Article
Astronomy & Astrophysics
M. Rejkuba, W. E. Harris, L. Greggio, D. Crnojevic, G. L. H. Harris
Summary: The extended stellar halos of galaxies contain important clues for investigating their assembly history and evolution. We investigate the resolved stellar content and the extended halo of NGC 5128 as a function of galactocentric distance, and trace the halo outward to its currently detectable limits.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Kotaro Fukushima, Shogo B. Kobayashi, Kyoko Matsushita
Summary: This study investigates the abundance distributions of various elements in the cool core of the Centaurus cluster. The results show a significant drop in abundance within the central region, with different detectors and atomic codes yielding different values. The abundance ratios exhibit a relatively flat radial distribution. The observed abundance pattern is consistent with solar composition but challenging to explain with the latest supernova nucleosynthesis models.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
R. E. Miura, D. Espada, A. Hirota, C. Henkel, S. Verley, M. I. N. Kobayashi, S. Matsushita, F. P. Israel, B. Vila-Vilaro, K. Morokuma-Matsui, J. Ott, C. Vlahakis, A. B. Peck, S. Aalto, M. R. Hogerheijde, N. Neumayer, D. Iono, K. Kohno, H. Takemura, S. Komugi
Summary: A census of giant molecular clouds (GMCs) in the inner region of the Centaurus A galaxy reveals similarities with GMC properties in spiral galaxies but distinct features in the circumnuclear disc, possibly influenced by the active galactic nucleus and/or shear motions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Sanna Gulati, Debbijoy Bhattacharya, Subir Bhattacharyya, Nilay Bhatt, C. S. Stalin, V. K. Agrawal
Summary: The study of NGC 1275 found similar activity patterns in gamma-ray, X-ray, and UV spectrums, with strong flaring activity in gamma-rays in the fourth state. Short-term astronomical observations also revealed an increase in average flux and a shift in emission frequency.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Christopher S. Reynolds, Robyn N. Smith, Andrew C. Fabian, Yasushi Fukazawa, Erin A. Kara, Richard F. Mushotzky, Hirofumi Noda, Francesco Tombesi, Sylvain Veilleux
Summary: This study utilizes a Chandra HETG observation of NGC 1275 to examine the anatomy of its AGN, finding tension between the X-ray continuum and molecular gas absorption, potentially resolved by introducing a composite X-ray source. The dominant unabsorbed component is suggested to be the accretion disc corona, with the sub-dominant X-ray component being the jet working surface and/or expanding jet cocoon. Additionally, no photoionized absorbers/winds were detected, ruling out characteristics commonly seen in other Seyfert galaxies.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
M. Ozdogan Ela, A. Akyuz, N. Aksaker, S. Avdan, I. Akkaya Oralhan, A. Vinokurov, S. Allak, Y. Solovyeva, K. Atapin, D. Bizyaev
Summary: The study uses archival data from the Hubble Space Telescope to search for optical candidates of ultraluminous X-ray sources in two dwarf galaxies, confirming associations with young star groups and HII complexes. The X-ray spectral data suggest that the sources are in luminous hard states, consistent with long-term observations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
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
N. Sahakyan, P. Giommi
Summary: We present the results of a comprehensive analysis of the observations of the BL Lac object prototype BL Lacertae, covering a period of almost 13 years. The source exhibits strong variability in emission at all frequencies, with frequent spectral changes. Notably, several prominent gamma-ray flares, including one reaching a flux of (4.39 +/- 1.01) x 10(-6) photon cm(-2) s(-1), have been detected. The X-ray spectral variability during the brightest flare indicates a shift of the synchrotron peak to a higher frequency range. We systematically investigate the multiwavelength emission of BL Lacertae using leptonic models and find that the majority of the observed spectral energy distributions can be explained with a one-zone model. However, a two-zone leptonic scenario is required for a smaller subset of SEDs with soft and bright X-ray spectra and high energy gamma-ray observations. The HBL behavior observed during the brightest X-ray flare suggests the presence of a second emission zone beyond the broad-line region.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Efrain Gatuzz, J. S. Sanders, R. Canning, K. Dennerl, A. C. Fabian, C. Pinto, H. Russell, T. Tamura, S. A. Walker, J. ZuHone
