Multiwavelength Astronomy: Probing Natures Particle Accelerators - - PowerPoint PPT Presentation

Multiwavelength Astronomy: Probing Nature’s Particle Accelerators

Brenda Dingus Los Alamos National Lab dingus@lanl.gov

Shedding Some Light

• n Potential Neutrino Sources

Brenda Dingus Los Alamos National Lab dingus@lanl.gov

Brenda Dingus, 31 May 2008

Nature’s Particle Accelerators

HST Image of M87 (1994)

Black Hole producing relativistic jet of particles Binary Neutron Star Coalescing

Artist Conception of Short GRBs

Spinning Neutron Star powering a relativistic wind Massive Star Collapsing into a Black Hole

SuperComputer Calculation Chandra Image of Crab HESS TeV + x-ray

TeV image of Vela Jr. Supernova Remnant

Brenda Dingus, 31 May 2008

Astrophysical Particle Accelerators

Radio Optical X-ray GeV TeV E 2 dN/dE

• r

E dN/dln(E)

[ergs/cm2 sec] [ Photon Energy] Multiwavelength Spectral Energy Distribution

Brenda Dingus, 31 May 2008

Astrophysical Particle Accelerators

Radio Optical X-ray GeV TeV E 2 dN/dE

• r

E dN/dln(E)

[ergs/cm2 sec] [ Photon Energy] Multiwavelength Spectral Energy Distribution

Brenda Dingus, 31 May 2008

Electromagnetic Processes:

• Synchrotron Emission

– Probes Magnetic Field, Electron Energy

• Inverse Compton Scattering

– Probes Photon Field, Electron Energy

• Bremmstrahlung

– Probes Electron Energy, Matter Density

Hadronic Cascades

• p + p −> π+ + πo +… −> e + ν + γ +…
• p + γ −> π+ + πo +… −> e + ν + γ +…

E γ ~ E ν ~ 0.1 E p

Gamma-Ray Production

Brenda Dingus, 31 May 2008

Electromagnetic Processes:

• Synchrotron Emission

– Probes Magnetic Field, Electron Energy

• Inverse Compton Scattering

– Probes Photon Field, Electron Energy

• Bremmstrahlung

– Probes Electron Energy, Matter Density

Hadronic Cascades

• p + p −> π+ + πo +… −> e + ν + γ +…
• p + γ −> π+ + πo +… −> e + ν + γ +…

E γ ~ E ν ~ 0.1 E p

Gamma-Ray Production Which γ-ray sources are neutrino sources?

Brenda Dingus, 31 May 2008

Crab Pulsar Wind Nebula

Electron Energies

Synchrotron Self Compton (electrons Inverse Compton scatter on synchrotron emission) spectrum removes the degeneracy to determine B and the electron energies

Brenda Dingus, 31 May 2008

Active Galactic Nuclei

Suzaku BeppoSAX MAGIC, EBL corr. MAGIC, CAT

• M. Hayashida

ICRC 2007 Preliminary

Massive Black Hole Accelerates Jet of Particles to Relativistic Velocities

Urry & Padovani

Simultaneous variability of x-rays and TeV γ-rays supports Synchrotron Self Compton and/or Inverse Compton with external photons

Brenda Dingus, 31 May 2008

Supernova Remnants

HESS observation of RX J1713-39 shows γ-rays (false color) are spatially correlated with x-rays (contours) Supernova Remnants are believed to be the accelerators of Galactic cosmic rays. Therefore, γ-rays should be produced by cosmic rays interacting with molecular clouds near SNR.

