Investigating the correlations between IceCube high-energy neutrinos and Fermi-LAT gamma-ray observations

Abstract

We use 10 years of publicly available IceCube data to investigate the correlations between high-energy neutrinos and various Fermi-LAT gamma-ray samples. This work considers the following gamma-ray samples: the third Fermi-LAT catalog of high-energy sources (3FHL), > 100 GeV Fermi-LAT events, LAT 12-year source catalog (4FGL), the fourth catalog of active galactic nuclei (4LAC) and subsets of these samples. For each sample, both a single-source analysis and a joint likelihood analysis are performed. We find no indication that the sources in these samples produce significant high-energy neutrinos. From the null search results, we infer that each source population can produce no more than ∼0.3%-27% (at the 95% confidence level) of the IceCube's diffuse neutrino flux. Since we are using a larger (10 years) dataset of IceCube neutrinos, the constraints are improved by a factor of ∼2 compared to those based on 3 years of data.

Search for spatial coincidence between IceCube neutrinos and radio pulsars

“…We use the same unbinned maximum likelihood ratio method as in [17,[35][36][37], which was first proposed in [38] and is also used in time-integrated searches done by the IceCube Collaboration [33]. For our analysis we select those neutrino events, with declination within ±5 • of the pulsar.…”

“…Therefore, for the above reasons, a large number of works have explored possible contributions from galactic sources to the IceCube diffuse neutrino flux. This includes individual sources such as supernova remnants, X-ray binaries, pulsar wind nebulae, open clusters, LHAASO sources, as well as a diffuse galactic component due to cosmic ray interactions with the interstellar medium [10][11][12][13][14][15][16][17]. It is also important to look for coincidences sources which have hitherto not been considered.…”

A stacked search for spatial coincidences between IceCube neutrinos and radio pulsars

“…This way the test statistic becomes more sensitive, since any minor associations from individual pulsars could stack up to enhance the significance. For this purpose we follow the same methodology as [4][5][6]8] (based on the implementation first proposed in ref. [36]), which have also done a stacking search between neutrinos from the public IceCube catalog and various sources such as AGNs, FRBs, Fermi-LAT point sources.…”

“…A number of extragalactic sources have been considered which could contribute to the diffuse neutrino flux, such as blazars and other types of AGNs, star-forming galaxies, FRBs, GRBs, galaxy clusters, other ancillary extragalactic sources in Fermi-LAT catalog, etc by both the IceCube collaboration, and others using the publicly available IceCube dataset. A non-exhaustive list includes searches for correlation with extra-galactic sources such as AGNs and GRBs [4][5][6][7][8][9][10][11][12], FRBs [13][14][15], high energetic events from the Fermi-LAT catalog [8,16], and galaxy catalogs using the 2MASS survey [17].…”

Deepening gamma-ray point-source catalogues with sub-threshold information

“…The new methodological development we propose in this work can be exploited to obtain an extended catalogue, final product of this analysis, which, albeit only probabilistically defined, can be nonetheless very useful, for instance, in multi-wavelength (e.g. [15][16][17]) or in cross-correlation [18][19][20][21] analyses. Other methods to build γ-ray probabilistic catalogues have been attempted in the past, e.g.…”