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Michael Bietenholz, Hartebeesthoek Radio Observatory, South Africa

VLBI of Supernovae and Gamma Ray Bursts. Michael Bietenholz, Hartebeesthoek Radio Observatory, South Africa. Dr. Michael Gaylard. Introduction: Why Image Supernovae and GRBs with VLBI?. Resolution: we can resolve the explosive outflows.

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Michael Bietenholz, Hartebeesthoek Radio Observatory, South Africa

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  1. VLBI of Supernovae and Gamma Ray Bursts Michael Bietenholz, Hartebeesthoek Radio Observatory, South Africa

  2. Dr. Michael Gaylard

  3. Introduction: Why Image Supernovae and GRBs with VLBI? • Resolution: we can resolve the explosive outflows. • Normal supernova: 20000 km/s = 0.4 mas/yr at 10 Mpc, relativistic supernova or GRB, c = 0.6 mas/yr at 100 Mpc • Determine ejecta speed • Nature and geometry of the ejecta – jets? Clumpiness? Bipolar ejections? • Radio emission is usually due to the interaction of the ejecta with the surrounding material: from interaction we can learn about both ejecta and the surrounding material • Evolution of SN shells, shock acceleration, eventual merging with ISM • Compact remnant of a core-collapse SN? • Supernova rates, especially in dusty environments • Direct distances with the expanding shock front method – out to Virgo cluster

  4. Supernovae: Radio Detection of SNe • Optical: several hundred SNe are detected each year • Radio: Only core collapse (Type II, Type I b/c) detected to date (limits in Ia next talk). Only a few SNe detected each year in radio; total radio detections to date ~60 • Even fewer have been resolved by radio observations - so every VLBI observation is of great value

  5. RSNe Detected with VLBI Approximately 30 RSNe with flux densities > 1 mJy have been detected in radio, and >100 have upper limits.

  6. RSNe Detected with VLBI Approximately 30 RSNe with flux densities > 1 mJy have been detected in radio, and >100 have upper limits.

  7. Radio Lightcurves (SN 1993J) • Typical pattern seen in SNe with frequency-dependent rise and then a power-law decay after the supernova has become optically thin • Increase in the steepness of the decay at t≈ 2500 days (Bartel et al 2002)

  8. VLBI Movie of SN 1993J • Global Array VLBI at 8.4 GHz, then 5 GHz and 1.6 GHz for last epochs • 35 Epochs of VLBI

  9. Deceleration Radius scaled by t0.8 to show deviations from powerlaw expansion Bietenholz et al 2010

  10. μJy/beam Explosion Center 1.7 GHz Bietenholz et al, in prep • Global array: 18 antennas (EVN + VLBA + GBT). Used in-beam calibrator technique • Image background rms: 3.7 μJy/beam • Radius: 5.1 × 1017 cm (34,000 AU; 0.16 pc) • Expanding at ~7,500 km/sec • Limit on a PWN at centre? • 50 μJy at 1.6 GHz = 25% of Crab Nebula • Bietenholz et al 2003: 50 μJy at 8.4 GHz (stacked 3 epochs,1998-2000) • Marti-Vidal & Marcaide 2014: 102 μJy at 5.0 GHz (stacked images) 6 Mar 2010, day 6187 ~ 16 years after the explosion

  11. Central Component in SN1986J Multi-frequency VLBI Image: Contours, red: 5 GHz Blue  white: 15 GHz • Central component turned on at age ~15 yr •  0.8 milli-arcsec (1017 cm) • 200 × the current radio luminosity of the Crab Nebula at 15 GHz Bietenholz, Bartel & Rupen 2004

  12. Central Component in SN1986J Multi-frequency VLBI Image: Contours, red: 5 GHz Blue  white: 15 GHz Youngest Neutron Star or Black Hole? Bietenholz, Bartel & Rupen 2004

  13. SN 1987A Comparison of VLBI image to optical and X-ray images. Contours: VLBI at 1.7 GHz, 0.5, 1.5, 3, and 5 mJy/beam. Ng et al 2011

