Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Citations to the Article (1) (Citation History)
· Refereed Citations to the Article
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
Chandra/RXTE Observations of 4U1957+11: Ostensibly the Most Rapidly Spinning Galactic Black Hole
Authors:
Nowak, Michael; Juett, A.; Homan, J.; Yao, Y.; Wilms, J.; Schulz, N.; Canizares, C.
Affiliation:
AA(MIT Kavli Institute), AB(University of Maryland), AC(MIT Kavli Institute), AD(MIT Kavli Institute), AE(Erlangen-Nuernburg, Germany), AF(MIT Kavli Institute), AG(MIT Kavli Institute)
Publication:
American Astronomical Society, HEAD meeting #10, #14.04
Publication Date:
03/2008
Origin:
AAS
Bibliographic Code:
2008HEAD...10.1404N

Abstract

We present simultaneous Chandra-High Energy Transmission Gratings and Rossi X-ray Timing Explorer observations of a `soft state' of the black hole candidate 4U1957+11. These data are an excellent test of modern disk atmosphere models that include the effects of black hole spin. The HETG data show that a fitted disk model implies a highly inclined disk around a low mass black hole rapidly rotating with a* 1. We show, however, that pure Schwarzschild black hole models describe the data extremely well, albeit with large disk atmosphere ``color-correction'' factors. ``Standard'' color-correction factors are attained if one additionally incorporates mild Comptonization. We conclude that even with this extremely well-measured, nearly pure disk spectrum, it is very difficult to uniquely determine spin. We then present a series of 48 RXTE observations taken over the span of several years and at different brightness/hardness levels. These data prefer a spin of a* 1, even when including a mild Comptonization component; however, they also show evolution of the disk atmosphere color-correction factors. If the rapid spin models with standard atmosphere color-correction factors of 1.7 are to be believed, then 4U1957+11 can range from a 3 solar mass black hole at 10 kpc with a* 0.83 to a 16 solar mass black hole at 22 kpc with a* 1, with the latter being statistically preferred at high formal significance.
Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)
   

Find Similar Abstracts:

Use: Authors
Title
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints