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Astrophysics with 2 sr and 24/7 VHE Detectors. Brenda Dingus for the Milagro and HAWC collaborations. Milagro Gamma Ray Observatory @ 8600’ altitude near Los Alamos, NM

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astrophysics with 2 sr and 24 7 vhe detectors

Astrophysics with 2 sr and 24/7 VHE Detectors

Brenda Dingus for the Milagro and HAWC collaborations

Brenda Dingus

20 Oct 2005

slide2

Milagro Gamma Ray Observatory @ 8600’ altitude near Los Alamos, NM

Abdo9, R.Atkins,1,2 W. Benbow,3,4 D. Berley,5 E. Blaufuss5, D.G. Coyne,3 T. DeYoung,3,5 B.L. Dingus,6 D.E. Dorfan,3 R.W. Ellsworth,7 L. Fleysher,8 R.Fleysher8, M.M. Gonzalez,1,14 J.A. Goodman5, E. Hays5, C.M. Hoffman,6

C.P. Lansdell,5 J.T. Linnemann,9 J.E. McEnery,1,10 A.I. Mincer,8 M.F. Morales,3,11

P. Nemethy,8 D. Noyes,5 J.M. Ryan,12 F.W. Samuelson,6 P.M. Saz Parkinson,3

Shoup,13 G. Sinnis,6 A.J. Smith,5 G.W. Sullivan,5 D.A. Williams,3 X.W. Xu6

and G.B. Yodh13

Department of Physics, University of Wisconsin

Current Address: Department of Physics, University of Utah

Santa Cruz Institute for Particle Physics, University of California, Santa Cruz

Current address: Max-Plank-Institute fur Kernphysik

Deoartment of Physics, University of Maryland

Los Alamos National Laboratory

Department of Physics and Astronomy, George Mason University

Department of Physics, New York University

Department of Physics and Astronomy, Michigan State University

Current address: NASA Goddard Space Flight Center

Current address: Massachusetts Institute of Technology

Department of Physics, University of New Hampshire

Department of Physics and Astronomy, University of California, Irvine

UNAM, Mexico City

Brenda Dingus

20 Oct 2005

water cherenkov detectors
Water Cherenkov Detectors

e

m

g

8 meters

50 meters

80 meters

  • Detect Particles in Extensive Air Showers from Cherenkov light created in a covered pond containing filtered water.
  • Reconstruct shower direction from the time different photodetectors are hit.
  • Multi-kHz trigger rate mostly due to Extensive Air Showers created by cosmic rays
  • Field of view is ~2 sr and the average duty factor is nearly 100%

Milagro Cross Section Schematic

Brenda Dingus

20 Oct 2005

milagro minihawc hawc
Milagro, miniHAWC, HAWC
  • Design details about miniHAWC and HAWC are in other presentations.
  • #s below depends on source spectrum and declination plus trigger cuts.
    • Crab spectrum of dN/dE a E-2.59 was assumed.
    • Background was normalized from Milagro observations.
    • Detector latitude is arbitrarily same as Milagro, so Crab transits at 15o

Brenda Dingus

20 Oct 2005

slide5

Sensitivity of Milagro to the Crab Nebula

  • Post-Outrigger – data since 2003
    • Good angular reconstruction on
    • off-pond cores
    • Sensitivity: ~8s/yr on the Crab
    • 9.7s from 1.5yr
  • Pre-Outrigger – data since 2000
    • Optimized with MC simulations
    • Published detection of the Crab
    • (ApJ 595, 803 (2003))
    • Sensitivity: ~4.7s/yr on the Crab
    • 10.0s from 4.5yr

Brenda Dingus

20 Oct 2005

predicted tev agns
Predicted TeV AGNs

Standard

Deviations

  • 1-year HAWC observation
  • Costamante & Ghisellini AGN (31 sources)
  • Kneiske, Hartmann, Mannheim 2005 IR model absorption model
  • + known TeV sources
  • HAWC can monitor multiple AGN on daily to monthly timescales

Brenda Dingus

20 Oct 2005

glast agns
GLAST AGNs

Dermer & Davis, 1999

  • BL Lacs will be largest fraction of GLAST AGN.
  • Many will not be known at other wavelengths.
  • GLAST localization at flux threshold ~20’.
  • HAWC sensitivity extrapolated as E-2 down to 100 MeV is ~ GLAST flux threshold.
  • HAWC detection of GLAST sources would constrain redshift, location, and variability as well as point to targets for air Cherenkov telescopes.

Brenda Dingus

20 Oct 2005

energy measurement
Energy Measurement

Average Energy vs Compactness

Milagro is sensitive to energy above the median detected energy of 3 TeV.

HAWC should have similar capabilities above it’s median energy of 250 GeV.

Brenda Dingus

20 Oct 2005

slide9
GRBs
  • Rate of Satellite Triggers is Low
    • SWIFT 2/week
    • GLAST GBM 4/week but ~4o position error
    • GLAST LAT detection (10 g > 30 MeV) ~1/week with rapid positions ~1/month
  • HAWC fov ~1/6 of sky and duty factor ~100% so ~1 GRB/week is searched for VHE emission
  • HAWC will detect even high z GRBs IF VHE fluence is ~ keV fluence

Lines are 5s sensitivity to a known location within 20o of zenith

Brenda Dingus

20 Oct 2005

high energy component in grbs
High Energy Component in GRBs

Combined EGRET-BATSE observation shows a new high energy component with hard spectrum and more fluence.

