Very High Energy Astronomy Very High Energy Astronomy dP t f CTA dP t f CTA and Prospects for CTA and Prospects for CTA VERITAS VERITAS Cas A ACT CTA Rene A. Rene A. Ong Ong (UCLA) (UCLA) CTA Lowell Observatory Colloquium Lowell Observatory Colloquium 02 May 2013 02 May 2013
71
Embed
Very High Energy Astronomy andP t f CTAd Prospects for CTArene/talks/Lowell-CTA-May2013.pdfVery High Energy Astronomy andP t f CTAd Prospects for CTA VERITAS VERITAS Cas A ACT CTA
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Very High Energy AstronomyVery High Energy Astronomyd P t f CTAd P t f CTAand Prospects for CTAand Prospects for CTA
• Potential way to measure tiny extragalactic magnetictiny extragalactic magnetic field (EGMF). B ~ 10-9 - 10-18 G
AGN: Is the Universe too Transparent ?
Axion conversion ??Horns & MeyerarXiv:1201.471
Axion conversion ??Sanchez-Conde et al.,arXiv:0905.3270
UnID Sources: Galactic Center
GeV γ-raysInfraredFermi-LAT
• Jim Buckley
S. Murgia, “Dark Attack 2012”15o x 15o15o x 15o
TeV γ-raysGhez et al., 20121” x 1” TeV γ-rays
G V & T V i i i
1” x 1”
M. Beilicke et al.
GeV & TeV emission is:
• Intense & non-thermal• totally unexpected
t d t d ! “Gamma 2012”1o x 3o
• not understood !
Dark Matter ??
γ−ray SignalsDark Matter Detectionγ y g
χχ qq, γγ … “Universal” Spectrum
1.4 TeV Higgsino(Bergstrom)(Bergstrom)
Galactic Center
S t llitSatellites
Line signals
Halo
Extragalactic
Dark MatterDark MatterDM simulation (Pieri et al., 2011)
Dark MatterDark MatterAstronomyAstronomy
Dark Matter Resultsγ-ray DM limits But …
C Weniger “Gamma 2012”C. Weniger, Gamma 2012
Evidence for line at ~130 GeVJ. Conrad, “Gamma 2012”
No signal (yet)Limits at or approaching thermal relic cross section.
Evidence for line at 130 GeV~4σ (post trials).seen by several authors.close to Galactic center
VHE instruments probe high mass region not easily accessible.
close to Galactic center.systematic effect ?can be confirmed or refuted.
Summary of Key Science TopicsBottom line: Bottom line: GeVGeV and and TeVTeV gammagamma--ray sources are ubiquitous in ray sources are ubiquitous in the universe and probe extreme particle acceleration andthe universe and probe extreme particle acceleration andthe universe and probe extreme particle acceleration and the universe and probe extreme particle acceleration and particle interactions and propagation.particle interactions and propagation.
1. Where and how are the bulk of CR particles accelerated in our Galaxy and beyond?1. Where and how are the bulk of CR particles accelerated in our Galaxy and beyond? (one of the oldest surviving questions of astrophysics)
2. Can we understand the physics of jets, shocks & winds in the variety of sources we see, including pulsars, binaries, AGN, starbursts, and GRBs?see, including pulsars, binaries, AGN, starbursts, and GRBs?
3. How do black holes of all sizes efficiently particles? How are the structures (e.g. jets)formed and how is the accretion energy harnessed?
4 Wh t d hi h t ll b t th t f ti hi t f th4. What do high-energy gamma rays tell us about the star formation history of the Universe, intergalactic radiation fields, and the fundamental laws of physics?
5. What is the nature of dark matter and can we map its distribution through its particle i t ti ?interactions?
6. What new, and unexpected, phenomena will be revealed by exploring the non-thermalUniverse?
Bonus: Non-VHE science: e.g. optical interferometry, OSETI, etc.
