# Presentation: 016091

## Type II SN spectroscopic modeling

- Luc Dessart1  & D. John Hillier2
- (1University of Arizona; 2University of Pittsburgh)

_**Goal and Method:**_
- Use detailed non-LTE radiative transfer code CMFGEN and high-quality photospheric-phase Type II SN spectra to constrain core-collapse SN explosions, massive star evolution, and distances in the Universe

_*References:*_*   **Dessart & Hillier (2005ab, 2006ab); Brown et al. (2007);  *
*                      **Dessart et al. (2007ab, in prep.)*

## Radiative Transfer Issues

- Fast expansion => line-overlap (HHeCNOZ)
- Low-density => Scattering + non-LTE
- trecombination ~ texpansion => D/Dt effects
- 56Ni production => non-thermal excitation

**=> A Challenging Radiative Transfer Problem**

## Ambiguity due to line broadening and overlapSpectral features stem from multiple linesand multiple species => Line identification difficult

- _Ambiguity due to line broadening and overlap_Spectral features stem from multiple linesand multiple species => Line identification difficult

## Salient Features of the non-LTE CMFGEN codeHillier & Millier (1998); Dessart & Hillier (2005a)

- Solves the radiative transfer equation in the CMF under constraints of **Stat. and Radiative** Equilibrium
- Steady-state (but see end of talk)
- 1D; homogeneous monotonically-expanding ejecta
- Adaptive grid (~50-80 pts; 5 pts per tau decade)
- Key asset: metal line-blanketing
- All rates included explicitly (radiative + collisional)
- All continuum and line opacity sources included explicitly (no opacity sampling)
- Large model atom (up to 25 species x [1-12] ionization states; ~1000 levels; ~10000 transitions); use of super-levels
- Fine frequency grid, with ~100000 frequency points
- Synthetic spectrum covers from ~100A to ~5m
**Recently added**: relativistic effects, 56Ni energy deposition, chemical stratification included, DJ/Dt, Dn/Dt
- Method: Input **GLOBAL** quantities (L0, R0, v0, Xi, etc)

## Case Studies with CMFGEN: Photospheric-Phase Evolution of SN1999em, SN2005cs, and SN2006bp

-    Multi-epoch Multi-wavelength Observations from Swift, Lick, Keck, NTT, HST, WHT, VLT, HET, Mount Whipple,  in the UV, optical, and near-IR.
-    **Sources**: *Hamuy, Leonard, Filippenko, Baron, Pastorello, CfA, Quimby, Brown, Immler, Milne ...*), covering from 3-7 days to ~45 days after discovery
*    **See Dessart & Hillier (2006a; 2007 in prep)*

## Case Study: SN2005cs

**Case Study: SN2005cs**

**Blue crosses**: Swift fluxes
**Black curve**: Observed spectrum                                 (CfA, Pastorello et al. 2006)
**Red curve**: reddened CMFGEN synthetic spectrum

- Weak optical lines: ****** ~ r****-20** ; fossil of breakout?

## UV line blanketing due to FeIII

- UV line blanketing due to FeIII
- Isolated lines AlIII1900, MgII2800A
- Optical lines of HI, HeI, NII, and OII

- UV flux fading
- Optical lines strengthening:  ~ r-12

## Stronger line blanketing in UV; FeII kicking-in, MgII
HI & HeI strengthening; NII/OII weakening
 ~ r-10 ; Flattening density distribution 

- HI & HeI strengthening; NII/OII weakening
-  ~ r-10 ; Flattening density distribution

## Stronger line blanketing in UV; FeII strengthening, MgII

- Stronger line blanketing in UV; FeII strengthening, MgII
- HI & HeI strengthening; FeII emerging in optical

- UV flux weak (blanketing + cooling)
- HeI weak; FeII, SiII, OI emerging in optical

- Negligible UV flux (ejecta recombined)
- Strong blanketing in optical

- Strong blanketing in optical (FeII, TiII) and HI, SiII; Strong CaII3800A

## The same + FeII in H trough

- The same + FeII in H trough

## The same + CaII8500A + NaID, strong TiII/FeII at 4200A

- H underestimated

## FeII ubiquitous

- H strongly underestimated
- Vphot ~ 2200km/s (down from 7000km/s on day 1)

## Outstanding Problems: HI lines at Recombination epoch (99br, 99em, 05cs, 06bp etc...)

- Expansion & recombination times comparable (R/V ~ 1/Ne)
**Dn/Dt ******** 0 **&** energy from changes in ionization/excitation ***(see also:* *Utrobin & Chugai 2005; Utrobin talk)*
- Effects: frozen ionization, line modified => HI lines , NaI5895A, HeI10830A (DH06b)  Barium abundance in 87A (UC05)

_**99em at 45 days**_

- D/Dt: **No**

- D/Dt: **Yes**

## But D/Dt effects present even at early times

**All** species are affected
- H fully ionized => Effect** Not** tied to recombination energy
- HeI lines strongly affected (Not an 56Ni effect!). XHe
- Dn/Dt effects likely important in **all** SN ejecta

- D/Dt: No

- D/Dt: **Yes**

## Results

- Spectral evolution reflects the ejecta cooling (key to have multi-wavelength observations: Swift, optical, and near-IR).
- Key role played by line-blanketing (CNO and metals)
- BSG/RSG composition,  He/N enhanced first, C and O enhanced later, **Z********  ****throughout**
- Steep density gradient (n~20 flattening to 10); break-out?
- Time-dependence effects at all times, strong at 1-2 months
- At present, little constraint on stellar evolution; later times...

**Forthcoming:** ***Full star simulations from shock break-out to nebular phase, with DJ/Dt and Dn/Dt***

## Use of Type II SN as distance indicators:

**Method:**
-        1) Assume homologous expansion, i.e. R ~ V t
-        2) Minimize the scatter, between epochs, of the distance  modulus S(t ,texp)  m(t) - MS(t,texp) - AS, S={B,V,I}, for a set of guesses on the explosion time texp, or improved EPM

**SN1999em**: 11.5 Mpc (DH06a), 12.5Mpc (SEAM), 11.7Mpc (Cepheid)
**SN2005cs**:    8.9Mpc (Dessart et al. 2007), 7.6 Mpc (PNLF, SBF),      9.6Mpc  (HII regions; Sandage & Tamman 1974); 7.1Mpc (Takats &Vinko 2006, with EPM, SCM)
**SN2006bp**: 17Mpc (Dessart et al. 2007), 17Mpc (Tully 1988)
- Accurate to 5-10%
- Alternate distance indicator
- Independent check on Hubble constant
-  use out to z~1-5 with JWST

## Core-Collapse SN Properties (with our inferred distance)

-  Range of energetics
-  Kinetic energy <=> Bolometric Luminosity

## Many insights permitted by non-LTE calculations (line identifications, abundances)
Common photospheric origin for UV + optical in 05cs.
Importance of multi-wavelength observations (reddening, ionization); Swift + monitoring from the ground
Time dependence plays a critical role (ionization, line strengths) 
Time dependence is likely to play a role in all SN ejecta.
Type II SN reliable distance indicators

- Common photospheric origin for UV + optical in 05cs.
- Importance of multi-wavelength observations (reddening, ionization); **Swift + monitoring from the ground**
**Time dependence** plays a critical role (ionization, line strengths)
**Time dependence** is likely to play a role in all SN ejecta.
- Type II SN reliable distance indicators

**Conclusions**