A SEARCH FOR TEV NEUTRINO EMISSION WITH ICECUBE COINCIDENT WITH SWIFT BAT FLARES FROM BLAZARS

Open Access
Author:
Movit, Steven
Graduate Program:
Astronomy and Astrophysics
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
August 19, 2011
Committee Members:
  • Douglas Cowen, Dissertation Advisor
  • Douglas Cowen, Committee Chair
  • Stephane Coutu, Committee Member
  • Tyce De Young, Committee Member
  • Eric D Feigelson, Committee Member
  • Michael Eracleous, Committee Member
Keywords:
  • neutrino astrophysics
  • wavelets
  • Swift
  • IceCube
Abstract:
Abstract One of the most important unsolved questions in astrophysics is the source of the ultra-high energy ( >TeV scale) cosmic rays (UHECR) that are seen here on Earth by detectors such as Auger. One potential source for these UHECR is black hole engines in active galaxies. It is known that active galaxies have jets of relativistic charged particles that follow their rotational axes, however the composition of these jets is still unknown, and hadrons must be present in the cosmic accelerators. Neutrino detections coincident with photon flaring from AGN would provide strong evidence for hadrons in blazar jets. If no hadrons are present, gamma-ray production in AGN jets would be driven by electron synchrotron-self Compton processes. In an attempt to test the hadronic hypothesis for blazar jets, we developed a catalog of significant hard x-ray photon excesses from blazars using the Swift BAT monitoring catalog and a new wavelet approach adapted from the statistics literature. This approach was applied for the first time to an astronomical time series. We processed the Swift monitoring data from April 2008 until May 2009, to correspond with the 40 string season of IceCube, a neutrino detector located at the South Pole. Previous analyses have produced a neutrino data set known as the Point Source selection, which was a starting point for our timing and spatial coincidence analysis. This sample of IceCube events contains only muon neutrino charged-current events which were reconstructed with a very high degree of confidence. We strongly reduced noise contamination of the final sample through simple cuts on the photon flares and some new techniques in the wavelet denoising involving testing overlapping time series. While no on-source neutrinos were found, this analysis remains an excellent prescription for future studies, and we have set upper bounds on neutrino flux from each of the four AGN from which X-ray flares were seen, ranging from 3.23·10^−7 to 3.82 · 10^−6 GeV/cm^2/sec.