaring state, using data from radio to VHE $\gamma$ rays taken with OVRO, KAIT, KVA, NOT, some telescopes of the GASP-WEBT collaboration at the Teide, Crimean, and St. Petersburg observatories, \textit{Swift}-UVOT, \textit{Swift}-XRT, \textit{Fermi}-LAT, FACT and MAGIC. With simultaneous observations of the flare, we built the broadband SED and studied it in the framework of a leptonic and an hadronic model. The VHE $\gamma$-ray observations show a flux level of 55\% of the Crab Nebula flux above 300\,GeV, similar to the historical maximum of 1995. The combination of MAGIC and \textit{Fermi}-LAT spectra provides an unprecedented characterization of the inverse-Compton peak for this object during a flaring episode. The $\Gamma$ index of the intrinsic spectrum in the VHE $\gamma$-ray band is $2.04\pm0.12_{\rm stat}\pm0.15_{\rm sys}$. We find the source in an extreme state with a shift of the position of the synchrotron peak to frequencies above or equal to $10^{18}$\,Hz, Comment: Accepted in MNRAS. Corresponding authors: M. Manganaro, A. Arbet Engels, D. Dorner

Published
2021
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13. The interaction of supernova 2018evt with a substantial amount of circumstellar matter – An SN 1997cy-like event.

Author

(杨轶), Yi Yang, Baade, Dietrich, Hoeflich, Peter, Wang, Lifan, Cikota, Aleksandar, Chen, Ting-Wan, Burke, Jamison, Hiramatsu, Daichi, Pellegrino, Craig, Howell, D Andrew, McCully, Curtis, Valenti, Stefano, Schulze, Steve, Gal-Yam, Avishay, Wang, Lingzhi, Filippenko, Alexei V, Maeda, Keiichi, Bulla, Mattia, Yao, Yuhan, and Maund, Justyn R

Subjects
VERY large telescopes, CIRCUMSTELLAR matter, SUPERNOVAE, COMMONS
Abstract

A rare class of supernovae (SNe) is characterized by strong interaction between the ejecta and several solar masses of circumstellar matter (CSM) as evidenced by strong Balmer-line emission. Within the first few weeks after the explosion, they may display spectral features similar to overluminous Type Ia SNe, while at later phase their observation properties exhibit remarkable similarities with some extreme case of Type IIn SNe that show strong Balmer lines years after the explosion. We present polarimetric observations of SN 2018evt obtained by the ESO Very Large Telescope from 172 to 219 d after the estimated time of peak luminosity to study the geometry of the CSM. The non-zero continuum polarization decreases over time, suggesting that the mass-loss of the progenitor star is aspherical. The prominent H α emission can be decomposed into a broad, time-evolving component and an intermediate-width, static component. The former shows polarized signals, and it is likely to arise from a cold dense shell (CDS) within the region between the forward and reverse shocks. The latter is significantly unpolarized, and it is likely to arise from shocked, fragmented gas clouds in the H-rich CSM. We infer that SN 2018evt exploded inside a massive and aspherical circumstellar cloud. The symmetry axes of the CSM and the SN appear to be similar. SN 2018evt shows observational properties common to events that display strong interaction between the ejecta and CSM, implying that they share similar circumstellar configurations. Our preliminary estimate also suggests that the circumstellar environment of SN 2018evt has been significantly enriched at a rate of ∼0.1 M⊙ yr−1 over a period of >100 yr. [ABSTRACT FROM AUTHOR]

Published
2023
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14. Multiwavelength study of the gravitationally lensed blazar QSO B0218+357 between 2016 and 2020