Summary: We present a detailed analysis of the velocity structure of the Centaurus cluster using XMM-Newton observations. The velocity structure of the intracluster medium is similar to the velocity structure of the main galaxies, and the cold fronts likely move in a plane perpendicular to our line of sight with low velocity. Additionally, the kinetic component contributes less than 25% to the total energetic budget for a radius larger than 30 kpc.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Russell J. Smith
Summary: This article introduces a new method to analyze unresolved stellar populations using spectroscopic data and Poisson sampling fluctuations. Through principal components analysis, it is found that most of the variation in red-optical spectra can be attributed to three 'fluctuation eigenspectra', which can potentially reconstruct the giant-star spectral sequence.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Kavita Kumari, G. C. Dewangan, I. E. Papadakis, Max W. J. Beard, I. M. McHardy, K. P. Singh, D. Bhattacharya, S. Bhattacharyya, S. Chandra
Summary: We studied the accretion disc-corona connection in Seyfert 1 galaxies through simultaneous UV/X-ray observations of NGC 4593 and NGC 7469 using AstroSat. X-ray and UV data were analyzed, and cross-correlation analysis was performed. The results showed different time lags between X-ray and UV variations in the two galaxies, favoring different models. Our findings provide direct observational evidence for variable intrinsic UV emission and can contribute to the understanding of the accretion process in active galactic nuclei.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
D. Chatzigiannakis, A. Simionescu, F. Mernier
Summary: This study presents a robust representation of the chemical and thermal structure in the galaxy group NGC 5813. The results show a prominent distribution of cool gas along the group's NE-SW direction, correlating with the interaction between the supermassive black hole in the central galaxy and the intra-group medium. The chemical structure of the intra-group medium remains near Solar on average across the group, suggesting efficient mixing processes. The uniform abundance distribution implies the presence of complex dynamical processes in NGC 5813.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Duccio Macconi, Paola Grandi, Myriam Gitti, Cristian Vignali, Eleonora Torresi, Fabrizio Brighenti
Summary: This study presents the first detection of a single X-ray cavity within the interstellar medium of the small Fanaroff-Riley type I radio galaxy NGC 5141 using Chandra. The central active galactic nucleus of NGC 5141 is found to be able to heat the interstellar medium and balance its cooling luminosity.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Max W. J. Beard, Ian M. McHardy, Kavita Kumari, Gulab C. Dewangan, Iossif Papadakis, Dipankar Bhattacharya, Kulinder Pal Singh, Daniel Kynoch, Mayukh Pahari
Summary: We conducted a 140 ks observation of NGC 4593 with XMM-Newton, obtaining simultaneous and continuous pn X-ray and OM UV (UVW1 2910 angstrom) light curves. Our observations provided better sampling of short-time-scale variations compared to previous studies. The results show that UVW1 lags behind the X-rays by 29.5 +/- 1.3 ks, similar to previous findings from Swift monitoring.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Neeraj Kumari, Arghajit Jana, Sachindra Naik, Prantik Nandi
Summary: We conducted a detailed analysis of a small flaring event in the narrow-line Seyfert 1 galaxy NGC 4051 using XMM-Newton and NuSTAR observations. The flare showed an increase in the count rate and a decrease in the reflection fraction, indicating a change in coronal properties. This suggests that the flaring event was due to changes in the corona rather than the accretion disc.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Martijn S. S. L. Oei, Reinout J. van Weeren, Martin J. Hardcastle, Andrea Botteon, Tim W. Shimwell, Pratik Dabhade, Aivin R. D. J. G. I. B. Gast, Huub J. A. Roettgering, Marcus Brueggen, Cyril Tasse, Wendy L. Williams, Aleksandar Shulevski
Summary: This paper introduces a newly discovered giant radio galaxy Alcyoneus, which is one of the largest structures in the universe. Through observation and analysis, researchers found that some characteristics of this galaxy are lower than the average level, but similar to other giant radio galaxies. Therefore, it is concluded that the formation of giant radio galaxies does not necessarily require very massive stars or central black holes, and a low-density environment may be an explanation.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
Kyle Finner, Scott W. W. Randall, M. James Jee, Elizabeth L. L. Blanton, Hyejeon Cho, Tracy E. E. Clarke, Simona Giacintucci, Paul Nulsen, Reinout van Weeren
Summary: A study on CIZA J0107.7+5408, a dissociative merger of galaxy clusters, reveals that the mass distribution of the cluster is consistent with the distribution of galaxies but significantly offset from the X-ray brightness peaks.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
