General relativistic effects and the near-infrared and X-ray variability of Sgr A* I

Abstract

The near-infrared (NIR) and X-ray emission of Sagittarius A* shows occasional bright flares that are assumed to originate from the innermost region of the accretion flow. We identified $25$ $4.5\mu m$ and $24$ X-ray flares in archival data obtained with the \textit{Spitzer} and \textit{Chandra} observatories. With the help of general relativistic ray-tracing code, we modeled trajectories of ``hot spots'' and studied the light curves of the flares for signs of the effects of general relativity. Despite their apparent diversity in shape, all flares share a common, exponential impulse response, a characteristic shape that is the building block of the variability. This shape is symmetric, that is, the rise and fall times are the same. Furthermore, the impulse responses in the NIR and X-ray are identical within uncertainties, with an exponential time constant $\tau \sim 15$ minute. The observed characteristic flare shape is inconsistent with hot-spot orbits viewed edge-on. Individually modeling the light curves of the flares, we derived constraints on the inclination of the orbital plane of the hot spots with respect to the observer ($i\sim 30^{\circ },<75^{\circ }$) and on the characteristic timescale of the intrinsic variability (tens of minutes).

References in corpus (27)

• First Sagittarius A* Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole in the Center of the Milky Way
• First Sagittarius A* Event Horizon Telescope Results. VI: Testing the Black Hole Metric
• First Sagittarius A* Event Horizon Telescope Results. V. Testing Astrophysical Models of the Galactic Center Black Hole
• First Sagittarius A* Event Horizon Telescope Results. III: Imaging of the Galactic Center Supermassive Black Hole
• First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multi-wavelength Observations, Data Processing, and Calibration
• First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
• The Submillimeter Bump in Sgr A* from Relativistic MHD Simulations
• Flaring Activity of Sgr A* at 43 and 22 GHz: Evidence for Expanding Hot Plasma
• A Constant Spectral Index for Sagittarius A* During Infrared/X-ray Intensity Variations
• A Magnetohydrodynamic Model for the Formation of Episodic Jets
• Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter
• Sgr A* near-infrared flares from reconnection events in a magnetically arrested disc
• Ab Initio Horizon-Scale Simulations of Magnetically Arrested Accretion in Sagittarius A* Fed by Stellar Winds
• Time Dependent Models of Flares from Sagittarius A*
• Orbital motion near Sagittarius A* -- Constraints from polarimetric ALMA observations
• Magnetic Hair and Reconnection in Black Hole Magnetospheres
• NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A* flares
• Dynamically important magnetic fields near the event horizon of Sgr A*
• 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
• Spitzer/IRAC Observations of the Variability of Sgr A* and the Object G2 at 4.5 microns
• Bright X-ray flares from Sgr A*
• Hard Synchrotron Spectra from Magnetically Dominated Plasma Turbulence
• Diffraction Limited Imaging Spectroscopy of the SgrA* Region using OSIRIS, a new Keck Instrument
• Asymmetric structure in Sgr A* at 3mm from closure phase measurements with VLBA, GBT and LMT
• A formal method for identifying distinct states of variability in time-varying sources: SgrA* as an example
• Multi-wavelength Variability of Sagittarius A* in July 2019

Cited by in corpus (6)

• Polarimetry and Astrometry of NIR Flares as Event Horizon Scale, Dynamical Probes for the Mass of Sgr A*
• Dynamics and Emission Properties of Flux Ropes from Two-Temperature GRMHD Simulations with Multiple Magnetic Loops
• Forward Ray Tracing and Hot Spots in Kerr Spacetime
• General Relativistic effects and the NIR variability of Sgr A* II: A systematic approach to temporal asymmetry
• Investigating non-Keplerian motion in flare events with astrometric data
• Photometric Constraints on Intermediate-mass Black Holes in the Galactic Centre