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Related papers: Radio Variability of Sgr A* at Centimeter Waveleng…

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The supermassive black hole Sagittarius A* (Sgr A*) exhibits temporal and spectral variability across the electromagnetic spectrum. However, variability at radio frequencies below ~ 5 GHz for timescales shorter than a day remains largely…

A radio source at the Galactic center Sgr A* is a prime supermassive black hole candidate and therefore key to developing our understanding of them. Time variations in the 230 GHz band flux of Sgr A* have been found with the Atacama Large…

High Energy Astrophysical Phenomena · Physics 2020-04-08 Yuhei Iwata , Tomoharu Oka , Masato Tsuboi , Makoto Miyoshi , Shunya Takekawa

We determine the characteristics of the 7mm to 20cm wavelength radio variability in Sgr A* on time scales from days to three decades. The amplitude of the intensity modulation is between 30 and 39% at all wavelengths. Analysis of uniformly…

Astrophysics · Physics 2009-11-13 Jean-Pierre Macquart , Geoff Bower

We present the results of a 3.3-year project to monitor the flux density of Sagittarius A* at 2.0, 1.3, and 0.7 cm with the VLA. The fully calibrated light curves for Sgr A* at all three wavelengths are presented. Typical errors in the flux…

Astrophysics · Physics 2009-11-10 R. M. Herrnstein , J. -H. Zhao , G. C. Bower , W. M. Goss

Sagittarius A* (Sgr A*) is the variable radio, near-infrared (NIR), and X-ray source associated with accretion onto the Galactic center black hole. We present an analysis of the most comprehensive NIR variability dataset of Sgr A* to date:…

We present the results of near-infrared (2 and 3 microns) monitoring of Sgr A*-IR with 1 min time sampling using the natural and laser guide star adaptive optics (LGS AO) system at the Keck II telescope. Sgr A*-IR was observed continuously…

We have performed monitoring observations of the flux density toward the Galactic center compact radio source, Sagittarius A* (Sgr A*), which is a supermassive black hole, from 1996 to 2005 using the Nobeyama Millimeter Array of the…

We report new observations with the Very Large Array, Atacama Large Millimeter Array, and Submillimeter Array at frequencies from 1.0 to 355 GHz of the Galactic Center black hole, Sagittarius A*. These observations were conducted between…

We have performed monitoring observations of the 3-mm flux density toward the Galactic Center compact radio source Sgr A* with the Australia Telescope Compact Array since 2005 October. Careful calibrations of both elevation-dependent and…

Astrophysics of Galaxies · Physics 2009-07-22 Juan Li , Zhi-Qiang Shen , Atsushi Miyazaki , Lei Huang , R. J. Sault , Makoto Miyoshi , Masato Tsuboi , Takahiro Tsutsumi

Sgr A* is variable at radio and submillimeter wavelengths on hourly time scales showing time delays between the peaks of flare emission as well as linearly polarized emission at millimeter and sub-mm wavelengths. To determine the…

Astrophysics · Physics 2009-11-13 F. Yusef-Zadeh , M. Wardle , W. D. Cotton , C. O. Heinke , D. A. Roberts

We compile and analyse long term (~10 year) submillimetre (1.3, 0.87, 0.43 mm, submm) wavelength light curves of the Galactic centre black hole, Sagittarius A*. The 0.87 and 0.43 mm data are taken from the literature, while the majority of…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Jason Dexter , Brandon Kelly , Geoffrey C. Bower , Daniel P. Marrone , Jordan Stone , Richard Plambeck , Sheperd S. Doeleman

We report new infrared measurements of the supermassive black hole at the Galactic Center, Sgr A*, over a decade that was previously inaccessible at these wavelengths. This enables a variability study that addresses variability timescales…

The compact radio source Sgr\,A*, associated with the super massive black hole at the center of the Galaxy, has been studied with VLBA observations at 3 frequencies (22, 43, 86\,GHz) performed on 10 consecutive days in May 2007. The total…

Astrophysics of Galaxies · Physics 2015-05-20 R. -S. Lu , T. P. Krichbaum , A. Eckart , S. König , D. ~Kunneriath , G. Witzel , A. Witzel , J. A. Zensus

We report the presence of a 106-day cycle in the radio variability of Sgr A* based on an analysis of data observed with the Very Large Array (VLA) over the past 20 years. The pulsed signal is most clearly seen at 1.3 cm with a ratio of…

Astrophysics · Physics 2009-10-31 Jun-Hui Zhao , G. C. Bower , W. M. Goss

We present measurements with the VLBA of the variability in the centroid position of Sgr A* relative to a background quasar at 7-mm wavelength. We find an average centroid wander of 71 +/- 45 micro-arcsec for time scales between 50 and 100…

Astrophysics · Physics 2009-11-13 Mark J. Reid , Avery E. Broderick , Abraham Loeb , Mareki Honma , Andreas Brunthaler

We study short-timescale 340 GHz flux-density variability of Sgr A* using ALMA Cycle 3 observations. Careful self-calibration enabled 10 s snapshot imaging with very high effective image-domain SNR, allowing high-cadence monitoring of…

We analyzed 11 epochs of archival Atacama Large Millimeter/submillimeter Array (ALMA) data to investigate flux density variability of Sgr A* at 340 GHz. In one epoch, the light curve exhibits two short-timescale components with…

High Energy Astrophysical Phenomena · Physics 2026-05-13 Kazuki Yanagisawa , Tomoharu Oka , Tatsuya Kotani , Ryo Ariyama , Kazuki Yanagihara , Yuhei Iwata

We present the first detection from the Spitzer Space Telescope of 4.5 micron variability from Sgr A*, the emitting source associated with the Milky Way's central black hole. The >23 hour continuous light curve was obtained with the IRAC…

High Energy Astrophysical Phenomena · Physics 2015-06-22 J. L. Hora , G. Witzel , M. L. N. Ashby , E. E. Becklin , S. Carey , G. G. Fazio , A. Ghez , J. Ingalls , L. Meyer , M. R. Morris , H. A. Smith , S. P. Willner

We present the result of 6 years monitoring of SgrA*, radio source associated to the supermassive black hole at the centre of the Milky Way. Single dish observations were performed with the Itapetinga radio telescope at 7 mm, and the…

Astrophysics of Galaxies · Physics 2012-11-01 Pedro Paulo B. Beaklini , Zulema Abraham

Context. The compact radio and near-infrared (NIR) source Sagittarius A* (Sgr A*) associated with the supermassive black hole in the Galactic center was observed at 7 mm in the context of a NIR triggered global Very Long Baseline Array…

Astrophysics of Galaxies · Physics 2016-02-17 C. Rauch , E. Ros , T. P. Krichbaum , A. Eckart , J. A. Zensus , B. Shahzamanian , K. Muzic
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