Flaring Activity of Sgr A* at 43 and 22 GHz: Evidence for Expanding Hot Plasma

Abstract

We have carried out Very Large Array (VLA) continuum observations to study the variability of Sgr A* at 43 GHz ($\lambda$=7mm) and 22 GHz ($\lambda$=13mm). A low level of flare activity has been detected with a duration of $\sim$ 2 hours at these frequencies, showing the peak flare emission at 43 GHz leading the 22 GHz peak flare by $\sim 20$ to 40 minutes. The overall characteristics of the flare emission are interpreted in terms of the plasmon model of Van der Laan (1966) by considering the ejection and adiabatically expansion of a uniform, spherical plasma blob due to flare activity. The observed peak of the flare emission with a spectral index ${\nu }^{-\alpha }$ of $\alpha$=1.6 is consistent with the prediction that the peak emission shifts toward lower frequencies in an adiabatically-expanding self-absorbed source. We present the expected synchrotron light curves for an expanding blob as well as the peak frequency emission as a function of the energy spectral index constrained by the available flaring measurements in near-IR, sub-millimeter, millimeter and radio wavelengths. We note that the blob model is consistent with the available measurements, however, we can not rule out the jet of Sgr A*. If expanding material leaves the gravitational potential of Sgr A*, the total mass-loss rate of nonthermal and thermal particles is estimated to be $\le 2\times 10^{-8}$ M${}_{\odot }$ yr${}^{-1}$. We discuss the implication of the mass-loss rate since this value matches closely with the estimated accretion rate based on polarization measurements.

Revised with new Figures 1 and 2, 17 pages, 4 figures, ApJ (in press)

References in corpus (31)

• On the Fate of Gas Accreting at a Low Rate onto a Black Hole
• Chandra X-ray Spectroscopic Imaging of Sgr A* and the Central Parsec of the Galaxy
• Nonthermal Electrons in Radiatively Inefficient Accretion Flow Models of Sagittarius A*
• Near-infrared flares from accreting gas around the supermassive black hole at the Galactic Centre
• SINFONI in the Galactic Center: young stars and IR flares in the central light month
• Three-dimensional MHD Simulations of Radiatively Inefficient Accretion Flows
• The Supermassive Black Hole at the Galactic Center
• Advection-Dominated Accretion Model of Sagittarius A*: Evidence for a Black Hole at the Galactic Center
• GRS 1915+105 and the Disc-Jet Coupling in Accreting Black Hole Systems
• X-ray emitting young stars in the Orion Nebula
• Variable Infrared Emission from the Supermassive Black Hole at the Center of the Milky Way
• A Jet-ADAF model for Sgr A*
• Interferometric Detection of Linear Polarization from Sagittarius A* at 230 GHz
• Imaging Optically-Thin Hot Spots Near the Black Hole Horizon of Sgr A* at Radio and Near-Infrared Wavelengths
• Interferometric Measurements of Variable 340 GHz Linear Polarization in Sagittarius A*
• First Simultaneous NIR/X-ray Detection of a Flare from SgrA*
• The "missing" YSOs in the central parsec of the Galaxy: evidence for star formation in a massive accretion disk and a top-heavy IMF
• A Multi-Wavelength Study of Sgr A*: The Role of Near-IR Flares in Production of X-ray, Soft $\gamma$-ray and Sub-millimeter Emission
• The Flare Activity of SgrA*; New Coordinated mm to X-Ray Observations
• Variability of Sagittarius A* - Flares at 1 Millimeter
• Circular Polarization of Radio Emission from Relativistic Jets
• Variations in the spectral slope of Sgr A* during a NIR flare
• Intra-day Variability of Sagittarius A* at 3 Millimeters
• The Magnetohydrodynamics of Convection-Dominated Accretion Flows
• Infrared synchrotron oscillations in GRS 1915+105
• The Variability of Sagittarius A* at Centimeter Wavelengths
• Stochastic Electron Acceleration During the NIR and X-ray Flares in Sagittarius A*
• Synchrotron Radiation From Radiatively Inefficient Accretion Flow Simulations: Applications to Sgr A*
• Intra-Day Variation of Sagittarius A* at Short Millimeter Wavelengths
• New Constraints on the Nature of Radio Emission in Sagittarius A*
• Understanding the Radio Variability of Sgr A*

Cited by in corpus (118)

