[vsnet-grb-info 13183] GRB 130427A: High-energy neutrino search

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14520
SUBJECT: GRB 130427A: High-energy neutrino search
DATE:    13/05/01 14:09:45 GMT
FROM:    Erik Blaufuss at U. Maryland/IceCube  <blaufuss at icecube.umd.edu>

Search for high-energy neutrinos in coincidence with GRB 130427A

The IceCube collaboration (icecube.wisc.edu) reports:

We used the data from IceCube to perform several searches for high-energy neutrinos in spatial and temporal 
coincidence with GRB 130427A (A. Maselli et al., GCN 14485). 

The first analysis is an automated online search for muon neutrino multiplets of two or more neutrinos in coincidence
within 100 seconds and 3.5 degrees. The search has a threshold of ~1 TeV and does not depend on an external GRB
trigger. No such multiplet was found. 

A second offline analysis is a likelihood based search for muon neutrinos with energies ~1 TeV and higher, with a primary 
background of atmospheric neutrinos and atmospheric muons. Data was scanned in the T90=162.83 s window reported by Swift BAT (S. D. 
Barthelmy et al., GCN 14470), and found no neutrinos.  We also performed a series of rolling time-window searches 
covering a window of interest of +/- 1 hour relative to the burst time and again found no neutrinos.

A final search focused on  neutrinos of all flavors with energies ~100 TeV and higher that have interaction vertices that fall within the detector in a window 
of interest of +-1 day. Because the intrinsic background for this search is very low only temporal information was used 
in this search. No neutrinos were found in this search.

Implications with respect to neutrino fluence for this GRB will be reported elsewhere. 

IceCube is a kilometer cubed neutrino telescope located at the geographic South Pole sensitive to neutrinos above 
~100 GeV. Previous limits on the emission of neutrinos by GRBs have been presented in R. Abbasi et al., Nature 484, 
351–354 (2012). A description of the multiplet search is found in R. Abbasi et al., A&A 539, A60 (2012). Funding 
acknowledgement and author list for IceCube are listed [http://icecube.wisc.edu/collaboration/authors/current here]