Joe Michail (CfA)
Revealing Sgr A*’s Mid-IR Flares with JWST/MIRI Observations
Abstract: Sgr A* exhibits flaring activity on hourly timescales at radio, (sub)millimeter, near-IR, and X-ray frequencies. Mid-IR flares, which bridge those observed in the submillimeter and near-IR bands, had remained undetected due to the limited sensitivity and angular resolution of available mid-IR telescopes. The launch of JWST and its MIRI instrument in 2021, with its exquisite photometric stability and sensitivity, enabled us to make the first detection of a mid-IR flare from Sgr A* in April 2024. In this talk, I will discuss our analysis of this first flare. The time evolution of the spectrum at four simultaneously observed mid-IR wavelengths using MIRI’s wide spectral bandwidth found a steepening in its mid-IR spectral index, suggestive of synchrotron cooling. We model the spectral and flux evolution using an orbiting synchrotron hotspot, finding a magnetic field strength of 60-90 Gauss. The derived properties suggest that magnetic reconnection and turbulence are driving particle acceleration. Finally, I will briefly highlight ongoing work with the full 30 hours of MIRI observations obtained in 2024.
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Дата на публикация: 6 март, 2025
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