An Update from the CTA Design Study the next generation Cherenkov Telescope Array A. Zech (for CTA) SF2A Meeting, Besançon
Very High Energy γ-ray astronomy γ-ray VHE γ-rays (E > ~100 GeV) are observed indirectly through the Cherenkov light from showers of secondary charged particles in the atmosphere. The CTA design will profit from the experience with today's Cherenkov arrays (H.E.S.S., MAGIC, VERITAS, CANGAROO) 2
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The Milky Way seen by H.E.S.S. 4
The Milky Way seen by H.E.S.S. γ-ray emission from molecular clouds in the Galactic Center 5
Some open questions in VHE Still looking forastrophysics Statistics with a not too severely biased source distribution Origin and propagation of Galactic cosmic rays (only SNR? tracking via diffuse emission?) Understanding of processes around pulsars, binary systems Understanding of PWN structure & morphology Detailed understanding of acceleration & emission processes in AGN Discovery of VHE gamma rays from starburst galaxies, clusters of galaxies, GRB Signs for ultra-high energy cosmic ray acceleration sites Cosmology with gamma rays Detection of Dark Matter Fundamental physics (test Lorenz Violation, quantum gravity...) 6
e.g. AGN: a more complete picture with CTA CTA will allow to explore less TeV-active classes of AGN (other than blazars) discovery of the radio galaxy Cen A by H.E.S.S., (Aharonian et al. 2009) prediction of the flux from quasar 3C 273, (Lenain et al. 2008) CTA 7
Scientific objectives of CTA 8
CTA performance goals Gain of factor 10 in sensitivity, down to mcrab: => deeper VHE vision, new source classes Very large spectral coverage ( a few 10 GeV to above 100 TeV ) => new source classes, explore emission mechanisms Improved angular resolution down to arc-minute range => mapping of extended sources in high resolution Temporal resolution down to sub-minute time scale => variability studies of pulsars, binaries, blazars Flexibility of operations => different operation modes: deep field, monitoring, survey, alerts Full sky coverage using North & South installations 9
The Milky Way as CTA would see it Galactic plane as seen by H.E.S.S. CTA view CTA/AGIS Simulations Digel + Funk (Stanford) + Hinton (Leeds) 10
The Milky Way as CTA would see it Galactic plane as seen by H.E.S.S. CTA view CTA/AGIS Simulations Digel + Funk (Stanford) + Hinton (Leeds) 11
How to achieve these objectives 12
Expected sensitivity for CTA GLAST -11 Crab 2 E x F(>E) [TeV/cm s] 10-12 10 10% Crab MAGIC -13 10 H.E.S.S. 1% Crab CTA? -14 10 10 100 1000 4 10 10 5 E [GeV] 13
Expected sensitivity for CTA GLAST -11 Crab 2 E x F(>E) [TeV/cm s] 10-12 10 10% Crab MAGIC -13 10 AGN and pulsar physics H.E.S.S. 1% Crab CTA? -14 10 e.g. 4 x 23 m 10 Deep TeV sky 100 coverage 1000 E [GeV] e.g. 23 x 12 m 4 10 Exploration of the 5 EHE 10regime of galactic sources e.g. 32 x 6 m 14
Low-energy section energy threshold of some 10 GeV Southern Side: galactic & extragalactic sources Northern Side: extragalactic sources Core array: mcrab sensitivity in the 100 GeV 10 TeV domain High-energy section 10 km2 area at multi-tev energies 15
Preliminary angular resolution predictions Adapted from Funk, Reimer, Torres, Hinton 2008 1 MILAGRO HAWK 0.1 1 Limit (WH) CTA Sims. 0.01 The ongoing mass production of simulated events will provide more detailed predictions. 16
The CTA Consortium > 50 institutes (9 in France), 16 countries (~ 300 scientists) Present partners : Germany, France, Spain, Italy, Poland, Ireland, UK, South-Africa, Armenia, Switzerland, Finland, Czech Republic, Netherlands, Namibia, Sweden, Japan Others interested : Argentina, Denmark, Russia Coordination/discussions with US scientists, who work on a project similar to CTA: AGIS (Advanced Gamma-ray Imaging System) Regular general CTA meetings since 2006 (Berlin, Paris, Barcelona, Padova, Cracow, Zürich (Oct. 5-8) ) MoU adopted at the Cracow meeting spokesperson: W. Hofmann (MPIK Heidelberg) co-spokesperson: M. Martinez (IFAE Barcelona) 17
Putting CTA on the (road)map since 2008: highly ranked on the ASTRONET roadmap highly ranked in the European Strategy of ASPERA (one of the two most advanced projects beside KM3Net) entered into ESFRI roadmap as the only new project in Physical Sciences & Engineering, promoted from "emergent" to "future goal" considered a high priority in the French roadmap (together with E-ELT) 18
The CTA Design Study: Updates from the Working Packages (a selection) 19
Organisation of the Working Packages Site area, height environmental conditions Array Physics (MC) telescope types, size, fov telescope cost trigger options Telescope data Optical layout and mirror facets Photon detectors observatory quality management management weight fov Electronics Structure Camera Mount & dish 20
WP PHYSICS => objectives: definition of the science case for CTA and study of technical requirements for the different science objectives Evaluate technical requirements for optimal science return together with WP-MC Define list of priority sources for observation programme Investigate CTA integration into multiwavelength observations Dark Matter / Fund. Physics EBL / Cosmology AGN (LUTH) CR / Clusters / Starbursts MQ / Binaries CR / SNRs / Mol. Clouds PWNe Pulsars / Glob. Clusters Surveys / Sub-arrays (LAOG) Extended / Diffuse Srcs. MW / Transients / GRBs Intensity Interferometry DC Light / CR composition 21
