Cherenkov Telescope Array

Transcription

1 Cherenkov Telescope Array Giovanni Lamanna (on behalf of the CTA consortium) LAPP - Laboratoire d'annecy-le-vieux de Physique des Particules, Université de Savoie, CNRS/IN2P3, Annecy-le-Vieux, France Rencontres de Moriond March 9-16, 2013

2 Outline - Introduction - CTA concept - CTA project - CTA key issues - CTA Science - Conclusions

3 CTA concept in EU/USA roadmaps 1. Aspera ESFRI Decadal Survey Aspera Update OCDE Astronet 2010

4 Current IACT experiments

5 CTA: a worldwide challenge

6 Significant boosts of capabilities + breakthroughs Boost Boost Boost New New New Increase sensitivity by up to a factor 10 at 1 TeV, Boost the detection area for transient phenomena and at the highest energies, Increase the angular resolution while maintaining a large field of view Provide energy coverage from some tens of GeV to beyond 100 TeV, and have 2-sites, flexibility of operation, allowing for sub-array and simultaneous multi-mode runs. Operate as an Observatory. 6

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9 CTA telescopes: 4 types, 3 classes, a great challenge

10 CTA sites candidates

11 CTA data flow CTA is a PB big data scale project and operating as an Observatory Proposal handling Science Management Operation Planning Data archive Data reduction Monte Carlo simulation Data Dissemination Telescope Operation Data Acquisition Performance monitoring On-site analysis execution

12 Sensitivity in units of Crab flux

13 Resolutions

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15 Addressing key science questions 1. Where and how are the bulk of CR particles accelerated in our Galaxy and beyond? Understanding transitions in the CR spectra. (one of the oldest surviving questions of astrophysics) 2. How cosmic-rays propagate, interact, and heat the environment? Which are the consequences from Galactic to cosmological scenarios? 3. What makes black holes of all sizes such efficient particle accelerators? 4. What do high-energy gamma-rays tell us about the star formation history of the Universe, the structure of spacetime, or the fundamental laws of physics? 5. What is the nature of dark matter? Can it be discovered via indirect searches? Can we map dark matter halos? 6. Are there short-timescale phenomena at very high energies? Are GRBs gamma-ray emitter? Is there new Galactic phenomenology to uncover?

16 CTA unique science goals The ability of producing the deepest surveys of the sky (with unprecendented angular and energy resolution, and energy coverage) at gamma-ray energies Unique in the sense that no other instrument has a similar ability in the same energy regime. The ability to perform the first sensitive observation of short timescale phenomenology at gammaray energies 16

17 As a function of event duration / integration time Fermi-LAT signal is limited above 10 GeV, and its sensitivity decreases rapidly with event duration. ½ hour: x month: x

18 THE CORE SCIENCE TOPICS: EXAMPLES OF GOALS VS REQUIREMENTS 18

19 The origin and propagation of cosmic-rays 19

20 The origin and propagation of cosmic-rays Goal: Test SNR-origin of comic-rays; and lepto-hadronic production & propagation Requirements Build SNR population (leading to an essentially complete Galactic sample) Resolve bright SNR filaments and shells with up to 1-3 arcmin at 10 TeV (measuring width of filaments can help resolve the issue of leptonic or hadronic acceleration there, comparison with X-ray observations) Sensitivity at 50 TeV should be enough to detect plausible pevatron candidates in short times (>3σ excess in 8-10 hours), to be followed by depeer observation 20

21 Building up the SNR population 21

22 Resolving structures (e.g., RXJ & Vela Jr.) 22

23 Galactic diffusion properties, illumination 23

24 The origin and propagation of cosmic-rays Goal: Assess cosmic-ray population in galaxies/starbursts and clusters; test of large scale variations of CR distribution, study CR propagation in turbulent magnetic fields associated with SFRs, study ionization of molecular cloud cores in SFRs Requirements: Angular resolution of 3 arcmin useful to map at high-energies closest SFR such as the Gal. Center, or 30 Dor in the LMC and compare with GeV maps; Large field of view with relatively flat and deep sensitivity to allow for diffuse, low-brightness emission from clusters to be detected Improve on spectral measurements of closest starbursts, LIRGs, and ULIRGs; in particular, determination of high-energy cutoff, and eventually distinguishing central / halo contribution, understanding of the pressure contribution of CRs inside and outside of SFRs 24

25 Detection of starbursts, normal galaxies 25

26 The origin and propagation of cosmic-rays Goal: Understand the population of PWN, which are their order parameters, how do they correlate at different frequencies Requirements: Enlarge PWN population up to an homogeneous Galactic sample (at least 40 to 80% of G , or Kes 75 all detectable for CTA up to the other side of the Galaxy). CTA can reasonably expect to find all young pulsars in the galaxy - via their PWN emission Large field of view with relatively flat and deep sensitivity to allow PWN coverage (a minimum of radial flat response to sample currently known sources, radial preferred to allow mapping old systems) Angular resolution is required to understand composite systems, often unresolved when observed with the present instruments 26

