Searching for
                    <i>γ</i>
                    -ray emission from Reticulum II by Fermi-LAT

Zhao, Y.; Bi, Xiao-Jun; Yin, Peng-Fei; Zhang, Xinmin

doi:10.1088/1674-1137/42/2/025102

Cited by 10 publications

(14 citation statements)

References 69 publications

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“…Annihilation and decay factors for Reticulum II have been calculated by several groups, which are consistent for similar assumptions for theoretical priors [15,88]. Reticulum II is also interesting because it has a small associated gamma-ray excess, though this is not statistically significant [89,90,91].…”

Section: Fermi-lat Resultssupporting

confidence: 72%

Dark matter in dwarf spheroidal galaxies and indirect detection: a review

Strigari

2018

Rep. Prog. Phys.

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Indirect dark matter searches targeting dwarf spheroidal galaxies (dSphs) have matured rapidly during the past decade. This has been because of the substantial increase in kinematic data sets from the dSphs, the new dSphs that have been discovered, and the operation of the Fermi-LAT and many ground-based gamma-ray experiments. Here we review the analysis methods that have been used to determine the dSph dark matter distributions, in particular the 'J-factors', comparing and contrasting them, and detailing the underlying systematics that still affect the analysis. We discuss prospects for improving measurements of dark matter distributions, and how these interplay with future indirect dark matter searches.

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Section: Fermi-lat Resultssupporting

confidence: 72%

Dark matter in dwarf spheroidal galaxies and indirect detection: a review

Strigari

2018

Rep. Prog. Phys.

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“…Of these, an excess over backgrounds was reported earlier for Reticulum II some time ago [24], when the so-called Pass 7 data were used. Subsequent analyses, using the Pass 8 data, found no such excess but instead bib-by-bin upper limits on the γ-ray energy distribution [25,26], which was matching well with similar limits in the case of other dwarf spheroidal galaxies.…”

Section: Contentssupporting

confidence: 72%

“…The pair-annihilation of the neutralino DM leads, among other things, to photons in various frequency bands. Of these, a large volume of data has accumulated in the radio and γ-ray ranges (with some observations of X-ray data as well [7]), either in the form of actual excess(es) [19][20][21][22][23][24] or as upper limits [8,[25][26][27][28] on the flux from some specific source. A systematic and comprehensive way of using them to probe DM scenarios essentially should comprise all or some of the following steps:…”

Section: Contentsmentioning

confidence: 99%

“…Side by side, investigations have been carried out to find the best fit for the GC excess and the Pass 7 claim [42], thereby pointing towards the optimum DM profile encapsulated in the J-factor that determines the flux. It has however been assumed there that the Reticulum II excess is real, something that has been contradicted by the Pass 8 data released later [25,26]. At the same time, attempts have been made to simultaneously fit the radio synchrotron data from the Coma cluster and the Reticulum II excess as per the Pass 7 claim [43].…”

Section: Contentsmentioning

confidence: 99%

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Dark matter, extra-terrestrial gamma-rays and the MSSM: a viability study

Kar

Mitra²,

Mukhopadhyaya

et al. 2018

J. Cosmol. Astropart. Phys.

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We fit the γ-ray excess from the galactic centre (GC) in terms of parameters of the minimal supersymmetric standard model (MSSM). Consistency with other γ-ray observation, such as those from dwarf spheroidal galaxies, is also ensured, in addition to the constraints from direct dark matter search. Furthermore, we expect the contribution to the relic density from the MSSM dark mater candidate, namely, the lightest neutralino, should not go below the stipulated value; otherwise it will amount to going beyond the MSSM by including some additional dark matter source. After a detailed scan of the parameter space in terms of four representative types of particle spectra, we identify the ones that are best fit to the observed data. However, these two are somewhat unsatisfactory in terms of χ 2 min as well as p-values. In some case(s), the unacceptability of low-χ 2 min regions due to direct search constraint is responsible for this. In others, the observed shape of the γ-ray spectrum makes the fits unsatisfactory. The imposed lower limit on relic density, too, has a role to play all along. On the whole, the conclusion is that the MSSM is not a very satisfactory fit for the GC γ-ray compounded with other cosmological observations and direct search limits.

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“…It may be of some interest to note that, in case of Ret-II, several recent studies have detected a slight excess in γ-emission [33,45,47,[51][52][53]. Though the significance of excess emission from Ret-II is quite lower than Fermi -LAT's threshold value for detection, this excess emission is suspected to be the evidence of WIMP annihilation in Ret-II [33,52,53,100].…”

Section: Comparison Of the Constraints On The Dm Annihilation Cross Smentioning

confidence: 99%

Analysis of Fermi-LAT data from Tucana-II: possible constraints on the Dark Matter models with an intriguing hint of a signal

Bhattacharjee

Majumdar

Biswas

et al. 2019

J. Cosmol. Astropart. Phys.

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Tucana-II (Tuc-II), a recently discovered and confirmed Ultra Faint Dwarf Spheroidal galaxy, has a high mass to light ratio as well as a large line-of-sight stellar velocity dispersion, thus making it an ideal candidate for an indirect dark matter (DM) search. In this paper, we have analyzed nine years of γ-ray data obtained from the Fermi-LAT instrument from the direction of Tuc-II. The fact that a very weak significant γ-ray excess (2.2σ) over the background of Tuc-II have been detected from the location of this galaxy. We have observed that this excess of γ-ray emission from the of location Tuc-II rises with longer periods of data. If WIMP pair annihilation is assumed for this faint emission, for bb annihilation channel the test statistics (TS) value peaks at DM mass ∼ 14 GeV and for τ + τ − annihilation channel it peaks at DM mass 4 GeV. It is then called for an estimation of the 95% confidence level upper limit of the possible velocity weighted self-annihilation cross-section of the DM particles (WIMPs) within Tuc-II by fitting the observed γ-ray flux with spectra expected for DM annihilation. The estimated upper limits of the cross-sections from Tuc-II are then compared with two other dwarf galaxies that are considered to be good DM candidates in several studies. We have also compared our results with the cross-sections obtained in various popular theoretical models of the WIMPs to find that our results impose reasonable tight constraints on the parameter spaces of those DM models. In the concluding section, we compared our results with the similar results obtained from a combined dSph analysis by the Fermi-LAT collaboration as well as the results obtained from the studies of DM in the dwarf galaxies by the major ground-based Cherenkov experiments.

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Searching for γ -ray emission from Reticulum II by Fermi-LAT

Cited by 10 publications

References 69 publications

Dark matter in dwarf spheroidal galaxies and indirect detection: a review

Dark matter in dwarf spheroidal galaxies and indirect detection: a review

Dark matter, extra-terrestrial gamma-rays and the MSSM: a viability study

Analysis of Fermi-LAT data from Tucana-II: possible constraints on the Dark Matter models with an intriguing hint of a signal

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