J/MNRAS/496/2663 Canes Venatici I images with LOFAR (Vollmann+, 2020)
Radio constraints on dark matter annihilation in Canes Venatici I with LOFAR.
Vollmann M., Heesen V., Shimwell T., Hardcastle M.J., Brueggen M., Sigl G.,
Roettgering H.
<Mon. Not. R. Astron. Soc. 496, 2663-2672 (2020)>
=2020MNRAS.496.2663V 2020MNRAS.496.2663V (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Radio sources
Keywords: astroparticle physics - galaxies: dwarf - dark matter -
Abstract:
Dwarf galaxies are dark matter-dominated and therefore promising
targets for the search for weakly interacting massive particles
(WIMPs), which are well-known candidates for dark matter.
Annihilation of WIMPs produce ultra-relativistic cosmic-ray electrons
and positrons that emit synchrotron radiation in the presence of
magnetic fields. For typical magnetic field strengths (few G) and
O(GeV-TeV) WIMP masses (and thus typical electron energies of the same
order) this emission peaks at hundreds of MHz. Here, we use the
non-detection of 150-MHz radio continuum emission from the dwarf
spheroidal galaxy 'Canes Venatici I' with the LOw-Frequency ARray
(LO-FAR) to derive constraints on the annihilation cross section of
WIMPs into primary electron-positron and other fundamental
particle-antiparticle pairs. In this first-of-its-kind LOFAR study, we
obtain new constraints on annihilating WIMP dark matter (DM). Using
conservative estimates for the magnetic field strengths and diffusion
coefficients, we obtain limits that are comparable with those by the
Fermi Large Area Telescope (Fermi-LAT) using gamma-ray observations.
Assuming s-wave annihilation and WIMPs making up 100% of the DM
density, our limits exclude several thermal WIMP realisations in the
[2, 20]-GeV mass range. A more ambitious multi-wavelength and
multi-target LOFAR study could improve these limits by a few orders of
magnitude.
Description:
We present Low-Frequency Array (LOFAR) maps of Canes Venatici I. Data
are at full angular resolution, low angular resolution
(FWHM=20arcsec), with sources included and subtracted. We also added
three fake sources in order to test our source detection. These were
20mJy (FWHM=500arcsec), 5mJy (FWHM=250arcsec), and 80mJy
(FWHM=1000) arcsec. The data were CLEANed with WSCLEAN v2.7, using
Briggs robust weighting 0.2, and a lower (u,v) cut of 160 lambda.
Low-Frequency array (LOFAR), high band antennae (HBA)
Objects:
---------------------------------------------------
RA (2000) DE Designation(s)
---------------------------------------------------
13 28 03.5 +33 33 21 CVn I = NAME CVn I dSph
---------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 164 6 List of fits images
fits/* . 6 Individual fits images
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 50 A21 "datime" Obs.date Observation date
52- 58 F7.3 MHz Freq Observed frequency
60- 64 I5 Kibyte size Size of FITS file
66-114 A49 --- FileName Name of FITS file, in subdirectory fits
116-164 A49 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Volker Heesen, volker.heesen(at)hs.uni-hamburg.de
(End) Patricia Vannier [CDS] 08-Jun-2020