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At high redshift, due to both observational limitations and the variety of galaxy morphologies in the early universe, measuring galaxy structure can be challenging. Non-parametric measurements such as the CAS system have thus become an…

Astrophysics of Galaxies · Physics 2021-09-08 C. Tohill , L. Ferreira , C. J. Conselice , S. P. Bamford , F. Ferrari

Active Galactic Nuclei (AGN) represent the growth phases of the supermassive black holes in the center of almost every galaxy. Powerful, highly ionized winds, with velocities $\sim 0.1- 0.2c$ are a common feature in X--ray spectra of…

Astrophysics of Galaxies · Physics 2015-09-23 Andrew King , Ken Pounds

Deep learning, especially convolutional neural networks, has triggered accelerated advancements in computer vision, bringing changes into our daily practice. Furthermore, the standardized deep learning modules (also known as backbone…

Computer Vision and Pattern Recognition · Computer Science 2022-12-02 Hongzhi Zhu , Robert Rohling , Septimiu Salcudean

Only a small fraction of local galaxies harbor an accreting black hole, classified as an active galactic nucleus (AGN). However, many stellar systems are plausibly expected to host black holes, from globular clusters to nuclear star…

Astrophysics of Galaxies · Physics 2015-05-20 Marta Volonteri , Massimo Dotti , Duncan Campbell , Mario Mateo

We propose a new method to create compact convolutional neural networks (CNNs) by exploiting sparse convolutions. Different from previous works that learn sparsity in models, we directly employ hand-crafted kernels with regular sparse…

Computer Vision and Pattern Recognition · Computer Science 2018-09-12 Chun-Fu Chen , Quanfu Fan , Marco Pistoia , Gwo Giun Lee

The growth of supermassive black holes across cosmic time leaves a radiative imprint recorded in the X-ray background (XRB). The XRB spectral shape suggests that a large population of distant, hidden nuclei must exist, which are now being…

Cosmology and Nongalactic Astrophysics · Physics 2013-04-15 Roberto Gilli

Models of superdense star clusters at the center of galaxies are investigated to see whether such objects can be stable and long-lived based on evaporation and collision time-scales and stability criteria. We find that physically reasonable…

Astrophysics · Physics 2008-02-03 J. W. Moffat

We use semi-analytic models implemented in the Millennium Simulation to analyze the merging histories of dark matter haloes and of the galaxies that reside in them. We assume that supermassive black holes only exist in galaxies that have…

Astrophysics · Physics 2009-11-13 Lan Wang , Guinevere Kauffmann

We evaluate the ability of Convolutional Neural Networks (CNNs) to predict galaxy cluster masses in the BAHAMAS hydrodynamical simulations. We train four separate single-channel networks using: stellar mass, soft X-ray flux, bolometric…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-07 Z. Yan , A. J. Mead , L. Van Waerbeke , G. Hinshaw , I. G. McCarthy

We present hydrodynamical N-body simulations of clusters of galaxies with feedback taken from semi-analytic models of galaxy formation. The advantage of this technique is that the source of feedback in our simulations is a population of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 C. J. Short , P. A. Thomas

The idea of searching for gravitational waves using cavities in strong magnetic fields has recently received significant attention. Specifically, discussions focus on cavities with relatively small volumes, which are currently employed in…

General Relativity and Quantum Cosmology · Physics 2023-08-23 Kristof Schmieden , Matthias Schott

We report on the construction of a deep convolutional neural network that can reproduce the sensitivity of a matched-filtering search for binary black hole gravitational-wave signals. The standard method for the detection of well modeled…

Instrumentation and Methods for Astrophysics · Physics 2018-04-11 Hunter Gabbard , Michael Williams , Fergus Hayes , Chris Messenger

Hydrodynamic simulations of galaxies with active galactic nuclei (AGN) have typically employed feedback that is purely local: i.e., an injection of energy to the immediate neighborhood of the black hole. We perform GADGET-2 simulations of…

Astrophysics of Galaxies · Physics 2015-05-28 D. Clay Hambrick , Jeremiah P. Ostriker , Thorsten Naab , Peter H. Johansson

There is increasing evidence that globular clusters retain sizeable black hole populations at present day. This is supported by dynamical simulations of cluster evolution, which have unveiled the spatial distribution and mass spectrum of…

High Energy Astrophysical Phenomena · Physics 2021-08-18 Nicholas Kaaz , Kyle Kremer , Katie Auchettl , Enrico Ramirez-Ruiz

Globular star clusters contain thousands to millions of old stars packed within a region only tens of light years across. Their high stellar densities make it very probable that their member stars will interact or collide. There has been…

Astrophysics · Physics 2011-08-17 Thomas J. Maccarone , Arunav Kundu , Stephen E. Zepf , Katherine L. Rhode

This dissertation elaborates on X-ray polarisation features of astrophysical environments near accreting black holes. Although the work was originally assigned to supermassive black holes in active galactic nuclei, the results are also…

High Energy Astrophysical Phenomena · Physics 2024-08-26 Jakub Podgorný

We report the discovery of three low-mass black hole candidates residing in the centers of low-mass galaxies at z<0.3 in the Chandra Deep Field - South Survey. These black holes are initially identified as candidate active galactic nuclei…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 M. Schramm , J. D. Silverman , J. E. Greene , W. N. Brandt , B. Luo , Y. Q. Xue , P. Capak , Y. Kakazu , J. Kartaltepe , V. Mainieri

Compact remnants -- stellar mass black holes and neutron stars formed in the inner few parsec of galactic centres are predicted to sink into the central parsec due to dynamical friction on low mass stars, forming a high concentration cusp…

Astrophysics · Physics 2008-11-26 Sergei Nayakshin , Rashid Sunyaev

Clusters of galaxies are the most massive objects in the Universe and precise knowledge of their mass structure is important to understand the history of structure formation and constrain still unknown types of dark contents of the…

Cosmology and Nongalactic Astrophysics · Physics 2012-11-06 Naomi Ota

The TNG-Cluster magnetohydrodynamic cosmological simulations, produce a diverse population of X-ray cavities in the intracluster medium (ICM) of simulated galaxy clusters. These arise from episodic, high velocity, kinetic energy injections…

Astrophysics of Galaxies · Physics 2025-04-01 Marine Prunier , Annalisa Pillepich , Julie Hlavacek-Larrondo , Dylan Nelson