# Presentation: 584305

## Circumstellar interaction around supernovae 

- Roger Chevalier
- University of Virginia

- SN 1987A

- Collaborators: C. Fransson, N. Chugai, J. Blondin, A. Soderberg,...

## Final density profile – outer power law

- Outer steep
- power law
- ~r-9.8

**Matzner & **
**McKee 99**

## Shock breakout

- The radiation dominated shock breaks out when the radiation can freely stream
- Formation of thin, dense shell
- The external medium is accelerated: *v*~r-2
- The shock disappears and re-forms as a viscous shock when the radius has ~doubled

- Fransson 82

## Cold dense shell

- Most important for extended progenitor              e.g., Type IIP SN

- Blondin, RAC

- Cas A radio
- NRAO/AUI

- SN 1993J – radio VLBI  (Marcaide et al.)

## Model radio light curves

- Pure SSA (synchrotron self-absorption)

- SSA + external FFA

## Type Ic SN 1994I in M51

- Model with synchrotron self-absorption and interaction of outer steep power law profile with a wind
- -1.0 spectrum, R~t0.9

- Data from Weiler, Stockdale,....

- Free-free absorption by external wind

## Synchrotron self-absorption

- At peak of light curve (and p=3)
- Angular size (measurable by VLBI) only weakly dependent on D

- Type II – lower velocity, turn-on due to free-free absorption or combined with SSA; luminosity range due to cs density
- Radiative cooling at reverse shock wave, except at lowest cs density

- Peak luminosities of radio supernovae

## Mass loss in final red supergiant phase

- IIP

- IIL

- IIP

- IIL

## Type IIP Supernovae

-                                                                            SN 2004et

- Relativistic particle spectrum affected by inverse Compton or synchrotron losses

- RAC, Fransson, Nymark 06

## Type IIP SN 2006bp

- Optical

- UV

- X-ray

- Swift/Immler

- X-ray

- Swift/Immler

## High velocity H feature

- Chugai, RAC, Utrobin 07

- Recombined ejecta

- Photosphere

- No interaction

- Interaction

## Comparison with SN 1999em

- H

- He I 10830

- Thick line is the model (dM/dt≈1x10-6M/yr for vw=10 km/s)
- Data from Elmhamdi et al. 03

## X-ray properties and optical line velocities of SN 2004et

- Rho et al. 07

- X-ray luminosity

- Highest velocity in lines

- Effects of early cold dense shell are significant

- forward sh.

- reverse sh.

## Optical emission from interaction

- SN 1995N     Type IIn

- SN 1993J     Type IIb
- Fransson, RAC,... 05

## Type IIn

- 95N

- Lyman  pumping of Fe II lines
- Fransson, RAC,....

- Infrared

- X-ray

- Gerardy et al. 02

## SN 2001em: Type Ic → Type IIn

- Shell at radius 10 times smaller than around SN 1987A   (1017 cm)
- Shell mass about equal to ejecta  mass
- Mass loss rate >10-3 M/yr for ~1000 yr      (for vw=10 km/s)

- Chugai & RAC 06

## Type Ia (or  Ic)    → IIn

- Deng et al. 2004

## SN 2002ic – turned into IIn

- Most of the emission is formed in a quasi-continuum from the region of circumstellar interaction
- Mass loss rate  ≥2 x 10-3 M/year
- But, not detected in radio or X-ray (note also  SN 2006gy)

- Chugai, RAC,PL 04

- Type Ib/c – higher velocity, turn-on due to synchrotron self-absorption; luminosity range due to cs density?
- Radiative cooling not important

- Peak luminosities of radio supernovae

## Deductions from radio

- Generally consistent with interaction with ~r-2 wind region  (2 x 1015 to 3 x 1017 cm)
- Power law index of electron energy distribution p=3
- Velocity near radio peak ~30,000 km/sec
- Range of peak roughly consistent with range of wind densities for Galactic WR stars if B=0.1 (requires amplification of wind magnetic field)

- Chandra   Immler et al. 02

- SN 1994I at 7 years

## Nonthermal particle distribution

- Ellison, Berezhko, Baring 00

- p

- e

- e

## Model radio – X-ray spectrum of SN Ic

-       RAC & Fransson 06

**Inverse Compton**

**Photosphere**

- Synchrotron

## Model light curves

- Radio

- X-ray

- Power law
- spectrum

- SN 1997ef

- SN 1994I

- Cosmic ray
- dominated

## X-rays 

- Thermal emission too low (if wind densities like WR wind density)
- Inverse Compton scattering of photospheric photons by relativistic electrons may be important near maximum light
- Extrapolation of radio synchrotron to X-ray too low, especially when allow for synchrotron cooling, but a cosmic ray dominated shock can help

- Radio emission from SNe 2006aj, 1998bw, 2003lw (all GRB associated) suggests relativistic expansion

## Final comments

- Type IIP – Look for relation between progenitor mass and mass loss
- Type IIn – probably a heterogeneous group of objects; information on strong mass loss events
- Type Ib/c with GRB - deciphering the environment still a problem