Author

Acciari, V A, primary, Ansoldi, S, additional, Antonelli, L A, additional, Arbet Engels, A, additional, Artero, M, additional, Asano, K, additional, Baack, D, additional, Babić, A, additional, Baquero, A, additional, Barres de Almeida, U, additional, Barrio, J A, additional, Batković, I, additional, Becerra González, J, additional, Bednarek, W, additional, Bellizzi, L, additional, Bernardini, E, additional, Bernardos, M, additional, Berti, A, additional, Besenrieder, J, additional, Bhattacharyya, W, additional, Bigongiari, C, additional, Biland, A, additional, Blanch, O, additional, Bonnoli, G, additional, Bošnjak, Ž, additional, Busetto, G, additional, Carosi, R, additional, Ceribella, G, additional, Cerruti, M, additional, Chai, Y, additional, Chilingarian, A, additional, Cikota, S, additional, Colak, S M, additional, Colombo, E, additional, Contreras, J L, additional, Cortina, J, additional, Covino, S, additional, D’Amico, G, additional, D’Elia, V, additional, Da Vela, P, additional, Dazzi, F, additional, De Angelis, A, additional, De Lotto, B, additional, Delfino, M, additional, Delgado, J, additional, Delgado Mendez, C, additional, Depaoli, D, additional, Di Pierro, F, additional, Di Venere, L, additional, Do Souto Espiñeira, E, additional, Dominis Prester, D, additional, Donini, A, additional, Dorner, D, additional, Doro, M, additional, Elsaesser, D, additional, Fallah Ramazani, V, additional, Fattorini, A, additional, Ferrara, G, additional, Fonseca, M V, additional, Font, L, additional, Fruck, C, additional, Fukami, S, additional, García López, R J, additional, Garczarczyk, M, additional, Gasparyan, S, additional, Gaug, M, additional, Giglietto, N, additional, Giordano, F, additional, Gliwny, P, additional, Godinović, N, additional, Green, J G, additional, Green, D, additional, Hadasch, D, additional, Hahn, A, additional, Heckmann, L, additional, Herrera, J, additional, Hoang, J, additional, Hrupec, D, additional, Hütten, M, additional, Inada, T, additional, Inoue, S, additional, Ishio, K, additional, Iwamura, Y, additional, Jiménez, I, additional, Jormanainen, J, additional, Jouvin, L, additional, Kajiwara, Y, additional, Karjalainen, M, additional, Kerszberg, D, additional, Kobayashi, Y, additional, Kubo, H, additional, Kushida, J, additional, Lamastra, A, additional, Lelas, D, additional, Leone, F, additional, Lindfors, E, additional, Lombardi, S, additional, Longo, F, additional, López-Coto, R, additional, López-Moya, M, additional, López-Oramas, A, additional, Loporchio, S, additional, Machado de Oliveira Fraga, B, additional, Maggio, C, additional, Majumdar, P, additional, Makariev, M, additional, Mallamaci, M, additional, Maneva, G, additional, Manganaro, M, additional, Mannheim, K, additional, Maraschi, L, additional, Mariotti, M, additional, Martínez, M, additional, Mazin, D, additional, Menchiari, S, additional, Mender, S, additional, Mićanović, S, additional, Miceli, D, additional, Miener, T, additional, Minev, M, additional, Miranda, J M, additional, Mirzoyan, R, additional, Molina, E, additional, Moralejo, A, additional, Morcuende, D, additional, Moreno, V, additional, Moretti, E, additional, Neustroev, V, additional, Nigro, C, additional, Nilsson, K, additional, Nishijima, K, additional, Noda, K, additional, Nozaki, S, additional, Ohtani, Y, additional, Oka, T, additional, Otero-Santos, J, additional, Paiano, S, additional, Palatiello, M, additional, Paneque, D, additional, Paoletti, R, additional, Paredes, J M, additional, Pavletić, L, additional, Peñil, P, additional, Perennes, C, additional, Persic, M, additional, Prada Moroni, P G, additional, Prandini, E, additional, Priyadarshi, C, additional, Puljak, I, additional, Rhode, W, additional, Ribó, M, additional, Rico, J, additional, Righi, C, additional, Rugliancich, A, additional, Saha, L, additional, Sahakyan, N, additional, Saito, T, additional, Sakurai, S, additional, Satalecka, K, additional, Saturni, F G, additional, Schleicher, B, additional, Schmidt, K, additional, Schweizer, T, additional, Sitarek, J, additional, Šnidarić, I, additional, Sobczynska, D, additional, Spolon, A, additional, Stamerra, A, additional, Strom, D, additional, Strzys, M, additional, Suda, Y, additional, Surić, T, additional, Takahashi, M, additional, Tavecchio, F, additional, Temnikov, P, additional, Terzić, T, additional, Teshima, M, additional, Tosti, L, additional, Truzzi, S, additional, Tutone, A, additional, Ubach, S, additional, van Scherpenberg, J, additional, Vanzo, G, additional, Vazquez Acosta, M, additional, Ventura, S, additional, Verguilov, V, additional, Vigorito, C F, additional, Vitale, V, additional, Vovk, I, additional, Will, M, additional, Wunderlich, C, additional, Zarić, D, additional, de Palma, F, additional, D’Ammando, F, additional, Barnacka, A, additional, Sahu, D K, additional, Hodges, M, additional, Hovatta, T, additional, Kiehlmann, S, additional, Max-Moerbeck, W, additional, Readhead, A C S, additional, Reeves, R, additional, Pearson, T J, additional, Lähteenmäki, A, additional, Björklund, I, additional, Tornikoski, M, additional, Tammi, J, additional, Suutarinen, S, additional, Hada, K, additional, and Niinuma, K, additional

