Cherenkov Telescope Array Status Report. Salvatore Mangano (CIEMAT) On behalf of the CTA consortium

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1 Cherenkov Telescope Array Status Report Salvatore Mangano (CIEMAT) On behalf of the CTA consortium

2 Outline Very-High-Energy Gamma-Ray Astronomy Cherenkov Telescope Array (CTA) Expected Performance of CTA Science Goals - Standard Model - Beyond Standard Model Conclusion 2

3 Gamma-Rays Instruments Earth's atmosphere is opaque for gamma-rays Direct detection in space Indirect detection from ground 3

4 Imaging Air Cherenkov Technique 4

5 Stereoscopic Detection Stereoscopy: Better background rejection Better angular resolution Better energy resolution 5

6 Reconstruction Methods Image Intensity Orientation Shape Gamma/Particle Energy Direction Primary particle Id Goal of Reconstruction Methods Separate gamma-ray like from background events Reconstruct energy and direction Camera image of telescope Color encodes light intensity Monte Carlo simulation (Corsika and sim_telarray) Image analysis (Hillas method) Full pixel information (Model analysis) Machine learning technique Test performance using Monte Carlo simulation 6

7 Present Cherenkov Telescope Arrays 7

8 Detection of Sources TeVCat 2017 Whipple detected first gamma-ray source (Crab Nebula) in 1989 Today around 160 sources with detailed source information 8

9 Objective of Future CTA Project Objective of CTA with respect to current instruments Improve sensitivity by an order of magnitude Extend energy range ~20 GeV to ~300 TeV Improve energy and angular resolution (factor 2-3) Widen telescope field of view Survey full sky Observe fast transient phenomena Allow very-high-energy gamma-ray astronomy to transit from source discovery to detailed source investigation Concept implementation Build array of telescopes Use different telescope sizes Operate on sites in both hemispheres Improve collection area 9

10 CTA Concept 10

11 CTA Telescope Types Large Size Telescope Medium Size Telescope fast slewing Small Size Telescopes Three different sizes of telescope optimized for three different energy ranges 11

12 MST and SST Prototypes SST-2M GCT Paris, France MST prototype Berlin, Germany SST-1M Krakow, Poland SST-2M ASTRI Sicily, Italy 12

13 LST Prototype Status March 2017: Foundation of LST at Roque de los Muchachos, La Palma, Spain 13

14 Collection Area Low-energy gamma-ray: high gamma-ray rate, low light yield require small ground area, large mirror area High-energy gamma-ray: low gamma-ray rate, high light yield require large ground area, small mirror area 14

15 World-Wide Cooperation 32 Countries 210 Institutes 1350 Members 15

16 Northern and Southern Sites Site negotiation completed with Instituto de Astrofisica de Canarias (La Palma/Spain) 16 Site negotiation progressing with European Southern Observatory (Paranal/Chile)

17 Possible Arrays Layout 4 LST 25 MST 70 SST 4 LST 15 MST North: Roque de los Muchachos Observatory, La Palma, Spain Monte Carlo simulation used to optimize array configurations 17

18 Full Sky Survey Galactic plus extragalactic science Mainly extragalatic science 18

19 Sensitivity Current instruments 19

20 Galactic Discovery Reach Angular resolution critical for source morphology and identification Expected: ~ 0.05 degrees at 1 TeV Due to increased sensitivity and larger FoV: Survey speed: ~ few 100 times faster than current instruments Ten fold increase in current number of sources 20

21 Science Themes 21

22 Science Themes Cosmic Particle Acceleration How and where are particle accelerated? Sites of acceleration in our galaxy and beyond Search of Pevatrons Cosmic ray interactions within galaxies and clusters Probing Extreme Environments Processes in relativistic jets, winds and explosions? Study in vicinity of neutron stars and black holes Probing Intergalatic Medium Extragalactic background light Magnetic fields Physics Beyond Standard Model Testing invariance of speed of light Axion-like particles Indirect Dark Matter searches 22

23 Galactic Acceleration Mechanism SNR Simulation Disentangle leptonic from hadronic models by extending energy up to 100 TeV Detection of SNR up to 100 TeV implies: Emission is hadronic, leptonic emission is highly suppressed 23 SNR are Pevatrons

24 AGN Acceleration Mechanism p synch synch-self-compton μ synch cascade With high-quality spectra from different AGN types and different redshifts CTA can unambiguously distinguish intrinsic spectral features 24

25 AGN Variablility Study of long time (years) and short time (minutes/seconds) variations Flux variation times sets limit to size of emitting region Simulation Study acceleration and cooling mechanism, duty cycle and breaks in power spectra Time series analysis CTA with large effective area is ideal to study timing properties of AGNs 25

26 Gamma-Ray Propagation with Multi-Million Years Journey Gamma-rays propagate 109 of years and interact with: intergalactic photon fields intergalactic magnetic fields space-time and axion-like particles Unique opportunity to study gamma-ray propagation over cosmological distances Study several sources at different distances helps to disentangle: intrinsic properties photon propagation properties Observe GeV and TeV components of AGN flux 26

27 Extragalactic Background Light (EBL) EBL measures integrated star formation history in Universe Direct measurement difficult because of foregrounds Absorbed spectra depends on: EBL strength gamma-ray energy redshift 27

28 EBL Measurement with CTA Absorption spectral signature allow measuring EBL (z) using large sample of AGN at different z (probe galaxy evolution) EBL at z~0 from mid UV to far IR with precision of ±10% 28

29 Measure Intergalatic Magnetic Field Magnetic field deflects electron-positron pairs changing angular distribution of cascade emission 1.5 deg 2.5 deg Searches of extended emission around blazers can constrain intergalactic magnetic field (IGMF) CTA with chance to measure strength of IGMF due to: improved angular resolution wide field of view 29

30 Axions (Increased Transparency of Universe) Photons to axions oscillations (an vice-verse) in magnetic field (similar to neutrino oscillation but need of magnetic field) Universe more transparent (axions do not interact with EBL) Modulation of spectra (conversion probability depends on energy) Need of observation of large set of sources of different classes and at different redshifts with high gamma-ray statistics to disentangle EBL from photon-axion mixing 30

31 Lorentz Invariance Violation (LIV) LIV Some quantum gravity theories predict LIV Observe rapidly varying AGNs/GRBs to provide limits on LIV Velocity dispersion across TeV energy range Change of spectra for highest energy photons Several AGNs to test propagation induced and intrinsic dispersion effects CTA will place better LIV constrains due to larger number of TeV sources at high redshifts 31

32 Dark Matter Detection Indirect detection 32

33 Indirect Dark Matter Searches Targets with different systematics: Astrophysics (J-factor): DM density distribution obtained from N-body simulations of DM clustering Important: Dark Matter content Astrophysical background Galactic Halo + large DM statistics diffuse astrophysical background astrophysical source confusion Dwarf Spheroidal Galaxies low DM statistics + low astrophysical background with small uncertainty Spectral Lines + No background => smoking gun very low DM statistics 33

34 Dark Matter Searches with CTA Galactic Halo Deep exposure 500 h Avoid inner region with astrophysical sources Close by Strong DM signal expected Thermal cross section Highly uncertain DM profile Careful control of systematic effects CTA perfectly suited: sensitivity energy resolution spatial resolution 34

35 Conclusion CTA is the next generation facility Construction already started Working prototypes exist Exciting science in both hemisphere CTA will open up very-high-energy astronomy to a wide community Thanks to CTA collaborators from whom I took many transparencies 35