Surveys with the Cherenkov Telescope Array

Dubus, G.; Contreras, J. L.; Funk, S.; Gallant, Y. A.; Hassan, Tarek; Hinton, J. A.; Inoue, Yoshiyuki; Knödlseder, J.; Martin, Pierrick; Mirabal, N.; Naurois, M. de; Renaud, M.

doi:10.1016/j.astropartphys.2012.05.020

Cited by 92 publications

(137 citation statements)

References 48 publications

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“…We therefore conclude that we cannot firmly claim a correlation neither with CO traced material nor with dust content enhancement, but all the tests performed present hints of it. The final proof of correlation is left for the future, when the forthcoming Cherenkov Telescope Array (CTA) observations will provide us with more sources (Dubus et al 2013). …”

Section: Stability Of the Resultsmentioning

confidence: 99%

On the possible correlation of Galactic very-high energy source locations and enhancements of the surface density in the Galactic plane

Pedaletti

Wilhelmi

Torres

2014

A&A

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Aims. The association of very-high energy sources with regions of the sky rich in dust and gas has been noticed in the study of individual very-high energy (VHE; E > ∼ 100 GeV) sources. However, the statistical significance of this correlation for the whole population of TeV detections has not been assessed yet. Here, we present a study of the association of VHE sources in the central Galactic region with positions of enhanced material content. Methods. We obtain estimates of the material content through two classical tracers: dust emission and intensity of the 12 CO(1 → 0) line. We make use of the recently released all-sky maps of astrophysical foregrounds of the Planck Collaboration, and of an extensive existing CO mapping of the Galactic sky. To test the correlation, we construct randomized samples of VHE source positions starting from the inner Galactic plane survey sources detected by the High Energy Stereoscopic System (H.E.S.S.) array. Results. We find hints of a positive correlation between positions of VHE sources and regions rich in molecular material, which reaches the 3.9σ level in the best of cases. The latter confidence is however decreased if variations in the selection criteria are considered, which lead us to conclude that a positive correlation cannot be firmly established yet. Forthcoming VHE facilities will be needed to firmly establish the correlation.

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Section: Stability Of the Resultsmentioning

confidence: 99%

On the possible correlation of Galactic very-high energy source locations and enhancements of the surface density in the Galactic plane

Pedaletti

Wilhelmi

Torres

2014

A&A

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“…Estimates for the number of actual objects that MACHETE could discover in five years differ from a handful (based on [31]) to several tens (based on [32]). …”

Section: Physics Goalsmentioning

confidence: 99%

“…This may include other active galaxies and other ex-tragalactic or galactic objects in general. Some of them may not emit or emit only weakly at longer wavelengths ("dark sources", see [31]). …”

Section: Physics Goalsmentioning

confidence: 99%

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MACHETE: A transit imaging atmospheric Cherenkov telescope to survey half of the very high energy γ -ray sky

Cortina

López-Coto

Moralejo

2016

Astroparticle Physics

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Current Imaging Atmospheric Cherenkov Telescopes for Very High Energy γ-ray astrophysics are pointing instruments with a Field of View up to a few tens of sq deg. We propose to build an array of two non-steerable (drift) telescopes. Each of the telescopes would have a camera with a FOV of 5×60 sq deg oriented along the meridian. About half of the sky drifts through this FOV in a year. We have performed a Montecarlo simulation to estimate the performance of this instrument. We expect it to survey this half of the sky with an integral flux sensitivity of ∼0.77% of the steady flux of the Crab Nebula in 5 years, an analysis energy threshold of ∼150 GeV and an angular resolution of ∼0.1 • . For astronomical objects that transit over the telescope for a specific night, we can achieve an integral sensitivity of 12% of the Crab Nebula flux in a night, making it a very powerful tool to trigger further observations of variable sources using steerable IACTs or instruments at other wavelengths.

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“…Their current sensitivity prevents an all-sky scan in a reasonable amount of time, and IACT observations must be pointed to targets of interest (see e.g. Dubus et al 2013 for a discussion of the capabilities of next generation instruments). Targeted AGN are selected based on their radio and X-ray spectra (Stecker et al 1996;Perlman 2000;Costamante & Ghisellini 2002) as well as based on their HE flux extrapolated to VHE (Tavecchio et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Flux upper limits for 47 AGN observed with H.E.S.S. in 2004−2011

Abramowski

Aharonian

Benkhali

et al. 2014

A&A

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Context. About 40% of the observation time of the High Energy Stereoscopic System (H.E.S.S.) is dedicated to studying active galactic nuclei (AGN), with the aim of increasing the sample of known extragalactic very-high-energy (VHE, E > 100 GeV) sources and constraining the physical processes at play in potential emitters. Aims. H.E.S.S. observations of AGN, spanning a period from April 2004 to December 2011, are investigated to constrain their γ-ray fluxes. Only the 47 sources without significant excess detected at the position of the targets are presented. Methods. Upper limits on VHE fluxes of the targets were computed and a search for variability was performed on the nightly time scale. Results. For 41 objects, the flux upper limits we derived are the most constraining reported to date. These constraints at VHE are compared with the flux level expected from extrapolations of Fermi-LAT measurements in the two-year catalog of AGN. The H.E.S.S. upper limits are at least a factor of two lower than the extrapolated Fermi-LAT fluxes for 11 objects. Taking into account the attenuation by the extragalactic background light reduces the tension for all but two of them, suggesting intrinsic curvature in the high-energy spectra of these two AGN. Conclusions. Compilation efforts led by current VHE instruments are of critical importance for target-selection strategies before the advent of the Cherenkov Telescope Array (CTA).

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Surveys with the Cherenkov Telescope Array

Cited by 92 publications

References 48 publications

On the possible correlation of Galactic very-high energy source locations and enhancements of the surface density in the Galactic plane

On the possible correlation of Galactic very-high energy source locations and enhancements of the surface density in the Galactic plane

MACHETE: A transit imaging atmospheric Cherenkov telescope to survey half of the very high energy γ -ray sky

Flux upper limits for 47 AGN observed with H.E.S.S. in 2004−2011

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