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
Clio Z. P. Heard, C. Martin Gaskell
Summary: In this study, the photometric variability of 4611 active galactic nuclei (AGNs) from the Sloan Digital Sky Survey (SDSS) Stripe 82 was analyzed. The spectral energy distribution (SED) of the variable flux as a function of wavelength was recovered. It was found that the SED of the variable component of the bluest AGNs is consistent with the F-nu proportional to nu(+1/3) spectrum predicted for an externally illuminated accretion disc. Some residual variable emission corresponding to the 'small blue bump' and other broad-line region variability was confirmed. The steeper optical spectra of the variable component were interpreted as being due to intrinsic reddening, supported by the correlation of the Balmer decrement with the colour excess of the variable component. The median internal reddening of SDSS AGNs in Stripe 82 with z < 0.4 was found to be E(B - V) approximate to 0.10, in agreement with the reddening derived from the Balmer decrement. Individual AGNs in the sample can have E(B - V) > 0.4.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Alessia Tortosa, Claudio Ricci, Francesco Tombesi, Luis C. Ho, Pu Du, Kohei Inayoshi, Jian-Min Wang, Jinyi Shangguan, Ruancun Li
Summary: This study presents the analysis of the physical properties of the accretion flow and X-ray emitting plasma in supermassive black holes accreting at extreme Eddington rates. The simultaneous observations of IRAS 04416+1215 with XMM-Newton and NuSTAR reveal interesting spectral features, including multiphase absorption structure, a soft excess component, and a hard X-ray emission dominated by a reflection component.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Mehdy Lefkir, Elias Kammoun, Didier Barret, Peter Boorman, Gabriele Matzeu, Jon M. Miller, Emanuele Nardini, Abderahmen Zoghbi
Summary: In this study, the X-ray properties of the highly variable AGN NGC 7582 are explored using XMM-Newton and NuSTAR archival observations. The results show long-term variability between observations and short-term variability within two observations, which has not been studied before. The best model for the X-ray properties of NGC 7582 is found to be a fully covering clumpy absorber, with obscuring clouds consistent with comet-like or spherical clouds with a non-uniform density profile.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
N. Chang, F. G. Xie, X. Liu, L. C. Ho, A-J Dong, Z. H. Han, X. Wang
Summary: The study re-analyzed a sample of Seyfert galaxies and found similarities in the X-ray origin of radio-quiet and radio-loud Seyferts, with all sources exhibiting a similar correlation slope. When considering luminosities in radio and X-rays, radio morphology and Seyfert classification played a role in the correlations observed.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Juan A. Fernandez-Ontiveros, Teo Munoz-Darias
Summary: The luminosity-excitation diagram (LED) based on mid-infrared nebular line fluxes reveals accretion states in active galactic nuclei (AGN). Soft state and hard state mainly appear in low-luminosity AGN, characterized by disc-dominated nuclei and nuclei with negligible disc contributions, respectively.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
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
Jiachen Jiang, Luigi C. Gallo, Dirk Grupe, Michael L. Parker
Summary: The study presents a spectral analysis of XMM-Newton observations of UGC 11763, indicating three spectral models that can explain the X-ray variability of the galaxy. Future high-resolution X-ray missions will help to further test these models on UGC 11763.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Bocheng Zhu, Feng Yuan, Suoqing Ji, Yingjie Peng, Luis C. Ho, Jeremiah P. Ostriker, Luca Ciotti
Summary: The fate of cosmological inflow in a massive elliptical galaxy and its impact on galaxy evolution are investigated through high-resolution hydrodynamic simulations. It is found that the inflow gas hardly enters the galaxy but becomes part of the circumgalactic medium (CGM). However, if the rate of cosmological inflow is increased, a small fraction of the inflow can enter the galaxy and significantly increase gas density and pressure in the CGM, leading to an increase in star formation rate (SFR) and black hole accretion rate (BHAR).
