THE COOL ACCRETION DISK IN ESO 243-49 HLX-1: FURTHER EVIDENCE OF AN INTERMEDIATE-MASS BLACK HOLE
- Canadian Institute for Theoretical Astrophysics, Toronto, ON M5S3H4 (Canada)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Universite de Toulouse, Universite Paul Sabatier, Observatoire Midi-Pyrenees, Institut de Recherche en Astrophysique et Planetologie (IRAP), Toulouse (France)
- Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH (United Kingdom)
With an inferred bolometric luminosity exceeding 10{sup 42} erg s{sup -1}, HLX-1 in ESO 243-49 is the most luminous of ultraluminous X-ray sources and provides one of the strongest cases for the existence of intermediate-mass black holes. We obtain good fits to disk-dominated observations of the source with BHSPEC, a fully relativistic black hole accretion disk spectral model. Due to degeneracies in the model arising from the lack of independent constraints on inclination and black hole spin, there is a factor of 100 uncertainty in the best-fit black hole mass M. Nevertheless, spectral fitting of XMM-Newton observations provides robust lower and upper limits with 3000 M{sub sun} {approx}< M {approx}< 3 x 10{sup 5} M{sub sun}, at 90% confidence, placing HLX-1 firmly in the intermediate-mass regime. The lower bound on M is entirely determined by matching the shape and peak energy of the thermal component in the spectrum. This bound is consistent with (but independent of) arguments based solely on the Eddington limit. Joint spectral modeling of the XMM-Newton data with more luminous Swift and Chandra observations increases the lower bound to 6000 M{sub sun}, but this tighter constraint is not independent of the Eddington limit. The upper bound on M is sensitive to the maximum allowed inclination i, and is reduced to M {approx}< 10{sup 5} M{sub sun} if we limit i {approx}< 75{sup 0}.
- OSTI ID:
- 21576597
- Journal Information:
- Astrophysical Journal, Vol. 734, Issue 2; Other Information: DOI: 10.1088/0004-637X/734/2/111; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
INVESTIGATING SLIM DISK SOLUTIONS FOR HLX-1 IN ESO 243-49
THE ORIGIN OF VARIABILITY OF THE INTERMEDIATE-MASS BLACK-HOLE ULX SYSTEM HLX-1 IN ESO 243-49