Anisotropies in the diffuse gamma-ray background measured by the Fermi LAT

Cuoco, A.; Linden, Tim; Mazziotta, M. N.; Siegal‐Gaskins, Jennifer M.; Vitale, V.; Komatsu, Eiichiro

doi:10.1103/physrevd.85.083007

Cited by 279 publications

(489 citation statements)

References 53 publications

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“…Components contributing to this background include blazars [4,5], star-forming and starburst galaxies [6], and misaligned active galaxies [7]. The combination of these sources gives reasonably good fit to the spectral data [5,8], while the anisotropies are consistent with the blazar component alone [3,9]. Independently of this, dark matter has emerged as the preferred explanation of many astrophysical and cosmological features through gravity (galactic rotation curves, Ω m Ω b , lensing by galaxy clusters, etc.).…”

Section: Introductionmentioning

confidence: 97%

Modelling the flux distribution function of the extragalactic gamma-ray background from dark matter annihilation

Feyereisen

Ando

Lee

2015

J. Cosmol. Astropart. Phys.

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Abstract. The one-point function (i.e., the isotropic flux distribution) is a complementary method to (anisotropic) two-point correlations in searches for a gamma-ray dark matter annihilation signature. Using analytical models of structure formation and dark matter halo properties, we compute the gamma-ray flux distribution due to annihilations in extragalactic dark matter halos, as it would be observed by the Fermi Large Area Telescope. Combining the central limit theorem and Monte Carlo sampling, we show that the flux distribution takes the form of a narrow Gaussian of 'diffuse' light, with an 'unresolved point source' power-law tail as a result of bright halos. We argue that this background due to dark matter constitutes an irreducible and significant background component for point-source annihilation searches with galaxy clusters and dwarf spheroidal galaxies, modifying the predicted signal-to-noise ratio. A study of astrophysical backgrounds to this signal reveals that the shape of the total gamma-ray flux distribution is very sensitive to the contribution of a dark matter component, allowing us to forecast promising one-point upper limits on the annihilation cross section. We show that by using the flux distribution at only one energy bin, one can probe the canonical cross section required for explaining the relic density, for dark matter of masses around tens of GeV.

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Section: Introductionmentioning

confidence: 97%

Modelling the flux distribution function of the extragalactic gamma-ray background from dark matter annihilation

Feyereisen

Ando

Lee

2015

J. Cosmol. Astropart. Phys.

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“…We have not seen the signature of dark matter particles in the EGRB spectrum, although they are considered as the possible origin of EGRB. As we known, Fermi-LAT has accurately measured the EGRB spectrum and the anisotropy of the EGRB [4] and the emission from dark matter is anisotropic and its spatial pattern is unique and predictable [90]. Therefore, we can obtain an upper limit on the annihilation cross section by comparing the expected EGRB angular power spectrum from dark matter annihilation with the measured spectrum.…”

Section: Conclusion and Discussionmentioning

confidence: 98%

“…The EGRB spectrum of blazars [33], star-forming galaxies (gray band [4]) and radio galaxies (black striped band [48]) as well as summation of these three populations (yellow band), compared to the intensity of the observed ERGB [5]. The figure is obtained from the report of Ref.…”

Section: Blazarsmentioning

confidence: 99%

“…The large area telescope (LAT [1]) onboard Fermi gamma-ray space telescope (Fermi) has measured the extragalactic diffuse gamma-ray background and then provided useful information for us to study the origins of the extragalactic gamma-ray background (EGRB) [2][3][4][5] .H o w e v e r ,t h e origin of the EGRB is still an unsolved problem. Observationally, an isotropic component of the EGRB emission was first detected by the SAS-2 satellite [6,7] and subsequently measured by the energetic gamma-ray experiment telescope (EGRET) [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Extragalactic Gamma‐Ray Background

Zeng¹,

Zhang²

2017

New Insights on Gamma Rays

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The origin of the extragalactic gamma-ray background (EGRB) is an important open issue in the gamma-ray astronomy. There are many theories about the origin of EGRB: (1) some truly diffuse processes, such as dark matter (DM) annihilation or decay, which can produce gamma rays; (2) gamma rays produced by energetic particles accelerated through induced shock waves during structure formation of the universe; (3) a lot of unidentified sources, including normal galaxies, starbursts and active galactic nuclei (AGNs), contain a large number of energetic particles and can emit gamma rays. Among various extragalactic sources, blazars including flat spectral radio quasars (FSRQs) and BL Lac objects are one of the most possible sources for EGRB. As continuous accumulation of the data observed by the Fermi Gamma-Ray Space Telescope, it is possible to directly construct gamma-ray luminosity function (GLF) of the blazars involving evolution information. In this chapter, based on the largest clean sample of AGNs provided by Fermi Large Area Telescope (LAT), we mainly study blazar's GLFs and their contribution to EGRB. In our study, we separately construct GLFs of FSRQs and BL Lacs and then estimate the contributions to EGRB, respectively. Further, we discuss the diffuse gamma ray from other astrophysical sources and the other possible origins of the EGRB.

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“…Fermi [18], and therefore one can treat the second term in the square bracket of Eq. (4.1) as a diagonal matrix proportional to δ ij δ ab .…”

Section: Covariance Matrix and Errors Of Cross Correlationmentioning

confidence: 99%

Power spectrum tomography of dark matter annihilation with local galaxy distribution

Ando

2014

J. Cosmol. Astropart. Phys.

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Abstract. Cross-correlating the gamma-ray background with local galaxy catalogs potentially gives stringent constraints on dark matter annihilation. We provide updated theoretical estimates of sensitivities to the annihilation cross section from gamma-ray data with Fermi telescope and 2MASS galaxy catalogs, by elaborating the galaxy power spectrum and astrophysical backgrounds, and adopting the Markov-Chain Monte Carlo simulations. In particular, we show that taking tomographic approach by dividing the galaxy catalogs into more than one redshift slice will improve the sensitivity by a factor of a few to several. If dark matter halos contain lots of bright substructures, yielding a large annihilation boost (e.g., a factor of ∼100 for galaxy-size halos), then one may be able to probe the canonical annihilation cross section for thermal production mechanism up to masses of ∼700 GeV. Even with modest substructure boost (e.g., a factor of ∼10 for galaxy-size halos), on the other hand, the sensitivities could still reach a factor of three larger than the canonical cross section for dark matter masses of tens to a few hundreds of GeV.

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Anisotropies in the diffuse gamma-ray background measured by the Fermi LAT

Cited by 279 publications

References 53 publications

Modelling the flux distribution function of the extragalactic gamma-ray background from dark matter annihilation

Modelling the flux distribution function of the extragalactic gamma-ray background from dark matter annihilation

Extragalactic Gamma‐Ray Background

Power spectrum tomography of dark matter annihilation with local galaxy distribution

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