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Observations of bright and variable "reflected" X-ray emission from molecular clouds located within inner hundred parsec of our Galaxy have demonstrated that the central supermassive black hole, Sgr A*, experienced short and powerful flares…

Astrophysics of Galaxies · Physics 2019-03-18 E. Churazov , I. Khabibullin , R. Sunyaev , A. Vikhlinin , G. Ponti , C. Federrath , S. Walch

Gas infall and accretion play a fundamental role in galaxy formation, and several processes of accretion are reviewed. In particular the cold accretion may solve to some extent the angular momentum problem in disk formation, while it is…

Astrophysics · Physics 2007-07-10 F. Combes

Studies of the inner few parsecs at the Galactic Centre provide evidence of a supermassive black hole, associated with the unusual, variable radio and infrared source Sgr A*. Our major aim is the study and analysis of the physical processes…

High Energy Astrophysical Phenomena · Physics 2016-02-03 E. M. Howard

It has long been known that galaxy interactions are associated with enhanced star formation. In a companion paper, we explored this connection by applying a variety of statistics to SDSS data. In particular, we showed that specific star…

Astrophysics · Physics 2009-11-13 Cheng Li , Guinevere Kauffmann , Timothy M. Heckman , Simon D. M. White , Y. P. Jing

In recent years, the evidence for the existence of an ultra-compact concentration of dark mass associated with the radio source Sgr A* in the Galactic Center has become very strong. However, an unambiguous proof that this object is indeed a…

Astrophysics · Physics 2009-10-31 Heino Falcke , Fulvio Melia , Eric Agol

Context. The properties of the accretion flow surrounding the supermassive central black hole of the Galaxy, Sgr A*, will be scrutinized by the new-generation instrument GRAVITY and the Event Horizon Telescope (EHT). Developing fast,…

High Energy Astrophysical Phenomena · Physics 2019-04-17 F. H. Vincent , M. A. Abramowicz , A. A. Zdziarski , M. Wielgus , T. Paumard , G. Perrin , O. Straub

We present a new semi-analytic model for the common growth of black holes (BHs) and galaxies within a hierarchical Universe. The model is tuned to match the mass function of BHs at z=0 and the luminosity functions of active galactic nuclei…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Eyal Neistein , Hagai Netzer

Black hole accretion flows can be divided into two broad classes: cold and hot. Cold accretion flows, which consist of cool optically thick gas, are found at relatively high mass accretion rates. Prominent examples are the standard thin…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Feng Yuan , Ramesh Narayan

We present 3D, adaptive mesh refinement simulations of G2, a cloud of gas moving in a highly eccentric orbit towards the galactic center. We assume that G2 originates from a stellar wind interacting with the environment of the Sgr A* black…

Astrophysics of Galaxies · Physics 2015-06-19 Fabio De Colle , A. C. Raga , Flavio F. Contreras-Torres , Juan C. Toledo-Roy

We review the current status of the understanding how the accretion onto the central black hole proceeds in Active Galaxies. Standard accretion disk is a key element in all relatively bright active galaxies like Seyferts and quasars,…

High Energy Astrophysical Phenomena · Physics 2019-02-07 Bozena Czerny , Mohammad-Hassan Naddaf

We examine 1D two-temperature accretion flows around a supermassive black hole, adopting the specific angular momentum \lambda, the total specific energy \epsilon and the input accretion rate \dot M_{input} = 4.0x10^{-6} solar mass/yr…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Toru Okuda

We present Athena++ grid-based, hydrodynamic simulations of accretion onto Sagittarius A* via the stellar winds of the $\sim 30$ Wolf-Rayet stars within the central parsec of the galactic center. These simulations span $\sim$ 4 orders of…

High Energy Astrophysical Phenomena · Physics 2018-06-26 Sean M. Ressler , Eliot Quataert , James M. Stone

The region bounded by the inner tens of light years at the center of the Milky Way contains five principal components that coexist within the central deep gravitational potential well. These constituents are a black hole candidate (Sgr~A*)…

Astrophysics · Physics 2015-06-24 F. Yusef-Zade , F. Melia , M. Wardle

We studied the final phases of galactic mergers, focusing on interactions between supermassive black holes (SMBHs) and the interstellar medium in a central sub-kpc region, using an N-body/hydrodynamics code. This numerical experiment aims…

Astrophysics of Galaxies · Physics 2020-02-26 Takeru Kawaguchi , Naomichi Yutani , Keiichi Wada

We show that observations by Backer and collaborators over the past two decades constrain the time derivative of the proper motion of Sgr A* to be less than 0.14 mas yr^{-2}. Using this result and a preliminary measurement by Eckart and…

Astrophysics · Physics 2009-10-30 Andrew Gould , Solange V. Ramirez

The detection of a mm/Sub-mm ``bump'' in Sgr A*'s radio spectrum suggests that at least a portion of its overall emission is produced within a compact accretion torus. This inference is strengthened by observations of strong linear…

Astrophysics · Physics 2009-11-10 Siming Liu , Fulvio Melia

I review radiatively inefficient accretion flow models for the 2.6 million solar mass black hole (BH) in the Galactic Center. I argue for a 'concordance model' of Sgr A*: both theory and observations suggest that hot ambient gas around the…

Astrophysics · Physics 2009-11-07 Eliot Quataert

We analyze 134 ks Chandra ACIS-I observations of the Galactic Centre (GC) performed in July 2011. The X-ray image with the field of view $17' \times 17'$ contains the hot plasma surrounding the Sgr~A*. The obtained surface brightness map…

High Energy Astrophysical Phenomena · Physics 2015-09-09 A. Rozanska , P. Mroz , M. Moscibrodzka , M. Sobolewska , T. P. Adhikari

The centers of elliptical galaxies host supermassive black holes that significantly affect the surrounding interstellar medium through feedback resulting from the accretion process. The evolution of this gas and of the nuclear emission…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 S. Pellegrini , L. Ciotti , J. P. Ostriker

Accretion studies have been focused on the flow around bodies with point mass gravitational potentials, but few general results are available for non-point mass distributions. Here, we study the accretion flow onto non-divergent, core…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 J. P. Naiman , Enrico Ramirez-Ruiz , Douglas N. C. Lin