WP MC => objectives: simulation of air showers and detector response to find an optimised design Test different configurations (telescope types and array layout) to optimize performance for a given cost Base configurations defined by Toy Models (LLR, Leeds); these are then fully simulated More detailed studies in parallel (e.g. usefulness of fine temporal information per pixel, systematics between air shower simulators,...) 22
WP MC: mass production Large scale simulation of Hyper-Array with 275 telescopes of 5 different types, sizes, Selection of candidate sub-arrays under cost constraints Study of performance Assessment within the WP PHYSICS ~ 0.5 Billion events generated during last few months, using the Grid (Spain, France, Germany, Switzerland, ) coordinated by LAPP 23
WP MC: preliminary sensitivity curves small = 14m large = 28m (K. Bernlohr, 2008) 24
WP SITE & ATAC => objectives: to determine the most suitable location for CTA (S & N) based on a set of relevant criteria; atmospheric monitoring Choice of potential sites based on existing data (meteo, satellites) and tools some criteria: e.g. study of cloud cover and Atmospheric transparency, Light pollution elevation of sites in South Africa Cloud cover, aerosols Altitude (1600-3500m) Wind (speed <40km/h) use of the FriOwl Area, Infrastructure software thanks to E. Graham and ESO Local support Precise measurements to follow on a small number of candidates. Current list of some potential sites ( incomplete! ): South: Argentina, Namibia, South Africa, Chile... North: Morocco, Mexico, Canaries... 25
WP TEL/MIR: MST mounting scheme CEA/IRFU Saclay Observatoire de Paris Meudon / LUTH / H. Castarede DESY Berlin MPIK HD 26
The next steps 27
Time-line for CTA Design Study & Beyond Design Study 06 07 08 09 10 11 12 13 Site exploration Array layout Telescope design Com ponent prototypes Array prototype Array construction Partial operation Very funding dependent! System fully operational in 2018 28
CTA in context of HE/VHE Gamma-Ray Facilities Illustration from J.A.Hinton Should have rewarding overlaps with Fermi (2nd phase), Simbol-X (2015-2020), & other large projects... AUGER, LOFAR, ALMA, JWST 2013+, E-ELT 2017+, SKA & pathfinders (2015/2019+), KM3NeT, IXO, LISA 29
CTA the first VHE gamma-ray OBSERVATORY An astronomical observatory, open to requests for observing time (ToO) Support for users (observation and data analysis) Part of the observation time reserved for the CTA consortium Data public after a certain delay (to be defined) Data archiving and dissemination according to VO standards 30
Thank you for your attention! For more information on CTA: http://www.cta-observatory.org Simulated CTA/AGIS Galactic Plane Survey (Funk, Hinton, Digel, Hermann, Gamma-08)
http://www.cta-observatory.org Not to be confused with the "other" CTAs...
WP MIR => objective: definition of the mirror design Area 1-2.5 m2, Shape = hexagonal Weight < 30 kg/panel PSF < 0.6mrad (or half pixel size) Rigidity Operating temperature range: -10 C to +30 C. Reflectance > 80% for 300-600 nm Proven Solutions: Aluminzed glass (H.E.S.S. solution) Average cost, suffers from ageing, high weight Machined Aluminium on alu honeycomb (MAGIC solution) High cost, low ageing, low weight New Solutions proposed: Mirrors in carbon-epoxy composite Probable low cost, low weight, unknown performance Mirrors in polyeurethane foam with glass front face (CEA Saclay) Probable low cost, low weight, unknown performance 33
WP FPI => objectives: Focal Plane Instrumentation (photodetectors + camera mechanics) Decision to have a fully-integrated camera Testing Camera protection window, Winston cone light-guides either with mylar foil or aluminium deposition on moulded form Mechanics for cameras under study, including automatic lids, integration of calibration systems for PMTs, telescope pointing, etc. PMT measurement of many samples (standard, super/ultra-bialkali, hemispherical window, multi-anode, flat-panel...) in coming months. Studies of new technologies (e.g. SiPM) a Photonis PM test samples future upgrade option @ MPI-P 34
WP ELEC => objective: definition of the electronics & trigger Analogue pipeline solution for the in-camera acquisition, several GHz-sampling most probable solution (existing SAM, DRS3, future DRS4, NeCTAr, from IRFU/IN2P3 and PSI/Pisa). Aim to integrate the maximum functionality in ASIC (=cost+reliability) Camera-level Trigger, by sectors / clusters (INFN Pisa/Padova, MPI-P) Read-out using the maximum of commercial components / protocols... Inter-telescope trigger with central array clock-distribution over fibre (à la Antares), event time-stamping, real-time (re)programmable coincidence determination (APC/MPI-K) DRS4 chip 35
WP TEL => objective: definition of the telescope structures Three telescope sizes being studied with diameters 6/12/23m Field of view 6-8 for 6&12 m, 5 for 23 m Dish type spherical for 6 m, parabolic for 23 m f/d as large as affordable (1.4 2) Stiffness adapted to active mirror control for PSF 6m diameter < 1mrad 30 year lifetime MPI-K / IFJ PAN 23m diameter MPI-P 12m diameter ANL 36
WP DATA => objectives: definition of the data structure at several levels, processing, archiving and dissemination Plan data architecture, for telescope control, observation planning, access to ~0.5 PB/yr of data in various forms (raw, DSTs, maps...) definition of data standards for VHE gamma-ray data (compliant with VO standards) dissemination of high level data for the astrophysics community (light curves, spectra,...), definition of data formats (FITS, VOTable...) interface with the Virtual Observatory (VO) and multi-messenger science; collaboration with CDS 37