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Title (Barnard College / Columbia University) TeV blazars The - - PowerPoint PPT Presentation

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Fermi-Jansky: Our evolving understanding of AGN Saint Michaels, MD - November 10-12 2011 Meeting Blazar observations above 100 GeV with VERITAS Manel Errando Title (Barnard College / Columbia University) TeV blazars The VERITAS

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SLIDE 1

Title

Authors

Meeting

Blazar observations above 100 GeV with VERITAS

Manel Errando (Barnard College / Columbia University)

Fermi-Jansky: Our evolving understanding of AGN Saint Michaels, MD - November 10-12 2011

  • TeV blazars
  • The

VERITAS observatory

  • VERITAS blazar program
  • New blazar discoveries
  • Mrk 421 flare
  • BL Lac flare
  • Conclusions
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SLIDE 2

TeV AGN population

2

HBL 33 IBL 4 LBL 4 FSRQ 3 FR I 4

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MAGIC Fermi Swift/BAT RXTE/PCA Swift/XRT Swift/UVOT ROVOR NewMexicoSkies MITSuME GRT GASP WIRO OAGH SMA VLBA_core(BP143) VLBA(BP143) VLBA(BK150) Metsahovi Noto VLBA_core(MOJAVE) VLBA(MOJAVE) OVRO RATAN Medicina Effelsberg

Mrk 421

Radio IR-optical-UV X-ray Fermi VHE

5 10 15 20 0 0.03 0.1 0.3 ? redshift

Γ low state tvar

HBL

harder detecta ble ~3 min

IBL

weak 1 day

LBL

not seen ~15min

FSRQ

softer not seen ~10min

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SLIDE 3
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SLIDE 4

4

3.5°

  • 499 PMTs
  • 500 MSPS sampling FADCs
  • 3-level trigger
  • 106 m2 tessellated
  • Recoated every ~4 years

12 m

  • Situated at 1280m altitude at Whipple Observatory in Arizona
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SLIDE 5

VERITAS observatory

VERITA VERITAS

Location 31°40′N, 110°57′W, 1.3km Array configuration 4 x 12m telescopes Energy range 100 GeV < Eɣ < 30 TeV Energy resolution 15 - 20% Field of view 3.5° Angular resolution < 0.1° Sensitivity 1% Crab in 26hr Duty cycle 10-12% (1000hr\yr)

5

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SLIDE 6

VERITAS AGN program

  • Multi-year plan to observe 14 northern TeV blazars

– Mid-distance hard spectrum HBLs – Bright nearby HBLs – All northern IBLs and LBLs

  • Discovery program

– Most of it is ToO based (optical, Fermi-LAT) – Extensive program for FSRQs – Accumulating long exposures on good candidates

  • Multiwavelength campaigns

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Name Class z

M 87 FR I 0.004 Mrk 421 HBL 0.031 Mrk 501 HBL 0.034 1ES 2344+514 HBL 0.044 1ES 1959+650 HBL 0.048 BL Lacertae LBL 0.069 W Comae IBL 0.102 RGB J0710+591 HBL 0.125 1H 1426+428 HBL 0.129 1ES 1215+303 LBL 0.130? 1ES 0806+524 HBL 0.138 1ES 0229+200 HBL 0.140

1ES 1440+122 HBL 0.163 RX J0648.7+1516 HBL 0.179 1ES 1218+304 HBL 0.182 RBS 0413 HBL 0.190 1ES 0414+009 HBL 0.287 1ES 0502+675 HBL 0.341? PG 1553+114 HBL 0.350 3C 66A IBL 0.444? PKS 1424+240 IBL ? VER J0521+211 HBL ?

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SLIDE 7

VERITAS blazar discoveries

  • All

VERITAS discoveries in the TeV band triggered MWL observations and SEDs are published with GeV (Fermi-LAT), X- ray (Swift, RXTE), optical & radio data.

  • Typically SSC models reproduce the SED
  • f HBLs, while low-frequency-peaked
  • bjects seem to prefer SSC + EC.

7

3C 66A

Abdo et al. 2010

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SLIDE 8

New low-latitude blazars

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  • VER J0521+211

RX J0648.7+1516

1 period = 1 month = 1 dark run

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SLIDE 9

New low-latitude blazars

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  • VER J0521+211

RX J0648.7+1516

4000 4200 4400 4600 4800 5000 5200 5400 Wavelength (Å) 0.0 0.5 1.0 1.5 2.0 2.5 Flux (1014 erg s1 cm2 Å1) z = 0.179

Ca K Ca H G band

4000 4200 4400 4600 4800 5000 5200 5400 Wavelength (Å) 0.0 0.5 1.0 1.5 2.0 2.5 Flux (1014 erg s1 cm2 Å1) 5500 6000 6500 7000 Wavelength (Å) 0.0 0.5 1.0 1.5 2.0 2.5 Flux (1014 erg s1 cm2 Å1)

Mg I Na I

5500 6000 6500 7000 Wavelength (Å) 0.0 0.5 1.0 1.5 2.0 2.5 Flux (1014 erg s1 cm2 Å1)

]
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ergs cm
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XRT Flux 2-10 keV [10 5 10 15 20 25 30 35 40 10

Swift XRT

MJD 55120 55130 55140 55150 55160 55170 55180 55190 55200 55210 ]
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VHE Flux > 200 GeV [10 1 2 3 4 5 6 7

VERITAS

Redshift of 0.179 Aliu et al 2011, arXiv:1110.5949 Aliu et al, in prep.

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SLIDE 10

Mrk 421

  • Major flares in 2008 and 2010
  • Huge flare on Feb 17 2010

– Flux reaches ~10 crab – doubling times ~5-10min – 10σ/2min bin

10

spectral hardening with increasing flux

ApJ submitted (2010)

Aliu et al, in prep.

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SLIDE 11

BL Lac flare

BL Lacertae

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  • Very bright flare observed in June 28
  • 20σ in a 20 min run
  • Intra-night variability
  • Coincident with a ‘extreme hardening’
  • f the GeV spectrum measured by

Fermi

Aliu et al, in prep.

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SLIDE 12

BL Lac flare

12

halving time ~ 15 min 40 min

Aliu et al, in prep.

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SLIDE 13

Multiwavelength observations

  • Diagnostic to better understand GeV

spectral features in LBLs and FSRQs: see if the spectrum continues beyond 100 GeV

  • Extensive MW campaign to observe

flaring FSRQs (3C 279 and 4C 21.35) from radio to TeV energies.

  • Approved Fermi-LAT pointed
  • bservations simultaneous with X-ray

and ground-based observations.

  • Coverage at

VHE (VERITAS & MAGIC), gamma-ray (Fermi), X-ray & UV (Swift), Optical-IR (SMARTS, MDM, KVA, ...) and radio (OVRO).

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Energy [GeV] 1 10

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10) × Pointed mode ( 1.0) × North survey ( 0.1) × Standard survey (

time [minutes] 100 200 300 400 500 600 700 ]

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Exposure [cm 500 1000 1500 2000 2500 3000

3

10 ×

Pointed mode North survey Standard survey

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SLIDE 14

Summary

  • VERITAS is monitoring a sample of

northern TeV blazars

  • Continuous observations allow

better studies of spectral and flux variations, sub-hour variability

  • Multiwavelength program with GeV,

X-ray, optical coverage

  • Discovery efforts continue: new

HBLs, extend to LBLs, FSRQs

  • Good synergy with Fermi:

– Trigger for gamma-ray high states – Good sampling of Compton peak

14

1ES 1218+304 1ES 1215+303 W Comae