Recent tev observations of blazars connections to glast
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Recent TeV Observations of Blazars & Connections to GLAST. Frank Krennrich Iowa State University VERITAS Collaboration. GSFC, October 24, 2002. AGN. VERITAS Collaboration:. Frank Krennrich ([email protected]) for the VERITAS collaboration. Collaboration members:

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Recent TeV Observations of Blazars & Connections to GLAST

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Recent tev observations of blazars connections to glast

Recent TeV Observations of Blazars & Connectionsto GLAST

Frank Krennrich

Iowa State University

VERITAS Collaboration

GSFC,

October 24, 2002

AGN


Veritas collaboration

VERITAS Collaboration:

Frank Krennrich ([email protected])

for the VERITAS collaboration

Collaboration members:

Iowa State U.

Leeds U. (U.K.)

McGill University (Canada)

Purdue U.

Smithsonian Astrophysical Observatory

UCLA

University College, Dublin (Ireland)

U. of Chicago

U. of Utah

Washington U.


Outline

Outline

  • Introduction

     atmospheric Cherenkov imaging technique

     brief overview of TeV blazars

  • Astrophysics results with Whipple 10m telescope

     Mrk 421 2000/2001, Mrk 501 1997 spectra

     H1426+428, 1ES1959+650

  • Next generation instrument: VERITAS

  • VERITAS – GLAST connection

  • Summary


History of the whipple 10m

History of the Whipple 10m

0.01 – 100 TeV

Imaging Camera

Area ~ 100,000 m2

E ~ 0.2 – 100 TeV

Dq/q~ 0.2 o

100 optical photons/m2 TeV

within a few ns


Recent tev observations of blazars connections to glast

Cosmic Ray Rejection Technique

g-ray

proton

  • g-ray images:

    - narrow, short, smooth

  • Hadronic images:

    - broad, long

    - local muons, patchy

  • hadron rejection: 99.7% (10-3)

Courtesy W.Hofmann

Crab Nebula

7 s in 1hour


Science highlights whipple 10m

Science Highlights: Whipple 10m

  • 1997 Flare of Mrk 501

  • z = 0.034

  • 1989 Discovery of TeV

  • photons from the Crab

Weekes et al. 1989, ApJ, 342, 379

37

Catanese et al. 1997, ApJ, 487, L143

151

  • 2001 Discovery of

  • H1426+428

  • (z = 0.129)

  • 1992 TeV photons from

  • the blazar Mrk 421

  • z = 0.031

Horan et al. 2002, ApJ, 571, 753

Petry et al. 2002, ApJ, in press

Punch et al. 1992, Nature, 358, 477

109

489

  • 2001 Flare Mrk 421

  • 1996 Giant & short flare

  • from

  • Mrk 421

~10 Crab

Krennrich et al. 2001, ApJL, 560, L45

489

Gaidos et al. 1996, Nature, 383, 319

Krennrich et al. 2002, ApJL, 575, L9

109


Recent tev observations of blazars connections to glast

  • “Whipple”

    blazars

    at 300 GeV

    Mrk 421 0.031

    Mrk 501 0.034

    1ES2344 0.044

    1ES1959 0.048

    H1426 0.129

  • > 70 “EGRET” blazars at 1 GeV

  • Redshift z = 0.03 – 2.28

z

Mrk 421

H1426+428

Mrk 501

1ES1959+650

1ES2344+514

3C66

1ES2155-304

TeV blazar


Search for new tev blazars

Search for new TeV Blazars:

PKS 2155-304

Mrk 501

Mrk 421

H1426+428

1ES1959+650

1ES2344+514

Costamante, L. & Ghisellini, G. 2001, A&A, 384, 56


Recent tev observations of blazars connections to glast

Mrk 501

  • z = 0.034

  • X-ray BL

  • Marginal GeV

  • > 40 s TeV

Mrk 421

  • z = 0.031

  • X-ray BL

  • Weak GeV

  • > 86 s TeV


Multiwavelength spectra

Multiwavelength spectra

Mrk 501

Mrk 421

  • Peak at 1 keV/~50 GeV

  • X-ray/TeV correlation

  • Peak: 100 keV/200 GeV

  • X-ray/TeV correlation

Catanese et al., ???

Catanese & Weekes, PASP, 111, 3191193 (1999)


Mrk 421 in 2000 2001

Mrk 421 in 2000/2001:

  • 23,000 g-rays at

    E> 300 GeV

Courtesy of J. Holder (see also Holder et al., 2001, Proc. 27th ICRC, Hamburg)


Mrk 421 mrk 501 spectra

Mrk 421/Mrk 501 spectra

Mrk 501

dN/dE ~ E-1.95K 0.07 e –(E/ E )

  • with E0 = 4.6 K 0.8 TeV

0

Samuelson et al. 1998, ApJL, 501, L17

Krennrich et al. 1999, ApJ, 511, 149

Mrk 421

dN/dE ~ E-2.14K 0.03 e –(E/E )

  • with E0 = 4.3 K 0.3 TeV

  • (- 1.4 + 1.7 TeV)syst

0

Krennrich et al. 2001, ApJL, 560, L45


Mrk 421 spectral variability

Mrk 421 <spectral variability>

 on average, g-ray

luminosity peak

shifts to larger energies

with increasing flux!

