Testing the dark matter origin of the WMAP-Planck haze with radio observations of spiral galaxies

Abstract

If the Galactic WMAP radio haze, as recently confirmed by Planck, is produced by dark matter annihilation or decay, similar diffuse radio halos should exist around other galaxies with physical properties comparable to the Milky Way. If instead the haze is due to an astrophysical mechanism peculiar to the Milky Way or to a transient event, a similar halo need not exist around all Milky Way "twins". We use radio observations of 66 spiral galaxies to test the dark matter origin of the haze. We select galaxies based on morphological type and maximal rotational velocity, and obtain their luminosities from a 1.49 GHz catalog and additional radio observations at other frequencies. We find many instances of galaxies with radio emission that is less than 5% as bright as naively expected from dark matter models that could produce the Milky Way haze, and at least 3 galaxies that are less than 1% as bright as expected, assuming dark matter distributions, magnetic fields, and cosmic ray propagation parameters equal to those of the Milky Way. For reasonable ranges for the variation of these parameters, we estimate the fraction of galaxies that should be expected to be significantly less bright in radio, and argue that this is marginally compatible with the observed distribution. While our findings therefore cannot rule out a dark matter origin for the radio haze at this time, we find numerous examples (including the Andromeda Galaxy) where, if dark matter is indeed the origin of the Milky Way haze, some mechanism must be in place to suppress the corresponding haze of the external galaxy. We point out that Planck data will offer opportunities to improve this type of constraint in a highly relevant frequency range and for a potentially larger set of candidate galaxies.

Radio constraints on dark matter annihilation in Canes Venatici I with LOFAR†

“…Similar recent studies are the ones of Regis et al (2017); Leite et al (2016); Marchegiani & Colafrancesco (2016); Beck & Colafrancesco (2016); Natarajan et al (2015Natarajan et al ( , 2013. Nevertheless, most of the indirect-detection searches with radio data have focused so far on other types of targets (mostly the Galactic Centre) (Bertone et al 2001(Bertone et al , 2002Colafrancesco et al 2006;Bertone et al 2009;Fornengo et al 2011Fornengo et al , 2012aHooper et al 2012;Carlson et al 2013;Storm et al 2013;Regis et al 2014;Cirelli & Taoso 2016;Storm et al 2017;Lacroix et al 2017;McDaniel et al 2018); the same is true in the context of multi-messenger studies (Regis & Ullio 2008).…”

Updated galactic radio constraints on Dark Matter

“…More recently, a few works have shifted the focus to much larger JCAP07(2016)041 regions (or the whole) of the galactic halo, which can provide more robust results [21][22][23][24][25][26][27]. Outer galaxies and galaxy clusters have also been considered [7,15,[28][29][30][31][32][33] as well as isotropic signals of extragalactic origin [34][35][36].…”

Radio Constraints of Dark Matter: A Review and Some Future Perspectives

“…Generally speaking, the thermal dark matter scenario is allowed by the constraints for masses above ∼50-100 GeV. On the other hand, the measurements from the Wilkinson Microwave Anisotropy Probe (WMAP) and the Planck detector have revealed some excess of microwave emission from the region around the center of our galaxy (the WMAP-Planck haze), which may originate from dark matter annihilation [65,66]. The best-fit dark matter mass could be of the order ∼100 GeV or larger [65].…”