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Zhiyuan Yao, Feng Yuan, Jeremiah P. Ostriker
Summary: This study extends previous research on AGN feedback by exploring the uncertainties of parameter values, finding that the velocity of AGN wind has the most significant impact on controlling the typical accretion rate, AGN luminosity, and BH mass growth.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
K. Sriram, D. Nour, C. S. Choi
Summary: Understanding the radiative and physical structures of the inner region of active galactic nuclei (AGNs) is crucial for determining the causes of their activities. This study investigates the correlations between X-ray, mid-infrared, and different components of Balmer emission lines in AGNs. The results reveal linear dependencies between X-ray luminosity and broad Balmer emission lines, as well as strong dependencies on the optical continuum luminosity and mid-infrared luminosity. The study also identifies break points in the correlations between X-ray power-law index, Gamma, and the mass of black holes, as well as between Gamma and the full width at half-maximum (FWHM) of H alpha and H beta broad components.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
D. Nour, K. Sriram
Summary: Soft X-ray emission is crucial in regulating the optical and UV emission in AGNs. A study of 1811 AGNs showed dependencies between various parameters and soft X-ray luminosity. The analysis found a correlation between FWHMMg II and FWHMH beta 0.554, suggesting the UV emission comes from a region outside the BLR associated with H beta emission. Strong correlations were also found between optical and UV luminosities. The dependencies of optical continuum luminosities on soft excess changed with redshift.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Jiachen Jiang, Thomas Dauser, Andrew C. Fabian, William N. Alston, Luigi C. Gallo, Michael L. Parker, Christopher S. Reynolds
Summary: This study models the X-ray spectra of IRAS 13224-3809 using multiple flux-resolved XMM-Newton spectra and finds that no additional component is required to fit the soft X-ray excess. The study also calculates the average illumination distance between the corona and the reflection region in IRAS 13224-3809.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jiachen Jiang, Askar B. Abdikamalov, Cosimo Bambi, Christopher S. Reynolds
Summary: We re-analyze the XMM-Newton and NuSTAR observing campaigns for the well-studied, X-ray-bright AGN MCG-06-30-15, considering a disc model with finite thickness. By fitting the disc reflection spectra in the data, we find a black hole spin of 0.87-0.99, which is consistent with previous measurements based on razor-thin disc models. Additionally, we assume an isotropic, point-like geometry for the corona, and find that such a geometry overestimates the disc reflection fraction parameter. Thin disc models with a free reflection fraction parameter provide a better fit when considering the disc thickness.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Jiachen Jiang, Huaqing Cheng, Luigi C. Gallo, Luis C. Ho, Douglas J. K. Buisson, Andrew C. Fabian, Fiona A. Harrison, Michael L. Parker, Christopher S. Reynolds, James F. Steiner, John A. Tomsick, Dominic J. Walton, Weimin Yuan
Summary: The Seyfert 1 galaxy KUG 1141+371 has shown a simultaneous flux increase in the optical and UV bands over the past decade, with the latest observations indicating significant changes in UVW2 flux and steady increase in soft X-ray flux. The study suggests that these multiwavelength luminosity changes are likely due to an increase in mass accretion rate, and detailed X-ray spectral analysis reveals variability in X-ray continuum emission and soft excess emission. Additionally, SED models indicate a simultaneous increase in disc temperature and decreasing inner disc radius with increasing accretion rate. Finally, the study discusses a possible connection between KUG 1141+371 and black hole transients in outburst.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Engineering, Chemical
Oluwaseyi Ogunsola, Jazil Bin Shahid, Paul Michael
Summary: The effect of fluid properties on hydraulic cylinder rod seal stick-slip friction was investigated. The study findings provide a foundation for the development of fluids that can enhance the control and safety of hydraulic equipment.
CHEMICAL ENGINEERING & TECHNOLOGY
(2023)
Article
Astronomy & Astrophysics
S. Komossa, A. Kraus, D. Grupe, M. L. Parker, A. Gonzalez, L. C. Gallo, M. A. Gurwell, S. Laine, S. Yao, S. Chandra, L. Dey, J. L. Gomez, K. Hada, D. Haggard, A. R. Hollett, H. Jermak, S. Jorstad, T. P. Krichbaum, S. Markoff, C. McCall, J. Neilsen, M. Nowak
Summary: We are conducting the most extensive and longest multiyear, multiwavelength monitoring project on OJ 287. The MOMO project covers a wide range of wavelengths and aims to understand disk-jet physics and test the binary black hole scenario of OJ 287.
ASTRONOMISCHE NACHRICHTEN
(2023)
Article
Astronomy & Astrophysics
W. Kollatschny, D. Grupe, M. L. Parker, M. W. Ochmann, N. Schartel, E. Romero-Colmenero, H. Winkler, S. Komossa, P. Famula, M. A. Probst, M. Santos-Lleo
Summary: IRAS 23226-3843, a changing-look AGN, experienced a strong X-ray and UV flux outburst in 2019. During the outburst, it showed significant variations in the X-ray and optical continuum, as well as changes in the H α emission-line profiles. One year later, its optical spectral type changed to become a Seyfert type 2 object.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Anthony Kirilov, Sergei Dyda, Christopher S. Reynolds