Brenda Dingus, 31 May 2008

GRBs Observed up to 20 GeV

High Energy Component Varies Slower than Low Energy Component

(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) Evidence of Much More Fluence in a Higher Energy Component

(Atkins, 2003, Ap J 583 824)

GRB940217 GRB970417 GRB941017

Brenda Dingus, 31 May 2008

Galactic Source Characteristics

• Angularly Extended
• High Energy Particles can move

away from the accelerator before interacting to produce gamma-rays

• Hard Spectrum
• Typical Differential photon index of

dN/dE ~ E -2.3 (i.e. harder than the

• bserved Galactic cosmic rays of

dN/dE ~ E -2.7 )

• Source Classes
• Pulsars
• Pulsar Wind Nebula
• Supernova Remnants
• X-ray Binaries
• Massive Stellar Winds
• Molecular Clouds
• Galactic Center
• Dark Accelerators (gamma-ray

sources without counterparts)

HESS Pulsar Wind Nebulae

1o 0.5o 0.5o 1o

Brenda Dingus, 31 May 2008

Extragalactic Source Characteristics

Extreme Rapid Variability

• Few minute variations probe

size scales smaller than Schwarzschild radius

Hard Intrinsic Spectrum Source Classes

• Blazars (active galactic

nuclei with jets pointed at Earth)

–FSRQs at GeV energies –BL Lacs at TeV energies

• M87 (nearby non-blazar

active galactic nucleus)

• GRBs (up to 20 GeV)
• EGRET high latitude

unidentified sources

PKS2155-304 Aharonian, et al. 2007

PKS 2155-304

• < 2 hr flare with > 50x quiescent flux
• Few week moderate state preceded flare

Most TeV blazars not variable

• Observation bias?

Brenda Dingus, 31 May 2008

Gamma-Ray Detectors

Space-Based Imaging Atmospheric Cherenkov Telescopes Extensive Air Shower Detectors

Brenda Dingus, 31 May 2008

Space Based Gamma-Ray Telescopes

Compton Observatory 1991-2000

• BATSE, OSSE, Comptel at ~< MeV
• EGRET 30 MeV – 30 GeV

GLAST 5 June 2008 !!!

• ~50 x EGRET’s sensitivity
• 1 day of GLAST = 9 yrs of EGRET

γ e+ e–

calorimeter (energy measurement) particle tracking detectors conversion foil anticoincidence shield

Pair-Conversion Telescope

EGRET GLAST

Brenda Dingus, 31 May 2008

TeV Observational Techniques

Atmospheric Cherenkov Telescope Extensive Air Shower Detector

Ground Based Gamma-Ray Astronomy

HESS,MAGIC,VERITAS Milagro, Tibet AS, ARGO

Brenda Dingus, 31 May 2008

Gamma-Ray Detectors ~ Current Capabilities

Extensive Air Shower (EAS) Observatories Imaging Atmospheric Cherenkov Telescopes (IACTs) Space-Based GLAST 10-12 (Milagro lifetime) 10-13 (50 hours) 10-12(1 year) Sensitivity (ergs/cm2sec) 85% (55o) 2.7 sr ~10% 0.5o >>99% 1 m2 1 GeV 95% 10% Duty Cycle (45o) 1.8 sr (2o) 0.003 sr Aperture ~50% ~15% Energy Resolution 0.7o 0.05o Angular Resolution >95% >99% Background Rejection 104 m2 104 m2 Area 20 TeV 1 TeV Optimal γ-ray Energy

HESS MAGIC VERITAS Milagro Tibet ASγ ARGO EGRET AGILE GLAST

Brenda Dingus, 31 May 2008

The 100 MeV Catalog of EGRET GLAST will detect 1000s of sources as well as new classes of sources

Brenda Dingus, 31 May 2008 Jim Hinton ICRC 2007

TeV Catalog

Brenda Dingus, 31 May 2008

Abdo, et al. ApJ Lett 2007

Milagro Observation of Galactic Sources

• 5 of the 7 Milagro TeV Excesses have GeV counterparts.
• Only 13 GeV counterparts in this region - excluding Crab.
• Probability of the chance coincidence is 3x10-6

LS I + 61 303 HESS J0632+057 IC443

H H

Brenda Dingus, 31 May 2008

Abdo, et al. ApJ Lett 2007

Milagro Observation of Galactic Sources

• 5 of the 7 Milagro TeV Excesses have GeV counterparts.
• Only 13 GeV counterparts in this region - excluding Crab.
• Probability of the chance coincidence is 3x10-6

