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)

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

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 - dependent) absorption with time • Power law flux density decline after max • Final approach to optically, thin constant

Radio Supernovae (RSNe) Interesting variations:

• Clumpiness in CSM; variations in Mdot; early time synchrotron self-absorption

“Standard” Light Curves

Type Ib/c Type II

CSM Sampling

‘

More Recent Examples

SN1994I (Ic) SN1993J (II)

SN1993J VLBI

Expansion of SN 1993J from age 5 months to age 31 months

SN1987A -- Radio

SN1987A -- Optical

SN1979C -- Radio

SN1980K -- Radio

Luminosity vs. Time to 6 cm Peak

Evolution of RSNe into SNRs

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

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?

Gamma-Ray Bursts with Optical Counterparts

Peak Fluxes

GRB -ray1

X-ray2

/X Ratio

Optical3 Radio4

Host Galaxy

Brightness5

z

970228 3.5 2.3 80 20.5 -- 24.6

970508 1.2 3.0 25 19.8 1.2 25.8 0.8356

970828 4.9 1.9 158 -- 0.27 24.5 0.9587

971214 2.3 2.5 56 21.7 -- 25.5 3.4127

980326 1.3 4.7 17 21.0 -- 25.3 --

980329 13.3 7.0 120 23.6 0.25 26.3 < 3.97

980425 1.1 2.6 26 13.7 49 14.3 0.00857

980519 4.7 2.9 100 20.4 0.1 24.7 --

980613 0.63 0.7 57 22.9 -- 24.4 1.0967

980703 2.6 4.0 40 20.1 1.0 23.0 0.9676

990123 16.4 4.0 252 8.95 2.6 24.3 1.6006

990510 8.16 2.02 249 19.2 -- -- 1.6196

990712 ? ? ? 17.85 -- 22.0 0.436

991208 ? -- -- 18.7 2.1 -- 0.7066

991216 67.5 -- -- 18.8 0.94 24.5 1.027

1 photons cm-2 s-1 (50-300 keV); conversion factor, photons to ergs, = 6.15 x 10-7 2 x 10-8 ergs cm-2 s-1 (2-10 keV) 3 R band magnitude 4 milli Jansky, at 8.4 GHz (10 GHz for GRB 970828 and GRB 980425) 5 R band magnitude, corrected for galactic extinction 6 redshift from OT 7 redshift from host galaxy http://cossc.gsfc.gov/cossc/batse/counterparts/GRB_table.html

SN 1998bw Radio Light Curves

1

10

100

1 10 100 1000Time since Explosion (t - t0) in days

GRB 980508 -- Early

GRB 980508 -- Late

GRB 980519

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

Schematic of Fireball + Relativistic Blast Wave

RSN Luminosity at Peak

Luminosity vs. Time Delay(at 6cm maximum)

23.00

24.00

25.00

26.00

27.00

28.00

29.00

30.00

31.00

32.00

33.00

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

Log(days; explode to 6cm max)

Log

(lu

msi

ty @

6cm

max

; er

g/s/

Hz)

87A

97X 84L

83N 96cb

81K

94I

90B

85L

80K

93J

86E

70G

82aa

79C

78K

86J

88Z

Type IbType Ic

Type II95N

97eg

98bw

Notes to self: (1)Add Ia limits (2) Add T_b = 10^12 K curves

GRB Radio Luminosity at Peak

GRB Radio Luminosity vs. Time Delay(at 6cm maximum)

23.00

24.00

25.00

26.00

27.00

28.00

29.00

30.00

31.00

32.00

33.00

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

Log(days; explode to 6cm max)

Log

(lu

msi

ty @

6cm

max

; er

g/s/

Hz)

980425

GRBs

The Sensitivity Problem

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 on line mapping precludes RSN searches

SKA could: • Extend RSN detections to mv

max ~ 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

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

Recommendations

One would like to see: • Sensitivity of 1 Jy (preferably 0.1 Jy) in 30

minutes• Resolution <1” @ 1.4 GHz (prefer @ 327 MHz) • Simultaneous, multi frequency observations • Real time, on line editing, calibration & snapshot

mapping• Near circular snapshot beam

FINISH