Universität zu Köln

Boyce, H., Haggard, D., Witzel, G., von Fellenberg, S., Willner, S. P., Becklin, E. E., Do, T., Eckart, A., Fazio, G. G., Gurwell, M. A., Hora, J. L., Markoff, S., Morris, M. R., Neilsen, J., Nowak, M., Smith, H. A. and Zhang, S. (2022). Multiwavelength Variability of Sagittarius A* in 2019 July. Astrophys. J., 931 (1). BRISTOL: IOP Publishing Ltd. ISSN 1538-4357

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Abstract

We report a timing analysis of near-infrared (NIR), X-ray, and submillimeter data during a 3 day coordinated campaign observing Sagittarius A*. Data were collected at 4.5 mu m with the Spitzer Space Telescope, 2-8 keV with the Chandra X-ray Observatory, 3-70 keV with NuSTAR, 340 GHz with ALMA, and 2.2 mu m with the GRAVITY instrument on the Very Large Telescope Interferometer. Two dates show moderate variability with no significant lags between the submillimeter and the infrared at 99% confidence. A moderately bright NIR flare (F-K similar to 15 mJy) was captured on July 18 simultaneous with an X-ray flare (F2-10 keV similar to 0.1 counts s(-1)) that most likely preceded bright submillimeter flux (F-340 GHz similar to 5.5 Jy) by about +34(-33)(+14) minutes at 99% confidence. The uncertainty in this lag is dominated by the fact that we did not observe the peak of the submillimeter emission. A synchrotron source cooled through adiabatic expansion can describe a rise in the submillimeter 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 nonthermal synchrotron source with lower electron densities, we cannot rule out an unrelated chance coincidence of this bright submillimeter flare with the NIR/X-ray emission.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Boyce, H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Haggard, D. UNSPECIFIED UNSPECIFIED UNSPECIFIED Witzel, G. UNSPECIFIED UNSPECIFIED UNSPECIFIED von Fellenberg, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Willner, S. P. UNSPECIFIED UNSPECIFIED UNSPECIFIED Becklin, E. E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Do, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Eckart, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Fazio, G. G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Gurwell, M. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hora, J. L. UNSPECIFIED UNSPECIFIED UNSPECIFIED Markoff, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Morris, M. R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Neilsen, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Nowak, M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Smith, H. A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Zhang, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-690038
DOI:	10.3847/1538-4357/ac6104
Journal or Publication Title:	Astrophys. J.
Volume:	931
Number:	1
Date:	2022
Publisher:	IOP Publishing Ltd
Place of Publication:	BRISTOL
ISSN:	1538-4357
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language SUPERMASSIVE BLACK-HOLE; MAGNETAR SGR J1745-2900; NEAR-INFRARED FLARES; X-RAY FLARE; GALACTIC-CENTER; RADIO VARIABILITY; SPECTRAL INDEX; LIGHT CURVES; EMISSION; SUBMILLIMETER Multiple languages Astronomy & Astrophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/69003