• Hot Accretion Flows Around Black Holes
• The Galactic Center Massive Black Hole and Nuclear Star Cluster
• Testing black hole candidates with electromagnetic radiation
• An X-ray, IR, and Submillimeter Flare of Sagittarius A*
• Testing Properties of the Galactic Center Black Hole Using Stellar Orbits
• A Chandra/HETGS Census of X-ray Variability From Sgr A* During 2012
• Methods for detecting flaring structures in Sagittarius A* with high frequency VLBI
• A Magnetohydrodynamic Model for the Formation of Episodic Jets
• Key Science Goals for the Next-Generation Event Horizon Telescope
• Sgr A* and General Relativity
• Testing the No-Hair Theorem with Observations in the Electromagnetic Spectrum. III. Quasi-Periodic Variability
• Towards the event horizon -- the supermassive black hole in the Galactic Center
• Coupled jet-disk model for Sgr A*: explaining the flat-spectrum radio core with GRMHD simulations of jets
• Millimeter Flares and VLBI Visibilities from Relativistic Simulations of Magnetized Accretion onto the Galactic Center Black Hole
• The Size, Shape, and Scattering of Sagittarius A* at 86 GHz: First VLBI with ALMA
• Simultaneous Chandra, CSO and VLA Observations of Sgr A*: The Nature of Flaring Activity
• 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
• Source-intrinsic near-infrared properties of Sgr A*: Total intensity measurements
• How to hide large scale outflows: size constraints on the jets of Sgr A*
• Time Dependent Models of Flares from Sagittarius A*
• Unprecedented variability of Sgr A* in NIR
• Testing the No-Hair Theorem with Observations of Black Holes in the Electromagnetic Spectrum
• Polarimetry and Astrometry of NIR Flares as Event Horizon Scale, Dynamical Probes for the Mass of Sgr A*
• Prospects for testing the nature of Sgr A*'s NIR flares on the basis of current VLT- and future VLTI-observations
• Polarized NIR and X-ray Flares from SgrA*
• An 8 hour characteristic time-scale in submillimetre light curves of Sagittarius A*
• The Position of Sagittarius A*: III. Motion of the Stellar Cusp
• Sgr A* flares: tidal disruption of asteroids and planets?
• NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A* flares
• Distinguishing black holes and wormholes with orbiting hot spots
• Simultaneous NIR/sub-mm observation of flare emission from SgrA*
• Galactic Center Research: Manifestations of the Central Black Hole
• Jet-lag in Sgr A*: What size and timing measurements tell us about the central black hole in the Milky Way
• Rapid Variability of Sgr A* across the Electromagnetic Spectrum
• The Proper Motion of the Galactic Center Pulsar Relative to Sagittarius A*
• ALMA and VLA measurements of frequency-dependent time lags in Sagittarius A*: evidence for a relativistic outflow
• Near infrared flares of Sagittarius A*: Importance of near infrared polarimetry
• Evidence for A Parsec-scale Jet from The Galactic Center Black Hole: Interaction with Local Gas
• A 600 minute near-infrared lightcurve of Sagittarius A*
• Concurrent X-ray, near-infrared, sub-millimeter, and GeV gamma-ray observations of Sgr A*
• Constraining particle acceleration in Sgr A* with simultaneous GRAVITY, Spitzer, NuSTAR and Chandra observations
• The Flux Distribution of Sgr A*
• The Intrinsic Two-Dimensional Size of Sagittarius A*
• On the orientation of the Sagittarius A* system
• Multiwavelength VLBI observations of Sagittarius A*
• Modeling mm- to X-ray flare emission from SgrA*
• The instrumental polarization of the Nasmyth focus polarimetric differential imager NAOS/CONICA (NACO) at the VLT - Implications for time-resolved polarimetric measurements of Sgr A*
• Polarized light from Sgr A* in the near-infrared $K_s$-band
• Metrics and Motivations for Earth-Space VLBI: Time-Resolving Sgr A* with the Event Horizon Telescope
• Effect of Electromagnetic Interaction on Galactic Center Flare Components
• Testing the No-Hair Theorem with Observations of Black Holes in the Electromagnetic Spectrum
• The extreme luminosity states of Sagittarius A*
• Statistics of X-ray flares of Sagittarius A*: evidence for solar-like self-organized criticality phenomenon
• Magnetic reconnection plasmoid model for Sagittarius A* flares
• Silhouettes of invisible black holes
• Zooming in on a sleeping giant: milliarcsecond HSA imaging of the black hole binary V404 Cyg in quiescence
• An Inverse Compton Scattering Origin of X-ray Flares from Sgr A*
• Variations in emission from episodic plasmoid ejecta around black holes
• Multiwavelength Light Curves of Two Remarkable Sagittarius A* Flares
