Year: 2016
Type: article
Abstract: ABSTRACT The Fermi bubbles are two lobes filled with non-thermal particles that emit gamma rays, extend vertically from the Galactic center, and formed from either nuclear star formation or accretion activity on Sgr A*. Simulations predict a range of shock strengths as the bubbles expand into the surrounding hot gas halo ( K), but with significant uncertainties in the energetics, age, and thermal gas structure. The bubbles should contain thermal gas with temperatures between 106 and 108 K, with potential X-ray signatures. In this work, we constrain the bubbles’ thermal gas structure by modeling O vii and O viii emission line strengths from archival XMM-Newton and Suzaku data. Our emission model includes a hot thermal volume-filled bubble component cospatial with the gamma-ray region, and a shell of compressed material. We find that a bubble/shell model with cm−3 and with log(T) ≈ 6.60–6.70 is consistent with the observed line intensities. In the framework of a continuous Galactic outflow, we infer a bubble expansion rate, age, and energy injection rate of km s−1, Myr, and erg s−1. These estimates are consistent with the bubbles forming from a Sgr A* accretion event rather than from nuclear star formation.
Source: The Astrophysical Journal
Authors: Matthew J. Miller, Joel N. Bregman
Institution: University of Michigan
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: THE MILKY WAY HAS A HOT HALO OF GAS AT LEAST TENS OF KPC IN SIZE, PROBABLY EXTENDING TO THE VIRIAL RADIUS, IF NOT BEYOND. INITIAL STUDIES OF THE HOT, IF GALAXIES HAD THE COSMOLOGICAL BARYON-TO-DARK MATTER RATIO, THEY WOULD HAVE 3-30 TIMES THEIR OBSERVED BARYON MASS. THESE MISSING BARYONS ARE UNDETE
OpenAlex ID: W2505955626