On-going radio observations of H1743-322
ATel #1384; M. P. Rupen, V. Dhawan, A. J. Mioduszewski (NRAO)
on 11 Feb 2008; 23:45 UT
Credential Certification: Michael P. Rupen (firstname.lastname@example.org)
Subjects: Radio, X-ray, Black Hole, Transient
Referred to by ATel #: 1385
We report on-going observations of the black hole transient H1743-322
(ATel #1348, #1349, #1352, #1378) with the Very Large Array (VLA) in its
moderately extended 'B' configuration, under observing program AR642.
The 8.46 GHz observations show the following flux density evolution:
Date MJD 8.46 GHz flux density
Jan. 10 54475.72 6.39 +/- 0.06 mJy
Jan. 19 54484.67 1.05 +/- 0.07 mJy
Jan. 21 54486.76 0.81 +/- 0.06 mJy
Feb. 3 54499.74 0.50 +/- 0.07 mJy
Feb. 5 54501.64 0.54 +/- 0.08 mJy
Feb. 6 54502.56 0.39 +/- 0.09 mJy
Feb. 9 54505.66 0.56 +/- 0.05 mJy
Interleaved observations on Feb. 9 gave a flux density of 0.56 +/- 0.06 mJy
at 4.86 GHz. This flat spectrum and low radio flux density are consistent
with the source entering the low/hard state (cf. ATel #1378).
The error bars above are statistical, and do not include an additional ~10%
systematic uncertainty, e.g., due to uncertainties in the flux density scale.
We confirm the tentative detection of linearly polarized radio emission
reported in ATel #1352, with an 8 +/- 1% detection on Jan. 10 at 8.46 GHz.
This polarized emission was seen at roughly the same flux density (0.5 mJy) and
along the same polarization angle (electric field vectors oriented east/west).
The magnetic field vectors are thus perpendicular to the (previous)
ejection axis, suggesting terminal shock rather than jet emission during the
decay of the radio outburst.
However, no extended ejecta are seen on any of the above dates. The best
limits come from 22.46 GHz imaging on Jan. 10, with a resolution
(FWHM) 0.69 x 0.25 arcsec oriented roughly north/south.
Further VLA observations are on-going.
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