Second Scale Submillimeter Variability of Sagittarius A* during flaring activity of 2019: On the Origin of Bright Near Infrared Flares

Abstract

In 2019, Sgr A* - the supermassive black hole in the Galactic Center - underwent unprecedented flaring activity in the near infrared (NIR), brightening by up to a factor of 100 compared to quiescent values. Here we report ALMA observations of Sgr A*'s continuum variability at 1.3 mm (230 GHz) - a tracer of the accretion rate - conducted one month after the brightest detected NIR flare and in the middle of the flaring activity of 2019. We develop an innovative light curve extraction technique which (together with ALMA's excellent sensitivity) allows us to obtain the light curves which are simultaneously of high time resolution (2 seconds) and high signal-to-noise ratio (~ 500). We construct an accurate intrinsic structure function of the Sgr A* submm variability, improving on previous studies by about two orders of magnitude in timescale and one order of magnitude in sensitivity. We compare the June 2019 variability behavior with that of 2001-2017, and suggest that the most likely cause of the bright NIR flares is magnetic reconnection.

arXiv commentv2: several comments, clarifications, references, and a derivation added. 9 pages, 2 figures, 1 table. Accepted to ApJL. ; v1: 8 pages, 2 figures, 1 table

References in corpus (22)

• Hot Accretion Flows Around Black Holes
• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A*
• Magnetic Reconnection and Hot Spot Formation in Black Hole Accretion Disks
• An X-ray, IR, and Submillimeter Flare of Sagittarius A*
• On the use of structure functions to study blazar variability: caveats and problems
• A powerful flare from Sgr A* confirms the synchrotron nature of the X-ray emission
• Variability of Sagittarius A* - Flares at 1 Millimeter
• Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter
• Variability Timescale and Spectral Index of Sgr A* in the Near Infrared: Approximate Bayesian Computation Analysis of the Variability of the Closest Supermassive Black Hole
• Simultaneous Multi-Wavelength Observations of Sgr A* during 2007 April 1-11
• Time Dependent Models of Flares from Sagittarius A*
• Unprecedented variability of Sgr A* in NIR
• An 8 hour characteristic time-scale in submillimetre light curves of Sagittarius A*
• The Surprisingly Small Impact of Magnetic Fields On The Inner Accretion Flow of Sagittarius A* Fueled By Stellar Winds
• Galactic Center Research: Manifestations of the Central Black Hole
• Rapid Variability of Sgr A* across the Electromagnetic Spectrum
• The Flux Distribution of Sgr A*
• ALMA Observations of the Terahertz Spectrum of Sagittarius A*
• An Inverse Compton Scattering Origin of X-ray Flares from Sgr A*
• Time Variations in the Flux Density of Sgr A* at 230 GHz Detected with ALMA
• S0-2 star, G1- and G2-objects and flaring activity of the Milky Way's Galactic Center black hole in 2019

Cited by in corpus (15)

• First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
• Black hole flares: ejection of accreted magnetic flux through 3D plasmoid-mediated reconnection
• Millimeter light curves of Sagittarius A* observed during the 2017 Event Horizon Telescope campaign
• The internal Faraday screen of Sagittarius A*
• Hot methanol in the [BHB2007] 11 protobinary system: hot corino versus shock origin? : FAUST V
• General relativistic hydrodynamic simulations of perturbed transonic accretion
• Flares and their echoes can help distinguish photon rings from black holes with space-Earth very long baseline interferometry
• Multi-wavelength Variability of Sagittarius A* in July 2019
• Testing the linear relationship between black hole mass and variability timescale in low-luminosity AGN at submillimeter wavelengths
• ALMA Astrometry of the Objects within 0.5 pc of Sagittarius A${}^{\ast }$
• Detection Prospects of Electromagnetic Signatures from OGLE-2011-BLG-0462
• The Bardeen-Petterson Effect as an Observable Support for the Blanford-Payne Process Black Hole Jet Production
• Full-polarization millimeter wavelength variability of Sagittarius A* during the 2018 EHT campaign
• Search for long-term variability of HESS J1745-290
• Remarkable correspondence of Sagittarius A* submillimeter variability with a stellar-wind-fed accretion flow model