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RADIO EMISSION FROM SNe & GRBs, AND THE NEED FOR SKA

RADIO EMISSION FROM SNe & GRBs, AND THE NEED FOR SKA. Kurt W. Weiler (NRL) Collaborators: Schuyler D. Van Dyk (IPAC/Caltech) Christina K. Lacey (NRC/NRL) Nino Panagia (STScI/ESA) Richard A. Sramek (NRAO/VLA) Marcos Montes (NRL) http://rsd-www.nrl.navy.mil/7214/weiler/. Supernovae (SNe).

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RADIO EMISSION FROM SNe & GRBs, AND THE NEED FOR SKA

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  1. RADIO EMISSION FROM SNe & GRBs, AND THE NEED FOR SKA Kurt W. Weiler (NRL) Collaborators:Schuyler D. Van Dyk (IPAC/Caltech)Christina K. Lacey (NRC/NRL) Nino Panagia (STScI/ESA) Richard A. Sramek (NRAO/VLA) Marcos Montes (NRL) http://rsd-www.nrl.navy.mil/7214/weiler/

  2. Supernovae (SNe) • Play a vital role in galactic evolution: • Nucleosynthesis, chemical enrichment, energy input into ISM • production of stellar remnants, production of cosmic rays • A primary goal of SN research: • Understanding progenitor stars and explosion mechanisms for different SNe types • SNe types: Ia, Ib/c, II (also IIn, IIb) • SNe Ia not radio sources to limit of VLA sensitivity

  3. Radio Supernovae (RSNe) • 27 RSNe detected by in the radio; 17 objects extensively studied • Analysis of radio emission provides vital insight into SN shock/CSM interaction • Nature of pre-SN evolution • Nature of the progenitor • All RSNe have in common: • Nonthermal synchrotron with high TB • Decrease in (l - dependent) absorption with time • Power­law flux density decline after max • Final approach to optically, thin constant a

  4. Radio Supernovae (RSNe) • Interesting variations: • Clumpiness in CSM; variations in Mdot; early time synchrotron self-absorption

  5. Type Ib/c Type II “Standard” Light Curves

  6. CSM Sampling ‘

  7. SN1994I (Ic) SN1993J (II) More Recent Examples

  8. SN1993J VLBI • Expansion of SN 1993J from age 5 months to age 31 months

  9. SN1987A -- Radio

  10. SN1987A -- Optical

  11. SN1979C -- Radio

  12. SN1980K -- Radio

  13. Luminosity vs. Time to 6 cm Peak

  14. Evolution of RSNe into SNRs

  15. SUMMARY (1 of 2) • SNe classes are distinct in radio emission properties (thus distinct in CSM environments): • SNe Ia are undetectable at VLA’s limiting sensitivity • SNe Ib/c turn on and off quickly • SNe II show a wide range of properties • RSNe are sensitive to Mdot/wwind (~ pre-SN mass loss rate) • RSNe sample the CSM => properties of the pre-SN wind density & structure -- unique stellar evolution probe

  16. SUMMARY (2 of 2) • SN 1978K shows evidence for a (possibly associated) HII region along the line of sight. • SN 1979C & SN 1980K show evidence for very rapid stellar evolution in the presupernova phase • SN 1993J shows evidence for a change in mass loss rate in the last ~10,000 years before explosion • RSNe may be distance indicators • Now, what about 1998bw and GRBs?

  17. http://cossc.gsfc.gov/cossc/batse/counterparts/GRB_table.htmlhttp://cossc.gsfc.gov/cossc/batse/counterparts/GRB_table.html

  18. SN 1998bw Radio Light Curves

  19. GRB 980508 -- Early

  20. GRB 980508 -- Late

  21. GRB 980519

  22. Radio Observations of GRBs • If present, radio observations of the GRB afterglow can yield: • Size and expansion velocity of the fireball • Through IS scattering • Through changing spectral shape with time • Density & structure of the CSM • As for RSNe • VLBI observations • confirming size & shape • Providing lower distance limits

  23. Schematic of Fireball + Relativistic Blast Wave

  24. RSN Luminosity at Peak

  25. GRB Radio Luminosity at Peak

  26. The Sensitivity Problem

  27. Conclusions • Current VLA is severely sensitivity limited for SN studies • Can only detect SNe with mvmax ~ 12 -- 14 (out to ~Virgo cluster) • ~1300 SNe known; ~ 25 radio detections • ~150 new discoveries/year; only 1-2 radio detections • No Type Ia SN ever detected • No VLA on­line mapping precludes RSN searches • SKA could: • Extend RSN detections to mvmax ~ 19 • ~50 radio detections/year • Discover ``hidden'' SNe • Improve SN statistics not limited by absorption/dust • Improve knowledge of Type Ia progenitors • Provide a new cosmological distance probe

  28. Conclusions • Current VLA is severely sensitivity limited for GRB studies • Can only detect a few GRBs • Thousands of GRBs known; ~ dozen radio detections • >300 new discoveries/year; only 1-2 radio detections • Not enough radio to distinguish types (fast-hard, slow-soft) • SKA could: • Extend GRB searches • tens of detections/year • Establish GRB CSM properties • (Possibly) distinguish GRB classes • Increase knowledge of relativistic jet/fireball physics

  29. Recommendations • One would like to see: • Sensitivity of 1 mJy (preferably 0.1 Jy) in 30 minutes • Resolution <1” @ 1.4 GHz (prefer @ 327 MHz) • Simultaneous, multi­frequency observations • Real­time, on­line editing, calibration & snapshot mapping • Near circular snapshot beam

  30. FINISH

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