[vsnet-grb-info 19612] GRB 170714A: NOEMA non-detection of the Bastille Day Burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21356
SUBJECT: GRB 170714A: NOEMA non-detection of the Bastille Day Burst
DATE:    17/07/18 14:30:07 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte at iaa.es>

A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D.A. Kann 
(HETH/IAA-CSIC), S. Schulze (Weizmann Institute), L. Izzo, 
C.C. Thoene (HETH/IAA-CSIC) and M. Krips (IRAM) report:

We observed the field of GRB 170714A (D'Ai et al. GCN 21340) 
using the NOrthern Extended Millimeter Array (NOEMA, Plateau 
de Bure, France) tuned at 92.5 GHz. Observations were 
performed between 3:10 and 5:15 UT on 17 July 2017 (2.66 days 
after the burst) and consisted of 1.33 hr on target with a bandwidth 
of 3.6 GHz and using 8 antennas.

We do not detect any source consistent with the afterglow position 
(de Ugarte Postigo et al. GCN 21346) down to a 3-sigma limit of 
150 uJy. We do note the presence of an unrelated source 12” 
Northwest of the afterglow position with a flux density of ~0.19 mJy, 
which is coincident with an extended source in our GTC images.

This burst has been proposed to be either an ultra-long GRB or a
relativistic tidal-disruption event (Kann et al., GCN 21345). We 
note that this deep non-detection, together with the non-detection 
from the VLA (Horesh et al. GCN 21352) are consistent with a 
scenario of an ULGRB like GRBs 101225A, 111209A and 130925A, 
which have been faint at radio wavelengths (Frail, GCN 11550, 
Zauderer et al., GCN 11770; Hancock et al., GCNs 12664, 12804; 
Horesh et al. 2015, ApJ, 812, 86). Relativistic tidal-disruption events 
such as Sw J1644 and SwJ2058 have been found to be much 
brighter in radio wavelengths (e.g., Zauderer et al. 2011, Nature, 
476, 425, Berger et al. 2012, ApJ, 748, 36, Zauderer et al., 2013, 
ApJ, 767, 152; Cenko et al. 2012, ApJ, 753, 77).