F. Ubertosi, M. Gitti, F. Brighenti, M. McDonald, P. Nulsen, M. Donahue, G. Brunetti, S. Randall, M. Gaspari, S. Ettori, M. Calzadilla, A. Ignesti, L. Feretti, E. L. Blanton
Summary: By analyzing 427 ks Chandra observations of the galaxy cluster RBS 797, we discovered three nested pairs of weak shocks with a total energy of approximately 6 x 10(61) erg. The central AGN drives a pair of weak shocks every 20-30 Myr. Thermodynamic analysis reveals evidence of ICM condensation into colder gas between and behind the X-ray cavities. The mechanical power of the AGN can balance the ICM radiative losses.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Iu. V. Babyk, B. R. McNamara, P. E. J. Nulsen, H. R. Russell, A. C. Edge, Leo Blitz
Summary: A strong correlation is found between atmospheric pressure and molecular gas mass in central cluster galaxies and early-type galaxies. This correlation also extends to atmospheric gas density, indicating the possibility of molecular clouds condensing from hot atmospheres. The ratio of molecular to atomic hydrogen in these systems exceeds unity, suggesting that ambient pressure plays a significant role in the conversion of atomic hydrogen into molecules, similar to normal spiral galaxies.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Mojegan Azadi, Belinda Wilkes, Joanna Kuraszkiewicz, Jonathan McDowell, Ralf Siebenmorgen, Matthew Ashby, Mark Birkinshaw, Diana Worrall, Natasha Abrams, Peter Barthel, Giovanni G. Fazio, Martin Haas, Soley Hyman, Rafael Martinez-Galarza, Eileen T. Meyer
Summary: The ARXSED model is used to fit the spectral energy distributions of AGNs and their host galaxies, and it indicates that nonthermal emission contributes significantly to the observed flux at wavelengths from 1.25 mm to 850 μm. Strong radio-linked X-ray emission is predicted to be present in more than half of the sample sources. The estimated BH mass, Eddington ratio, and spin of the sample AGNs are consistent with previous spectroscopic analyses.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
F. Massaro, S. V. White, A. Garcia-Perez, A. Jimenez-Gallardo, A. Capetti, C. C. Cheung, W. R. Forman, C. Mazzucchelli, A. Paggi, N. P. H. Nesvadba, J. P. Madrid, I. Andruchow, S. Cellone, H. A. Pena-Herazo, R. Grossova, B. Balmaverde, E. Sani, V. Chavushyan, R. P. Kraft, V. Reynaldi, C. Leto
Summary: The discoveries made from observations of radio sources listed in the Third Cambridge Catalog (3CR) have significantly influenced our understanding of radio galaxies and quasars since the early sixties. However, most of the data collected on 3CR sources to date has been obtained with outdated instruments and lacks updates. To overcome these limitations and expand the coverage to the Southern Hemisphere, a new catalog called G4Jy-3CRE has been created, based on the GLEAM 4 Jy (G4Jy) catalog and using the same selection criteria as the 3CR. This new catalog includes 264 powerful radio sources with a limiting sensitivity of 9 Jy at approximately 178 MHz, located at declinations below -5 degrees. Optical counterparts of the radio cores were searched using archival radio maps and optical images from the Pan-STARRS, DES, and DSS databases, and redshift estimates for the G4Jy-3CRE sources were collected from a thorough literature search, resulting in 145 reliable measurements.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Astronomy & Astrophysics
M. J. T. Mace, M. Birkinshaw, Z. M. Leinhardt
Summary: The phenomenon of precipitation of dusty material from the ring plane on to Saturn via unstable orbits is called ring rain. The question of whether silicates and organics precipitate faster than water ice from Saturn's rings onto the planet remains open. This paper investigates the stability of orbiting, stochastically charged dust particles and their potential deposition on the planet, ejection from the system, or stability over time. The study reveals the complex relationship between launch locations and deposition latitudes, emphasizing the need for averaging distributions and predicting observable emission strength.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
John A. ZuHone, Paul E. J. Nulsen, Po-Hsun Tseng, Hsi-Yu Schive, Tom W. Jones
Summary: The study finds that the Fanaroff-Riley Class II radio galaxy Cygnus A hosts jets that interact with the intercluster medium (ICM) and produce radio emission, X-ray cavities, cocoon shocks, and X-ray hotspots. A peculiar hole feature, which appears as a deficit in X-ray emission, is observed surrounding one hotspot. Through relativistic hydrodynamic simulations, the researchers propose that the hole of emission surrounding the hotspot may be produced by Doppler de-boosting of the emission from the reflected jet, as seen by an observer with a sight line nearly along the axis of the outgoing material.
