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The origin of irradiation and fluorescence of the 6.4 keV bright giant molecular clouds surrounding Sgr A*, the central supermassive black hole of our Galaxy, remains enigmatic. Testing the theory of a past active period of Sgr A* requires…

Astrophysics of Galaxies · Physics 2015-03-18 F. Marin , F. Muleri , P. Soffitta , V. Karas , D. Kunneriath

A cold neutral and extremely dim accretion disk may be present as a remnant of a past vigorous activity around the black hole in our Galactic Center (GC). Here we discuss ways to detect such a disk through its interaction with numerous…

Astrophysics · Physics 2009-11-07 Sergei Nayakshin , Rashid Sunyaev , .

Solar flares are major space weather events that result from the explosive conversion of stored magnetic energy into bulk motion, plasma heating, and particle acceleration. While the standard flare model has proven highly successful in…

Solar and Stellar Astrophysics · Physics 2025-10-09 Joel T. Dahlin , Spiro K. Antiochos , Peter F. Wyper , Jiong Qiu , C. Richard DeVore

The supermassive black hole Sagittarius A* (Sgr A*) is located at the dynamical center of the Milky Way. In a recent study of the X-ray flaring activity from Sgr A* using Chandra, XMM-Newton and Swift data from 1999 to 2015, it has been…

High Energy Astrophysical Phenomena · Physics 2020-04-15 E. Mossoux , B. Finociety , J. -M. Beckers , F. H. Vincent

We report on a successful, simultaneous observation and modelling of the millimeter (mm) to near-infrared (NIR) flare emission of the Sgr A* counterpart associated with the supermassive black hole at the Galactic centre (GC). We present a…

Understanding how energy is released in flares is one of the central problems of solar and stellar astrophysics. Observations of high temperature flare plasma hold many potential clues as to the nature of this energy release. It is clear,…

Solar and Stellar Astrophysics · Physics 2020-05-27 Jeffrey W. Reep , Harry P. Warren , Christopher S. Moore , Crisel Suarez , Laura A. Hayes

We report on the structure and evolution of a current sheet that formed in the wake of an eruptive X8.3 flare observed at the west limb of the Sun on September 10, 2017. Using observations from the EUV Imaging Spectrometer (EIS) on Hinode…

Solar and Stellar Astrophysics · Physics 2018-02-28 Harry P. Warren , David H. Brooks , Ignacio Ugarte-Urra , Jeffrey W. Reep , Nicholas A. Crump , George A. Doschek

Multi-wavelength monitoring of Sgr A* flaring activity confirms the presence of embedded structures within the disk on size scales commensurate with the innermost accretion region, matching size scales that are derived from observed light…

High Energy Astrophysical Phenomena · Physics 2015-11-10 E M Howard

We report on recent near-infrared (NIR) and X-ray observations of Sagittarius A* (Sgr A*), the electromagnetic manifestation of the ~4x10^6 solar masses super-massive black hole (SMBH) at the Galactic Center. The goal of these coordinated…

Recent high resolution observations of the Galactic center black hole allow for direct comparison with accretion disk simulations. We compare two-temperature synchrotron emission models from three dimensional, general relativistic…

High Energy Astrophysical Phenomena · Physics 2010-10-26 Jason Dexter , Eric Agol , P. Chris Fragile , Jonathan C. McKinney

Sagittarius A* (Sgr A*), the supermassive black hole at the center of the Milky Way, undergoes large-amplitude near-infrared (NIR) flares that can coincide with the continuous rotation of the NIR emission region. One promising explanation…

High Energy Astrophysical Phenomena · Physics 2024-04-18 Arpiar Avetis Grigorian , Jason Dexter

In this paper we examine properties of the variable source Sgr A* in the near-infrared (NIR) using a very extensive Ks-band data set from NACO/VLT observations taken 2004 to 2009. We investigate the variability of Sgr A* with two different…

Magnetic reconnection is a fundamental physical process converting magnetic energy into not only plasma energy but also particle energy in various astrophysical phenomena. In this letter, we show a unique dataset of a solar flare where…

Solar and Stellar Astrophysics · Physics 2022-01-12 Lei Lu , Li Feng , Alexander Warmuth , Astrid M. Veronig , Jing Huang , Siming Liu , Weiqun Gan , Zongjun Ning , Beili Ying , Guannan Gao

In this article we summarise and discuss the infrared, radio, and X-ray emission from the supermassive black hole in the Galactic Centre, SgrA*. We include new results from near-infrared polarimetric imaging observations obtained on May…

Astrophysics · Physics 2008-11-26 S. Trippe , T. Paumard , T. Ott , S. Gillessen , F. Eisenhauer , F. Martins , R. Genzel

Sagittarius A* (Sgr A*) is the supermassive black hole residing at the center of the Milky Way. It has been the main target of an extensive multiwavelength campaign we carried out in April 2007. Herein, we report the detection of a bright…

High Energy Astrophysical Phenomena · Physics 2014-11-20 G. Trap , A. Goldwurm , R. Terrier , K. Dodds-Eden , S. Gillessen , R. Genzel , E. Pantin , P. O. Lagage , P. Ferrando , G. Belanger , D. Porquet , N. Grosso , F. Yusef-Zadeh , F. Melia

Current sheet is believed to be the region of energy dissipation via magnetic reconnection in solar flares. However, its properties, for example, the dynamic process, have not been fully understood. Here we report a current sheet in a solar…

Solar and Stellar Astrophysics · Physics 2018-02-07 Y. Li , J. C. Xue , M. D. Ding , X. Cheng , Y. Su , L. Feng , J. Hong , H. Li , W. Q. Gan

The accretion flow around the Galactic Center black hole Sagittarius A* (Sgr A*) is expected to have an electron temperature that is distinct from the ion temperature, due to weak Coulomb coupling in the low-density plasma. We present four…

High Energy Astrophysical Phenomena · Physics 2018-05-31 Andrew Chael , Michael E. Rowan , Ramesh Narayan , Michael D. Johnson , Lorenzo Sironi

The Galactic center supermassive black hole, Sgr A*, has experienced a strong, unprecedented flare in May 2019 when its near-infrared luminosity reached much brighter levels than ever measured. We argue that an explosive event of particle…

High Energy Astrophysical Phenomena · Physics 2020-03-18 Eduardo M. Gutiérrez , Rodrigo Nemmen , Fabio Cafardo

The supermassive black hole Sgr A* is located at the Milky Way center. We studied its flaring activity close to the DSO/G2 pericenter passage to constrain the physical properties and origin of the flares. Simultaneous/coordinated…

High Energy Astrophysical Phenomena · Physics 2016-04-27 E. Mossoux , N. Grosso , H. Bushouse , A. Eckart , F. Yusef-Zadeh , R. L. Plambeck , F. Peissker , M. Valencia-S. , D. Porquet , W. D. Cotton , D. A. Roberts

Flux ropes erupting from the vicinity of the black hole are thought to be a potential model for the flares observed in Sgr\,A$^*$. In this study, we examine the radiative properties of flux ropes that emerged from the vicinity of the black…

High Energy Astrophysical Phenomena · Physics 2024-08-07 Hong-Xuan Jiang , Yosuke Mizuno , Indu K. Dihingia , Antonios Nathanail , Ziri Younsi , Christian M. Fromm