Gamma-ray halo around the M31 galaxy as seen by the Fermi LAT

Пширков, М. С.; Vasiliev, V. V.; Постнов, К. А.

doi:10.48550/arxiv.1501.03460

Cited by 3 publications

(3 citation statements)

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“…Additionally, the FIR luminosities for these systems are significantly smaller than the typical galaxies in our analysis. Detailed γ-ray analyses of these galaxies exist in the literature [27,[29][30][31], and we will compare our results to these systems in the discussion. Third, we remove the system NGC 2146 from our analysis, noting that the system is coincident with a γ-ray source (3FGL J0707.0+7741).…”

Section: Models a Gamma-ray Data Analysismentioning

confidence: 96%

Star-forming galaxies significantly contribute to the isotropic gamma-ray background

Linden

2017

Phys. Rev. D

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The origin of the isotropic gamma-ray background (IGRB) -the portion of the extragalactic gammaray sky that is not resolvable into individual point sources -provides a powerful probe into the evolution of the high-energy universe. Star-forming galaxies (SFGs) are among the most likely contributors to the IGRB, though their contribution is difficult to constrain because their flux distribution is dominated by numerous faint sources. We produce a novel joint-likelihood analysis of the γ-ray emission from 584 SFGs, utilizing advanced statistical techniques to compare the distribution of low-significance excesses against the non-Poissonian γ-ray background fluctuations. We first examine the theoretically well-motivated relationship between the far-IR and γ-ray luminosities of SFGs, utilizing a model where the γ-ray luminosity is given by log10(Lγ/(erg s −1 )) = α log10(LIR/(10 10 L )) + β. We calculate best-fit parameters α = 1.18 ± 0.15, β = 38.49 ± 0.24, with a log-normal dispersion in this relationship given by σ = 0.39 ± 0.12. The best-fit values of α and β are consistent with previous studies. We find a larger dispersion in the far-IR to γ-ray correlation than previous studies. This dispersion is significant at the level of 5.7σ. These results imply that SFGs significantly contribute to the IGRB, producing between 61.0 +30.2 −18.3 % of the total IGRB intensity above an energy of 1 GeV. Along with recent works, this strongly indicates that multiple source classes provide comparable contributions to the IGRB intensity. We discuss the implication of these results for the interpretation of the IceCube neutrinos.

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Section: Models a Gamma-ray Data Analysismentioning

confidence: 96%

Star-forming galaxies significantly contribute to the isotropic gamma-ray background

Linden

2017

Phys. Rev. D

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“…Following its the initial detection [2], M 31 has appeared in both the 2FGL catalogue (J0042.5+4114 [3]) and the 3FGL catalogue (J0042.5+4117 [4]), in both cases as a point source. Analyses have also been published in [14] where they examine dark matter limits from M 31 and in [15] where evidence for γ-ray emission from a spatially extended halo around M 31 is presented. We have conducted an updated analysis of the Fermi-LAT data, using the LATAnalysisScripts and Fermi Science Tools v9r33p0 to conduct a binned (0.1 • ) analysis.…”

Section: Updated Fermi-lat Analysismentioning

confidence: 99%

VERITAS Observations of M31 (the Andromeda Galaxy)

Bird¹

2016

Proceedings of the 34th International Cosmic Ray Conference — PoS(ICRC2015)

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Diffuse gamma rays are tracers of cosmic rays, providing information on their origin, interaction and diffusion through a galaxy. M 31 (the Andromeda Galaxy) is the closest spiral galaxy to the Milky Way (d = 780 kpc) and is very well studied at all wavelengths. Thus it is a prime target for the study of diffuse gamma-ray emission. The very-high-energy (VHE, E > 100 GeV) gamma-ray observatory VERITAS has conducted 54 hours of observations of M 31 and an upper limit on the VHE flux is presented along with an updated Fermi-LAT (0.1 < E < 300 GeV) analysis. These observations will be compared with predictions of the gamma-ray flux derived from models of the inelastic scattering of VHE cosmic rays of the interstellar medium (ISM) and the interstellar radiation field. M 31 provides an ideal opportunity to probe this mechanism. Its proximity and spatial extent, significantly larger than the VERITAS point spread function but smaller than the field-of-view, potentially enables the star-forming ring, 10 kpc from the galaxy core, with its dense ISM and numerous supernova remnants to be resolved.

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“…Under the assumption of a smooth halo, the cross section upper limit is very similar, ∼ 5 × 10 −25 cm 3 s −1 . More recently there has also been the claim of an extendend excess attributed to a cosmic-ray halo (Pshirkov, Vasiliev, and Postnov, 2015).…”

Section: E M31mentioning

confidence: 99%

Wimp searches with gamma rays in the Fermi era: Challenges, methods and results

Conrad

Cohen-Tanugi

Strigari

2015

J. Exp. Theor. Phys.

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The launch of the gamma-ray telescope Fermi Large Area Telescope (Fermi -LAT) started a pivotal period in indirect detection of dark matter. By outperforming expectations, for the first time a robust and stringent test of the paradigm of weakly interacting massive particles (WIMPs) is within reach. In this paper, we discuss astrophysical targets for WIMP detection and the challenges they present, review the analysis tools which have been employed to tackle these challenges, and summarize the status of constraints on and the claimed detections in the WIMP parameter space. Methods and results will be discussed in comparison to Imaging Air Cherenkov Telescopes. We also provide an outlook on short term and longer term developments.

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Gamma-ray halo around the M31 galaxy as seen by the Fermi LAT

Cited by 3 publications

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Star-forming galaxies significantly contribute to the isotropic gamma-ray background

Star-forming galaxies significantly contribute to the isotropic gamma-ray background

VERITAS Observations of M31 (the Andromeda Galaxy)

Wimp searches with gamma rays in the Fermi era: Challenges, methods and results

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