Krennrich, F. et al. 2002, ApJL, 575, L9


Mrk 501 1997 vs mrk 421 high state

<Mrk 501> 1997 vs. Mrk 421 high state

Mrk 501 1997 average

 spectral index varies

but cutoff region

remains stable!

 imagine instrument

with 20 times the

sensitivity of Whipple

  • separate constant from

    variable component

     IR-background density

Mrk 421 high state (set I)


Mrk 421 spectral variability1

Mrk 421: spectral variability:

VHE-g-ray

X-ray

Krennrich et al. 2002, ApJL, 575, L9

Property of a specific blazar or emission mechanism?

Fossati et al. 2000, ApJ, 541, 166

Krennrich et al. 1999, ApJ, 511, 149


Hourly spectral variability

½ Hourly Spectral Variability:

Feb. 2

Feb. 27

Feb. 1

P = 3.4 x 10-3

March 19

March 25

March 27

P = 8.5 x 10-4

P = 4.0 x 10-3


Hourly spectral variability1

½ Hourly Spectral Variability

VERITAS collaboration (in preparation)


X ray tev correlation mrk 421

X-ray/TeV correlation: Mrk 421

X-ray/TeV lightcurve

TeV lightcurve &

TeV spectral variation

preliminary

preliminary

preliminary

VERITAS collaboration (in preparation)

Courtesy of G. Fossati , J. Buckley & M. Jordan


H1426 428

weak signal ~ 80mCrab

H1426+428:

2000

2000

2001

2001

from Horan et al. 2002, ApJ, 571, 753


H1426 428 spectrum

H1426+428 spectrum:

Whipple 2001:

dN/dE ~ E-3.50K 0.35 K 0.05

Petry et al. 2002, ApJ, in press

HEGRA 2001:

dN/dE ~ E-2.60K 0.6 K 0.05

Aharonian et al. 2002, A&A, 384, L23

Whipple+HEGRA:

dN/dE ~ E-3.54K 0.27 K 0.05

Petry et al. 2002, ApJ, in press


2002 flares from 1es1959 650

2002 Flares from 1ES1959+650:

IAU circular 7903 (VERITAS collaboration), 2002

Holder et al. 2002, in preparation


Conclusion from blazar observations

Conclusion from blazar observations

  • Spectral cutoffs for Mrk 421/501 at ~ 4 TeV:

     possible evidence for absorption from IR background

     or due to internal break due to sKN~ E-1 (when ghnsoft > me c2)

  • Spectral variability (Mrk 421):

     g-ray luminosity peak shifts with <flux> increase

     a-flux correlation holds over 5 years!

  • Rapid variability (Mrk421):

     tvariability ~ 15 min.  g ~ 10  emission region 10-4 - 10-5 pc

  • H1426+428:

     first detection of blazar with z ~ 0.129 at E >300 GeV

     steep spectrum: dN/dE ~ E-3.54K 0.27 K 0.05

  • Future:

    source list steadily growing (5 Whipple blazars)  VERITAS


Veritas very energetic radiation imaging telescope array system

VERITAS: Very Energetic Radiation Imaging Telescope Array System

  • 50 GeV – 50 TeV

  • Area:

    = 100,000 m2 (1 TeV)

    = 40,000 m2 (300 GeV)

    = 1,000 m2 (50 GeV)

  • Angular res.: 0.03o – 0.14o

  • Energy resolution: 10-18%

  • Observation strategy:

    pointed exposures


Arrays of imaging telescopes i

Arrays of Imaging Telescopes I

VERITAS

- 50 GeV – 50 TeV

- Dq/q~ [email protected]

~ [email protected]

- Flux sensitivity:

15 mCrab @100GeV

5 mCrab @300GeV

80 m


Design

DESIGN

12 m Reflectors

500 PMT

Cameras

3.5o FOV

7-telescope Array


Technical progress

Telescope: mount, mirrors

Camera: PMTs, amps

Electronics:

FADCs, trigger

DAQ:

High speed

Readout & analysis

TECHNICAL PROGRESS


Telescope

TELESCOPE

Pedestal

Overall Optical Support Structure

Accomodates 12m mirror


Camera

CAMERA

PMT Installation

Camera Box Construction

Cabling inside


Front end

FRONT-END

PMT Assembly

Amplifiers

Current Monitoring


Point source sensitivity

Point Source Sensitivity

VERITAS

Stacee

HESS

MAGIC

Cangaroo III


Glast veritas cross calibration crab nebula

GLAST/VERITAS cross-calibration: Crab Nebula

  • Overlap: 50 GeV – 100 GeV - 1 TeV

  • GLAST:

  • DE/E ~ 5-10% @ 10 GeV –100 GeV

  • VERITAS:

    DE/E ~ 20-10% @ 50 GeV-1000 GeV

  • 20-25% uncertainty in the absolute energy of IACTs!

     fix with GLAST/VERITAS cross-

    calibration using overlap!

  • GLAST (40 days exposure)

     150 (10) photons above 10 (100) GeV

     10% accuracy in absolute E

GLAST

VERITAS

Hillas et al., ApJ, 503, 744 (1998)


Connections

GLAST

Connections:

  • Unified AGN picture

     ~ several 103 GeV blazars

     blazar classification studies

    (GeV blazars)

  • Jet models

     broad studies

    daily-yearly flux variations

  • EBL cutoff

     probe 0.1 mm – 0.01 mm

  • Blazar spectra

     20 MeV – 100 GeV

  • Unified AGN picture

     ~ 102 sub-TeV blazars

     classification studies

    (extreme blazars)

  • Jet models

     detailed studies

    min. - yearly spectral variations

  • EBL cutoff

     probe 0.1 mm – 50 mm

  • Blazar spectra

     50 GeV – 50 TeV


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