Published
2021
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15. An imaging polarimetry survey of Type Ia supernovae: are peculiar extinction and polarization properties produced by circumstellar or interstellar matter?

Author

Chu, Matthew R, primary, Cikota, Aleksandar, additional, Baade, Dietrich, additional, Patat, Ferdinando, additional, Filippenko, Alexei V, additional, Wheeler, J Craig, additional, Maund, Justyn, additional, Bulla, Mattia, additional, Yang, Yi, additional, Höflich, Peter, additional, and Wang, Lifan, additional

Published
2021
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16. Spectropolarimetry of the Type Ia SN 2019ein rules out significant global asphericity of the ejecta

Author

Patra, Kishore C, primary, Yang (杨轶), Yi, additional, Brink, Thomas G, additional, Höflich, Peter, additional, Wang, Lifan, additional, Filippenko, Alexei V, additional, Kasen, Daniel, additional, Baade, Dietrich, additional, Foley, Ryan J, additional, Maund, Justyn R, additional, Zheng, WeiKang, additional, Hung, Tiara, additional, Cikota, Aleksandar, additional, Wheeler, J Craig, additional, and Bulla, Mattia, additional

Published
2021
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18. Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and γ-ray activity in 2015–2016

Author

Acciari, V A, primary, Ansoldi, S, additional, Antonelli, L A, additional, Asano, K, additional, Babić, A, additional, Banerjee, B, additional, Baquero, A, additional, de Almeida, U Barres, additional, Barrio, J A, additional, González, J Becerra, additional, Bednarek, W, additional, Bellizzi, L, additional, Bernardini, E, additional, Bernardos, M, additional, Berti, A, additional, Besenrieder, J, additional, Bhattacharyya, W, additional, Bigongiari, C, additional, Blanch, O, additional, Bonnoli, G, additional, Bošnjak, Ž, additional, Busetto, G, additional, Carosi, R, additional, Ceribella, G, additional, Cerruti, M, additional, Chai, Y, additional, Chilingarian, A, additional, Cikota, S, additional, Colak, S M, additional, Colombo, E, additional, Contreras, J L, additional, Cortina, J, additional, Covino, S, additional, D’Amico, G, additional, D’Elia, V, additional, Da Vela, P, additional, Dazzi, F, additional, De Angelis, A, additional, De Lotto, B, additional, Delfino, M, additional, Delgado, J, additional, Mendez, C Delgado, additional, Depaoli, D, additional, Girolamo, T Di, additional, Pierro, F Di, additional, Venere, L Di, additional, Espi neira, E Do Souto, additional, Prester, D Dominis, additional, Donini, A, additional, Doro, M, additional, Ramazani, V Fallah, additional, Fattorini, A, additional, Ferrara, G, additional, Foffano, L, additional, Fonseca, M V, additional, Font, L, additional, Fruck, C, additional, Fukami, S, additional, López, R J García, additional, Garczarczyk, M, additional, Gasparyan, S, additional, Gaug, M, additional, Giglietto, N, additional, Giordano, F, additional, Gliwny, P, additional, Godinović, N, additional, Green, J G, additional, Green, D, additional, Hadasch, D, additional, Hahn, A, additional, Heckmann, L, additional, Herrera, J, additional, Hoang, J, additional, Hrupec, D, additional, Hütten, M, additional, Inada, T, additional, Inoue, S, additional, Ishio, K, additional, Iwamura, Y, additional, Jormanainen, J, additional, Jouvin, L, additional, Kajiwara, Y, additional, Karjalainen, M, additional, Kerszberg, D, additional, Kobayashi, Y, additional, Kubo, H, additional, Kushida, J, additional, Lamastra, A, additional, Lelas, D, additional, Leone, F, additional, Lindfors, E, additional, Lombardi, S, additional, Longo, F, additional, López, M, additional, López-Coto, R, additional, López-Oramas, A, additional, Loporchio, S, additional, Fraga, B