Article
Astronomy & Astrophysics
Jeffrey Mckaig, Claudio Ricci, Stephane Paltani, K. K. Gupta, Nicholas P. Abel, Y. Ueda
Summary: This paper investigates the relationship between the scattered component of soft X-ray in obscured active galactic nuclei (AGNs) and the primary X-ray continuum. Through simulations of scattered X-ray radiation, the authors find that the scattered component is related to the inclination angle and covering factor, and the negative correlation between the scattering component and the column density can only be explained by a positive correlation between the column density and the covering factor.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Arghajit Jana, Neeraj Kumari, Prantik Nandi, Sachindra Naik, Arka Chatterjee, Gaurava K. Jaisawal, Kimitake Hayasaki, Claudio Ricci
Summary: The study on the changing-look active galactic nucleus NGC 1566 during its outburst in June 2018 revealed a significant increase in X-ray intensity. Analysis of the X-ray data and modeling showed a strong soft X-ray excess during the outburst, potentially originating from the warm Comptonizing region in the inner accretion disc. The sudden rise in luminosity observed is likely caused by an increase in the accretion rate.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
A. Malizia, L. Bassani, R. Landi, M. Molina, N. Masetti, E. Palazzi, G. Bruni, A. Bazzano, P. Ubertini, A. J. Bird
Summary: In this study, we updated and expanded the list of active galactic nuclei (AGN) detected by INTEGRAL. We identified 83 new AGN and found that half of them are located behind the Galactic plane. With X-ray data from various sources, we were able to associate high-energy emitters with X-ray counterparts and analyze the spectral characteristics of these new AGN. This ongoing effort aims to provide the scientific community with a well-classified and spectrally characterized sample of active galaxies.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Arghajit Jana, Claudio Ricci, Sachindra Naik, Atsushi Tanimoto, Neeraj Kumari, Hsiang-Kuang Chang, Prantik Nandi, Arka Chatterjee, Samar Safi-Harb
Summary: We present a detailed study of the highly obscured active galaxy NGC 4507 and explore the properties of the X-ray source and obscuring material. The primary X-ray emission is stable, with a high equatorial column density and variable line-of-sight column density. The covering factor of Compton-Thick material is around 0.35.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
X. Xiang, D. R. Ballantyne, S. Bianchi, A. De Rosa, G. Matt, R. Middei, P-o Petrucci, A. Rozanska, F. Ursini
Summary: The X-ray spectra of active galactic nuclei (AGNs) often exhibit an excess of emission at energies less than or similar to 2 keV, known as the 'soft excess'. This excess emission could be originated from ionized relativistic reflection from the inner accretion disk or Comptonization of thermal emission in a warm corona. The reXcor model combines these two effects, providing predictions for various soft excess shapes and sizes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Muryel Guolo, Daniel Ruschel-Dutra, Dirk Grupe, Bradley M. Peterson, Thaisa Storchi-Bergmann, Jaderson Schimoia, Rodrigo Nemmen, Andrew Robinson
Summary: The study analyzes the historical multiwavelength emission of the `Changing Look' AGN in NGC 2992 and finds a direct correlation between the presence and flux of Hα BEL and the X-ray luminosity, suggesting the AGN is operating at the threshold mass accretion rate between two accretion modes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
J. M. M. Neustadt, J. T. Hinkle, C. S. Kochanek, M. T. Reynolds, S. Mathur, M. A. Tucker, R. Pogge, K. Z. Stanek, A. Payne, B. J. Shappee, T. w-s Holoien, K. Auchettl, C. Ashall, T. de Jaeger, D. Desai, A. Do, W. B. Hoogendam, M. E. Huber
Summary: NGC 5273 is an AGN that exhibits optical and X-ray variability. By analyzing data from 2000 to 2022, researchers found that the AGN underwent multiple changing-look events, transitioning between different types of Seyfert galaxies. The varying luminosity and Eddington ratio of the source seem to influence how the broad-line region reprocesses the continuum emission.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Carolina Andonie, Claudio Ricci, Stephane Paltani, Patricia Arevalo, Ezequiel Treister, Franz Bauer, Marko Stalevski
Summary: In this study, we constructed a self-consistent X-ray model to investigate the circumnuclear environments of supermassive black holes. By incorporating various reprocessing structures, the model successfully reproduces the morphology and spectral properties of the target object.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jia-Lai Kang, Jun-Xian Wang, Wen-Yong Kang
Summary: Investigating variations of the cut-off energy E-cut with X-ray flux and photon index Gamma in individual active galactic nuclei (AGNs) has revealed different patterns, indicating the involvement of multiple underlying mechanisms. Additionally, the observation of softer spectra in two Seyfert galaxies as they brighten in X-ray is a common phenomenon in AGNs. The discoveries shed new light on the coronal physics in AGNs and possible underlying physical mechanisms.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
I Pal, C. S. Stalin, L. Mallick, P. Rani
Summary: This study investigates the variation in kT(e) in three AGN, NGC 3227, NGC 5548, and MR 2251-178, using multiple epochs of data from NuSTAR. Evidence of kT(e) variation is found in NGC 3227, but no conclusive evidence is found in MR 2251-178 or NGC 5548.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Nan Ding, Qiusheng Gu, Yunyong Tang, Dingrong Xiong, Xiaotong Guo, Xinpeng Xu, Xiongfei Geng, Xue Ge, Yongyun Chen
