The properties and fate of the galactic center G2 cloud
- Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
- (United States)
The object G2 was recently discovered descending into the gravitational potential of the supermassive black hole (BH) Sgr A*. We test the photoionized cloud scenario, determine the cloud properties, and estimate the emission during the pericenter passage. The incident radiation is computed starting from the individual stars at the locations of G2. The radiative transfer calculations are conducted with CLOUDY code and 2011 broadband and line luminosities are fitted. The spherically symmetric, tidally distorted, and magnetically arrested cloud shapes are tested with both the interstellar medium dust and 10 nm graphite dust. The best-fitting magnetically arrested model has the initial density n {sub init} = 1.8 × 10{sup 5} cm{sup –3}, initial radius R {sub init} = 2.2 × 10{sup 15} cm = 17 mas, mass m {sub cloud} = 4 M {sub Earth}, and dust relative abundance A = 0.072. It provides a good fit to 2011 data, is consistent with the luminosities in 2004 and 2008, and reaches an agreement with the observed size. We revise down the predicted radio and X-ray bow shock luminosities to be below the quiescent level of Sgr A*, which readily leads to non-detection in agreement to observations. The magnetic energy dissipation in the cloud at the pericenter coupled with more powerful irradiation may lead to an infrared source with an apparent magnitude m{sub L{sup ′}}≈13.0. No shock into the cloud and no X-rays are expected from cloud squeezing by the ambient gas pressure. Larger than previously estimated cloud mass m {sub cloud} = (4-20) M {sub Earth} may produce a higher accretion rate and a brighter state of Sgr A* as the debris descend onto the BH.
- OSTI ID:
- 22351372
- Journal Information:
- Astrophysical Journal, Vol. 783, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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