Chandra Detections of Two Quiescent Black Hole X-Ray Transients

Using the Chandra X-Ray Observatory, we have detected the black hole transients V4641 Sgr and XTE J1859+226 in their low-luminosity quiescent states. The 0.3-8 keV luminosities are (4.0) × 1031 (d/7 kpc)2 ergs s-1 and (4.2) × 1031 (d/11 kpc)2 ergs s-1 for V4641 Sgr and XTE J1859+226, respectively. With the addition of these two systems, 14 out of the 15 transients with confirmed black holes (via compact object mass measurements) now have measured quiescent luminosities or sensitive upper limits. The only exception is GRS 1915+105, which has not been in quiescence since its discovery in 1992. The luminosities for V4641 Sgr and XTE J1859+226 are consistent with the median luminosity of 2 × 1031 ergs s-1 for the systems with previous detections. Our analysis suggests that the quiescent X-ray spectrum of V4641 Sgr is harder than for the other systems in this group, but because of the low statistical quality of the spectrum, it is not clear if V4641 Sgr is intrinsically hard or if the column density is higher than the interstellar value. Focusing on V4641 Sgr, we compare our results to theoretical models for X-ray emission from black holes in quiescence. Also, we obtain precise X-ray positions for V4641 Sgr and XTE J1859+226 via cross-correlation of the X-ray sources detected near our targets with IR sources in the Two Micron All Sky Survey catalog.

[1]  M. Garcia,et al.  The X-Ray Spectra of Black Hole X-Ray Novae in Quiescence as Measured by Chandra , 2001, astro-ph/0111134.

[2]  R. P. Fender,et al.  Initial low/hard state, multiple jet ejections and X-ray/radio correlations during the outburst of XTE J1859+226 , 2001, astro-ph/0112137.

[3]  F. A. Aharonian,et al.  External Compton emission from relativistic jets in Galactic black hole candidates and ultraluminous X-ray sources , 2002 .

[4]  R. Fender.  Powerful jets from black hole X-ray binaries in low/hard X-ray states , 2000, astro-ph/0008447.

[5]  Simon T. Garrington,et al.  Light Curves and Radio Structure of the 1999 September Transient Event in V4641 Sagittarii (=XTE J1819–254=SAX J1819.3–2525) , 2000 .

[6]  P. Jonker,et al.  Jet-dominated states: an alternative to advection across black hole event horizons in ‘quiescent’ X-ray binaries , 2003, astro-ph/0306614.

[7]  M. C. Weisskopf,et al.  An Overview of the Performance and Scientific Results from the Chandra X‐Ray Observatory , 2001, astro-ph/0110308.

[8]  S. Kitamoto,et al.  Long-term X-ray variability and state transition of GX 339-4 , 2001, astro-ph/0110039.

[9]  Ping Zhao,et al.  Dynamical Evidence for a Black Hole in the Microquasar XTE J1550–564 , 2001, astro-ph/0112101.

[10]  Sera Markoff,et al.  A jet model for the broadband spectrum of XTE J1118+480. Synchrotron emission from radio to X-rays in the , 2000, astro-ph/0010560.

[11]  J. Orosz,et al.  Optical Observations of GRO J1655–40 in Quiescence. I. A Precise Mass for the Black Hole Primary , 1996, astro-ph/9610211.

[12]  Roger D. Blandford,et al.  On the fate of gas accreting at a low rate on to a black hole , 1998, astro-ph/9809083.

[13]  N. Masetti,et al.  The X‐ray transient XTE J1859 + 226 in outburst and quiescence , 2002 .

[14]  P. Kaaret,et al.  X-Ray Emission from the Jets of XTE J1550–564 , 2002, astro-ph/0210401.

[15]  K. Menou,et al.  Xmm-newton observations of two black hole x-ray transients in quiescence , 2002, astro-ph/0209587.

[16]  G. Ghisellini,et al.  The bulk kinetic power of the jets of GRS 1915+105 , 1998, astro-ph/9810029.

[17]  L. Bildsten,et al.  Coronal X-Ray Emission from the Stellar Companions to Transiently Accreting Black Holes , 1999, astro-ph/9912304.

[18]  W. Cash,et al.  Parameter estimation in astronomy through application of the likelihood ratio. [satellite data analysis techniques , 1979 .

[19]  A. Tzioumis,et al.  Radio/X-ray correlation in the low/hard state of GX 339-4 , 2003, astro-ph/0301436.

[20]  J. Dickey,et al.  H I in the Galaxy , 1990 .

[21]  Robert Rosner,et al.  A Wavelet-Based Algorithm for the Spatial Analysis of Poisson Data , 2001 .

[22]  Ramesh Narayan,et al.  A New Model for Black Hole Soft X-Ray Transients in Quiescence , 1995, astro-ph/9508014.

[23]  P. Kaaret,et al.  Large-Scale, Decelerating, Relativistic X-ray Jets from the Microquasar XTE J1550-564 , 2002, Science.

[24]  E. Quataert,et al.  Convection-dominated Accretion Flows , 1999, astro-ph/9912440.

[25]  Thomas J. Maccarone,et al.  Do X-ray binary spectral state transition luminosities vary? , 2003, astro-ph/0308036.

[26]  Michael R. Garcia,et al.  Multiwavelength Spectrum of the Black Hole XTE J1118+480 in Quiescence , 2003, astro-ph/0304535.

[27]  A universal radio-X-ray correlation in low/hard state black hole binaries , 2003, astro-ph/0305231.

[28]  Charles D. Bailyn,et al.  A Black Hole in the Superluminal Source SAX J1819.3–2525 (V4641 Sgr) , 2000, astro-ph/0103045.

[29]  I. Mirabel,et al.  Sources of Relativistic Jets in the Galaxy , 1999, astro-ph/9902062.