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Recent Results and the Future of Radio Afterglow Observations Alexander van der Horst Astronomical Institute Anton Pannekoek University of Amsterdam.

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Presentation on theme: "Recent Results and the Future of Radio Afterglow Observations Alexander van der Horst Astronomical Institute Anton Pannekoek University of Amsterdam."— Presentation transcript:

1 Recent Results and the Future of Radio Afterglow Observations Alexander van der Horst Astronomical Institute Anton Pannekoek University of Amsterdam

2 Suite of radio follow-up observatories Very Large Array Very Large Array Westerbork Synthesis Radio Telescope Westerbork Synthesis Radio Telescope Australian Telescope Compact Array Australian Telescope Compact Array Giant Metrewave Radio Telescope Giant Metrewave Radio Telescope Ryle Telescope Ryle Telescope Combined Array for Millimeter-wave Astronomy Combined Array for Millimeter-wave Astronomy

3 New era in radio follow-up observations Very Large Array  Jansky Very Large Array Very Large Array  Jansky Very Large Array Westerbork Synthesis Radio Telescope  Apertif Westerbork Synthesis Radio Telescope  Apertif Australian Telescope Compact Array Australian Telescope Compact Array Giant Metrewave Radio Telescope Giant Metrewave Radio Telescope Ryle Telescope  Arcminute Microkelvin Imager Ryle Telescope  Arcminute Microkelvin Imager Combined Array for Millimeter-wave Astronomy Combined Array for Millimeter-wave Astronomy Atacama Large Millimeter Array Atacama Large Millimeter Array Low Frequency Array Low Frequency Array MeerKAT MeerKAT Australian SKA Pathfinder Australian SKA Pathfinder Murchison Widefield Array Murchison Widefield Array Long Wavelength Array Long Wavelength Array SquareKilometerArray

4 Broadband spectrum Piran 2003 Radio observations: Radio observations: Peak flux & frequency Peak flux & frequency Self-absorption frequency Self-absorption frequency Non-relativistic evolution Non-relativistic evolution Scintillation & image size Scintillation & image size Wijers & Galama 1999

5 Physical parameters Electron energy distribution index p Electron energy distribution index p Energy in electrons ε e Energy in electrons ε e Fraction of emitting electrons ξ Fraction of emitting electrons ξ Energy in magnetic field ε B Energy in magnetic field ε B Blast wave energy E Blast wave energy E Density of circumburst medium n Density of circumburst medium n Structure of circumburst medium k Structure of circumburst medium k Jet opening angle θ 0 Jet opening angle θ 0 Observing angle θ obs Observing angle θ obs

6 GRB 030329 Van der Horst, Kamble et al. 2008 Berger, Kulkarni et al. 2003 Pihlstrom, Taylor et al. 2007

7 Current radio afterglow sample Chandra & Frail 2012 1/3 of observed GRBs detected in radio 1/3 of observed GRBs detected in radio Narrow observed flux range Narrow observed flux range Sensitivity limited Sensitivity limited No clear correlations with other wave bands (optical?) No clear correlations with other wave bands (optical?) Detected radio afterglows brighter in prompt emission, X rays & optical Detected radio afterglows brighter in prompt emission, X rays & optical Biased because of strategy Biased because of strategy

8 Average light curves Chandra & Frail 2012 Forward & reverse shock Forward & reverse shock Bright future for 8 GHz and above (including ALMA) Bright future for 8 GHz and above (including ALMA) How about low radio frequencies? How about low radio frequencies?

9 Radio predictions: p & ε e

10 Radio predictions: ε B & n

11 Radio predictions: E & z

12 Radio calorimetry GRB 970508 & GRB 980703 (Berger et al. 2004) Late-time evolution: no relativistic complications Late-time evolution: no relativistic complications Blast wave spherical?  Progenitor constraints Blast wave spherical?  Progenitor constraints Very low frequencies and/or very late times Very low frequencies and/or very late times GRB 030329 with LOFAR (Van der Horst, Kamble et al. 2008)

13 LOFAR: afterglows & prompt emission (Very) late-time afterglows: (Very) late-time afterglows: Automatic monitoring on various timescales Automatic monitoring on various timescales Complementing the radio afterglow sample Complementing the radio afterglow sample Automated response: Automated response: Triggers by high-energy satellites or LOFAR Triggers by high-energy satellites or LOFAR New beam formed pointing to GRB location New beam formed pointing to GRB location

14 LOFAR: afterglows & prompt emission AARTFAAC: Amsterdam-ASTRON Radio Transients Facility And Analysis Centre AARTFAAC: Amsterdam-ASTRON Radio Transients Facility And Analysis Centre 24/7 all-sky monitor with 6 central stations 24/7 all-sky monitor with 6 central stations Piggy-back mode in all LOFAR observations Piggy-back mode in all LOFAR observations LBA: whole sky, HBA: 1000 deg 2 LBA: whole sky, HBA: 1000 deg 2 Transient Buffer Boards Transient Buffer Boards 5 second storage 5 second storage Dispersion delay  subband approach Dispersion delay  subband approach Coming soon: LOFAR UK-Chibolton responding to Swift triggers (1 hour follow-up) Coming soon: LOFAR UK-Chibolton responding to Swift triggers (1 hour follow-up)

15 Reverse shock – radio flares Optical flash  early radio flare Optical flash  early radio flare Probe GRB ejecta & jet magnetization Probe GRB ejecta & jet magnetization Melandri, Kobayashi et al. 2010 Kulkarni, Frail et al. 1999

16 AMI fast follow-up Large array at 15 GHz Large array at 15 GHz ~0.13 mJy rms in 10 minutes ~0.13 mJy rms in 10 minutes 5.5’ primary beam 5.5’ primary beam ~30’’ synthesised beam ~30’’ synthesised beam First responses within 4-5 minutes!! First responses within 4-5 minutes!!

17 AMI fast follow-up Large array at 15 GHz Large array at 15 GHz ~0.13 mJy rms in 10 minutes ~0.13 mJy rms in 10 minutes 5.5’ primary beam 5.5’ primary beam ~30’’ synthesised beam ~30’’ synthesised beam First responses within 4-5 minutes!! First responses within 4-5 minutes!!

18 AMI observations of GRB 120422A Staley, Titterington et al., in prep.

19 Dark bursts Rol, Van der Horst et al. 2008 Van der Horst, Kouveliotou et al. 2009 GRB 051022 Radio X-ray Host galaxy Host galaxy High redshift High redshift Intrinsic? Intrinsic?

20 Compact binary mergers Sub-relativistic dynamically ejected outflow Sub-relativistic dynamically ejected outflow Detectable up to ~300 Mpc  LIGO/VIRGO Detectable up to ~300 Mpc  LIGO/VIRGO Short GRBs(?)  relativistic jet Short GRBs(?)  relativistic jet Piran, Nakar & Rosswog 2012

21 Conclusions Dawn of a new radio era: Dawn of a new radio era: Many SKA pathfinders Many SKA pathfinders Upgrades of new facilities Upgrades of new facilities Extensions of the frequency & time domains Extensions of the frequency & time domains Radio observations crucial for pinning down afterglow physics Radio observations crucial for pinning down afterglow physics Current sample sensitivity limited Current sample sensitivity limited Probing parameter space of “regular” afterglows Probing parameter space of “regular” afterglows Studies of early reverse shock emission and possible coherent prompt emission Studies of early reverse shock emission and possible coherent prompt emission


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