Searching for dark matter subhalos in the Fermi-LAT second source catalog

Belikov, Alexander V.; Buckley, Matthew R.

doi:10.1103/physrevd.86.043504

Cited by 58 publications

(57 citation statements)

References 56 publications

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“…In these searches, the signal is proportional to the square of the DM density and hence, the presence of substructure could produce an enhancement (or boost) over the expected signal from the smooth distribution of DM in the host halo. Moreover, the closest of these subhalos might represent by themselves prime targets for indirect DM detection (Baltz et al 2000;Tasitsiomi & Olinto 2002;Koushiappas et al 2004;Diemand et al 005b;Baltz et al 2007;Pieri et al 2008;Kuhlen et al 2008;Buckley & Hooper 2010;Belikov et al 2012;Ackermann et al 2012;Mirabal et al 2012;Zechlin & Horns 2012;Berlin & Hooper 2014;Bertoni et al 2015;Schoonenberg et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Characterization of subhalo structural properties and implications for dark matter annihilation signals

Moliné

Sánchez‐Conde

Palomares‐Ruiz

et al. 2017

Mon. Not. R. Astron. Soc.

164

295

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A prediction of the standard ΛCDM cosmological model, also confirmed by N-body simulations, is that dark matter (DM) halos are teeming with numerous self-bound substructure, or subhalos. The precise properties of these subhalos represent important probes of the underlying cosmological model. In this work, we use data from the N-body Via Lactea II and ELVIS Milky Way-size simulations to learn about the structure of subhalos with masses 10 6 − 10 11 h −1 M . Thanks to a superb subhalo statistics, by taking a profileindependent approach, we study subhalo properties as a function of the distance to the host halo center and subhalo mass, and provide a set of fits that, including both dependences, accurately describe the subhalo structure. With this at hand, we also investigate the role of subhalos on the search for DM via its annihilation products. Indeed, previous work has shown that subhalos are expected to boost the DM signal of their host halos significantly. Yet, these works have traditionally assumed that subhalos exhibit similar structural properties than those of field halos of the same mass, while it is well known from simulations that subhalos are more concentrated. Building upon the results from our N-body data analysis, we refine the substructure boost model of Sánchez-Conde & Prada (2014). We find boost values that are a factor 2 − 3 higher than previous ones. We further refine our boost model to include unavoidable tidal stripping effects on the subhalo population. For field halos, this only introduces a moderate (∼ 20% − 30%) suppression of the boost. Yet, for subhalos like those hosting the dwarf satellite galaxies of the Milky Way, tidal stripping does play a critical role, the total boost for these objects being only at the level of a few tens of percent in the most optimistic cases. Finally, we provide a parametrization of the boost factor for field halos that can be safely applied over a wide halo mass range.

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Section: Introductionmentioning

confidence: 99%

Characterization of subhalo structural properties and implications for dark matter annihilation signals

Moliné

Sánchez‐Conde

Palomares‐Ruiz

et al. 2017

Mon. Not. R. Astron. Soc.

164

295

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“…In doing so, we expand on previous work [12][13][14][15][16][17] in a number of ways. Firstly, we consider not only subhalos which would appear as point-like sources to Fermi, but also derive limits based on searches for spatially extended sources, as applicable to the case of particularly large or nearby subhalos.…”

Section: Introductionmentioning

confidence: 99%

Stringent constraints on the dark matter annihilation cross section from subhalo searches with the Fermi Gamma-Ray Space Telescope

