LOFAR detection of V404 Cyg at 150 MHz
ATel #7720; Jess Broderick, Adam Stewart, Rob Fender (Oxford), James Miller-Jones (Curtin), Kunal Mooley, Malgorzata Pietka (Oxford)
on 26 Jun 2015; 20:56 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Kunal Mooley (firstname.lastname@example.org)
Subjects: Radio, Binary, Black Hole, Transient, Variables
We report on the detection of the current activity in V404 Cyg / GS 2023+338 (e.g. ATels #7646, #7647, #7650, #7658, #7661, #7667, #7671, #7701, #7708, #7714 and #7716) with the Low-Frequency Array (LOFAR). A 6.6-hour high-band (115-189 MHz) observation was carried out between 2015 June 23 22:00 UTC and June 24 04:39 UTC (MJD 57196.917 to 57197.193), using the full Dutch array. A preliminary reduction suggests that the source has a 150 MHz flux density of approximately 30 mJy (8 sigma). This is the first LOFAR detection of a transient X-ray binary, and these low-radio-frequency measurements will be crucial in understanding the self-absorption and electron energy spectrum associated with the synchrotron emission. Further LOFAR monitoring is ongoing.
We thank the ASTRON Radio Observatory for rapidly scheduling our observations, and very promptly pre-processing the data.