Article
Astronomy & Astrophysics
Zhensong Hu, Yuanyuan Su, Zhiyuan Li, Kelley M. Hess, Ralph P. Kraft, William R. Forman, Paul E. J. Nulsen, Sarrvesh S. Sridhar, Andra Stroe, Junhyun Baek, Aeree Chung, Dirk Grupe, Hao Chen, Jimmy A. Irwin, Christine Jones, Scott W. Randall, Elke Roediger
Summary: Understanding the impact of environment on the activity of active galactic nuclei (AGNs) is crucial for studying the formation and growth of supermassive black holes (SMBHs) and their coevolution with host galaxies. New Chandra X-ray observations in the Antlia cluster reveal the presence of nuclear X-ray sources, with a higher number of X-ray AGN detected in early-type galaxies and primarily hosted by the younger subcluster.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Akos Bogdan, Ildar Khabibullin, Orsolya E. Kovacs, Gerrit Schellenberger, John ZuHone, Joseph N. Burchett, Klaus Dolag, Eugene Churazov, William R. Forman, Christine Jones, Caroline Kilbourne, Ralph P. Kraft, Erwin Lau, Maxim Markevitch, Dan McCammon, Daisuke Nagai, Dylan Nelson, Anna Ogorzalek, Benjamin D. Oppenheimer, Arnab Sarkar, Yuanyuan Su, Nhut Truong, Sylvain Veilleux, Stephan Vladutescu-Zopp, Irina Zhuravleva
Summary: The circumgalactic medium (CGM) is important in galaxy evolution as it affects various processes such as star formation and metal retention. X-ray absorption studies are a promising way to probe the CGM. Traditional methods using bright quasars have limitations, but high spectral resolution X-ray microcalorimeters provide a new approach.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
V. Olivares, Y. Su, W. Forman, M. Gaspari, F. Andrade-Santos, P. Salome, P. Nulsen, A. Edge, F. Combes, C. Jones
Summary: We study the AGN feedback in nearby galaxy clusters, discovering that disturbed clusters show higher cavity power compared to relaxed clusters for a given cooling luminosity, indicating a difference in cooling and feedback efficiency. Disturbed clusters also have asymmetric cavities and may be influenced by the ICM weather. In addition, warm filaments in a significant number of clusters are found to be associated with AGN feedback, enhancing turbulence or uplift.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Charles E. E. Romero, Massimo Gaspari, Gerrit Schellenberger, Tanay Bhandarkar, Mark Devlin, Simon R. R. Dicker, William Forman, Rishi Khatri, Ralph Kraft, Luca Di Mascolo, Brian S. S. Mason, Emily Moravec, Tony Mroczkowski, Paul Nulsen, John Orlowski-Scherer, Karen Perez Sarmiento, Craig Sarazin, Jonathan Sievers, Yuanyuan Su
Summary: The observations of the galaxy cluster Zwicky 3146 suggest that it does not exhibit significant pressure substructure in the intracluster medium. A study of the cluster using SZ and X-ray data reveals fluctuation spectra that indicate injection scales and a change in the thermodynamic state in the central region. Comparison with simulations and other studies provides insights into the fluctuations in Zwicky 3146 and other clusters.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Alessandro Ignesti, Marisa Brienza, Benedetta Vulcani, Bianca M. Poggianti, Antonino Marasco, Rory Smith, Martin J. Hardcastle, Andrea Botteon, Ian D. Roberts, Jacopo Fritz, Rosita Paladino, Myriam Gitti, Anna Wolter, Neven Tomicic, Sean McGee, Alessia Moretti, Marco Gullieuszik, Alexander Drabent
Summary: We report the serendipitous discovery of an unprecedented interaction between the radio lobe of a radio galaxy and a spiral galaxy. The interaction, which occurred between the central galaxy GIN 049 and the spiral galaxy JO36, resulted in a positive feedback event for JO36, leading to a significant increase in its star formation rate.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
F. Massaro, S. V. White, A. Paggi, A. Jimenez-Gallardo, J. P. Madrid, C. Mazzucchelli, W. R. Forman, A. Capetti, C. Leto, A. Garcia-Perez, C. C. Cheung, V. Chavushyan, N. P. H. Nesvadba, I. Andruchow, H. A. Pena-Herazo, E. Sani, R. Grossova, V. Reynaldi, R. P. Kraft, B. Balmaverde, S. Cellone
Summary: We constructed a new catalog of extragalactic radio sources with the aim of increasing the number of powerful radio galaxies and quasars. Through X-ray analysis, we found X-ray counterparts for some radio sources, with some showing extended X-ray emission.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Astronomy & Astrophysics
M. Stimpson, M. J. Hardcastle, M. G. H. Krause
Summary: In this study, we present relativistic magnetohydrodynamic simulations of jets interacting with spherically symmetric cluster atmospheres. By analyzing synthetic emission maps and examining dynamic, energetic, and polarimetric data, we find that the cluster atmosphere and jet power play a crucial role in shaping the morphology and energy distribution of the jets.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)