Subject: ATEL #1558: No radio pulsations detected from SGR 1627-41 following renewed X-ray activity 
Date: Thursday, 5 June 2008 10:42 AM
From: atel@astronomerstelegram.org
To: John Sarkissian <john.sarkissian@csiro.au>
Conversation: ATEL #1558: No radio pulsations detected from SGR 1627-41 following renewed X-ray activity 

We send this ATEL to you at the author's request.

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ATEL #1558                                                           ATEL #1558

Title:          No radio pulsations detected from SGR 1627-41 following renewed
                X-ray activity
Author: F. Camilo (Columbia U.), J. Sarkissian (ATNF)
Queries:        fernando@astro.columbia.edu
Posted: 4 Jun 2008;  23:42  UT
Subjects:       Radio, X-ray, Neutron Stars, Pulsars, Soft Gamma-ray Repeaters,
                Transients

Starting on May 28, 2008, the SGR 1627-41 displayed X-ray bursting and
enhanced flux after nearly 10 years of relative inactivity (ATEL #1548,
#1549, #1555).  Two magnetars are known to emit radio pulses (Camilo
et   al. 2007, ApJ, 666, L93), and in at least one case these are transient
and have followed an X-ray outburst after many years in quiescence 
(Camilo et al. 2006, Nature, 442, 892).  Therefore, although previous
radio searches of SGR 1627-41 have been unsuccessful, we are searching
for radio emission following its recent renewed burst of activity. 

On May 30 and again on June 1, 2008, we used the ATNF Parkes telescope
in Australia to search for radio emission from SGR 1627-41 using   its
multibeam receiver operating at a central frequency of 1374 MHz.   We recorded
data for 30 min on each occasion across a bandwidth of 288   MHz, with
time and frequency resolution of, respectively, 1 ms and 3 MHz.   We analyzed
the data using standard pulsar search techniques, looking for   both average
emission and single dispersed pulses, but found no pulsar   candidate at
any period, including the tentative 6.4 s period of the SGR.   The period-averaged
flux density limit from these searches at 1.4 GHz   is 0.5 mJy for an approximately
sinusoidal pulse profile, and a factor   of about 3 lower for a duty cycle
of 10%.     

Assuming a distance of 11 kpc, the above flux density limit for 10%
duty cycle corresponds to a pseudo-luminosity limit of approximately
20   mJy kpc^2.  This limit is only somewhat constraining: it is significantly
smaller than the 1.4 GHz luminosity of both known radio magnetars at
their peak (~100-200 mJy kpc^2), but is much larger than the smallest
known luminosities of ordinary young pulsars (~1 mJy kpc^2).  Further
observations are planned.

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