LS I + 61 303 HESS J0632+057 IC443

H H

AMANDA’s 3 Lowest Chance Probability Source Excesses

Brenda Dingus, 31 May 2008

Multiwavelength Milky Way

0.1 GeV Milagro 10 TeV gamma-ray TeV gamma ray

Milagro HESS

Brenda Dingus, 31 May 2008

Galactic Diffuse γ-rays

Gamma-rays probe

Cosmic Rays Fluxes and Spectra outside the Earth’s environment

Different spatial and

spectral characteristics of electrons and protons

GALPROP Conventional (solid) and Optimized (dashed) Models

65

• < l < 85
• |b| < 2
• 30
• < l < 65
• |b| < 2
• Milagro

Obs. Inverse Compton Scattering CMB Dust Starlight Pion Decay Extragalactic Background Brems.

Brenda Dingus, 31 May 2008

Galactic Diffuse Emission (Spatial Distribution)

Cygnus Region 65o<longitude<85o Inner Galaxy 30o<longitude<65o

GALPROP Model πo decay Inverse Compton Total GALPROP Model πo decay Inverse Compton Total

• Different Latitude Distribution for Different Regions of the Galaxy
• Milagro Measures Width of Galaxy at TeV energies
• Pionic Component Width determined by Matter Density
• Inverse Compton Component Width determined by diffusion of electrons

γ/TeV/cm2/sr/sec @ 15 TeV γ/TeV/cm2/sr/sec @ 15 TeV

Brenda Dingus, 31 May 2008

Extensive Air Shower Detectors Survey the TeV Sky

Tibet AS γ ARGO Milagro

Brenda Dingus, 31 May 2008

Crab Nebula Mrk 421 Cygnus Region

Milagro Performed Deepest Survey of TeV Gamma-Ray Sky

Detected Crab Nebula and Mrk421 (known TeV sources) 7 New TeV Galactic source candidates (Abdo, et al. ApJ Lett 2007)

• Several candidates are angularly extended few deg. diameter
• 5 of 7 are consistent with 14 GeV sources in Milagro f.o.v.

1 is Geminga -- the brightest GeV source in Milagro f.o.v.

• 3 confirmed by Tibet AS, 1 confirmed by HESS

Brenda Dingus, 31 May 2008

Future of EAS Detectors

Milagro Turned Off April 2008

• 4 years of operation of full detector
• See this month’s CERN Courier for

general highlights

ARGO producing 1st results

• ~2 x sensitivity of Milagro

High Altitude Water Cherenkov (HAWC) Observatory is next generation version of Milagro

• > 10 x sensitivity of Milagro

– HAWC: Detect Crab in ~ 1 day (5σ) – Milagro: Detects Crab in 3 months

• < $10M including new site

HAWC Detector Design

• 900 water tanks

(5 meter diameter and 4.3 meter deep

• One 8” PMT/tank
• Tank array covers

area of 150m x 150m with 78% coverage

DAQ trailer Road HAWC Tank Array in GEANT 4

Brenda Dingus, 31 May 2008

Tanks vs Pond

Less expensive Build incrementally Expandable &

upgradeable GEANT4 Simulation

Muon (thinned 1/50) produces up to 100s of pes depending

• n impact

parameter 100 MeV γ−ray (thinned 1/200) produces 1pe/60 MeV independent of impact parameter

Brenda Dingus, 31 May 2008

HAWC Site Location is Sierra Negra, Mexico

• 4100 m above sea level
• Easy Access
• 2 hr drive from Puebla
• 4 hr drive from Mexico City
• Existing Infrastructure
• Few km from the US/Mexico

Large Millimeter Telescope

• Power, Internet, Roads
• Sierra Negra Scientific

Consortium of ~7 projects

• Excellent Mexican

Collaborators

• ~15 Faculty at 7 institutions

have submitted proposal to CONACYT for HAWC

• Experience in HEP, Auger, and

astrophysics (including TeV)

