Follow-up radio and X-ray observations of 4U1630-47
ATel #685; E. Gallo (UCSB), J. Tomsick (UCSD), R. Fender (Southampton), T. Tzioumis (ATNF), R. Sault (ATNF), T. Maccarone (Southampton), T. Belloni (INAF-OAB)
on 5 Jan 2006; 19:56 UT
Credential Certification: Elena Gallo (egallo@science.uva.nl)
Subjects: Radio, X-ray, Binary, Black Hole, Transient
Observations with the Australia Telescope Compact Array of the black hole binary 4U1630-47, performed on December 21, 25, 27 and 29, failed to detect a radio counterpart to the outbursting X-ray source (ATEL #675) on any of the four dates. Measured rms noise levels are respectively 0.12, 0.10, 0.26, 0.25 mJy at 4.8 GHz and a factor about two lower at 8.6 GHz. When the 4 data sets are added together, this results in a 3 sigma upper limit of 0.14 mJy at 8.6 GHz and 0.30 mJy at 4.8 GHz.
Pointed RXTE observations occurred on December 23, 24, 26, 27, 28, and 29. All energy spectra are well-described by a disc-blackbody plus power-law model corrected for absorption, with absorbed 3-25 keV fluxes ranging from 5.2x10^-9 to 5.6x10^-9 ergs cm^-2 s^-1. The best fit spectral parameters are in the following ranges: N_H = 8.1x10^22 to 9.5x10^22 cm^-2; kTin = 1.27 to 1.33 keV; Gamma = 2.7 to 3.8. The ratio of the disc flux to the total flux (2-20 keV, unabsorbed) varied from 0.69 to 0.89. The power spectrum of the longest observation indicates a low level of timing noise, rms = 2.8% +/- 0.6% (0.01-10 Hz),
and no detectable quasi-periodic oscillations.
The X-ray spectral and timing properties indicate that the source was in the canonical High/Soft state (equivalent to the Thermal-Dominant state in the McClintock & Remillard 2005 state definitions) during December 23-29. This is also consistent with the radio non-detection because black hole binaries are usually radio quiet in this state.
