Multi-wavelength Variability of Sagittarius A* in July 2019

Abstract

We report timing analysis of near-infrared (NIR), X-ray, and sub-millimeter (submm) data during a three-day coordinated campaign observing Sagittarius A*. Data were collected at 4.5 micron with the Spitzer Space Telescope, 2-8 keV with the Chandra X-ray Observatory, 3-70 keV with NuSTAR, 340 GHz with ALMA, and at 2.2 micron with the GRAVITY instrument on the Very Large Telescope Interferometer. Two dates show moderate variability with no significant lags between the submm and the infrared at 99% confidence. July 18 captured a moderately bright NIR flare (F_K ~ 15 mJy) simultaneous with an X-ray flare (F ~ 0.1 cts/s) that most likely preceded bright submm flux (F ~ 5.5 Jy) by about +34 (+14 -33) minutes at 99% confidence. The uncertainty in this lag is dominated by the fact that we did not observe the peak of the submm emission. A synchrotron source cooled through adiabatic expansion can describe a rise in the submm once the synchrotron-self-Compton NIR and X-ray peaks have faded. This model predicts high GHz and THz fluxes at the time of the NIR/X-ray peak and electron densities well above those implied from average accretion rates for Sgr A*. However, the higher electron density postulated in this scenario would be in agreement with the idea that 2019 was an extraordinary epoch with a heightened accretion rate. Since the NIR and X-ray peaks can also be fit by a non-thermal synchrotron source with lower electron densities, we cannot rule out an unrelated chance coincidence of this bright submm flare with the NIR/X-ray emission.

Accepted for publication in The Astrophysical Journal

References in corpus (34)

• An Update on Monitoring Stellar Orbits in the Galactic Center
• An Unambiguous Detection of Faraday Rotation in Sagittarius A*
• An Improved Distance and Mass Estimate for Sgr A* from a Multistar Orbit Analysis
• Polarimetry of near-infrared flares from Sagittarius A*
• Flaring Activity of Sgr A* at 43 and 22 GHz: Evidence for Expanding Hot Plasma
• Observational appearance of inefficient accretion flows and jets in 3D GRMHD simulations: Application to Sgr~A*
• A Constant Spectral Index for Sagittarius A* During Infrared/X-ray Intensity Variations
• Electron and proton heating in trans-relativistic magnetic reconnection
• A polarised infrared flare from Sagittarius A* and the signatures of orbiting plasma hotspots
• Near-infrared polarimetry setting constraints on the orbiting spot model for Sgr A* flares
• Time Dependent Models of Flares from Sagittarius A*
• Tidal effects on small bodies by massive black holes
• Polarized NIR and X-ray Flares from SgrA*
• NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A* flares
• The Surprisingly Small Impact of Magnetic Fields On The Inner Accretion Flow of Sagittarius A* Fueled By Stellar Winds
• Simultaneous NIR/sub-mm observation of flare emission from SgrA*
• Jet-lag in Sgr A*: What size and timing measurements tell us about the central black hole in the Milky Way
• ALMA and VLA measurements of frequency-dependent time lags in Sagittarius A*: evidence for a relativistic outflow
• Constraining particle acceleration in Sgr A* with simultaneous GRAVITY, Spitzer, NuSTAR and Chandra observations
• The X-ray Flux Distribution of Sagittarius A* as Seen by Chandra
• The Flux Distribution of Sgr A*
• On the orientation of the Sagittarius A* system
• Polarized light from Sgr A* in the near-infrared $K_s$-band
• A power-law break in the near-infrared power spectrum of the Galactic center black hole
• Spectral and Imaging properties of Sgr A* from High-Resolution 3D GRMHD Simulations with Radiative Cooling
• Spitzer/IRAC Observations of the Variability of Sgr A* and the Object G2 at 4.5 microns
• Locating the intense interstellar scattering towards the inner Galaxy
• Detection of faint stars near SgrA* with GRAVITY
• Diffraction Limited Imaging Spectroscopy of the SgrA* Region using OSIRIS, a new Keck Instrument
• The Variability of Polarized Radiation from Sgr A*
• Sagittarius A* High Energy X-ray Flare Properties During NuSTAR Monitoring of the Galactic Center from 2012 to 2015
• Second Scale Submillimeter Variability of Sagittarius A* during flaring activity of 2019: On the Origin of Bright Near Infrared Flares
• Simultaneous Monitoring of X-ray and Radio Variability in Sagittarius A*
• A Swift study of long-term changes in the X-ray flaring properties of Sagittarius A*

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• New Evidence for a Flux-independent Spectral Index of Sgr A* in the Near-infrared
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