Brenda Dingus, 31 May 2008

HAWC Collaboration

USA:

Los Alamos National Laboratory Brenda Dingus, Gus Sinnis, Petra Huntemeyer, John Pretz University of Maryland Jordan Goodman, Andrew Smith, Vlasios Vasileiou, Greg Sullivan University of Utah Dave Kieda University of New Mexico John Matthews Michigan State University Jim Linnemann Pennsylvania State University Ty DeYoung NASA/Goddard Space Flight Center Julie McEnery University of New Hampshire James Ryan University of California, Irvine Gaurang Yodh

Mexico:

Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE)

Alberto Carramiñana, Eduardo Mendoza

Universidad Nacional Autónoma de México (UNAM)

Instituto de Astronomía: Magdalena González, Dany Page, William Lee, Hector Hernández, Deborah Dultzin, Erika Benitez Instituto de Física: Arturo Menchaca, Rubén Alfaro, Andres Sandoval, Ernesto Belmont Instituto de Ciencias Nucleares: Lukas Nellen, G. Medina-Tanco Instituto de Geofísica: José Valdés Galicia, Alejandro Lara

Benemérita Universidad Autónoma de Puebla

Humberto Salazar, Oscar Martínez, Cesar Álvarez, Arturo Fernández

Universidad Michoacana de San Nicolás de Hidalgo Luis Villaseñor CINVESTAV Arnulfo Zepeda Universidad de Guanajuato

David Delepine, Gerardo Moreno, Marco Reyes, Luis Ureña, Victor Migenes

Brenda Dingus, 31 May 2008

HAWC Sensitivity

e µ γ

(a) Larger Effective Area at

Lowest Energies

(b) Better Angular

Resolution

(c) Improved Background

Rejection

=> 10-15 x improvement in flux sensitivity => (10-15)2 = 100-200 x faster to observe same flux

(a) (b) (c)

100 GeV 1 TeV 10TeV 100 TeV 100 GeV 1 TeV 10TeV 100 TeV

Hadron Efficiency Ang. Res. (deg) Eff. Area (m2)

100 GeV 1 TeV 10TeV 100 TeV 100 GeV 1 TeV 10TeV 100 TeV

10-3 105 0.3o

Brenda Dingus, 31 May 2008

E F(>E) (TeV/cm2s) Sensitivity to Crab-like (dN/dE=E-2.6) Point Source

GeV

HESS/VERITAS, MAGIC,

Whipple, CTA sensitivity in 50 hours, (~0.2 sr/year)

GLAST sensitivity in 1

year (4π sr)

HAWC sensitivity in 1(5)

years shown as solid (dashed) line (2π sr)

HAWC exposure

>10 TeV in 5 years is 5x1015 cm2sec = 1 km2 x 140 hrs

Brenda Dingus, 31 May 2008

HAWC’s Field of View

= 2.6 π sr = 1.8 π sr

Brenda Dingus, 31 May 2008

HAWC Science Objectives

Constrain the origin of cosmic rays via HAWC’s

• bservations of γ-rays up to 100 TeV from

discrete sources and the Galactic plane.

Probe particle acceleration in extreme magnetic

and gravitational fields via HAWC’s observations

• f transient TeV sources, such as gamma ray

bursts and supermassive black holes.

Explore new TeV physics via HAWC’s unbiased

sky survey with a detection threshold of ~30 mCrab in two years.

Brenda Dingus, 31 May 2008

HESS J1616-508

0.2 Crab @ 1 TeV α=-2.3 Highest energy ~20 TeV

HAWC’s High Energy Reach

Brenda Dingus, 31 May 2008

HESS J1616-508

0.2 Crab @ 1 TeV α=-2.3 Highest energy ~20 TeV Simulated HAWC data for 1 year with no cutoff

HAWC’s High Energy Reach

Brenda Dingus, 31 May 2008

HESS J1616-508

0.2 Crab @ 1 TeV α=-2.3 Highest energy ~20 TeV Simulated HAWC data for 1 year with 40 TeV exponential cutoff

HAWC’s High Energy Reach

Brenda Dingus, 31 May 2008

HAWC’s Transient Reach

Orphan Flare

• Some TeV flares are correlated with x-ray flares

and some are orphan TeV flares -- excellent candidates for neutrino sources.