Machado de Oliveira, additional, Maggio, C, additional, Majumdar, P, additional, Makariev, M, additional, Mallamaci, M, additional, Maneva, G, additional, Manganaro, M, additional, Maraschi, L, additional, Mariotti, M, additional, Martínez, M, additional, Mazin, D, additional, Mender, S, additional, Mićanović, S, additional, Miceli, D, additional, Miener, T, additional, Minev, M, additional, Miranda, J M, additional, Mirzoyan, R, additional, Molina, E, additional, Moralejo, A, additional, Morcuende, D, additional, Moreno, V, additional, Moretti, E, additional, Munar-Adrover, P, additional, Neustroev, V, additional, Nigro, C, additional, Nilsson, K, additional, Ninci, D, additional, Nishijima, K, additional, Noda, K, additional, Nozaki, S, additional, Ohtani, Y, additional, Oka, T, additional, Otero-Santos, J, additional, Palatiello, M, additional, Paneque, D, additional, Paoletti, R, additional, Paredes, J M, additional, Pavletić, L, additional, Pe nil, P, additional, Perennes, C, additional, Persic, M, additional, Moroni, P G Prada, additional, Prandini, E, additional, Priyadarshi, C, additional, Puljak, I, additional, Rhode, W, additional, Ribó, M, additional, Rico, J, additional, Righi, C, additional, Rugliancich, A, additional, Saha, L, additional, Sahakyan, N, additional, Saito, T, additional, Sakurai, S, additional, Satalecka, K, additional, Schleicher, B, additional, Schmidt, K, additional, Schweizer, T, additional, Sitarek, J, additional, Šnidarić, I, additional, Sobczynska, D, additional, Spolon, A, additional, Stamerra, A, additional, Strom, D, additional, Strzys, M, additional, Suda, Y, additional, Surić, T, additional, Takahashi, M, additional, Tavecchio, F, additional, Temnikov, P, additional, Terzić, T, additional, Teshima, M, additional, Torres-Albà, N, additional, Tosti, L, additional, Truzzi, S, additional, van Scherpenberg, J, additional, Vanzo, G, additional, Acosta, M Vazquez, additional, Ventura, S, additional, Verguilov, V, additional, Vigorito, C F, additional, Vitale, V, additional, Vovk, I, additional, Will, M, additional, Zarić, D, additional, Arbet-Engels, A, additional, Baack, D, additional, Balbo, M, additional, Beck, M, additional, Biederbeck, N, additional, Biland, A, additional, Bretz, T, additional, Bruegge, K, additional, Buss, J, additional, Dorner, D, additional, Elsaesser, D, additional, Hildebrand, D, additional, Iotov, R, additional, Klinger, M, additional, Mannheim, K, additional, Neise, D, additional, Neronov, A, additional, Noethe, M, additional, Paravac, A, additional, Sliusar, V, additional, Theissen, F, additional, Walter, R, additional, Valverde, J, additional, Horan, D, additional, Giroletti, M, additional, Perri, M, additional, Verrecchia, F, additional, Leto, C, additional, Sadun, A C, additional, Moody, J W, additional, Joner, M, additional, Marscher, A P, additional, Jorstad, S G, additional, Lähteenmäki, A, additional, Tornikoski, M, additional, Ramakrishnan, V, additional, Järvelä, E, additional, Vera, R J C, additional, Righini, S, additional, and Lien, A Y, additional

