First mid-infrared detection and modeling of a flare from Sgr A*
Abstract
The time-variable emission from the accretion flow of Sgr A*, the supermassive black hole at the Galactic Center, has long been examined in the radio-to-mm, near-infrared (NIR), and X-ray regimes of the electromagnetic spectrum. However, until now, sensitivity and angular resolution have been insufficient in the crucial mid-infrared (MIR) regime. The MIRI instrument on JWST has changed that, and we report the first MIR detection of Sgr A*. The detection was during a flare that lasted about 40 minutes, a duration similar to NIR and X-ray flares, and the source's spectral index steepened as the flare ended. The steepening suggests synchrotron cooling is an important process for Sgr A*'s variability and implies magnetic field strengths 40--70 Gauss in the emission zone. Observations at with the Submillimeter Array revealed a counterpart flare lagging the MIR flare by 10 minutes. The observations can be self-consistently explained as synchrotron radiation from a single population of gradually cooling high-energy electrons accelerated through (a combination of) magnetic reconnection and/or magnetized turbulence.
Cite
@article{arxiv.2501.07415,
title = {First mid-infrared detection and modeling of a flare from Sgr A*},
author = {Sebastiano D. von Fellenberg and Tamojeet Roychowdhury and Joseph M. Michail and Zach Sumners and Grace Sanger-Johnson and Giovanni G. Fazio and Daryl Haggard and Joseph L. Hora and Alexander Philippov and Bart Ripperda and Howard A. Smith and S. P. Willner and Gunther Witzel and Shuo Zhang and Eric E. Becklin and Geoffrey C. Bower and Sunil Chandra and Tuan Do and Macarena Garcia Marin and Mark A. Gurwell and Nicole M. Ford and Kazuhiro Hada and Sera Markoff and Mark R. Morris and Joey Neilsen and Nadeen B. Sabha and Braden Seefeldt-Gail},
journal= {arXiv preprint arXiv:2501.07415},
year = {2025}
}
Comments
Accepted for publication ApJL