Prompt GRB Optical Follow-up Experiments ... - Follow-up observations for HETE2, Swift, Integral...

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Transcript of Prompt GRB Optical Follow-up Experiments ... - Follow-up observations for HETE2, Swift, Integral...

  • Prompt GRB Optical Follow-up Experiments

    Hye-Sook Park

    Lawrence Livermore National Laboratory Livermore, CA USA

  • Hye-Sook Park

    Upper Limits on the Prompt Optical Emission

    From G. G. William’s PhD thesis (2000)

  • Hye-Sook Park

    • Gamma Ray Bursts are flashes of γ-ray radiation above 0.1 MeV emanating from point sources, isotropically but inhomogenously distributed in the universe and lasting 1~1000 seconds

    • The BATSE detectors on the CGRO satellite detect ~1 GRB everyday

    • Most Powerful Explosion Since the Big Bang !! — NASA press release May 6, 1998

    • Dedicated and automated system • Rapid response utilizing GCN • Wide field-of-view system to cover error box of

    early time notice

    Experimental Goal & Method

    LOTIS at LLNL

    GRB satellites

    LOTIS

    GCN

    LOTIS attempts to detect optical radiation simultaneously with the γ -ray bursts to understand γ -ray burst production mechanism

  • Hye-Sook Park

    LOTIS GRB Counterpart Search Experiments

    - 17.6 x 17.6 deg Total FOV - Canon Telephoto f/1.8 lenses (200 mm focal length, 11 cm aperture) - 4 of 2048 x 2048 CCD cameras - Rapidly slewing mount - Weather-proof clam shell housing - Weather station

    - Limiting mV ~ 15 - GRB response time: < 5 sec - Simultaneous γ to optical flux ratios - Site: LLNL’s test site in California - Operation: Oct ‘96 ~ current - 100% automated system

  • Hye-Sook Park

    Simultaneous GRB Counterpart Searches with LOTIS

    GRB970223

    GRB970919 GRB971006 Time since trigger (sec)

    G am

    m a

    ra y

    in te

    ns ity

    ( c/

    se c)

    0 10 20 30

  • Hye-Sook Park

    • There are only 2 events that attempted to see prompt optical signal along with other follow-ups during CGRO/BeppoSAX/IPN era

    • GRB971227 by LOTIS – no optical flash (Williams et al., ApJ 519, L25) • GRB990123 by ROTSE – optical flash (Akerlof et al. 1999, Nature, 398, 400)

    Prompt optical signal and afterglows

  • Hye-Sook Park

    GRB971227: LOTIS obtained 500 images of the X-ray afterglow area from 10 sec to 6 hours; Quasi-simultaneous (10 sec after the burst) limit ~ mV=12.3 (GCNC #19)

    GRB971227

    Cala Alto 2.2 m telescope image; 24 hrs later; J-Band

    BeppoSAX 1.5 arcmin error circle

    mV=12.3

    LOTIS Image; 10 sec after

    mV=10.1

  • Hye-Sook Park

    GRB971227 LOTIS Result mag = 12.3 at 10 sec after the burst mag = 14.2 at 20 min after the burst

    LOTIS

    γ-ray (Band fit)

    X-ray (SAX NFI)

    R-band Castro-Tirado

    Williams et al., ApJ 519, L25

  • Hye-Sook Park

    Gamma-ray fluxes not correlated with the simultaneous optical

    R-Band Light Curve

    GRB990123: Prompt optical flash observed by ROTSE

    Akerlof et al. 1999, Nature, 398, 400

    P01322-hsp-u-011

    ROTSE Observation (Jan 23, 1999)

    Galama et al. 1999, Nature, 398,394; Briggs, Band et al. 1999, astro-ph/9903247

    Gamma-ray spectra can’t be extrapolated

    GRB990123 Prompt Spectrum

  • Hye-Sook Park

    Prompt counterparts of Gamma-Ray Bursts: Current understandings and outstanding scientific questions

    • Bright optical flash signal: — Is GRB990123 an unique

    event? — Is Prompt broadband

    spectrum produced by the external reverse shock? (Sari & Piran ApJ 520, 641)

    • No optical flashing events: — ~30 events do not have prompt

    optical signals (Williams ApJ 519 L25, Akerlof ApJ 532 L25)

    — Can prompt signal tell story about progenitors?

    — Is prompt signal obscured by GRB birth-site environment?

    — Is prompt signal dimmer than mag~15?

    — Why early and later time light curves are different?

    — When does afterglow start? – 20 sec? 20 min? 2 hours?

    More prompt measurements are needed

  • Hye-Sook Park

    Prompt Optical Flash - may be explained by reverse shock (Sari, Soderberg, Ramirez-Ruiz)

    • Great energy (1051-53ergs) released in a small volume -> Relativistic outflow

    — Progenitor unknown • Gamma-Ray Burst

    — Inhomogeneities within the outflow result in “internal” shock

    • Optical, radio, x-ray Afterglows — “External” shock forms where the

    outflow plows into the surrounding medium

    • Prompt Optical — “Reverse” shock propagates back into

    the relativistic medium (Sari & Piran ApJ, 520, 641)

    Synchrotron spectra from reverse shock model:

    E52=5.0; tA=10.0; εe=εB=0.5; S=2.33x10-7 ergcm-2

    A: n1=0.02, Γ=200 B: n1=0.02; Γ=400 C: n1=0.1; Γ=400 D: n1=0.1; Γ=400

  • Hye-Sook Park

    LOTIS upper-limits vs. GRB990123

    LOTIS upper limits are inconsistent with predicted magnitude by extrapolating grb990123 flux or peak flux

    Similar results by ROTSE (Akerlof ApJ 532, L25)

    990123

  • Hye-Sook Park

    Predicted magnitude of the Prompt Optical Flashes

    Parameters: γo = Lorentz factor n1 = circumburster material density εe = fraction of equipartition electron energy εB = magnetic field Colors = LOTIS detection probability

    LOTIS upper limits favor small n1 and large γ0 as well as large εe and small εB.