Published
2020
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19. An intermittent extreme BL Lac: MWL study of 1ES 2344+514 in an enhanced state

Author

Acciari, MAGIC Collaboration: V A, primary, Ansoldi, S, primary, Antonelli, L A, primary, Arbet Engels, A, primary, Babić, A, primary, Banerjee, B, primary, Barres de Almeida, U, primary, Barrio, J A, primary, Becerra González, J, primary, Bednarek, W, primary, Bellizzi, L, primary, Bernardini, E, primary, Berti, A, primary, Besenrieder, J, primary, Bhattacharyya, W, primary, Bigongiari, C, primary, Blanch, O, primary, Bonnoli, G, primary, Bošnjak, Ž, primary, Busetto, G, primary, Carosi, R, primary, Ceribella, G, primary, Cerruti, M, primary, Chai, Y, primary, Chilingaryan, A, primary, Cikota, S, primary, Colak, S M, primary, Colin, U, primary, Colombo, E, primary, Contreras, J L, primary, Cortina, J, primary, Covino, S, primary, D’Elia, V, primary, Da Vela, P, primary, Dazzi, F, primary, De Angelis, A, primary, De Lotto, B, primary, Delfino, M, primary, Delgado, J, primary, Depaoli, D, primary, Di Pierro, F, primary, Di Venere, L, primary, Do Souto Espiñeira, E, primary, Dominis Prester, D, primary, Donini, A, primary, Doro, M, primary, Elsaesser, D, primary, Fallah Ramazani, V, primary, Fattorini, A, primary, Ferrara, G, primary, Foffano, L, primary, Fonseca, M V, primary, Font, L, primary, Fruck, C, primary, Fukami, S, primary, García López, R J, primary, Garczarczyk, M, primary, Gasparyan, S, primary, Gaug, M, primary, Giglietto, N, primary, Giordano, F, primary, Godinović, N, primary, Gliwny, P, primary, Green, D, primary, Hadasch, D, primary, Hahn, A, primary, Herrera, J, primary, Hoang, J, primary, Hrupec, D, primary, Hütten, M, primary, Inada, T, primary, Inoue, S, primary, Ishio, K, primary, Iwamura, Y, primary, Jouvin, L, primary, Kajiwara, Y, primary, Kerszberg, D, primary, Kobayashi, Y, primary, Kubo, H, primary, Kushida, J, primary, Lamastra, A, primary, Lelas, D, primary, Leone, F, primary, Lindfors, E, primary, Lombardi, S, primary, Longo, F, primary, López, M, primary, López-Coto, R, primary, López-Oramas, A, primary, Loporchio, S, primary, Machado de Oliveira Fraga, B, primary, Maggio, C, primary, Majumdar, P, primary, Makariev, M, primary, Mallamaci, M, primary, Maneva, G, primary, Manganaro, M, primary, Maraschi, L, primary, Mariotti, M, primary, Martínez, M, primary, Mazin, D, primary, Mender, S, primary, Mićanović, S, primary, Miceli, D, primary, Miener, T, primary, Minev, M, primary, Miranda, J M, primary, Mirzoyan, R, primary, Molina, E, primary, Moralejo, A, primary, Morcuende, D, primary, Moreno, V, primary, Moretti, E, primary, Munar-Adrover, P, primary, Neustroev, V, primary, Nigro, C, primary, Nilsson, K, primary, Ninci, D, primary, Nishijima, K, primary, Noda, K, primary, Nogués, L, primary, Nozaki, S, primary, Ohtani, Y, primary, Oka, T, primary, Otero-Santos, J, primary, Paiano, S, primary, Palatiello, M, primary, Paneque, D, primary, Paoletti, R, primary, Paredes, J M, primary, Pavletić, L, primary, Peñil, P, primary, Peresano, M, primary, Persic, M, primary, Prada Moroni, P G, primary, Prandini, E, primary, Puljak, I, primary, Ribó, M, primary, Rico, J, primary, Righi, C, primary, Rugliancich, A, primary, Saha, L, primary, Sahakyan, N, primary, Saito, T, primary, Sakurai, S, primary, Satalecka, K, primary, Schleicher, B, primary, Schmidt, K, primary, Schweizer, T, primary, Sitarek, J, primary, Šnidarić, I, primary, Sobczynska, D, primary, Spolon, A, primary, Stamerra, A, primary, Strom, D, primary, Strzys, M, primary, Suda, Y, primary, Surić, T, primary, Takahashi, M, primary, Tavecchio, F, primary, Temnikov, P, primary, Terzić, T, primary, Teshima, M, primary, Torres-Albà, N, primary, Tosti, L, primary, van Scherpenberg, J, primary, Vanzo, G, primary, Vazquez Acosta, M, primary, Ventura, S, primary, Verguilov, V, primary, Vigorito, C F, primary, Vitale, V, primary, Vovk, I, primary, Will, M, primary, Zarić, D, primary, Baack, FACT Collaboration: D, primary, Balbo, M, primary, Beck, M, primary, Biederbeck, N, primary, Biland, A, primary, Blank, M, primary, Bretz, T, primary, Bruegge, K, primary, Bulinski, M, primary, Buss, J, primary, Doerr, M, primary, Dorner, D, primary, Hildebrand, D, primary, Iotov, R, primary, Klinger, M, primary, Mannheim, K, primary, Achim Mueller, S, primary, Neise, D, primary, Neronov, A, primary, Nöthe, M, primary, Paravac, A, primary, Rhode, W, primary, Sedlaczek, K, primary, Shukla, A, primary, Sliusar, V, primary, Tani, L, primary, Theissen, F, primary, Walter, R, primary, Acosta Pulido, MWL Collaborators: J, primary, Filippenko, A V, primary, Hovatta, T, primary, Kiehlmann, S, primary, Larionov, V M, primary, Max-Moerbeck, W, primary, Raiteri, C M, primary, Readhead, A C S, primary, Šegon, M, primary, Villata, M, primary, and Zheng, W, primary

