Multiwavelength study of the flaring activity of Sgr A* in 2014 February-April

Abstract

The supermassive black hole Sgr A* is located at the Milky Way center. We studied its flaring activity close to the DSO/G2 pericenter passage to constrain the physical properties and origin of the flares. Simultaneous/coordinated observations were made in 2014 Feb-Apr with XMM-Newton, HST/WFC3, VLT/SINFONI, VLA and CARMA. We detected 2 X-ray and 3 NIR flares on Mar. 10 and Apr. 2 with XMM-Newton and HST and 2 NIR flares on Apr. 3 and 4 with VLT. The Mar. 10 X-ray flare has a long rise and a rapid decay. Its NIR counterpart peaked 4320s before the X-ray peak implying a variation in the X-ray-to-NIR flux ratio. This flare may be a single flare where change in the flux ratio is explained by the adiabatic compression of a plasmon or 2 close flares with simultaneous X-ray/NIR peaks. We observed an increase in the rising radio flux density on Mar. 10 with the VLA. It could be the delayed emission from a NIR/X-ray flare preceding our observation. The Apr. 2 X-ray flare occurred for HST in the Earth occultation of Sgr A*. We thus only observed the start of its NIR counterpart. After the occultation, we observed the decay phase of a bright NIR flare with no X-ray counterpart. On Apr. 3, 2 CARMA flares were observed. The 1rst one may be the delayed emission of a VLT NIR flare. We thus observed 7 NIR flares whose 3 have an X-ray counterpart. We studied the physical parameters of the flaring region for each NIR flare but none of the possible radiative processes can be ruled out for the X-ray flares creation. Our X-ray flaring rate is consistent with those observed in the 2012 Chandra XVP campaign. No increase in the flaring activity was thus triggered close to the DSO/G2 pericenter passage. Moreover, higher X-ray flaring rates had already been observed with no increase in the quiescent level. There is thus no direct link between an X-ray flaring-rate increase and an accretion-rate change. (abridged)

Accepted version

References in corpus (16)

• Flaring Activity of Sgr A* at 43 and 22 GHz: Evidence for Expanding Hot Plasma
• X-ray hiccups from SgrA* observed by XMM-Newton. The second brightest flare and three moderate flares caught in half a day
• Radio and Millimeter Monitoring of Sgr A*: Spectrum, Variability, and Constraints on the G2 Encounter
• Simultaneous Chandra, CSO and VLA Observations of Sgr A*: The Nature of Flaring Activity
• Detection of Galactic Center source G2 at 3.8 $\mu$m during periapse passage
• The Galactic Center cloud G2 and its gas streamer
• NuSTAR detection of high-energy X-ray emission and rapid variability from Sagittarius A* flares
• Timing and Flux Evolution of the Galactic Center Magnetar SGR J1745-2900
• Simultaneous NIR/sub-mm observation of flare emission from SgrA*
• ALMA and VLA measurements of frequency-dependent time lags in Sagittarius A*: evidence for a relativistic outflow
• Monitoring the Dusty S-Cluster Object (DSO/G2) on its Orbit towards the Galactic Center Black Hole
• Dust-enshrouded star near supermassive black hole: predictions for high-eccentricity passages near low-luminosity galactic nuclei
• No asymmetric outflows from Sagittarius A* during the pericenter passage of the gas cloud G2
• ALMA backed NIR high resolution integral field spectroscopy of the NUGA galaxy NGC 1433
• No Microwave Flare of Sagittarius A* around the G2 Periastron Passing
• The Discovery of Radio Stars within 10 arcseconds of Sgr A* at 7mm

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• Detection of a 20 minute time lag observed from Sgr A* between 8 and 10 GHz with the VLA
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