Misaligned streamers around a Galactic Centre black hole from a single cloud's infall

Summary, in English

We follow the near radial infall of a prolate cloud on to a 4 x 10(6) M-circle dot supermassive black hole in the Galactic Centre using smoothed particle hydrodynamics. We show that a prolate cloud oriented perpendicular to its orbital plane naturally produces a spread in angular momenta in the gas which can translate into misaligned discs as is seen in the young stars orbiting Sagittarius A*. A turbulent or otherwise highly structured cloud is necessary to avoid cancelling too much angular momentum through shocks at closest approach. Our standard model of a 2 x 10(4) M-circle dot gas cloud brought about the formation of a disc within 0.3 pc from the black hole and a larger, misaligned streamer at 0.5 pc. A total of 1.5 x 10(4) M-circle dot of gas formed these structures. Our exploration of the simulation parameter space showed that when star formation occurred, it resulted in top-heavy initial mass functions with stars on eccentric orbits with semi-major axes 0.02-0.3 pc and inclinations following the gas discs and streamers. We suggest that the single event of an infalling prolate cloud can explain the occurrence of multiple misaligned discs of young stars.

• Author: W. E. Lucas; I. A. Bonnell; Melvyn B Davies; W. K. M. Rice
• Department/s: Lund Observatory - Has been reorganised
• Publishing year: 2013
• Language: English
• Pages: 353-365
• Publication/Series: Monthly Notices of the Royal Astronomical Society
• Volume: 433
• Issue: 1
• Links: http://dx.doi.org/10.1093/mnras/stt727
• Document type: Journal article
• Publisher: Oxford University Press
• Topic: Astronomy, Astrophysics and Cosmology
• Keywords: stars: formation; accretion discs; accretion; hydrodynamics; Galaxy:; centre
• Status: Published
• ISBN/ISSN/Other: ISSN: 1365-2966