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تسجيل مستخدم جديدSearching for VHE gamma-ray emission associated with IceCube neutrino alerts using FACT, H.E.S.S., MAGIC, and VERITAS
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The realtime follow-up of neutrino events is a promising approach to search for astrophysical neutrino sources. It has so far provided compelling evidence for a neutrino point source: the flaring gamma-ray blazar TXS 0506+056 observed in coincidence with the high-energy neutrino IceCube-170922A detected by IceCube. The detection of very-high-energy gamma rays (VHE, $mathrm{E} > 100,mathrm{GeV}$) from this source helped establish the coincidence and constrained the modeling of the blazar emission at the time of the IceCube event. The four major imaging atmospheric Cherenkov telescope arrays (IACTs) - FACT, H.E.S.S., MAGIC, and VERITAS - operate an active follow-up program of target-of-opportunity observations of neutrino alerts sent by IceCube. This program has two main components. One are the observations of known gamma-ray sources around which a cluster of candidate neutrino events has been identified by IceCube (Gamma-ray Follow-Up, GFU). Second one is the follow-up of single high-energy neutrino candidate events of potential astrophysical origin such as IceCube-170922A. GFU has been recently upgraded by IceCube in collaboration with the IACT groups. We present here recent results from the IACT follow-up programs of IceCube neutrino alerts and a description of the upgraded IceCube GFU system.
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The detection of an astrophysical flux of high-energy neutrinos by IceCube is a major step forward in the search for the origin of cosmic rays, as this emission is expected to originate in hadronic interactions taking place in or near cosmic-ray acce
lerators. No neutrino point sources, or a significant correlation with known astrophysical objects, have been identified in the IceCube data so far that could reveal the location of the neutrino emission sites. The hadronic interactions responsible for the neutrino emission should also lead to the production of high-energy gamma rays from neutral pion decays. The search for neutrino sources can therefore be performed by studying the spatial and temporal correlations between neutrino events and very-high-energy (VHE, E > 100 GeV) gamma rays. We report on the search for VHE gamma-ray emission at the reconstructed position of muon neutrino events detected by IceCube using the FACT, H.E.S.S., MAGIC, and VERITAS imaging atmospheric Cherenkov telescopes (IACTs). No significant steady gamma-ray counterparts have been identified for the neutrino events observed so far. Finally, we outline recent programs to perform prompt IACT observations of realtime IceCube neutrino event positions.
Supernova (SN) remnants are a well motivated candidate for the acceleration sites of cosmic rays with energies up to the knee (10^15 eV). It has been suggested that also young SNe (~<1 year after the explosion) may be able to accelerate cosmic rays t
o even higher energies. A smoking gun for cosmic-ray acceleration in young SNe would be the production of very-high-energy (VHE, >10 GeV) gamma-ray radiation. The H.E.S.S. imaging air Cherenkov telescope array is an instrument sensitive to such radiation. In this contribution, the pointing directions of the H.E.S.S. telescopes are compared to a recently published, extragalactic SN catalogue to identify coincidental observations. The results of the data analysis are discussed.
The High Altitude Water Cherenkov (HAWC) and IceCube observatories, through the Astrophysical Multimessenger Observatory Network (AMON) framework, have developed a multimessenger joint search for extragalactic astrophysical sources. This analysis loo
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We report the detection of very-high-energy (VHE) gamma-ray emission from supernova remnant (SNR) G106.3+2.7. Observations performed in 2008 with the VERITAS atmospheric Cherenkov gamma-ray telescope resolve extended emission overlapping the elongate
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