Browsing by Author "Gallant, Y."
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Item Prospects for observations of pulsars and pulsar wind nebulae with CTA(Elsevier, 2012-09-17) Oña-Wilhelmi, E.de; Rudak, B.; Barrio, J. A.; Contreras, J. L.; Gallant, Y.; Hadasch, D.; Hassan, T.; Lopez, M.; Mazin, D.; Mirabal, N.; Pedaletti, G.; Renaud, M.; Reyes, R. de los; Torres, D. F.; the CTA collaborationThe last few years have seen a revolution in very-high -ray astronomy (VHE; E > 100 GeV) driven largely by a new generation of Cherenkov telescopes (namely the H.E.S.S. telescope array, the MAGIC and MAGIC-II large telescopes and the VERITAS telescope array). The Cherenkov Telescope Array (CTA) project foresees a factor of 5 to 10 improvement in sensitivity above 0.1 TeV, extending the accessible energy range to higher energies up to 100 TeV, in the Galactic cut-off regime, and down to a few tens GeV, covering the VHE photon spectrum with good energy and angular resolution. As a result of the fast development of the VHE field, the number of pulsar wind nebulae (PWNe) detected has increased from one PWN in the early ’90s to more than two dozen firm candidates today. Also, the low energy threshold achieved and good sensitivity at TeV energies has resulted in the detection of pulsed emission from the Crab Pulsar (or its close environment) opening new and exiting expectations about the pulsed spectra of the high energy pulsars powering PWNe. Here we discuss the physics goals we aim to achieve with CTA on pulsar and PWNe physics evaluating the response of the instrument for different configurations.Item Surveys with the Cherenkov Telescope Array(Elsevier, 2012-06-02) Dubus, G.; Contreras, J.L.; Funk, S.; Gallant, Y.; Hassan, T.; Hinton, J.; Inoue, Y.; Knödlseder, J.; Martin, P.; Mirabal, N.; Naurois, M. de; Renaud, M.; the CTA ConsortiumSurveys 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”.