Summary: This study presents a systematic investigation on the mechanism of long/short timescale variability and the origin of soft X-ray excess for narrow-line Seyfert 1 galaxies. The results suggest that the variability in radio-quiet NLSy1s is caused by accretion fluctuation propagation mechanism and X-ray reprocessing mechanism, while the soft X-ray excess originates from relativistically smeared reflection.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
D. Sengupta, S. Marchesi, C. Vignali, N. Torres-Alba, E. Bertola, A. Pizzetti, G. Lanzuisi, F. Salvestrini, X. Zhao, M. Gaspari, R. Gilli, A. Comastri, A. Traina, F. Tombesi, R. Silver, F. Pozzi, M. Ajello
Summary: This study presents the broad-band X-ray spectral analysis of seven Compton-thick active galactic nuclei (CT-AGN) candidates selected from the Swift-BAT 100 month catalogue using archival NuSTAR data. The aim is to obtain a complete census of heavily obscured AGN in the local universe. The results confirm three bona fide CT-AGN, increasing the total number to 35 out of 414 AGN.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Ivan Munoz Rodriguez, Antonis Georgakakis, Francesco Shankar, Viola Allevato, Silvia Bonoli, Marcella Brusa, Andrea Lapi, Akke Viitanen
Summary: This paper investigates the influence of small-scale environment (<1 Mpc) on the growth of supermassive black holes by examining the occurrence of active galactic nuclei (AGNs) in massive clusters of galaxies. A flexible data-driven semi-empirical model is constructed based on a minimal set of parameters, assuming that the presence of AGNs in galaxies is independent of the surrounding environment. However, the model's predictions are inconsistent with observations, underestimating AGN fractions at high redshift and overestimating them at low redshift. These findings suggest a significant and redshift-dependent impact of the small-scale environment on black hole growth.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
R. Middei, A. Marinucci, V Braito, S. Bianchi, B. De Marco, A. Luminari, G. Matt, E. Nardini, M. Perri, J. N. Reeves, F. Vagnetti
Summary: We report on the short- and long-term X-ray properties of the nearby Seyfert 2 galaxy NGC 2992. The spectral properties of NGC 2992 are dominated by a highly variable nuclear continuum, with significant flux changes observed in the 2-10 keV energy band.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jeffrey McKaig, Claudio Ricci, Stephane Paltani, Shobita Satyapal
Summary: Recent observations have shown that a large portion of the mid-infrared spectrum of active galactic nuclei (AGNs) comes from the polar regions. In this paper, the effects of polar gas on the X-ray spectrum of AGNs are investigated using ray-tracing simulations. It is found that the polar gas leads to an increase in the equivalent width of several fluorescence lines below 5 keV. A filled geometry is unlikely for the polar component.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
E. J. Hampton, A. M. Medling, B. Groves, L. Kewley, M. Dopita, R. Davies, I-T. Ho, M. Kaasinen, S. Leslie, R. Sharp, S. M. Sweet, A. D. Thomas, J. Allen, J. Bland-Hawthorn, S. Brough, J. J. Bryant, S. Croom, M. Goodwin, A. Green, I. S. Konstantantopoulos, J. Lawrence, A. R. Lopez-Sanchez, N. P. F. Lorente, R. McElroy, M. S. Owers, S. N. Richards, P. Shastri
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2017)
Article
Astronomy & Astrophysics
Veeresh Singh, Hum Chand
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2018)
Article
Astronomy & Astrophysics
G. Risaliti, E. Lusso
Article
Astronomy & Astrophysics
Stephanie Juneau, Andy D. Goulding, Julie Banfield, Stefano Bianchi, Pierre-Alain Duc, I-Ting Ho, Michael A. Dopita, Julia Scharwaechter, Franz E. Bauer, Brent Groves, David M. Alexander, Rebecca L. Davies, David Elbaz, Emily Freeland, Elise Hampton, Lisa J. Kewley, Robert Nikutta, Prajval Shastri, Xinwen Shu, Frederic P. A. Vogt, Tao Wang, O. Ivy Wong, Jong-Hak Woo
Summary: There is growing evidence of physical influence between supermassive black holes and their host galaxies. A case study of NGC 7582 found that galactic substructure plays a role in affecting the collimation of ionized outflows and contributing to the obscuration of the active galactic nucleus. Through 3D spectroscopy, the study revealed a kinematically distinct core and outflowing cones over kiloparsec scales, providing insights into the role of galaxy substructure in fueling, feedback, and obscuration of AGNs.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
G. Risaliti, E. Lusso, E. Nardini, G. Bargiacchi, S. Bisogni, A. Sacchi, M. Signorini, B. Trefoloni
Summary: In the past few years, we have constructed a Hubble diagram of quasars up to redshift z approximately 7, utilizing the nonlinear relation between the x-ray and UV luminosities of quasars. This Hubble diagram reveals a deviation from the standard flat Delta CDM model at z > 1.5, exceeding 4 standard deviations. To ensure the validity of using quasars as standard candles, it is crucial to investigate potential systematics in sample selection and flux measurements, as well as redshift dependence of the relation. Our review highlights observational evidence supporting our method, including the agreement between the Hubble diagram of quasars and supernovae at the same redshift range, a constant slope of the relation at all redshifts, and the lack of redshift evolution in spectral properties of our sources.