Published
2020
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20. Detection of anomalous element distribution in the extremely slowly rotating magnetic O9.7 V star HD 54879.

Author

Järvinen, S P, Hubrig, S, Schöller, M, Cikota, A, Ilyin, I, Hummel, C A, and Küker, M

Subjects
STELLAR magnetic fields, MAGNETIC flux density, ASTRONOMICAL instruments, STELLAR atmospheres, STOKES parameters, MAGNETIC fields
Abstract

The O9.7 V star HD 54879 is currently the only massive magnetic star whose magnetic field geometry and rotation period are not constrained. Over the last 3 yr, we gathered additional observations of this star, obtained using various instruments at several astronomical facilities, with the aim to constrain the rotation period and the magnetic field geometry. The new data include the first full Stokes vector observations with the Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI), installed at the Large Binocular Telescope. The acquired spectropolarimetric observations show a very slow magnetic field variability related to the extremely slow rotation of HD 54879, which is also indicated in a dynamical spectrum, displaying variability of the Hα line. The most intriguing result of our study is the discovery of differences in longitudinal magnetic field strengths measured using different least-squares deconvolution (LSD) masks containing lines belonging to different elements. It is the first time that such a differential analysis of the field strength in dependence of the used lines is carried out for a magnetic O-type star. Since the LSD Stokes  I profiles of the studied O, Si, and He line masks remain stable over all observing epochs, we conclude that the detection of different field strengths using lines belonging to these elements is related to the different formation depths, with the He lines formed much higher in the stellar atmosphere compared to the silicon and the oxygen lines, and non-local thermodynamic equilibrium (NLTE) effects. Our numerical magnetospherical model suggests the presence of enhanced gas density that fills the volume inside the field lines close to the star. [ABSTRACT FROM AUTHOR]

