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Published March 20, 2014 | Published + Submitted
Journal Article Open

The Disk Wind in the Rapidly Spinning Stellar-mass Black Hole 4U 1630–472 Observed with NuSTAR


We present an analysis of a short NuSTAR observation of the stellar-mass black hole and low-mass X-ray binary 4U 1630−472. Reflection from the inner accretion disk is clearly detected for the first time in this source, owing to the sensitivity of NuSTAR. With fits to the reflection spectrum, we find evidence for a rapidly spinning black hole, a∗ = 0.985^(+0.005)_(−0.014) (1σ statistical errors). However, archival data show that the source has relatively low radio luminosity. Recently claimed relationships between jet power and black hole spin would predict either a lower spin or a higher peak radio luminosity. We also report the clear detection of an absorption feature at 7.03 ± 0.03 keV, likely signaling a disk wind. If this line arises in dense, moderately ionized gas (log ξ = 3.6+0.2 −0.3) and is dominated by He-like Fe xxv, the wind has a velocity of v/c = 0.043^(+0.002)_(−0.007) (12900^(+600)_(−2100) km s^(−1)). If the line is instead associated with a more highly ionized gas (log ξ = 6.1+0.7 −0.6), and is dominated by Fe xxvi, evidence of a blueshift is only marginal, after taking systematic errors into account. Our analysis suggests the ionized wind may be launched within 200–1100 Rg, and may be magnetically driven.

Additional Information

© 2014 American Astronomical Society. Received 2013 September 26; accepted 2014 January 15; published 2014 March 4. We would like to thank Julia Lee for her invaluable comments. This work was supported under NASA Contract No. NNG08FD60C, and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by NASA. L.N. wishes to acknowledge the Italian Space Agency (ASI) for financial support by ASI/INAF grant I/037/12/0-011/13.

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Published - 2041-8205_784_1_L2.pdf

Submitted - 1401.3646v1.pdf


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August 20, 2023
October 26, 2023