ExperimentalTechniques
Fermi Large Area Telescope (LAT)
Anti-CoincidenceShield
Si Strip TrackerShield
Calorimeter
~ 1 m2 2.5 sr30 MeV-300 GeV
Excellent surveyinstrument
Beyond 100 GeV
Steeply falling spectrum:
10x in Energy / 100-500 in flux10x in Energy / 100-500 in flux
• Large effective area needed to get detectable signals at VHE• Natural detector: the atmosphere• Natural detector: the atmosphere
Made first source detection• Made first source detection.(Crab Nebula in ~90 hours)
gamma ray? cosmic ray?g y cosmic ray?γ-ray cosmic ray
Page 34
Stereoscopy: Telescope Arrays
VHE Telescopes World-Wide Fermi
MAGIC
ARGO-YBJ
ARGO / YBJ
ARGO/YBJVERITAS
HESS CANGAROOHESS CANGAROO
VERITAS
• Four 12m telescopes
Collaboration of ~100 scientists23 Institutions in five countries• Four 12m telescopes• 500 pixel cameras (3.5o)• Site in southern Az (1300m)• ~1050 hrs/yr (inc moonlight)• ~1050 hrs/yr (inc. moonlight)Performance:• Energy threshold ~ 100 GeV• Ang resolution ~ 4 6’• Ang. resolution ~ 4-6• 1% Crab sensitivity (<25 hrs)
Rene A. Ong 29 Feb 2008 – Caltech Page 37Very Energy Radiation Imaging
Telescope Array System (VERITAS)
A VERITAS Telescope
350 Mirror Facets
12m reflector, f1.0 optics 500 pixel Camera
MotivatingCTA
From current arrays to CTAlight pool radius R 100 150R ≈100-150 m≈ typical telescope spacing
Sweet spot forbest triggering and reconstruction:
Most showers miss it!
Large detection areagmore images per showerlower trigger threshold
What one would love to haveWhat one would love to have:
Performance only limited byfluctuations in shower developmentfluctuations in shower development➜ 0.3’ angular resolution @ 1TeV
What one can (hopefully) afford:What one can (hopefully) afford:
Key design goals:Key design goals:1010--fold increased sensitivity at fold increased sensitivity at TeVTeV energiesenergies1010--fold increased effective energy coveragefold increased effective energy coverageLarger field of viewLarger field of view for surveysfor surveysImproved angular resolutionImproved angular resolutionp gp gFull sky coverage: an array in each hemisphereFull sky coverage: an array in each hemisphere
(one) possible configurationSouthern Array
Core-energy array:
Low-energy section:4 x 23 m tel. (LST)- Parabolic reflector
High-energy section:32 x 5-6 m tel. (SST)D i C tt fl tCore-energy array:
23 x 12 m tel. (MST)Davies-Cotton reflector- FOV: 7-8 degrees
CTA more sensitive on all time scales below ~few years
Simulated GRB (z=4.3)
Rich structure, with unparalleled statistics
Dark Matter
CTA τ+τ-
Design and Science Case
Implementing CTAImplementing CTAp gp g
A World-wide Effort
Telescopes Options
LSTLSTSSTSSTSSTSST
MSTMST--11MSTMST--22
MST Development (DESY, Germany)
“Inauguration” , May 2013
Proposed US ContributionsUS Group is comprised of 24 Institutions and 2 National LabsProposing to contribute broadly to CTA:p g y
• Extending the MST array with two-mirror SC telescopes• Novel camera technology, trigger, and readout• Data processing, archiving, science tools• Northern Site
SC TelescopeSC Telescope
23 midsized European 59 midsized
CTA-US
European telescopes
59 midsized telescopes
# of telescopes in reconstruction# of telescopes in reconstruction
SCT camera mechanical design
Candidate Sites
Proposed Sites in Arizona
West Site:West Site:Yavapai Ranch East Site:
Meteor Crater
Proposed Sites in ArizonaYavapai Ranch Meteor Crater
Night Sky & Cloud Cover
Mars Hill 30-yr Cloud RecordBrian Skiff, Jeff Hall (Lowell)
• VHE γ-rays probe astrophysics of GeV/TeV particle acceleration in the cosmos and search for new physics beyond the standard modelcosmos and search for new physics beyond the standard model.
• Among the many scientific questions being attacked are the origin of cosmic rays and the nature of dark mattercosmic rays and the nature of dark matter.
• The imaging atmospheric Cherenkov technique allows for sensitive telescopes with excellent angular & energy resolution.p g gy
• CTA is a proposed major observatory that would greatly expand our understanding of the VHE Universe, detecting many more sources and providing exquisite measurements of the source characteristics.
• The Lowell Observatory is already playing a very positive role in CTA and can certainly find a way to reap scientific benefit from the project.
“The real voyage of discovery consists, not in seeking new landscapes, but in having new eyes.”