    εe=0.005 εe=0.05 εe=0.5

    εB=0.5

    εB=0.05

    εB=0.005

    Fixed Variables: E52 = 5.0 tA = 10.0 s gamma-ray fluence = 5.0 x 10-7

  • Hye-Sook Park

    Super-LOTIS for HETE era

    Super-LOTIS - Follow-up observations for HETE2, Swift, Integral missions - 0.6 meter aperture: Boller-Chivens telescope -< 30 sec response time : light curve measurement from 30 sec to 4 hours - 2048 x 2048 CCD on prime focus - 0.8 x 0.8 deg FOV (1.5 arcsec/pixel) - Sensitivity: mV= 17 ~ 20 - V,R,I,Clear filter wheel - Moved to Kitt Peak in April 2000

    S-LOTIS

    WYN Solar Observatory

    Space Watch

    Kitt Peak, Arizona (USA)

  • Hye-Sook Park

    M88

    Sombrero (M104)

    The Whirlpool Galaxy (M51)

    M31

    51’FOV

    Super-LOTIS Image Gallery

  • Hye-Sook Park

    Super-LOTIS detected GRB010222 afterglow 23.6 hours after the burst. 13 summed image revealed the afterglow at R=20.0.

    Super-LOTIS Afterglow Detections: GRB010222

  • Hye-Sook Park

    Super-LOTIS for HETE era

    Super-LOTIS - Follow-up observations for HETE2, Swift, Integral missions - 0.6 meter aperture: Boller-Chivens telescope -< 30 sec response time : light curve measurement from 30 sec to 4 hours - 2048 x 2048 CCD on prime focus - 0.8 x 0.8 deg FOV (1.5 arcsec/pixel) - Sensitivity: mV= 17 ~ 20 - V,R,I,Clear filter wheel - Moved to Kitt Peak in April 2000

    S-LOTIS

    WYN Solar Observatory

    Space Watch

    Kitt Peak, Arizona (USA)

  • Hye-Sook Park

    M88

    Sombrero (M104)

    The Whirlpool Galaxy (M51)

    M31

    51’FOV

    Super-LOTIS Image Gallery

  • Hye-Sook Park

    Super-LOTIS detected GRB010222 afterglow 23.6 hours after the burst. 13 summed image revealed the afterglow at R=20.0.

    Super-LOTIS Afterglow Detections: GRB010222

  • Hye-Sook Park

    M88

    Sombrero (M104)

    The Whirlpool Galaxy (M51)

    M31

    51’FOV

    Super-LOTIS Image Gallery

  • Hye-Sook Park

    Super-LOTIS detected GRB010222 afterglow 23.6 hours after the burst. 13 summed image revealed the afterglow at R=20.0.

    Super-LOTIS Afterglow Detections: GRB010222

  • Hye-Sook Park

    Super-LOTIS detected GRB010222 afterglow 23.6 hours after the burst. 13 summed image revealed the afterglow at R=20.0.

    Super-LOTIS Afterglow Detections: GRB010222

  • Hye-Sook Park

    LOTIS observed the GRB 010921 optical afterglow area reported in GCNC #1107 on 09/21/2001 at 06:08:31 (52 min after the burst) during a routine sky patrol. We searched for an optical counterpart in the region of GRB 010921 and we found no source. The 10 sigma limits are: clear filter = 15.5 +/- 0.15; V filter = 15.9 +/- 0.15.

    LOTIS Clear Filter LOTIS V Filter DSS Image

    Afterglow reported in this area (GCNC 1107)

    20’

    20’

    N

    E

    V=13.0

    GRB010921: HETE/IPN localization LOTIS observation 52 min after the burst

  • Hye-Sook Park

    GRB010921- Super-LOTIS afterglow observation

    2.5’

    Super-LOTIS: T0+21.8 hr Super-LOTIS: T0+25.2 hr

    Super-LOTIS: T0+45.8 hr

    Super-LOTIS: T0+49.2 hr DSS Image DPOSS R Image

    http://www.srl.caltech.edu/~react/fits/GRB010921f.fits

    2.5’

    N E

    Super-LOTIS detected GRB010921 afterglow 21.8 hours after the burst. The measured afterglow intensities are: V=19.4 ± 0.2.

  • Hye-Sook Park

    GRB010921 light curve

    H. S. Park et al, ApjL, will be published on June 1, 2002.

    LOTIS data shows that the power-law decay curve for the afterglow cannot be extended to the early time.

  • Hye-Sook Park

    Other prompt optical counterpart search experiments Experiment Location Aper

    (cm) FOV Pixel

    Scale (arcsec)

    Sensitivity (V)

    Integration (sec)