197 citations · 1.7k across the 73 of their papers we have counts for
38 papers · 1 filter
X-ray properties of massive compact relic galaxies
Orsolya E. Kovacs, Norbert Werner, Akos Bogdan +1
We present the X-ray analysis of seven local compact elliptical galaxies (cEGs), selected for their morphological resemblance to high-redshift red nuggets. As likely descendants of…
Chandra Rules Out Super-Eddington Accretion Models For Little Red Dots
Andrea Sacchi, Akos Bogdan
One of the most puzzling discoveries by JWST is the population of high-redshift, red, and compact galaxies dubbed little red dots (LRDs). Based on broad-line diagnostics, these gal…
Detection of Anisotropies in the Circumgalactic Medium of Disk Galaxies: Supermassive Black Hole Activity or Star Formation-driven Outflows?
Andrea Sacchi, Akos Bogdan, Nhut Truong
Gamma and X-ray observatories have revealed spectacular structures in the emission of the tenuous hot gas surrounding the Milky Way (MW), known as the Fermi and eROSITA bubbles. Ga…
X-raying CAMELS: Constraining Baryonic Feedback in the Circum-Galactic Medium with the CAMELS simulations and eRASS X-ray Observations
Erwin T. Lau, Daisuke Nagai, Ákos Bogdán +7
The circumgalactic medium (CGM) around massive galaxies plays a crucial role in regulating star formation and feedback. Using the CAMELS simulation suite, we develop emulators for…
Deconvolving X-ray Galaxy Cluster Spectra Using a Recurrent Inference Machine
Carter Rhea, Julie Hlavacek-Larrondo, Alexandre Adam +4
Recent advances in machine learning algorithms have unlocked new insights in observational astronomy by allowing astronomers to probe new frontiers. In this article, we present a m…
A Deeper Look into eFEDS AGN Candidates in Dwarf Galaxies with Chandra
Adonis A. Sanchez, Amy E. Reines, Akos Bogdan +1
The ability to accurately discern active massive black holes (BHs) in nearby dwarf galaxies is paramount to understanding the origins and processes of "seed" BHs in the early Unive…
X-ray View of Little Red Dots: Do They Host Supermassive Black Holes?
Tonima Tasnim Ananna, Ákos Bogdán, Orsolya E. Kovács +2
The discovery of Little Red Dots (LRDs) -- a population of compact, high-redshift, dust-reddened galaxies -- is one of the most surprising results from JWST. However, the nature of…
A candidate supermassive black hole in a gravitationally-lensed galaxy at
Orsolya E. Kovacs, Akos Bogdan, Priyamvada Natarajan +8
While supermassive black holes (BHs) are widely observed in the nearby and distant universe, their origin remains debated with two viable formation scenarios with light and heavy s…
Unraveling the Mysteries of Galaxy Clusters: Recurrent Inference Deconvolution of X-ray Spectra
Carter Rhea, Julie Hlavacek-Larrondo, Ralph Kraft +3
In the realm of X-ray spectral analysis, the true nature of spectra has remained elusive, as observed spectra have long been the outcome of convolution between instrumental respons…
UNCOVER: The growth of the first massive black holes from JWST/NIRSpec -- spectroscopic redshift confirmation of an X-ray luminous AGN at z=10.1
Andy D. Goulding, Jenny E. Greene, David J. Setton +27
The James Webb Space Telescope is now detecting early black holes (BHs) as they transition from "seeds" to supermassive BHs. Recently Bogdan et al. (2023) reported the detection of…
X-ray metal line emission from the hot circumgalactic medium: probing the effects of supermassive black hole feedback
Nhut Truong, Annalisa Pillepich, Dylan Nelson +15
We derive predictions from state-of-the-art cosmological galaxy simulations for the spatial distribution of the hot circumgalactic medium (CGM, ) through its…
A high black hole to host mass ratio in a lensed AGN in the early Universe
Lukas J. Furtak, Ivo Labbé, Adi Zitrin +34
Early JWST observations have uncovered a new population of red sources that might represent a previously overlooked phase of supermassive black hole growth (Kocevski et al. 2023; M…