• The Variability of Polarized Radiation from Sgr A*
• Fundamental Plane of Black Hole Activity in Quiescent Regime
• Coordinated NIR/mm observations of flare emission from Sagittarius A*
• A magnetohydrodynamic model for multi-wavelength flares from Sagittarius~A${}^{\star }$ (I): model and the near-infrared and X-ray flares
• Multiwavelength study of the flaring activity of Sgr A* in 2014 February-April
• The Galactic centre mini-spiral in the mm-regime
• Sagittarius A* High Energy X-ray Flare Properties During NuSTAR Monitoring of the Galactic Center from 2012 to 2015
• Testing the nature of the supermassive black hole candidate in SgrA* with light curves and images of hot spots
• Evidence for a jet and outflow from Sgr A*: a continuum and spectral line study
• Rapid Intrinsic Variability of Sgr A* at Radio Wavelengths
• Time Variations in the Flux Density of Sgr A* at 230 GHz Detected with ALMA
• The intrinsic structure of Sagittarius A* at 1.3 cm and 7 mm
• Performance of astrometric detection of a hotspot orbiting on the innermost stable circular orbit of the galactic centre black hole
• Sixteen years of X-ray monitoring of Sagittarius A*: Evidence for a decay of the faint flaring rate from 2013 August, 13 months before a rise in the bright flaring rate
• Near-infrared polarimetry as a tool for testing properties of accreting super-massive black holes
• Study of the X-ray activity of Sgr A* during the 2011 XMM-Newton campaign
• Simultaneous Monitoring of X-ray and Radio Variability in Sagittarius A*
• The variability of Sagittarius A* at 3 millimeter
• Distinguishing an ejected blob from alternative flare models at the Galactic centre with GRAVITY
• A nonthermal bomb explains the near-infrared superflare of Sgr A*
• Formation of episodic jets and associated flares from black hole accretion systems
• General relativistic effects and the near-infrared and X-ray variability of Sgr A* I
• Multi-wavelength Observations of Sgr A*. I. 2019 July 18
• Probing spacetime around Sagittarius A* using modeled VLBI closure phases
• Black Holes Up Close
• Multi-wavelength Variability of Sagittarius A* in July 2019
• Constraining the accretion flow density profile near Sgr A* using the $L^{\prime }$-band emission of the S2 star
• Sgr A* and its Environment: Low Mass Star Formation, the Origin of X-ray Gas and Collimated Outflow
• Testing a class of non-Kerr metrics with hot spots orbiting SgrA${}^{\ast }$
• Soft gamma-ray constraints on a bright flare from the Galactic Center supermassive black hole
• An evolving hot spot orbiting around Sgr A*
• Fermi LAT observations of Sagittarius A*: Imaging Analysis
• Continuation of the X-ray monitoring of Sgr A*: the increase in bright flaring rate confirmed
• Monitoring the Galactic Centre with Australia Telescope Compact Array
• The Nature of Linearly Polarized Millimeter and Sub-millimeter Emission in Sagittarius A*
• No Microwave Flare of Sagittarius A* around the G2 Periastron Passing
• Coordinated multi-wavelength observations of Sgr A*
• Occultation of the Quiescent Emission from Sgr A* by IR Flares
• Polarized signatures of adiabatically expanding hotspots in Sgr A*'s accretion flow
• Correlation between Flux and Spectral Index during Flares in Sagittarius A*
• Flare emission from Sagittarius A*
• Detection of a 20 minute time lag observed from Sgr A* between 8 and 10 GHz with the VLA
• Signatures of an Encounter Between the G2 Cloud and a Jet from Sgr A*
• Long-term monitoring of Sgr A* at 7 mm with VERA and KaVA
• Time delays between radio and X-ray and between narrow radio bands of Sgr A* flares in the shock oscillation model
• Coordinated mm/sub-mm observations of Sagittarius A* in May 2007
• Time Lag in Intra-Day Variability of Sgr A* between the Light Curves at 90 and 102GHz
• The Jet in the Galactic Center: An Ideal Laboratory for Magnetohydrodynamics and General Relativity
• The Galactic Center Black Hole Laboratory
• The X-ray variation of M81* resolved by Chandra and NuSTAR
• SgrA* emission at 7mm: variability and periodicity
• Closing the gap: Follow-up observations of peculiar dusty objects close to Sgr A* using ERIS
• Sagittarius A* near-infrared flares polarization as a probe of space-time I: Non-rotating exotic compact objects
• Radiative energy from a reconnection region around massive black hole
• PATOKA: Simulating Electromagnetic Observables of Black Hole Accretion
• Time Lag in Sgr A* Intra-Day Variability between the light curves at 90 and 102 GHz
• Variability of Sagittarius A* at 3 GHz on minute-scale with MeerKAT
• Visible shapes of black holes M87* and SgrA*