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

Regis, Marco; Richter, L.; Colafrancesco, S.; Profumo, Stefano; Blok, W. J. G. de; Massardi, M.

doi:10.1093/mnras/stv127

Cited by 51 publications

(88 citation statements)

References 61 publications

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“…This leads to the largest possible values of flux that one could get from the current analysis. Stronger magnetic fields and lower values of D 0 are disfavoured by already existing observations [3,18,19,22,24]. DSph's which have larger D 0 and smaller magnetic fields (i.e.…”

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confidence: 88%

“…Higher D 0 (= 3 × 10 28 cm 2 s −1 ) can bring down these explorable limits of mχ to about 200 GeV or 50 GeV respectively. Note that B = 5 µG magnetic field is somewhat less realistic for the dSph galaxies considered here[24].…”

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confidence: 96%

“…Note that, while Milky Way magnetic field ∼ 2 µG can be realistic for nearby dwarf galaxies like Seg or Seg2, it might not be the case for other more distant dSphs where this value can be as low as a fraction of µG[24].…”

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confidence: 99%

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Constraints on dark matter annihilation in dwarf spheroidal galaxies from low frequency radio observations

Kar

Mitra²,

Mukhopadhyaya

et al. 2019

Phys. Rev. D

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We present the first observational limits on the predicted synchrotron signals from particle Dark Matter annihilation models in dwarf spheroidal galaxies at radio frequencies below 1 GHz. We use a combination of survey data from the Murchison Widefield Array (MWA) and the Giant Metre-wave Radio Telescope (GMRT) to search for diffuse radio emission from 14 dwarf spheroidal galaxies. For in-situ magnetic fields of 1 µG and any plausible value for the diffusion coefficient, our limits do not constrain any Dark Matter models. However, for stronger magnetic fields our data might provide constraints comparable to existing limits from gamma-ray and cosmic ray observations. Predictions for the sensitivity of the upgraded MWA show that models with Dark Matter particle mass up to ∼ 1.6 TeV (1 TeV) may be constrained for magnetic field of 2 µG (1 µG). While much deeper limits from the future low frequency Square Kilometre Array (SKA) will challenge the LHC in searches for Dark Matter particles, the MWA provides a valuable first step toward the SKA at low frequencies.

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confidence: 88%

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confidence: 96%

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Constraints on dark matter annihilation in dwarf spheroidal galaxies from low frequency radio observations

Kar

Mitra²,

Mukhopadhyaya

et al. 2019

Phys. Rev. D

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“…In Section II, the observing setup and data reduction process are summarized (see Paper I [34] and Paper II [35] for further details). Essentially, the dSph targets were observed with both a compact core and long baselines, with sensitivity below 0.1 mJy (0.05 mJy) for a synthesized beam of 1 arcmin (6 arcsec).…”

Section: Introductionmentioning

confidence: 99%

Local Group dSph radio survey with ATCA (III): constraints on particle dark matter

Regis¹,

Colafrancesco²,

Profumo³

et al. 2014

J. Cosmol. Astropart. Phys.

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We performed a deep search for radio synchrotron emissions induced by weakly interacting massive particles (WIMPs) annihilation or decay in six dwarf spheroidal (dSph) galaxies of the Local Group. Observations were conducted with the Australia Telescope Compact Array (ATCA) at 16 cm wavelength, with an rms sensitivity better than 0.05 mJy/beam in each field. In this work, we first discuss the uncertainties associated with the modeling of the expected signal, such as the shape of the dark matter (DM) profile and the dSph magnetic properties. We then investigate the possibility that point-sources detected in the proximity of the dSph optical center might be due to the emission from a DM cuspy profile. No evidence for an extended emission over a size of few arcmin (which is the DM halo size) has been detected. We present the associated bounds on the WIMP parameter space for different annihilation/decay final states and for different astrophysical assumptions. If the confinement of electrons and positrons in the dSph is such that the majority of their power is radiated within the dSph region, we obtain constraints on the WIMP annihilation rate which are well below the thermal value for masses up to few TeV. On the other hand, for conservative assumptions on the dSph magnetic properties, the bounds can be dramatically relaxed. We show however that, within the next 10 years and regardless of the astrophysical assumptions, it will be possible to progressively close in on the full parameter space of WIMPs by searching for radio signals in dSphs with SKA and its precursors.

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“…However, the experiment also allows detection of radio emission on scales of a few arcsec to about 15 arcmin, with a sensitivity of approximately 50 µJy at 2 GHz. The results concerning the diffuse emission are presented in Regis et al (2014a) (hereafter Paper II) and Regis et al (2014b) (hereafter Paper III).…”

Section: Introductionmentioning

confidence: 99%

Local Group dSph radio survey with ATCA – I: observations and background sources

Regis

Richter

Colafrancesco

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Dwarf spheroidal (dSph) galaxies are key objects in near-field cosmology, especially in connection to the study of galaxy formation and evolution at small scales. In addition, dSphs are optimal targets to investigate the nature of dark matter. However, while we begin to have deep optical photometric observations of the stellar population in these objects, little is known so far about their diffuse emission at any observing frequency, and hence on thermal and non-thermal plasma possibly residing within dSphs. In this paper, we present deep radio observations of six local dSphs performed with the Australia Telescope Compact Array at 16 cm wavelength. We mosaiced a region of radius of about one degree around three "classical" dSphs, Carina, Fornax, and Sculptor, and of about half of degree around three "ultra-faint" dSphs, BootesII, Segue2, and Hercules. The rms noise level is below 0.05 mJy for all the maps. The restoring beams FWHM ranged from 4.2 × 2.5 arcseconds to 30.0 × 2.1 arcseconds in the most elongated case. A catalogue including the 1392 sources detected in the six dSph fields is reported. The main properties of the background sources are discussed, with positions and fluxes of brightest objects compared with the FIRST, NVSS, and SUMSS observations of the same fields. The observed population of radio emitters in these fields is dominated by synchrotron sources. We compute the associated source number counts at 2 GHz down to fluxes of 0.25 mJy, which prove to be in agreement with AGN count models.

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

Cited by 51 publications

References 61 publications

Constraints on dark matter annihilation in dwarf spheroidal galaxies from low frequency radio observations

Constraints on dark matter annihilation in dwarf spheroidal galaxies from low frequency radio observations

Local Group dSph radio survey with ATCA (III): constraints on particle dark matter

Local Group dSph radio survey with ATCA – I: observations and background sources

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