Anisotropies in the gamma-ray sky from millisecond pulsars

Siegal‐Gaskins, Jennifer M.; Reesman, Rebecca; Pavlidou, V.; Profumo, Stefano; Walker, T. W.

doi:10.1111/j.1365-2966.2011.18672.x

Cited by 45 publications

(83 citation statements)

References 57 publications

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“…Cross-checking the average MSP intensities obtained with the prescription outlined above, and the results in Ref. [49] for |b| ≥ 40 o , we find a relative difference of about 30%, due to the theoretical uncertainties on the assumed logN-logS and the latitude profile. We consider such a discrepancy as an empirical theoretical uncertainty on the determination of K, and fix the unresolved MSPs contribution subtracting a 30% uncertainty from the estimated average intensity.…”

Section: Pulsars and Mspsmentioning

confidence: 52%

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Conservative upper limits on WIMP annihilation cross section from Fermi-LATγrays

2012

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The spectrum of an isotropic extragalactic γ-ray background (EGB) has been measured by the Fermi-LAT telescope at high latitudes. Two new models for the EGB are derived from the subtraction of unresolved point sources and extragalactic diffuse processes, which could explain from 30% to 70% of the Fermi-LAT EGB. Within the hypothesis that the two residual EGBs are entirely due to the annihilation of dark matter (DM) particles in the Galactic halo, we obtain stringent upper limits on their annihilation cross section. Severe bounds on a possible Sommerfeld enhancement of the annihilation cross section are set as well. Finally, we consider models for DM annihilation depending on the inverse of the velocity and associate the EGBs to photons arising from the annihilation of DM in primordial halos. Given our choices for the EGB and the minimal DM modelling, the derived upper bounds are claimed to be conservative.PACS numbers: 95.30. Cq,95.35+d,95.85.Pw,96.50.sb

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Section: Pulsars and Mspsmentioning

confidence: 52%

“…We adopt an empirical prescription outlined in Ref. [49], which is based on the spectra of the eight MSPs detected by Fermi in the first 9 months [50] of operation. The differential energy spectra of the Fermidetected MSPs are well described by a truncated power law:…”

Section: Pulsars and Mspsmentioning

confidence: 99%

Conservative upper limits on WIMP annihilation cross section from Fermi-LATγrays

2012

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“…These anisotropies in the IGRB provide a statistical measure of the properties of contributing source populations (the anisotropy encodes the flux distribution and clustering properties of the sources). Several studies have predicted the anisotropy arising from specific source classes that contribute to the IGRB, including blazars (50-53), starforming galaxies (54), Galactic millisecond pulsars (55), and Galactic and extragalactic dark matter annihilation and decay (50,(56)(57)(58)(59)(60).…”

Section: The Igrbmentioning

confidence: 99%

Separating astrophysical sources from indirect dark matter signals

Siegal‐Gaskins

2014

Proc. Natl. Acad. Sci. U.S.A.

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Indirect searches for products of dark matter annihilation and decay face the challenge of identifying an uncertain and subdominant signal in the presence of uncertain backgrounds. Two valuable approaches to this problem are (i) using analysis methods which take advantage of different features in the energy spectrum and angular distribution of the signal and backgrounds and (ii) more accurately characterizing backgrounds, which allows for more robust identification of possible signals. These two approaches are complementary and can be significantly strengthened when used together. I review the status of indirect searches with gamma rays using two promising targets, the Inner Galaxy and the isotropic gamma-ray background. For both targets, uncertainties in the properties of backgrounds are a major limitation to the sensitivity of indirect searches. I then highlight approaches which can enhance the sensitivity of indirect searches using these targets.indirect detection | multiwavelength studies I ndirect dark matter detection offers a promising approach to detecting dark matter in an astrophysical context and may provide a means of mapping its spatial distribution and constraining its particle nature. Current searches for signatures of dark matter annihilation or decay using gamma rays have made substantial progress in recent years (1-7), with sensitivity to dark matter annihilation beginning to reach the favored regions of parameter space for thermal relic weakly interacting massive particle (WIMP) dark matter (8, 9).The most robust constraints on indirect dark matter signals are obtained by placing limits on the total amplitude of a dark matter signal without attempting any background modeling. For a few targets, such as Milky Way dwarf spheroidal galaxies (1, 2), the expected backgrounds are small, and thus, the sensitivity is not significantly weakened by neglecting to model the backgrounds. However, for many favorable indirect search targets in gamma rays, including the Inner Galaxy and the isotropic gamma-ray background (IGRB), the guaranteed backgrounds are substantial and currently not strongly constrained. As a result, dark matter searches in these regions could be made considerably more sensitive by improved knowledge of backgrounds.Although most indirect searches to date have resulted in limits being placed, in some cases, intriguing hints of a possible signal have been uncovered. Several groups have reported an excess in GeV gamma-ray emission originating from the Galactic Center (3,5,7,(10)(11)(12) and Inner Galaxy (12, 13); here I use Galactic Center to refer to the region within a few degrees of the dynamical center of the Galaxy and Inner Galaxy to refer to the region extending a few tens of degrees from the Galactic Center. However, in all of these studies the putative dark matter signal was detected using an approach that required some form of background modeling. Due to uncertainties in the emission from non-dark matter sources in this region, the interpretation of these possible detections of e...

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“…[5][6][7][8][9][10][11][12] among others). Thus, a measurement of the gamma-ray angular power spectrum Our analysis will also quantify the impact of the new APS measurement in constraining the properties of the blazar population, e.g., its redshift evolution and distribution in luminosity (especially at low luminosities).…”

Section: Introductionmentioning

confidence: 99%

Astrophysical interpretation of the anisotropies in the unresolved gamma-ray background

et al. 2017

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Recently, a new measurement of the auto-and cross-correlation angular power spectrum (APS) of the isotropic gamma-ray background was performed, based on 81 months of data of the Fermi LargeArea Telescope (LAT). Here, we fit, for the first time, the new APS data with a model describing the emission of unresolved blazars. These sources are expected to dominate the anisotropy signal. The model we employ in our analysis reproduces well the blazars resolved by Fermi LAT. When considering the APS obtained by masking the sources in the 3FGL catalogue, we find that unresolved blazars under-produce the measured APS below ∼1 GeV. Contrary to past results, this suggests the presence of a new contribution to the low-energy APS, with a significance of, at least, 5σ. The excess can be ascribed to a new class of faint gamma-ray emitters. If we consider the APS obtained by masking the sources in the 2FGL catalogue, there is no under-production of the APS below 1 GeV, but the new source class is still preferred over the blazars-only scenario (with a significance larger than 10σ). The properties of the new source class and the level of anisotropies induced in the isotropic gamma-ray background are the same, independent of the APS data used. In particular, the new gamma-ray emitters must have a soft energy spectrum, with a spectral index ranging, approximately, from 2.7 to 3.2. This complicates their interpretation in terms of known sources, since, normally, star-forming and radio galaxies are observed with a harder spectrum. The new source class identified here is also expected to contribute significantly to the intensity of the isotropic gamma-ray background.

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Anisotropies in the gamma-ray sky from millisecond pulsars

Cited by 45 publications

References 57 publications

Conservative upper limits on WIMP annihilation cross section from Fermi-LATγrays

Conservative upper limits on WIMP annihilation cross section from Fermi-LATγrays

Separating astrophysical sources from indirect dark matter signals

Astrophysical interpretation of the anisotropies in the unresolved gamma-ray background

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