Evidence for an anomalous state in the black-hole candidate 4U 1630-47

Abstract

We have re-analyzed two EXOSAT Medium Energy observations during part of the 1984 X-ray outburst of the black-hole candidate transient system 4U 1630-47. One observation (May 10) shows fast timing properties (on timescales shorter than ~250 s) typical of those of other black hole candidates in their high states. The power-spectrum shows a power law with index 0.7 and fractional rms amplitude (0.001-1 Hz) of 2%. Another observation, obtained one month earlier (April 11), shows different fast timing behavior. The power spectrum of this observation can be described by a power law with index 1.5 and fractional rms amplitude (0.001-1 Hz) of 7%. This is inconsistent with the behavior during low, high or very high states known to occur in most of the black hole candidates. Instead, the timing properties resemble those recently reported from ASCA observations of the superluminal black-hole candidates GRS 1915+105 and GRO J1655-40 (X-ray Nova Sco 1994). This timing behavior may represent a new state of black hole candidates. In addition, the X-ray spectra of the three sources show similar properties. Since GRS 1915+105 and GRO J1655-40 exhibit superluminal jets, we propose that 4U 1630-47 is also a relativistic jet source.

7 pages. LaTeX. 1 figure. Accepted for ApJ Letters

References in corpus (1)

• First Results from the All-Sky Monitor on the Rossi X-ray Timing Explorer

Cited by in corpus (13)

• WATCHDOG: A Comprehensive All-Sky Database of Galactic Black Hole X-ray Binaries
• Absorption dips in the light curves of GRO J1655-40 and 4U 1630-47 during outburst
• Suzaku discovery of iron absorption lines in outburst spectra of the X-ray transient 4U 1630-472
• An X-Ray Dip in the X-Ray Transient 4U 1630-47
• XMM-Newton observations reveal the disappearance of the wind in 4U 1630-47
• ``Canonical'' Black Hole States in the Superluminal Source GRO J1655-40
• Three Spectral States of the Disk X-Ray Emission of the Black-Hole Candidate 4U 1630-47
• The Timing Evolution of 4U 1630-47 During its 1998 Outburst
• The IR counterpart of the black-hole candidate 4U 1630-47
• High frequency features in the 1998 outburst of 4U 1630-47
• Towards 4U 1630-47: a black-hole soft X-ray transient odyssey
• The QPO states of 4U 1630-47
• Absorption dips in GRO J1655-40: mapping the inner accretion disk