• HAWC would detect such a flare in <15 minutes

and promptly notify multiwavelength observers.

Brenda Dingus, 31 May 2008

Expect the Unexpected with Unbiased Surveys

For example, Milagro Observes Anisotropy in 10 TeV Cosmic Rays

• 10 deg size scale with a fractional excess of 7e-4 above the cosmic ray

background (15 σ)

• Excess is not gamma rays, but charged cosmic rays (7 σ)
• Explanations are difficult because the gyroradius of a 10 TeV proton in

a 1 µG field is 0.01 parsecs=2000 AU

• Maybe Geminga SNR??? Salvati & Sacco astroph0802.2181

Heliotail Geminga Galactic Plane

Brenda Dingus, 31 May 2008

Summary

• Multiwavelength Spectra probe Nature’s Particle Accelerators
• Gamma rays provide > 6 orders of magnitude of energy in the

multiwavelength spectrum

• The physics of these accelerators is constrained by gamma-

ray observations, but more information is needed

• Increased Sensitivity of New Gamma-Ray Observatories

guarantees New Discoveries

• Neutrino Detections would revolutionize our understanding

Brenda Dingus, 31 May 2008

Thank you to Neutrino 2008

• rganizers.

Good on ya!

Brenda Dingus, 31 May 2008

Cosmic Ray Anisotropy

1o RA bins (unsmoothed) for 10o<Dec.<20o Large Scale Feature at ~180 deg observed by many detectors. Smaller Scale Features require larger numbers of events.

Brenda Dingus, 31 May 2008

Milagro & Tibet AS γ Observations

• K. Munakata, M. Amenomori, et al AIP Conf Vol 932, 283

Mrk421 Crab Cygnus region Abdo, A. et al astroph0801.3827 Milagro Observation using Background Calculation over 2 hour (30o in RA) intervals Tibet AS Observation after subtracting model of large scale anisotropy

• K. Munakata, M. Amenomori, et al AIP Conf Vol 932, 283

Brenda Dingus, 31 May 2008

Galactic Sources are Extended

Sextended ≈ Spoint σ source σ detector

σEAS ~0.5o σIACT ~0.1o

HAWC’s large fov of 2 sr: Entire source & background are simultaneously observable Background is well measured

Brenda Dingus, 31 May 2008

Milagro Observation in Galactic Coordinates

Crab Nebula 30° 210° 90° 65° Cygnus Region

Brenda Dingus, 31 May 2008

• Gammas have

NARROW lateral distribution of electrons

• Protons have

BROAD lateral distribution of muons

Lateral Distribution of Extensive Air Showers

Brenda Dingus, 31 May 2008

Gamma/Hadron Separation

Gammas Protons

30 GeV 70 GeV 230 GeV 20 GeV 70 GeV 270 GeV

Size of HAWC Size of Milagro deep layer Energy Distribution at ground level

Rejection factor ~ e-<µ>

Brenda Dingus, 31 May 2008

Background Rejection in Milagro

Proton MC Proton MC Data Data γ MC γ MC

Hadronic showers contain penetrating component: µ’s & hadrons – Cosmic-ray showers lead to clumpier bottom layer hit distributions – Gamma-ray showers give smooth hit distributions

Brenda Dingus, 31 May 2008

Milagro Background Rejection (Cont’d)

( )

mxPE nFit fOut + fTop = A ∗

4

mxPE: maximum # PEs in bottom layer PMT fTop: fraction of hit PMTs in Top layer fOut: fraction of hit PMTs in Outriggers nFit: # PMTs used in the angle reconstruction

S/B increases with increasing A4 so analysis weights events by S/B as determined by the A4 value of the event

Background Rejection Parameter