HIGH-RESOLUTION CHANDRA HETG SPECTROSCOPY OF V404 CYGNI IN OUTBURST
Journal Article
·
· Astrophysical Journal Letters
- Department of Physics, 382 Via Pueblo Mall, Stanford, CA 94305 (United States)
- Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109-1107 (United States)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
As one of the best-characterized stellar-mass black holes, with good measurements of its mass, distance, and inclination, V404 Cyg is the ideal candidate to study Eddington-limited accretion episodes. After a long quiescent period, V404 Cyg underwent a new outburst in 2015 June. We obtained two Chandra HETG exposures of 20 and 25 ks. Many strong emission lines are observed; the ratio of Si He-like triplet lines gives an estimate for the formation region distance of 4 × 10{sup 11} cm. A narrow Fe Kα line is detected with an equivalent width greater than 1 keV in many epochs, signaling that we do not directly observe the central engine. Obscuration of the central engine and strong narrow emission lines signal that the outer disk may be illuminated, and its structure may help to drive the strong variability observed in V404 Cyg. In the highest flux phases, strong P-Cygni profiles consistent with a strong disk wind are observed, likely radiation or thermally driven as V404 Cyg approaches its Eddington limit. The kinetic power of this wind may be extremely high at >0.1 L{sub Bol}.
- OSTI ID:
- 22518690
- Journal Information:
- Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 813; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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