27 A visual comparison with the H.E.S.S. survey 27

28 Black holes as probes of the Star Formation History 28

29 Black holes and their use as probes of the SFH Goal: Build up a classified population of high and very-high energy emitting AGN (both in flaring and quiescent states), covering various types and redshifts, for studies on classification, unification scheme(s), evolution, gamma-ray origin... This includes the study of radio-galaxies (like M87, Cen A, IC 310, or NGC 1275); and their VHE-emitting location and also Radio Loud Seyferts (1-2 orders of mag. smaller black holes than in blazars but at 80% Eddington accretion rates); increase the range of parameters of the accretion-ejection explored at HE. Requirements: Sensitivity to measure of a large sample of AGN (both in flaring and quiescent state), preferentially by means of an unbiased survey Good angular resolution and astrometry: an accuracy of 5 in source localization will allow ruling out (or detecting) bright / compact knots along the kpc jets, from CTA data alone. 29

30 Black holes and their use as probes of the SFH Goal: Provide a detailed measurement of EBL strength and distinction between intrinsic and propagation effects Requirements: Have a low threshold: e.g., to measure an unattenuated part of the spectrum (with a minimum lever arm of half a decade in energy) for sources at a redshift of 1 (about 50% of the universe), an energy threshold of GeV is required Goal: Characterize the effects of TeV heating of the IGM, possible connection with structure formation problems - search of pair halos, measurement of IGMF Requirements: Relatively flat sensitivity of up to would enable to test extended emission around distant (up to 120 Mpc) for IGMF in the range of G and up. 30

31 Examples for EBL studies CTA: Simulation of quiescent spectrum of PKS (z=0.116): distinguishing different models for EBL (20 h of observation). Results using bright flares but shorter timescales (6 minutes) are entirely comparable. 31

32 (e.g., w./mkn 501, z~0.034) Examples for EBL studies: EBL today observe the same effect on spectra of different sources to become independent of possible intrinsic source features. The form of the wiggles will depend on the exact spectral shape of the correct EBL model, which is not known a priori. 32

33 Example of GRB c at z=4.3 in 45s -45 s observation of a bright burst at z=4.3; spectrum determination possible between 50 and 100 GeV (intrinsic spectrum extrapolated from Fermi-LAT) -20 s interval (harder spectrum, higher flux, from Fermi-LAT) allows to distinguish different EBL models 33

34 Dark matter and fundamental physics 34

35 Dark matter and fundamental physics Goal: To have exclusion ability for the canonical WIMP model: with averaged annihilation cross-section of cm 3 s 1 (possible with CTA under the prior requirements with 100 h observation of the GC vicinity for WIMP masses above 300 GeV). Complementarity of indirect / direct DM search: Scan of models that give too weak DM-nucleon scattering cross section, or with mass scale too high, difficult to see in direct experiments improved energy resolution increase the chances of detecting a possible spectral feature in the a DM-induced photon spectrum. Given the underlying uncertainties in both the particle physics and astrophysics of cosmic DM searches, general statements in terms of minimum requirements for detection are risky. 35

36 DM Searches Dwarf speheroidal galaxies are interesting objects for DM search but not the strongest science case for CTA. Galactic halo and (ex. Fornax) galaxy cluster are more promising 36

37 DM searches in the Galactic Center From S. Sarkar presentation at IAU

38 Dark matter and fundamental physics Goal: To do a precise testing of LIV. v/c ~ 1-(E/M) n, figure of merit for measurement is L (E n )/ t Improvements: higher energies (but mind EBL) (allowing tests of quadratic dependence, due to larger lever arm) larger redshifts finer time structures, better peak discrimination number of sources is essential to disentangle spectral evolution effects (e.g., spectrum hardening with time) (a solid limit, either lower or upper, would require concordancy with different classes of sources, e.g., both GRBs and AGNs) Much more detailed studies of known sources (Mrk 421-bright- PKS fast-, and 3C279 far-) and similar new flares yield sensitivity to LIV effects to ~10 19 GeV 38

39 CONCLUSIONS Very interesting and varied physics can be done with an observatory-scale facility in the VHE regime Physics impact of the facility will affect all topics in modern astrophysics, and will produce legacy datasets. Acknowledgments: 1) D. Torres, W. Hofmann for support material to this talk 2) Main authors of the CTA AP special issue from which figures of this talk have been extracted : - M. Doro, J. Conrad et al. - S. Inoue et al. - D. Mazin et al. - F. Acero et al. - E. de Ona-Wilhelmi et al. - J. M. Peredes et al.

40 Lynette Cook

41 THANK YOU 41