Multiwavelength Light Curves of Two Remarkable Sagittarius A* Flares

September 2018 • 2018ApJ...864...58F

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.

Abstract • 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.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2018ApJ...864...58F
• PDF https://iopscience.iop.org/article/10.3847/1538-4357/aad4a2/pdf
• PDF https://stacks.iop.org/0004-637X/864/58/pdf
• PREPRINT http://arxiv.org/abs/1807.07599
• DATA https://cda.harvard.edu/chaser?obsid=16966
• DATA https://nxsa.esac.esa.int/nxsa-web/#bibcode=2018ApJ...864...58F
• ELECTR https://doi.org/10.3847%2F1538-4357%2Faad4a2