Published
2022
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21. Testing the magnetar scenario for superluminous supernovae with circular polarimetry

Author

Cikota, Aleksandar, primary, Leloudas, Giorgos, additional, Bulla, Mattia, additional, Inserra, Cosimo, additional, Chen, Ting-Wan, additional, Spyromilio, Jason, additional, Patat, Ferdinando, additional, Cano, Zach, additional, Cikota, Stefan, additional, Coughlin, Michael W, additional, Kankare, Erkki, additional, Lowe, Thomas B, additional, Maund, Justyn R, additional, Rest, Armin, additional, Smartt, Stephen J, additional, Smith, Ken W, additional, Wainscoat, Richard J, additional, and Young, David R, additional

Published
2018
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22. Measurement of the extragalactic background light using MAGIC and Fermi-LAT gamma-ray observations of blazars up to z = 1

Author

Acciari, V A, primary, Ansoldi, S, additional, Antonelli, L A, additional, Arbet Engels, A, additional, Baack, D, additional, Babić, A, additional, Banerjee, B, additional, Barres de Almeida, U, additional, Barrio, J A, additional, Becerra González, J, additional, Bednarek, W, additional, Bellizzi, L, additional, Bernardini, E, additional, Berti, A, additional, Besenrieder, J, additional, Bhattacharyya, W, additional, Bigongiari, C, additional, Biland, A, additional, Blanch, O, additional, Bonnoli, G, additional, Busetto, G, additional, Carosi, R, additional, Ceribella, G, additional, Chai, Y, additional, Cikota, S, additional, Colak, S M, additional, Colin, U, additional, Colombo, E, additional, Contreras, J L, additional, Cortina, J, additional, Covino, S, additional, D’Elia, V, additional, Da Vela, P, additional, Dazzi, F, additional, De Angelis, A, additional, De Lotto, B, additional, Delfino, M, additional, Delgado, J, additional, Di Pierro, F, additional, Do Souto Espiñeira, E, additional, Domínguez, A, additional, Dominis Prester, D, additional, Dorner, D, additional, Doro, M, additional, Elsaesser, D, additional, Fallah Ramazani, V, additional, Fattorini, A, additional, Fernández-Barral, A, additional, Ferrara, G, additional, Fidalgo, D, additional, Foffano, L, additional, Fonseca, M V, additional, Font, L, additional, Fruck, C, additional, Galindo, D, additional, Gallozzi, S, additional, García López, R J, additional, Garczarczyk, M, additional, Gasparyan, S, additional, Gaug, M, additional, Godinović, N, additional, Green, D, additional, Guberman, D, additional, Hadasch, D, additional, Hahn, A, additional, Hassan, T, additional, Herrera, J, additional, Hoang, J, additional, Hrupec, D, additional, Inoue, S, additional, Ishio, K, additional, Iwamura, Y, additional, Kubo, H, additional, Kushida, J, additional, Lamastra, A, additional, Lelas, D, additional, Leone, F, additional, Lindfors, E, additional, Lombardi, S, additional, Longo, F, additional, López, M, additional, López-Coto, R, additional, López-Oramas, A, additional, Machado de Oliveira Fraga, B, additional, Maggio, C, additional, Majumdar, P, additional, Makariev, M, additional, Mallamaci, M, additional, Maneva, G, additional, Manganaro, M, additional, Mannheim, K, additional, Maraschi, L, additional, Mariotti, M, additional, Martínez, M, additional, Masuda, S, additional, Mazin, D, additional, Mićanović, S, additional, Miceli, D, additional, Minev, M, additional, Miranda, J M, additional, Mirzoyan, R, additional, Molina, E, additional, Moralejo, A, additional, Morcuende, D, additional, Moreno, V, additional, Moretti, E, additional, Munar-Adrover, P, additional, Neustroev, V, additional, Niedzwiecki, A, additional, Nievas Rosillo, M, additional, Nigro, C, additional, Nilsson, K, additional, Ninci, D, additional, Nishijima, K, additional, Noda, K, additional, Nogués, L, additional, Nöthe, M, additional, Paiano, S, additional, Palacio, J, additional, Palatiello, M, additional, Paneque, D, additional, Paoletti, R, additional, Paredes, J M, additional, Peñil, P, additional, Peresano, M, additional, Persic, M, additional, Prada Moroni, P G, additional, Prandini, E, additional, Puljak, I, additional, Rhode, W, additional, Ribó, M, additional, Rico, J, additional, Righi, C, additional, Rugliancich, A, additional, Saha, L, additional, Sahakyan, N, additional, Saito, T, additional, Satalecka, K, additional, Schweizer, T, additional, Sitarek, J, additional, Šnidarić, I, additional, Sobczynska, D, additional, Somero, A, additional, Stamerra, A, additional, Strom, D, additional, Strzys, M, additional, Surić, T, additional, Tavecchio, F, additional, Temnikov, P, additional, Terzić, T, additional, Teshima, M, additional, Torres-Albà, N, additional, Tsujimoto, S, additional, van Scherpenberg, J, additional, Vanzo, G, additional, Vázquez Acosta, M, additional, Vovk, I, additional, Will, M, additional, and Zarić, D, additional

