title: Particle Dark Matter Searches Outside the Local Group.
abstract: If dark matter (DM) is composed by particles which are nongravitationally coupled to ordinary matter, their annihilations or decays in cosmic structures can result in detectable radiation. We show that the most powerful technique to detect a particle DM signal outside the Local Group is to study the angular cross-correlation of nongravitational signals with low-redshift gravitational probes. This method allows us to enhance the signal to noise from the regions of the Universe where the DM-induced emission is preferentially generated. We demonstrate the power of this approach by focusing on GeV-TeV DM and on the recent cross-correlation analysis between the 2MASS galaxy catalogue and the Fermi-LAT γ-ray maps. We show that this technique is more sensitive than other extragalactic γ-ray probes, such as the energy spectrum and angular autocorrelation of the extragalactic background, and emission from clusters of galaxies. Intriguingly, we find that the measured cross-correlation can be well fitted by a DM component, with a thermal annihilation cross section and mass between 10 and 100 GeV, depending on the small-scale DM properties and γ-ray production mechanism. This solicits further data collection and dedicated analyses.
authors.affiliation: Dipartimento di Fisica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino, via Pietro Giuria 1, I-10125 Torino, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Regis
authors.affiliation: Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Science, P.O. Box 918-3, Beijing 100049, People's Republic of China.
authors.forename: Jun-Qing
authors.initials: JQ
authors.lastname: Xia
authors.affiliation: Dipartimento di Fisica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino, via Pietro Giuria 1, I-10125 Torino, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cuoco
authors.affiliation: Dipartimento di Matematica e Fisica, Università degli Studi "Roma Tre", via della Vasca Navale 84, I-00146 Roma, Italy.|INFN, Sezione di Roma Tre, via della Vasca Navale 84, I-00146 Roma, Italy.|INAF Osservatorio Astronomico di Roma, INAF, Osservatorio Astronomico di Roma, Monte Porzio Catone, Italy.
authors.forename: Enzo
authors.initials: E
authors.lastname: Branchini
authors.affiliation: Dipartimento di Fisica, Università di Torino and Istituto Nazionale di Fisica Nucleare, Sezione di Torino, via Pietro Giuria 1, I-10125 Torino, Italy.
authors.forename: Nicolao
authors.initials: N
authors.lastname: Fornengo
authors.affiliation: INAF Osservatorio Astronomico di Trieste, Via Giovanni Battista Tiepolo 11, I-34141 Trieste, Italy.|INFN, Sezione di Trieste, via Valerio 2, I-34127 Trieste, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Viel