Properties of the Line-of-Sight Velocity Field in the Hot and X-ray Emitting Circumgalactic Medium of Nearby Simulated Disk Galaxies
J. A. ZuHone, G. Schellenberger, A. Ogorzalek +16
The hot, X-ray-emitting phase of the circumgalactic medium of massive galaxies is believed to be the reservoir of baryons from which gas flows onto the central galaxy and into whic…
Resonant scattering of the OVII X-ray emission line in the circumgalactic medium of TNG50 galaxies
Dylan Nelson, Chris Byrohl, Anna Ogorzalek +15
We study the impact of resonantly scattered X-ray line emission on the observability of the hot circumgalactic medium (CGM) of galaxies. We apply a Monte Carlo radiative transfer p…
Circumgalactic Medium on the Largest Scales: Detecting X-ray Absorption Lines with Large-Area Microcalorimeters
Akos Bogdan, Ildar Khabibullin, Orsolya Kovacs +22
The circumgalactic medium (CGM) plays a crucial role in galaxy evolution as it fuels star formation, retains metals ejected from the galaxies, and hosts gas flows in and out of gal…
Evidence for heavy seed origin of early supermassive black holes from a z~10 X-ray quasar
Akos Bogdan, Andy Goulding, Priyamvada Natarajan +9
Observations of quasars reveal that many supermassive black holes (BHs) were in place less than 700 million years after the Big Bang. However, the origin of the first BHs remains a…
Constraints from dwarf galaxies on black hole seeding and growth models with current and future surveys
Urmila Chadayammuri, Akos Bogdan, Angelo Ricarte +1
Dwarf galaxies are promising test beds for constraining models of supermassive and intermediate-mass black holes (MBH) via their black hole occupation fraction (BHOF). Disentanglin…
X-ray Halos around Massive Galaxies: Data and Theory
Akos Bogdan, Mark Vogelsberger
The presence of gaseous X-ray halos around massive galaxies is a basic prediction of all past and modern structure formation simulations. The importance of these X-ray halos is fur…
Testing galaxy feedback models with the first resolved profiles of the circumgalactic medium
Urmila Chadayammuri, Akos Bogdan, Benjamin Oppenheimer +3
The hot ( K) phase of the circumgalactic medium (CGM) contains a large fraction of baryons in galaxies. It also retains signatures of the processes that shaped the galaxies,…
Detection of a Superluminous Spiral Galaxy in the Heart of a Massive Galaxy Cluster
Akos Bogdan, Lorenzo Lovisari, Patrick Ogle +5
It is well established that brightest cluster galaxies (BCGs), residing in the center of galaxy clusters, are typically massive and quenched galaxies with cD or elliptical morpholo…
Predictions for the X-ray circumgalactic medium of edge-on discs and spheroids
Anna Nica, Benjamin D. Oppenheimer, Robert A. Crain +5
We investigate how the X-ray circumgalactic medium (CGM) of present-day galaxies depends on galaxy morphology and azimuthal angle using mock observations generated from the EAGLE c…
The AGN Fraction in Dwarf Galaxies from eROSITA: First Results and Future Prospects
Lilikoi J. Latimer, Amy E. Reines, Akos Bogdan +1
Determining the fraction of nearby dwarf galaxies hosting massive black holes (BHs) can inform our understanding of the origin of "seed" black holes at high redshift. Here we searc…
Exploring Gravitationally-Lensed X-ray AGN Behind the RELICS clusters
Akos Bogdan, Orsolya E. Kovacs, Christine Jones +5
Although observations of high-redshift quasars demonstrate that many supermassive black holes (BHs) reached large masses within one billion years after the Big Bang, the origin of…
The Archetypal Ultra-Diffuse Galaxy, Dragonfly 44, is not a Dark Milky Way
Akos Bogdan
Due to the peculiar properties of ultra-diffuse galaxies (UDGs), understanding their origin presents a major challenge. Previous X-ray studies demonstrated that the bulk of UDGs la…