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Article overview
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G2 and Sgr A*: A Cosmic Fizzle At The Galactic Center | | Brian Morsony
; Brandon Gracey
; Jared Workman
; DooSoo Yoon
; | | Date: |
3 Aug 2015 | | Abstract: | We carry out a series of simulations of G2-type clouds interacting with the
black hole Sgr A* at the galactic center. We determine that the accretion rate
from the gas cloud onto Sgr A* for a range of simulation parameters, such as
cloud structure, background structure, background density, grid resolution, and
accretion radius. Regardless of the numerical considerations, the amount of
cloud material accreted is small, both compared to the total cloud mass and the
normal background accretion rate. The accretion rate will remain small for at
least 30 years after periapsis. We also model Br-gamma, bolometric, and X-ray
emission from the cloud with a variety of density profiles, and compare to
observational data. In simulations, the bolometric and X-ray luminosity have a
peak in luminosity lasting from about 1 year before to 1 year after periapsis,
a feature not detected in observations. Simulated Br-gamma emission remains
nearly flat with a small peak 1 month to 1 year before periapsis, depending on
how centrally concentrated the cloud is. Br-gamma emission decreases rapidly as
the cloud passes periapsis due to shock heating of the gas. Observations show
an increase of the FWHM of the Br-gamma line velocity dispersion leading up to
periapsis, consistent with our simulations. Reproducing observations of G2
likely requires two components for the object: an extended, cold gas cloud
responsible for the Br-gamma emission, and a compact core or dusty stellar
object dominating the bolometric luminosity. Any emission from a gaseous
component of G2 should be undetectable by 1 year after periapsis, due to shock
heating and expansion of the cloud. Any remaining emission should be from the
compact component of G2. | | Source: | arXiv, 1508.0384 | | Services: | Forum | Review | PDF | Favorites | |
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