ASTRONOMISCHE NACHRICHTEN
(2023)
Article
Astronomy & Astrophysics
Veeresh Singh, Sushant Dutta, Yogesh Wadadekar, C. H. Ishwara-Chandra
Summary: This study makes the first attempt to systematically search for small-size remnant radio galaxies (RRGs) in the XMM-LSS field, discovering 48 candidates with strong spectral curvature. The research reveals a new population of small-size remnant candidates that are often found in less dense environments and at higher redshifts (z>1.0), suggesting a relatively shorter active phase and/or low jet power as possible reasons for their small size.
Article
Astronomy & Astrophysics
E. S. Kammoun, E. Nardini, A. Zoghbi, J. M. Miller, E. M. Cackett, E. Gallo, M. T. Reynolds, G. Risaliti, D. Barret, W. N. Brandt, L. W. Brenneman, J. S. Kaastra, M. Koss, A. M. Lohfink, R. F. Mushotzky, J. Raymond, D. Stern
ASTROPHYSICAL JOURNAL
(2019)
Proceedings Paper
Physics, Applied
Eden Hennessey, Joanne Cole, Prajval Shastri, Jessica Esquivel, Chandralekha Singh, Rosie Johnson, Shohini Ghose
Proceedings Paper
Physics, Applied
Lekshmi Resmi, Prajval Shastri, Srubabati Goswami, Pragya Pandey, Vandana Nanal, Preeti Kharb, Urbasi Sinha, Tanusri Saha-Dasgupta, Suratna Das, Suchetana Chatterjee
Proceedings Paper
Physics, Applied
Prajval Shastri, Mike Dopita, Julie Banfield, Adam Thomas, Fergus Longbottom, M. N. Sundar, Chetna Duggal, Brent Groves, Preeti Kharb, Rebecca Davies, Lisa Kewley, Lalitha Sairam, Elise Hampton, Shalima Puthiyaveettil, Bethan James
Article
Astronomy & Astrophysics
W. Peter Maksym, Giuseppina Fabbiano, Martin Elvis, Margarita Karovska, Alessandro Paggi, John Raymond, Junfeng Wang, Thaisa Storchi-Bergmann, Guido Risaliti
ASTROPHYSICAL JOURNAL
(2019)
Article
Astronomy & Astrophysics
G. Fabbiano, A. Paggi, M. Karovska, M. Elvis, W. P. Maksym, G. Risaliti, Junfeng Wang
ASTROPHYSICAL JOURNAL
(2018)
Article
Astronomy & Astrophysics
Lilan Yang, Paolo Tozzi, Heng Yu, Elisabeta Lusso, Massimo Gaspari, Roberto Gilli, Emanuele Nardini, Guido Risaliti
ASTROPHYSICAL JOURNAL
(2018)
Article
Astronomy & Astrophysics
G. Fabbiano, M. Elvis, A. Paggi, M. Karovska, W. P. Maksym, J. Raymond, G. Risaliti, Junfeng Wang
ASTROPHYSICAL JOURNAL LETTERS
(2017)
Article
Astronomy & Astrophysics
Jingzhe Ma, Martin Elvis, G. Fabbiano, Mislav Balokovic, W. Peter Maksym, Mackenzie L. Jones, Guido Risaliti
ASTROPHYSICAL JOURNAL
(2020)