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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

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

slide5

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

slide7

“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

slide9

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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