  14. SN 1987A Comparison of VLBI image to optical and X-ray images. Contours: VLBI at 1.7 GHz, 0.5, 1.5, 3, and 5 mJy/beam. Ng et al 2011

  15. ULIRGs: Supernova Factories • Arp 220 (Conway et al), Arp 299 (Bondi, Neff, Ulvestad et al.), IRAS 23365+3604 (Romero-Cañizales, Pérez-Torreset al.) • High Sensitivity Array observations at 14 and Global VLBI at 8.4 GHz • 17 sources detected, mostly resolved at 14 GHz • VLBI crucial to distinguishing starburst and AGN Conway et al 2010

  16. Relativistic Expansion: SNe and GRBs • Long Duration GRB’s associated with Type Ibc supernovae • Collapse of massive star into a black hole powers highly relativistic jet • GRB’s are jets oriented near the line of sight • The jets not near the line of sight may be visible in radio Image: Saxton

  17. Relativistic Expansion: SNe and GRBs • Long Duration GRB’s associated with Type Ibc supernovae • Collapse of massive star into a black hole powers highly relativistic jet • GRB’s are jets oriented near the line of sight • The jets not near the line of sight may be visible in radio Image: Saxton

  18. SN2009bb SN 2009bb VLBI observations Peak brightness 613 μJy/bm, rms = 128 μJy/bm, VLBA, VLA, Hobart, Tidbinbilla2009 Jun 12 (age = 85 days) 40 Mpc Upper limit on angular size = 0.64 mas = 1.74c Bietenholz et al 2010

  19. Limits on Off-Axis Jets Off-axis jets could be detectable in the radio However, lower efficiency in par-ticle acceleration or lower magnetic field could dras-tically lower model curves Luminosity limits: Bietenholz et al 2014, and Soderberg et al 2006 (S2006) SN 2003gk Bietenholz et al 2014

  20. SN 2003gk VLBI Observations 8.4 GHz VLBA + Ef + Arecibo Age=~7.5 yrs (2011 Apr 11) Contours: 20, 30, 50, 70, 90% of peak of 86 μJy/ beam r = 1 light-year Bietenholz et al 2014

  21. Limits on Off-Axis Jets Off-axis jets could be detectable in the radio However, lower efficiency in par-ticle acceleration or lower magnetic field could dras-tically lower model curves Luminosity limits: Bietenholz et al 2014, and Soderberg et al 2006 (S2006) Bietenholz et al 2014

  22. Relativistic Expansion: GRB 030329 (SN 2003dh) 22 Apr 2003 Size ~1 pc = 3 light years VLBI Expansion Measurements: by Taylor et al. & Pihlstrom et al. show clear deceleration, with transition to non-relativistic regime at t ~ 1yr Taylor et al, 2004, 2005; Pihlstrom et al. 2007, Mesler et al 2012

  23. Relativistic Expansion: GRB 030329 (SN 2003dh) 22 Apr 2003 Size ~1 pc = 3 light years Speed of light VLBI Expansion Measurements: by Taylor et al. & Pihlstrom et al. show clear deceleration, with transition to non-relativistic regime at t ~ 1yr Taylor et al, 2004, 2005; Pihlstrom et al. 2007, Mesler et al 2012

  24. The Future of Supernova VLBI • More sensitivity – follow supernova for longer • Resolve older, more distant supernovae: Cas A is 1 μJy and 6 mas at 170 Mpc - fill in the gap between supernovae and supernova remnants • Supernova rates → star formation rates • Pop III Hypernova • GRBs and orphan afterglows

  25. VLBI Supernova Gallery SN 1979C SN 1987A SN 1986J SN 1993J SN 1996cr SN 2008iz SN 2011dh M82 SN 1996cr, 1993J, SN1986J, SN1979C: Bietenholz, Bartel et al; SN 2008iz Brunthaler et al 2010; M82 supernova/SNR: McDonald, Beswick, Argo et al

  26. Comparison of RSNe & SNRs McDonald et al., 2001

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