On the Sunyaev-Zel'dovich effect from dark matter annihilation or decay in galaxy clusters

Abstract

We revisit the prospects for detecting the Sunyaev Zel'dovich (SZ) effect induced by dark matter (DM) annihilation or decay. We show that with standard (or even extreme) assumptions for DM properties, the optical depth associated with relativistic electrons injected from DM annihilation or decay is much smaller than that associated with thermal electrons, when averaged over the angular resolution of current and future experiments. For example, we find: τ DM ∼ 10 −9 − 10 −5 (depending on the assumptions) for m χ = 1 GeV and a density profile ρ ∝ r −1 for a template cluster located at 50 Mpc and observed within an angular resolution of 10 ′′ , compared to τ th ∼ 10 −3 − 10 −2 . This, together with a full spectral analysis, enables us to demonstrate that, for a template cluster with generic properties, the SZ effect due to DM annihilation or decay is far below the sensitivity of the Planck satellite. This is at variance with previous claims regarding heavier annihilating DM particles. Should DM be made of lighter particles, the current constraints from 511 keV observations on the annihilation cross section or decay rate still prevent a detectable SZ effect. Finally, we show that spatial diffusion sets a core of a few kpc in the electron distribution, even for very cuspy DM profiles, such that improving the angular resolution of the instrument, e.g. with ALMA, does not necessarily improve the detection potential. We provide useful analytical formulae parameterized in terms of the DM mass, decay rate or annihilation cross section and DM halo features, that allow quick estimates of the SZ effect induced by any given candidate and any DM halo profile.

Can neutralinos in the MSSM and NMSSM scenarios still be light?

“…Nevertheless, it is worth mentioning that the mass range that is under consideration is not excluded neither by the ISR constraints at LEP [15] nor by the potential Sunyaev-Zel'dovich effect that might be generated by relatively light dark matter particles in clusters of galaxies. [16,17]. Although it is premature to draw any conclusion about the nature of the DAMA/LIBRA, CDMS and CoGeNT results, it is certainly worth reinvestigating the possible dark matter candidates that are expected in the low mass region.…”

Sunyaev-Zel’dovich effects from annihilating dark matter in the Milky Way: Smooth halo, subhalos, and intermediate-mass black holes

“…In the following, we use the formalism presented in Ref. [9], to which we refer the reader for more details.…”

“…Note that since the angular extent of the scale radii of our objects is larger than the reference angular resolution of 1', we can use the line-ofsight approximation of J 2 proposed in Ref. [9], which is analytical [denoted J 2 los in their Eq. (3.20)].…”

“…In this paper, we aim at studying the SZ effect as a possible signature complementary to other indirect probes of dark matter annihilation on the Galactic scale (e.g., [2][3][4][5][6][7]), even though it was recently shown to be hardly observable for galaxy clusters [8,9]. This study is partly motivated by the recent hint for $10 angular scale SZ signals in the WMAP 5-year data away from the Galactic plane by [10], potentially of Galactic origin, which might be explained by a column density of electrons of $10 22 cm À2 , i.e., an optical depth as large as $10 À3 .…”

The dark matter interpretation of the 511 keV line

“…However, if a dark mater halo profile in a cluster is found to be as spiky as a Moore profile or a Jaffe profile in the very inner part (corresponding to sub-arcsecond resolution), then one could constrain the MeV DM scenario by using the SZ effect. Indeed, in this case, there should be a visible displacement of the minimum in the function G( p, E k ) [74,78,79].…”