Resolving dark matter subhalos with future sub-GeV gamma-ray telescopes

Chou, Ti-Lin; Tanoglidis, Dimitrios

doi:10.1016/j.dark.2018.05.001

Cited by 12 publications

(13 citation statements)

References 48 publications

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“…A spacing of one degree ensures each sampled point is roughly independent (little overlap in the PSF) while still obtaining a representative sample of points at each declination. We perform these calculations assuming point source hypotheses since the expected characteristic size of a dwarf is on the scale of the HAWC PSF width, although some dark dwarfs may have slightly larger extent [14] [15]. Note that the points analyzed in Sec.…”

Section: Fit Resultsmentioning

confidence: 99%

Searching for dark matter sub-structure with HAWC

Abeysekara

Albert

Alfaro

et al. 2019

J. Cosmol. Astropart. Phys.

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Numerical simulations show that the dark matter halos surrounding galaxies are expected to contain many over-densities or sub-halos. The most massive of these sub-halos can be optically observed in the form of dwarf galaxies. However, most lower mass sub-halos are predicted to exist as dark dwarf galaxies: sub-halos like dwarf galaxies with no luminous counterpart. It may be possible to detect these unseen sub-halos from gamma-ray signals originating from dark matter annihilation. The High Altitude Water Cherenkov Observatory (HAWC) is a very high energy (500 GeV to >100 TeV) gamma ray detector with a wide fieldof-view and near continuous duty cycle, making HAWC ideal for unbiased sky surveys. We perform a search for gamma ray signals from dark dwarfs in the Milky Way halo with HAWC. We perform a targeted search of HAWC gamma-ray sources which have no known association with lower-energy counterparts, based on an unbiased survey of the entire sky. With no sources found to strongly prefer dark matter models, we calculate the ability of HAWC to observe dark dwarfs. We also compute the HAWC sensitivity to potential future detections for a given model of dark matter substructure. Assuming thermal dark matter, we find the corresponding J-factor of a dark dwarf required to reach the HAWC detection criterion is 5.79 × 10 20 GeV 2 cm −5 sr for one particular set of dark matter assumptions. HAWC is found to be able to competitively constrain dark matter annihilation from discovered halos with J-factors on the scale of 10 19 GeV 2 cm −5 sr or greater, with better constraints obtained on dark matter models with 10 TeV masses and sources that transit overhead.

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Section: Fit Resultsmentioning

confidence: 99%

Searching for dark matter sub-structure with HAWC

Abeysekara

Albert

Alfaro

et al. 2019

J. Cosmol. Astropart. Phys.

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“…If a large number of candidate subhalos without associations are found in recent (e.g., the 4FGL [124]) and future PS catalogs, methods including sub-threshold emission could provide decisively better constraints on annihilation properties. While the analysis presented in this paper focused on Fermi -LAT searches, it can also be applied to other observations such as those from the upcoming Cherenkov Telescope Array (CTA) [61,85,125] and proposed sub-GeV gamma-ray missions [126][127][128][129].…”

Section: Discussionmentioning

confidence: 99%

Harnessing the Population Statistics of Subhalos to Search for Annihilating Dark Matter

Somalwar,

Chang,

Mishra-Sharma

et al. 2020

Preprint

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The Milky Way's dark matter halo is expected to host numerous low-mass subhalos with no detectable associated stellar component. Such subhalos are invisible unless their dark matter annihilates to visible states such as photons. One of the established methods for identifying candidate subhalos is to search for individual unassociated gamma-ray sources with properties consistent with the dark matter expectation. However, robustly ruling out an astrophysical origin for any such candidate is challenging. In this work, we present a complementary approach that harnesses information about the entire population of subhalos-such as their spatial and mass distribution in the Galaxy-to search for a signal of annihilating dark matter. Using simulated data, we show that the collective emission from subhalos can imprint itself in a unique way on the statistics of observed photons, even when individual subhalos may be too dim to be resolved on their own. Additionally, we demonstrate that, for the models we consider, the signal can be identified even in the face of unresolved astrophysical point-source emission of extragalactic and Galactic origin. This establishes a new search technique for subhalos that is complementary to established methods, and that could have important ramifications for gamma-ray dark matter searches using observatories such as the Fermi Large Area Telescope and the Cherenkov Telescope Array.

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“…Also a complementary approach, looking for optical counterparts of Fermi -LAT extended and unidentified sources in GAIA data, gave null results [16]. Also, recent sensitivity predictions for DM subhalo identification with future gamma-ray instruments included a spatial analysis of DM halos [17,18].…”

Section: Introductionmentioning

confidence: 99%

Investigating the detection of dark matter subhalos as extended sources with Fermi-LAT

Di Mauro,

Stref,

Calore

2020

Preprint

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Cold dark matter (DM) models for structure formation predict that DM subhalos are present in the Galaxy. In the standard paradigm of DM as weakly interacting massive particle, subhalos are expected to shine in gamma rays and to provide a signal detectable with current instruments, notably with the Large Area Telescope (LAT) aboard the Fermi satellite. This is the main motivation behind searches for DM signals towards dwarf spheroidal galaxies and unidentified Fermi-LAT sources. A significant angular extension detected from unassociated sources located at relatively high latitudes is considered a "smoking gun" signature for identifying DM subhalos. In the present work, we systematically explore, by means of state-of-the-art models of cold DM halos in the Galaxy, the detectability of extended subhalos with Fermi-LAT. We simulate a DM signal exploring different assumptions of subhalos distribution in the Galaxy and DM profile, and reconstruct its flux through a realistic Fermi-LAT analysis pipeline. In the most optimistic case, we show that a detection of extended DM subhalos can be made for annihilation cross sections higher than 3 × 10 −26 cm 3 /s (for a 100 GeV DM mass), still compatible with existing gamma-ray constraints, and that, in this case, the preference for extension of the source (vs point-like hypothesis) is significant. For fainter signals, instead, halos not only do not show significant extension, but they are not even detectable significantly as point-like sources.

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Resolving dark matter subhalos with future sub-GeV gamma-ray telescopes

Cited by 12 publications

References 48 publications

Searching for dark matter sub-structure with HAWC

Searching for dark matter sub-structure with HAWC

Harnessing the Population Statistics of Subhalos to Search for Annihilating Dark Matter

Investigating the detection of dark matter subhalos as extended sources with Fermi-LAT

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