Detecting dark matter WIMPs in the Draco dwarf: A multiwavelength perspective

Colafrancesco, S.; Profumo, Stefano; Ullio, Piero

doi:10.1103/physrevd.75.023513

Cited by 179 publications

(291 citation statements)

References 85 publications

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“…In the local ISM n e ∼ 0.1 cm −3 [69]. In galaxy clusters the average gas density is ∼ 10 −3 cm −3 [38] and in dwarf spheroidals like Draco it is ∼ 10 −6 cm −3 [70]. Since the largest contribution to the production of electrons and positrons comes from the accumulated effect of annihilation in low-mass halos and subhalos, which have clearly low ambient densities of ordinary matter, we can safely neglect the impact of these three processes of energy loss.…”

Section: Discussionmentioning

confidence: 99%

Cosmic X-ray and gamma-ray background from dark matter annihilation

et al. 2011

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The extragalactic background light (EBL) observed at multiple wavelengths is a promising tool to probe the nature of dark matter. This radiation might contain a significant contribution from gamma-rays produced promptly by dark matter particle annihilation in the many halos and subhalos within our past-light cone. Additionally, the electrons and positrons produced in the annihilation give energy to the cosmic microwave photons to populate the EBL with X-rays and gamma-rays.To study these signals, we create full-sky maps of the expected radiation from both of these contributions using the high-resolution Millennium-II simulation of cosmic structure formation. Our method also accounts for a possible enhancement of the annihilation rate by a Sommerfeld mechanism due to a Yukawa interaction between the dark matter particles prior to annihilation. We use upper limits on the contributions of unknown sources to the EBL to constrain the intrinsic properties of dark matter using a model-independent approach that can be employed as a template to test different particle physics models. These upper limits are based on observational measurements spanning eight orders of magnitude in energy (from soft X-rays measured by the CHANDRA satellite to gamma-rays measured by the Fermi satellite), and on expectations for the contributions from non-blazar active galactic nuclei, blazars and star forming galaxies. To exemplify this approach, we analyze a set of benchmark Sommerfeld-enhanced models that give the correct abundance of dark matter, satisfy constraints from the cosmic microwave background, and fit the cosmic ray spectra measured by PAMELA and Fermi without any contribution from local substructure. We find that these models are in conflict with the EBL constraints unless the contribution of unresolved substructure is small and the dark matter annihilation signal dominates the EBL. We conclude that provided the collisionless cold dark matter paradigm is accurate, even for conservative estimates of the contribution from unresolved substructure and astrophysical backgrounds, the EBL is at least as sensitive a probe of these types of scenarios as the cosmic microwave background. More generally, our results disfavor an explanation of the positron excess measured by the PAMELA satellite based only on dark matter annihilation in the smooth Galactic dark matter halo.PACS numbers: 95.35.+d,95.85.Nv,95.85.Pw

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Section: Discussionmentioning

confidence: 99%

Cosmic X-ray and gamma-ray background from dark matter annihilation

et al. 2011

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“…Here the background uncertainty is less of a concern, but the signal must be distinguished from other astrophysical (point) sources. Again, a multiwavelength approach and the exploitation of spectral features [36,37,38] of the DM annihilation appears as a highly promising way to convincingly identify the origin of the signal.…”

Section: Energy Dependencementioning

confidence: 99%

Prospects for detecting supersymmetric dark matter in the Galactic halo

Springel

White

Frenk

et al. 2008

Nature

277

396

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Dark matter is the dominant form of matter in the universe, but its nature is unknown. It is plausibly an elementary particle, perhaps the lightest supersymmetric partner of known particle species 1 . In this case, annihilation of dark matter in the halo of the Milky Way should produce γ-rays at a level which may soon be observable 2, 3 .Previous work has argued that the annihilation signal will be dominated by emission from very small clumps 4, 5 (perhaps smaller even than the Earth) which would be most easily detected where they cluster together in the dark matter halos of dwarf satellite galaxies 6 . Here we show, using the largest ever simulation of the formation of a galactic halo, that such small-scale structure will, in fact, have a negligible impact on dark matter detectability. Rather, the dominant and likely most easily detectable signal will be produced by diffuse dark matter in the main halo of the Milky Way 7, 8 . If the main halo is strongly detected, then small dark matter clumps should also be visible, but may well contain no stars, thereby confirming a key prediction of the Cold Dark Matter (CDM) model.

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“…We also cross-checked our numerical solution against analytic solutions in the cases with only spatial-diffusion terms and with only the energy-loss term, and against the semi-analytic solution which makes use of Green's functions (see, e.g., (Colafrancesco, Profumo & Ullio 2006;Colafrancesco, Profumo & Ullio 2007)) for the full equation but with spatially constant D andĖ. The advantages of the Crank-Nicolson solution with respect to the latter is given by the much shorter computational time needed and by the possibility of having D(r) andĖ(r).…”

Section: Appendix A: Solution For Spherically-symmetric Transport Equmentioning

confidence: 99%

Local Group dSph radio survey with ATCA – II. Non-thermal diffuse emission

Regis

Richter

Colafrancesco

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Our closest neighbours, the Local Group dwarf spheroidal (dSph) galaxies, are extremely quiescent and dim objects, where thermal and non-thermal diffuse emissions lack, so far, of detection. In order to possibly study the dSph interstellar medium, deep observations are required. They could reveal non-thermal emissions associated with the very-low level of star formation, or to particle dark matter annihilating or decaying in the dSph halo. In this work, we employ radio observations of six dSphs, conducted with the Australia Telescope Compact Array in the frequency band 1.1-3.1 GHz, to test the presence of a diffuse component over typical scales of few arcmin and at an rms sensitivity below 0.05 mJy/beam. We observed the dSph fields with both a compact array and long baselines. Short spacings led to a synthesized beam of about 1 arcmin and were used for the extended emission search. The high-resolution data mapped background sources, which in turn were subtracted in the short-baseline maps, to reduce their confusion limit. We found no significant detection of a diffuse radio continuum component. After a detailed discussion on the modelling of the cosmic-ray (CR) electron distribution and on the dSph magnetic properties, we present bounds on several physical quantities related to the dSphs, such that the total radio flux, the angular shape of the radio emissivity, the equipartition magnetic field, and the injection and equilibrium distributions of CR electrons. Finally, we discuss the connection to far-infrared and X-ray observations.

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Detecting dark matter WIMPs in the Draco dwarf: A multiwavelength perspective

Cited by 179 publications

References 85 publications

Cosmic X-ray and gamma-ray background from dark matter annihilation

Cosmic X-ray and gamma-ray background from dark matter annihilation

Prospects for detecting supersymmetric dark matter in the Galactic halo

Local Group dSph radio survey with ATCA – II. Non-thermal diffuse emission

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