Summary: We use numerical hydrodynamics simulations to study line-driven winds from an accreting alpha-disc. We find that variations in disc luminosity correlate with variations in the mass flux of the wind, but this correlation disappears after a steady state is reached. The changing mass flux is primarily due to the formation of clumps and voids near the disc atmosphere.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. Komossa, A. Kraus, D. Grupe, A. G. Gonzalez, M. A. Gurwell, L. C. Gallo, F. K. Liu, I. Myserlis, T. P. Krichbaum, S. Laine, U. Bach, J. L. Gomez, M. L. Parker, S. Yao, M. Berton
Summary: Based on our Swift monitoring program, OJ 287 is well-monitored in the X-ray-UV-optical regime. We report the results of our radio monitoring of OJ 287 between 2015 and 2022, including Fermi gamma-ray observations. We analyze the radio flux and spectral variability, discuss its connection with multiwavelength emission, and study the extraordinary 2016/2017 outburst.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Erin Kara, Aaron J. Barth, Edward M. Cackett, Jonathan Gelbord, John Montano, Yan-Rong Li, Lisabeth Santana, Keith Horne, William N. Alston, Douglas Buisson, Doron Chelouche, Pu Du, Andrew C. Fabian, Carina Fian, Luigi Gallo, Michael R. Goad, Dirk Grupe, Diego H. Gonzalez Buitrago, Juan V. Hernandez Santisteban, Shai Kaspi, Chen Hu, S. Komossa, Gerard A. Kriss, Collin Lewin, Tiffany Lewis, Michael Loewenstein, Anne Lohfink, Megan Masterson, Ian M. McHardy, Missagh Mehdipour, Jake Miller, Christos Panagiotou, Michael L. Parker, Ciro Pinto, Ron Remillard, Christopher Reynolds, Daniele Rogantini, Jian-Min Wang, Jingyi Wang, Dan Wilkins
Summary: We present the first results from a 100-day observing campaign of the Seyfert 1 galaxy Mrk 335 using three instruments. Despite a low X-ray flux state, we observed UV-optical lags as expected. Interestingly, both low- and high-flux states revealed longer UV-optical lags than expected. The optical rise preceded a sharp rise in X-rays, suggesting a departure from previous reprocessing models.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Zuobin Zhang, Jiachen Jiang, Honghui Liu, Cosimo Bambi, Christopher S. Reynolds, Andrew C. Fabian, Thomas Dauser, Kristin Madsen, Andrew Young, Luigi Gallo, Zhibo Yu, John Tomsick
Summary: We present the results from a joint XMM-Newton + NuSTAR observation of the Seyfert 1 galaxy ESO 511-G030, showing that the source remained in a low flux and stable state. The broadband spectrum indicates the presence of a power-law continuum, a soft excess below 2 keV, a narrow iron Ka emission, and a high-energy cutoff. Two possible scenarios, a warm and optically thick Comptonizing corona or a relativistic reflection from a high-density inner disk, can explain the observed soft excess. All models require a low temperature for the hot corona.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
C. J. Bambic, H. R. Russell, C. S. Reynolds, A. C. Fabian, B. R. McNamara, P. E. J. Nulsen
Summary: We present the deepest Chandra observation of the galaxy M84 in the Virgo Cluster, revealing the origins of the accretion flow feeding the supermassive black hole. Our measurements show that the accretion flow is strongly influenced by the AGN's bipolar radio jets, rather than being solely dictated by the black hole's potential. The results also indicate that the density profile and accretion rate vary in different sectors around the AGN.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
P. Kosec, E. Kara, A. C. Fabian, F. Fuerst, C. Pinto, I. Psaradaki, C. S. Reynolds, D. Rogantini, D. J. Walton, R. Ballhausen, C. Canizares, S. Dyda, R. Staubert, J. Wilms
Summary: Kosec et al. analyze X-ray spectroscopic observations of outflowing hot material from an accreting neutron star and reveal the vertical distribution of the outflow structure using an innovative technique.
Article
Astronomy & Astrophysics
Julia Sisk-Reynes, Christopher S. Reynolds, Michael L. Parker, James H. Matthews, M. C. David Marsh
Summary: X-ray observations of AGNs in galaxy clusters, particularly with future X-ray observatories Athena and AXIS, can provide significant constraints on the existence of ALPs. Machine learning techniques can mitigate the effects of instrumental miscalibration and enhance sensitivity to ALP physics. A proposed AXIS/on-axis observation of NGC 1275 will further improve constraints on very-light ALPs.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Marina Orio, Keith Gendreau, Morgan Giese, Gerardo Juan M. Luna, Jozef Magdolen, Tod E. Strohmayer, Andy E. Zhang, Diego Altamirano, Andrej Dobrotka, Teruaki Enoto, Elizabeth C. Ferrara, Richard Ignace, Sebastian Heinz, Craig Markwardt, Joy S. Nichols, Michael L. Parker, Dheeraj R. Pasham, Songpeng Pei, Pragati Pradhan, Ron Remillard, James F. Steiner, Francesco Tombesi
Summary: The 2021 outburst of the symbiotic recurrent nova RS Oph was monitored using the Neutron Star Interior Composition Explorer Mission (NICER). The study provides a detailed view of the outburst development, revealing that the X-ray flux preceding the supersoft X-ray phase peaked almost 5 days after the optical maximum and originated from shocked ejecta. The study also finds that a quasi-periodic oscillation with varying amplitudes was consistently observed during the supersoft X-ray source (SSS) phase.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
K. Ross, C. Reynolds, N. Seymour, J. R. Callingham, N. Hurley-Walker, H. Bignall
Summary: In this study, VLBI imaging using the LBA was performed on two PS sources, MRC 0225-065 and PMN J0322-4820, which were found to be spectrally variable. The results showed that MRC 0225-065 consists of a bright core and two fainter lobes, while PMN J0322-4820 remains unresolved on milliarcsecond scales. The predicted morphology based on spectral variability was consistent with the structures observed in the LBA images.
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF AUSTRALIA
(2023)