Garbage Experiment Of The Day

This experiment is searching for dark matter that must have properties in a part of the dark matter parameter space that direct dark matter detection experiments and particle collider tests have already ruled out by a dozen orders of magnitude or more. It is also basically ruled out by the LAT collaboration.

It is arguably one of the biggest wastes of time in the astronomy community right now. I would never have voted to fund it, if I were sitting on a committee considering the proposal.

Numerous observations confirm the existence of dark matter (DM) at astrophysical and cosmological scales. Theory and simulations of galaxy formation predict that DM should cluster on small scales in bound structures called sub-halos or DM clumps. While the most massive DM sub-halos host baryonic matter, less massive, unpopulated sub-halos could be abundant in the Milky Way (MW), as well and yield high-energy gamma rays as final products of DM annihilation. Recently, it has been highlighted that the brightest halos should also have a sizeable extension in the sky. In this study, we examine the prospects offered by the Cherenkov Telescope Array Observatory (CTAO), a next-generation gamma-ray instrument, for detecting and characterizing such objects. Previous studies have primarily focused on high-latitude observations; here, we assess the potential impact of the CTAO's Galactic Plane Survey, which will provide unprecedentedly deep survey data for the inner five degrees of the Galactic plane. Our modeling accounts for tidal effects on the sub-halo population, examining the conditions under which DM sub-halos can be detected and distinguished from conventional astrophysical sources. We find that regions a few degrees above or below the Galactic plane offer the highest likelihood for DM sub-halo detection. For an individual sub-halo -- the brightest from among various realizations of the MW subhalo population -- we find that detection at the 5σ level is achievable for an annihilation cross section of ⟨σv⟩∼3×10^−25 cm^3/s for TeV-scale DM annihilating into bb¯. For a full population study, depending on the distribution and luminosity model of Galactic sub-halos, yet unconstrained cross sections in the range ⟨σv⟩∼10^−23−10^−22 cm^3/s for TeV DM candidates are necessary for the brightest sub-halos to be detected.

Christopher Eckner, et al., "Detecting dark matter sub-halos in the Galactic plane with the Cherenkov Telescope Array Observatory" arXiv:2501.09789 (January 16, 2025).