Multiwavelength Light Curves of Two Remarkable Sagittarius A Flares

• Published in: The Astrophysical journal Vol. 864; no. 1; pp. 58 - 64
• Main Authors: Fazio, G. G., Hora, J. L., Witzel, G., Willner, S. P., Ashby, M. L. N., Baganoff, F., Becklin, E., Carey, S., Haggard, D., Gammie, C., Ghez, A., Gurwell, M. A., Ingalls, J., Marrone, D., Morris, M. R., Smith, H. A.
• Format: Journal Article
• Language: English
• Published: 2230 Support The American Astronomical Society 01.09.2018; American Astronomical Society/ IOP Publishing; IOP Publishing
• Subjects: Accretion; accretion, accretion disks; Astrophysics; black hole physics; Deposition; Electromagnetic radiation; Emission; Flares; Fluctuations; Flux; Galaxies; Galaxy: center; infrared: general; Light curve; Mathematical analysis; Milky Way; Near infrared radiation; Radiation; submillimeter: general; Supermassive black holes; Variability; X-rays: individual (Sgr A); Accretion Disks; Accretion; Black Hole Physics; accretion; black hole physics; infrared: general; submillimeter: general; X-rays: individual (Sgr A); Galaxy: center; accretion disks
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/aad4a2

Sgr A*, the supermassive black hole (SMBH) at the center of our Milky Way Galaxy, is known to be a variable source of X-ray, near-infrared (NIR), and submillimeter radiation and therefore a prime candidate to study the electromagnetic radiation generated by mass accretion flow onto a black hole and/or a related jet. Disentangling the power source and emission mechanisms of this variability is a central challenge to our understanding of accretion flows around SMBHs. Simultaneous multiwavelength observations of the flux variations and their time correlations can play an important role in obtaining a better understanding of possible emission mechanisms and their origin. This paper presents observations of two flares that both apparently violate the previously established patterns in the relative timing of submillimeter/NIR/X-ray flares from Sgr A*. One of these events provides the first evidence of coeval structure between NIR and submillimeter flux increases, while the second event is the first example of the sequence of submillimeter/X-ray/NIR flux increases all occurring within ∼1 hr. Each of these two events appears to upend assumptions that have been the basis of some analytic models of flaring in Sgr A*. However, it cannot be ruled out that these events, even though unusual, were just coincidental. These observations demonstrate that we do not fully understand the origin of the multiwavelength variability of Sgr A* and show that there is a continued and important need for long-term, coordinated, and precise multiwavelength observations of Sgr A* to characterize the full range of variability behavior.