Surveys with the Cherenkov Telescope Array

G Dubus (1) , J L Contreras (2) , S Funk (3) , Y Gallant (4) , T Hassan (2) , J Hinton (5) , Y Inoue (3) , Jürgen Knödlseder (6) , P Martin (6) , N Mirabal (2) , M L de Naurois (7) , Matthieu Renaud (4)

1 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
2 UCM - Universidad Complutense de Madrid = Complutense University of Madrid [Madrid]
3 SLAC - SLAC National Accelerator Laboratory
4 LUPM - Laboratoire Univers et Particules de Montpellier
5 Department of Physics and Astronomy [Leicester]
6 IRAP - Institut de recherche en astrophysique et planétologie
7 LLR - Laboratoire Leprince-Ringuet

Surveys open up unbiased discovery space and generate legacy datasets of long-lasting value. One of the goals of imaging arrays of Cherenkov telescopes like CTA is to survey areas of the sky for faint very high energy gamma-ray (VHE) sources, especially sources that would not have drawn attention were it not for their VHE emission (e.g . the Galactic “dark accelerators”). More than half the currently known VHE sources are to be found in the Galactic Plane. Using standard techniques, CTA can carry out a survey of the region |l|<60° |b|<2° in 250 h (1/4th the available time per year at one location) down to a uniform sensitivity of 3 mCrab (a “Galactic Plane survey”). CTA could also survey 1/4th of the sky down to a sensitivity of 20 mCrab in 370 h of observing time (an “all-sky survey”), which complements well the surveys by the Fermi/LAT at lower energies and extended air shower arrays at higher energies. Observations in (non-standard) divergent pointing mode may shorten the “all-sky survey” time to about 100 h with no loss in survey sensitivity. We present the scientific rationale for these surveys, their place in the multi-wavelength context, their possible impact and their feasibility. We find that the Galactic Plane survey has the potential to detect hundreds of sources. Implementing such a survey should be a major goal of CTA. Additionally, about a dozen blazars, or counterparts to Fermi/LAT sources, are expected to be detected by the all-sky survey, whose prime motivation is the search for extragalactic “dark accelerators”.

Domaines: Astrophysique [astro-ph]

G Dubus, J L Contreras, S Funk, Y Gallant, T Hassan, et al.. Surveys with the Cherenkov Telescope Array. Astroparticle Physics, 2013, 43, pp.317 - 330. ⟨10.1016/j.astropartphys.2012.05.020⟩. ⟨hal-01381963⟩