Brenda Dingus 20 Oct 2005 Astrophysics with 2 sr and 24/7 VHE Detectors Brenda Dingus for the Milagro and HAWC collaborations

Brenda Dingus 20 Oct 2005 Milagro Gamma Ray 8600’ altitude near Los Alamos, NM Abdo 9, R.Atkins, 1,2 W. Benbow, 3,4 D. Berley, 5 E. Blaufuss 5, D.G. Coyne, 3 T. DeYoung, 3,5 B.L. Dingus, 6 D.E. Dorfan, 3 R.W. Ellsworth, 7 L. Fleysher, 8 R.Fleysher 8, M.M. Gonzalez, 1,14 J.A. Goodman 5, E. Hays 5, 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. Xu 6 and G.B. Yodh 13 1.Department of Physics, University of Wisconsin 2.Current Address: Department of Physics, University of Utah 3.Santa Cruz Institute for Particle Physics, University of California, Santa Cruz 4.Current address: Max-Plank-Institute fur Kernphysik 5.Deoartment of Physics, University of Maryland 6.Los Alamos National Laboratory 7.Department of Physics and Astronomy, George Mason University 8.Department of Physics, New York University 9.Department of Physics and Astronomy, Michigan State University 10.Current address: NASA Goddard Space Flight Center 11.Current address: Massachusetts Institute of Technology 12.Department of Physics, University of New Hampshire 13.Department of Physics and Astronomy, University of California, Irvine 14.UNAM, Mexico City

Brenda Dingus 20 Oct 2005 Water Cherenkov Detectors 8 meters e  80 meters 50 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 Median Energy Angular Res. Time for 5  on Crab 5  5  5  Milagro w/o outriggers 3 TeV0.75 o 1.1 years21,0003,8001,200 Milagro3 TeV0.5 o ½ year13,0002, miniHAWC700 GeV0.4 o 2 days1, HAWC250 GeV0.3 o ½ hour  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  E was assumed. –Background was normalized from Milagro observations. –Detector latitude is arbitrarily same as Milagro, so Crab transits at 15 o

Brenda Dingus 20 Oct 2005 Pre-Outrigger – data since 2000 Optimized with MC simulations Published detection of the Crab (ApJ 595, 803 (2003)) Sensitivity: ~4.7  /yr on the Crab 10.0  from 4.5yr Sensitivity of Milagro to the Crab Nebula Post-Outrigger – data since 2003 Good angular reconstruction on off-pond cores Sensitivity: ~8  /yr on the Crab 9.7  from 1.5yr

Brenda Dingus 20 Oct 2005 Predicted TeV AGNs  HAWC can monitor multiple AGN on daily to monthly timescales  1-year HAWC observation  Costamante & Ghisellini AGN (31 sources)  Kneiske, Hartmann, Mannheim 2005 IR model absorption model  + known TeV sources Standard Deviations

Brenda Dingus 20 Oct 2005 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 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 GRBs  Rate of Satellite Triggers is Low –SWIFT 2/week –GLAST GBM 4/week but ~4 o position error –GLAST LAT detection (10  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 5  sensitivity to a known location within 20 o of zenith

Brenda Dingus 20 Oct 2005 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) 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 ) GRB GRB GRB941017

Brenda Dingus 20 Oct 2005 VHE & GRBs  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 Razzaque, Meszaros & Zhang 2004 Zhang & Meszaros min 1 hr 1 day 1month HAWC Median Energy HAWC Median Energy

Brenda Dingus 20 Oct 2005 Searching for VHE transients  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 redshiftT 90 E iso (1) Assumptions: (2) Predictions: (3) Upper Limit on VHE Emission:

Brenda Dingus 20 Oct 2005 Other Transients  X-ray binaries –PSR 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  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 EGRET Diffuse Model  Milagro excess in overlapping 5.9 o bins in left fig.  Milagro excess convolved with 0.75 o psf in right fig. Milagro Galactic Source HEGRA detected TeV Source: TEV J2032_4130. PSF

Brenda Dingus 20 Oct 2005 EGRET Unidentified Sources & Milagro Morphology  > 100 MeV/cm 2 s  13EG J (34.7 ± 5.7) x EG J (123. ± 6.7) x EG J (59.1 ± 6.2) x EG J (24.7 ± 5.2) x EG J (25.9 ± 4.7) x EG J (73.0 ± 6.7) x EG J (29.2 ± 5.5) x rd EGRET Catalog sources shown with 95% position error circle. Flux of maximum point: 500mCrab (May be extended)

Brenda Dingus 20 Oct 2005  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 VHE Emission from Cosmic Rays Maddalena, 1986

Brenda Dingus 20 Oct 2005 Milagro’s Observation of the Galactic Plane (-2 O <b<2 O ) Consider Region l = 20 O -100 O Weighted Map:7.5  Exclude the Cygnus Region: l=20 O -75 O Weighted Map:5.8  Galactic longitude excludes Cygnus region Galactic longitude includes Cygnus region  =1.42 +/-.26

Brenda Dingus 20 Oct 2005 Integral Flux: Milagro & EGRET E -2.51±0.05 R1 (Gal. Long. 40 to 100 deg)  Based on 3ys of data, 4.5   Flux(>3.5 TeV) = (6.8±1.5±2.2)x 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 cm -2 sec -1 sr -1 (99% c.l.)  Spectral index to connect with EGRET < (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

Brenda Dingus 20 Oct 2005 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  ) –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