Upload
others
View
21
Download
0
Embed Size (px)
Citation preview
Search Results and Prospects from Atmospheric Cherenkov
Telescopes
Andrew W Smith University of Marland, College Park / NASA GSFC
From P5 report (Cosmic Frontier) Arrenberg et al.
Indirect Detection probes a wide range of theory space in DM
In an ideal situation, DM
should produce a
very recognizable
signal in gamma rays
Imaging Atmospheric Cherenkov Technique:
Primary gamma rays initiate EM showers w
particle v>c: Cherenkov pulses
HESS (Prague WG) Arrenberg et al.
Current TeV Experiments
VERITAS Southern AZ, USA 4x12m
MAGIC-II Canary Islands 2 x 17m
HESS-II Namibia
4x12.5, 1x 28
* Energy range: ~80 GeV to >30 TeV
* Energy resolution: 15% at 1 TeV * observation time per year: ~1200
hours * point source sensitivity: 1% Crab
in <30h, 10% in <30 min
Rough Performance Valuesfor Current Generation IACTs
Instrumental PSF
= ~600 ɣ/hr (0.1-50 TeV) in footprint of array
Current IACTs can detect (5σ) sources producing 6 ɣ/hr in 25 hrs
Indirect Detection of DM w/IACTs
Assume all the 𝛾s you didnt see is
this:Constrain this
Choose some ppp model to tell
you what you should have seen
Find an real astronomer to model this for
you
M𝜒
σv
Constraint s= Discrete SUSY parameter scan results.
Above curve = disallowed model
Indirect Detection of DM w/IACTs
This term is very sensitive to
fluctuations in methods progress?
Significant progress
M𝜒
σv
Constraint s= Discrete SUSY parameter scan results.
Above curve = disallowed model
What have we learned about this
equation?
Target Advantages Disadvantages
Galactic Center Close by, lots of DM Large 𝛾 BG
Galactic Substructure
Possibly local, Fermi-LAT sources Unknown distance, nature
Galaxy Clusters-Largest DM
concentrations in universe
-very distant (weak signal) -very extended -possible 𝛾 BG
Dwarf Galaxies -High Mass/Light -No likely 𝛾 BG
DM distribution can be very uncertain
IACT DM Targets
Target Advantages Disadvantages
Galactic Center Close by, lots of DM Large 𝛾 BG
Galactic Substructure
Possibly local, Fermi-LAT sources Unknown distance, nature
Galaxy Clusters-Largest DM
concentrations in universe
-very distant (weak signal) -very extended -possible 𝛾 BG
Dwarf Galaxies -High Mass/Light -No likely 𝛾 BG
DM distribution can be very uncertain
IACT DM Targets
Galactic Center
HESS >300 GeV
Peak of DM profile
2011 Abramowski et al. 112 Hours of H.E.S.S. Data
254 Hours of H.E.S.S. data 2015 Le Franc et al (ICRC)
HESS II
VERITAS Galactic Center (> 2 TeV)
VERITAS Observations will constrain multi-Tev
parameter space
VERITAS 100 hr estimate
Dwarf Spheroidal Searches
from Drlica-Wagner 2014/Ackermann et al 2015 and
source therein
J ~ (DM density profile)2 along line of sight
NFW Profile, 0.50 integration radiusSagittarius
from Drlica-Wagner 2014/Ackermann et al 2015 and
source therein
Sagittarius
HESSMAGIC
VERITAS
Dwarf Spheroidal Searches
Dwarf Spheroidal Searches
from Drlica-Wagner 2014/Ackermann et al 2015 and
source therein
Sagittarius
All 3 IACTs have accrued ~150-200 hrs
on dSphs.
MAGIC (165 hrs on Segue I) (Aleksic et al 2015)
VERITAS 215 hours on 4 dSphs Zitzer et al 2015)
HESS Combined Limits: 140 hours on 5 targets
(Abramowski et al 2014)
MAGIC (165 hrs on Segue I) (Aleksic et al 2015)
VERITAS 215 hours on 4 dSphs Zitzer et al 2015)
HESS Combined Limits: 140 hours on 5 targets
(Abramowski et al 2014)
Aleksic et al 2014
Likelihood methods improve limits by 2-3
MAGIC (Einasto)
VERITAS HESS
NATURAL CROSS SECTION
IACT Dwarf Spheroidal Limits
𝝌 𝝌 -> 𝜏+ 𝜏-
NFW
MAGIC (EInasto)
VERITASHESS dSph
NATURAL CROSS SECTION
HESS GC
𝝌 𝝌 -> 𝜏+ 𝜏-
NFW
IACT Dwarf Spheroidal Limits
Limits on 𝞆 𝞆 -> ɣ ɣ
HESS GC
VERITAS dSPHs
MAGIC Segue I
Where can we go from here?
MOU in preparation between IACTs
to combine data, joint likelihood methods may
improve limits on full data set
Where can we go from here?
CTA Design (S array)
Low energies Energy threshold 20-30 GeV 23 m diameter 4 telescopes (LST’s)
Medium energies 100 GeV – 10 TeV
9.5 to 12 m diameter 25 single-mirror telescopes
up to 24 dual-mirror telescopes (MST’s/SCTs)
High energies 10 km2 area at few TeV
3 to 4m diameter 70 telescopes
(SST’s)
Science Optimization under budget constraints
Hinton & Funk arXiv:1205.0832
HESS / VERITAS 100 hrs
Hinton & Funk arXiv:1205.0832
HESS / VERITAS 100 hrs
300 h
Galactic Plane Survey
525 h
300 h Fermi bubbles
Galactic PlaneSurvey
In the first 3 years of
observations, CTA will
observe the GC for >500
hours
Thermal DM
CTA
con
sorti
um, i
n pr
epar
atio
n
CTA GC Limits
CTA will probe deep into natural cross section within 3 years of operation
Silverwood, et al., JCAP 03, 055 (2015) Lefranc, et al., PRD 91, 12 (2015)
Summary-Current Generation of IACTs have developed and executed a multi-year DM search program (still in
progress)
-These programs (significant) have set deep limits, although still mostly separate from the natural cross section. Progress on combining limits.
-These programs have paved the way for upcoming searches with CTA, this search will
probe deep into the natural cross section within the first few years of operation