Berlin

2014

Phys. Rev. D

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The dark matter halo of the Milky Way is predicted to contain a very large number of smaller subhalos. As a result of the dark matter annihilations taking place within such objects, the most nearby and massive subhalos could appear as point-like or spatially extended gamma-ray sources, without observable counterparts at other wavelengths. In this paper, we use the results of the Aquarius simulation to predict the distribution of nearby subhalos, and compare this to the characteristics of the unidentified gamma-ray sources observed by the Fermi Gamma-Ray Space Telescope. Focusing on the brightest high latitude sources, we use this comparison to derive limits on the dark matter annihilation cross section. For dark matter particles lighter than ∼200 GeV, the resulting limits are the strongest obtained to date, being modestly more stringent than those derived from observations of dwarf galaxies or the Galactic Center. We also derive independent limits based on the lack of unidentified gamma-ray sources with discernible spatial extension, but these limits are a factor of ∼2-10 weaker than those based on point-like subhalos. Lastly, we note that four of the ten brightest high-latitude sources exhibit a similar spectral shape, consistent with 30-60 GeV dark matter particles annihilating to bb with an annihilation cross section on the order of σv ∼ (5 − 10) × 10 −27 cm 3 /s, or 8-10 GeV dark matter particles annihilating to τ + τ − with σv ∼ (2.0 − 2.5) × 10 −27 cm 3 /s.

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“…Previous attempts to pinpoint dark matter subhalos have systematically searched for unassociated sources with spectra that are consistent with dark matter annihilation (Buckley & Hooper 2010;Nieto et al 2011;Ackermann et al 2012a;Belikov et al 2012;Zechlin & Horns 2012;Berlin & Hooper 2014;Bertoni et al 2015Bertoni et al , 2016. Machine-learning classification targeting dark matter subhalos has also been performed using k-means clustering in the First Fermi LAT Catalog (1FGL; Mirabal et al 2010) and Random Forest in the Second Fermi LAT Catalog (2FGL; Mirabal et al 2012).…”

Section: Introductionmentioning

confidence: 99%

3fgl Demographics Outside the Galactic Plane Using Supervised Machine Learning: Pulsar and Dark Matter Subhalo Interpretations

Mirabal

Charles

Ferrara

et al. 2016

ApJ

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Nearly one-third of the sources listed in the Third Fermi Large Area Telescope (LAT) catalog (3FGL) remain unassociated. It is possible that predicted and even unanticipated gamma-ray source classes are present in these data waiting to be discovered. Taking advantage of the excellent spectral capabilities achieved by the Fermi LAT, we use machine-learning classifiers (Random Forest and XGBoost) to pinpoint potentially novel source classes in the unassociated 3FGL sample outside the Galactic plane. Here we report a total of 34 high-confidence Galactic candidates at. The currently favored standard astrophysical interpretations for these objects are pulsars or low-luminosity globular clusters hosting millisecond pulsars (MSPs). Yet these objects could also be interpreted as dark matter annihilation taking place in ultra-faint dwarf galaxies or dark matter subhalos. Unfortunately, Fermi LAT spectra are not sufficient to break degeneracies between the different scenarios. Careful visual inspection of archival optical images reveals no obvious evidence for low-luminosity globular clusters or ultra-faint dwarf galaxies inside the 95% error ellipses. If these are pulsars, this would bring the total number of MSPs at   b 5 | | to 106, down to an energy flux ≈4.0 × 10 −12 erg cm −2 s −1 between 100 MeV and 100 GeV. We find this number to be in excellent agreement with predictions from a new population synthesis of MSPs that predicts 100-126 highlatitude 3FGL MSPs depending on the choice of high-energy emission model. If, however, these are dark matter substructures, we can place upper limits on the number of Galactic subhalos surviving today and on dark matter annihilation cross sections. These limits are beginning to approach the canonical thermal relic cross section for dark matter particle masses below ∼100 GeV in the bottom quark (bb) annihilation channel.

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Searching for dark matter subhalos in the Fermi-LAT second source catalog

Cited by 58 publications

References 56 publications

Characterization of subhalo structural properties and implications for dark matter annihilation signals

Characterization of subhalo structural properties and implications for dark matter annihilation signals

Stringent constraints on the dark matter annihilation cross section from subhalo searches with the Fermi Gamma-Ray Space Telescope

3fgl Demographics Outside the Galactic Plane Using Supervised Machine Learning: Pulsar and Dark Matter Subhalo Interpretations

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