(Gonzalez, 2003 Nature 424, 749)

GRB940217

GRB941017

The highest energy gamma-ray detected by EGRET from a GRB was ~20 GeV and was over an hour late. (Hurley, 1994 Nature 372, 652)

Milagrito’s > 650 GeV observation implies a new mechanism with greater fluence than synchrotron. (Atkins, 2003, Ap J 583 824)

GRB970417

Brenda Dingus

20 Oct 2005

vhe grbs
VHE & GRBs

Razzaque, Meszaros & Zhang 2004

  • VHE Prompt emission constrains bulk Lorentz factors due to opacity in source
  • VHE early afterglow probes B field and electron energy densities
  • VHE lightcurve constrains quantum gravity

HAWC

Median Energy

Zhang & Meszaros 2001

1min

1 hr

1 day

1month

HAWC

Median Energy

Brenda Dingus

20 Oct 2005

searching for vhe transients
Searching for VHE transients

Eiso

redshift

T90

  • HAWC data can be searched for VHE transient within a few seconds
  • Milagro search yields model dependent limit on VHE fluence from GRBs
  • Model assumptions will be better constrained by SWIFT and GLAST

(1) Assumptions:

(3) Upper Limit on VHE Emission:

(2) Predictions:

Brenda Dingus

20 Oct 2005

other transients
Other Transients
  • X-ray binaries
    • PSR1259-63 has low duty cycle as observed by HESS for few months out of 3.4 year elliptical orbit
  • Microquasars
    • Variable at other wavelengths

Brenda Dingus

20 Oct 2005

hess galactic sources
HESS Galactic Sources
  • PWN, SNR, & UnID
  • Most HESS detections in the Galactic Plane are extended sources
  • Flux of HESS Sources is 2-20% of Crab Flux >300 GeV
  • Largest Source is Vela Jr with diameter of 2 degrees

(F. Aharonian et al., Astron. Astrophys. 437 (2005) L7-L10)

Brenda Dingus

20 Oct 2005

milagro galactic source
Milagro Galactic Source

EGRET Diffuse Model

  • Milagro excess in overlapping 5.9o bins in left fig.
  • Milagro excess convolved with 0.75o psf in right fig.

HEGRA detected TeV

Source: TEV J2032_4130.

PSF

Brenda Dingus

20 Oct 2005

egret unidentified sources milagro morphology
EGRET Unidentified Sources & Milagro Morphology
  • F > 100 MeV/cm2sg
  • 3EG J2016+3657 (34.7 ± 5.7) x 10-8 2.09
  • 3EG J2020+4017 (123. ± 6.7) x 10-8 2.08
  • 3EG J2021+3716 (59.1 ± 6.2) x 10-8 1.86
  • 3EG J2022+4317 (24.7 ± 5.2) x 10-8 2.31
  • 3EG J2027+3429 (25.9 ± 4.7) x 10-8 2.28
  • 3EG J2033+4118 (73.0 ± 6.7) x 10-8 1.96
  • 3EG J2035+4441 (29.2 ± 5.5) x 10-8 2.08

7

4

6

2

3rd EGRET Catalog sources shown with 95% position error circle.

3

1

5

Flux of maximum point: 500mCrab

(May be extended)

Brenda Dingus

20 Oct 2005

vhe emission from cosmic rays
VHE Emission from Cosmic Rays

Maddalena, 1986

  • Molecular Clouds
    • GLAST predicted to detect >100 molecular clouds (Torres, et al 2005)
    • Measures ratio of CO to Molecular Hydrogen and samples cosmic ray spectrum outside solar neighborhood
  • LMC and SMC
  • Starburst Galaxies
  • Galaxy Clusters

Brenda Dingus

20 Oct 2005

slide18

Milagro’s Observation of the Galactic Plane (-2O<b<2O)

Consider Region l = 20O-100O

Weighted Map: 7.5s

Exclude the Cygnus Region: l=20O-75O

Weighted Map: 5.8s

Galactic longitude 20-75 excludes Cygnus region

Galactic longitude 20-100 includes Cygnus region

s=1.42 +/- .26

Brenda Dingus

20 Oct 2005

integral flux milagro egret
Integral Flux: Milagro & EGRET

E-2.51±0.05

R1 (Gal. Long. 40 to 100 deg)

  • Based on 3ys of data, 4.5s
  • Flux(>3.5 TeV)

= (6.8±1.5±2.2)x10-11 cm-2 sec-1 sr-1

  • Spectral Index to connect with EGRET = -2.61± 0.03±0.05
  • With outriggers we can measure the spectrum at TeV energies
  • 2 more years of data needed for ±0.1 on spectral index at TeV energies

R2 (Gal. Long. 140 to 200 deg)

  • Flux(>3.5 TeV)

< 4 x 10-11cm-2 sec-1 sr-1 (99% c.l.)

  • Spectral index to connect with EGRET < -2.66 (99% c.l.)
  • Not yet a crisis but spectrum may be softer in outer Galaxy
  • Additional data will tell

Submitted to PRL

Brenda Dingus

20 Oct 2005

slide20
Brenda Dingus

20 Oct 2005

summary
Summary
  • Water Cherenkov Technique has been proven to work and is discovering new VHE phenomena
  • Future Water Cherenkov Detectors can have the sensitivity to
    • Detect multiple sources daily
    • Survey the sky for pt sources >1% of the Crab flux above 250 GeV in 2 years (5 s)
    • Search 2 sr of the sky for short duration transients with nearly 100% duty factor
    • Explore the morphology of extended sources such as the Galactic plane and molecular clouds

Brenda Dingus

20 Oct 2005