Published
2019
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25. Spatially resolved analysis of superluminous supernovae PTF 11hrq and PTF 12dam host galaxies

Author

Cikota, Aleksandar, primary, De Cia, Annalisa, additional, Schulze, Steve, additional, Vreeswijk, Paul M., additional, Leloudas, Giorgos, additional, Gal-Yam, Avishay, additional, Perley, Daniel A., additional, Cikota, Stefan, additional, Kim, Sam, additional, Patat, Ferdinando, additional, Lunnan, Ragnhild, additional, Quimby, Robert, additional, Yaron, Ofer, additional, Yan, Lin, additional, and Mazzali, Paolo A., additional

Published
2017
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27. Linear spectropolarimetry of polarimetric standard stars with VLT/FORS2.

Author

Cikota, Aleksandar, Patat, Ferdinando, Cikota, Stefan, and Faran, Tamar

Subjects
*ASTROPHYSICAL spectropolarimetry, *ASTRONOMICAL observations, *SPECTROGRAPHS, *VERY large telescopes, *WAVELENGTHS
Abstract

We reduced European Southern Observatory's archival linear spectropolarimetry data (4000-9000 Å) of six highly polarized and eight unpolarized standard stars observed between 2010 and 2016, for a total of 70 epochs, with the FOcal Reducer and low dispersion Spectrograph (FORS2) mounted at the Very Large Telescope. We provide very accurate standard stars polarization measurements as a function of wavelength, and test the performance of the spectropolarimetric mode (PMOS) of FORS2.We used the unpolarized stars to test the time stability of the PMOS mode, and found a small (≤0.1 per cent), but statistically significant, on-axis instrumental polarization wavelength dependence, possibly caused by the tilted surfaces of the dispersive element. The polarization degree and angle are found to be stable at the level of ≤0.1 per cent and ≤0.2 degrees, respectively. We derived the polarization wavelength dependence of the polarized standard stars and found that, in general, the results are consistent with those reported in the literature, e.g. Fossati et al., who performed a similar analysis using FORS1 data. The re-calibrated data provide a very accurate set of standards, which can be very reliably used for technical and scientific purposes. The analysis of the Serkowski parameters revealed a systematic deviation from the width parameter K reported by Whittet et al. This is most likely explained by incorrect effective wavelengths adopted in that study for the R and I bands. [ABSTRACT FROM AUTHOR]

Published
2017
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