NIRI Observations of Type Ia Supernovae

Christopher L. GerardyUniversity of Texas, Austin

Peter Garnavich Notre Dame

Peter Hoeflich, UT Austin

J. Craig Wheeler,

G. “Howie” Marion

Robert A. Fesen Dartmouth College

K. Nomoto Univ. Tokyo

K. Motohara

K. Maeda

Gemini Science 200424 May 2004

Type Ia SNe

• WD in a close binary

– Grows to near Mch

via accretion

• Thermonuclear runaway– C/O => 56Ni, Si/S,

Mg/O/Ne

• Standard(izable) candles Created with BinSim by R. Hynes

Devil in the details...

• Progenitor Systems?

• Final stages prior to runaway?

• Physics of the burning front– Ignition– Detonation or Deflagration

• Relevance to Cosmology:– Bias, evolution, “Secondary Parameters”

Devil in the details...

• Progenitor Systems?

• Final stages prior to runaway?

• Physics of the burning front– Ignition– Detonation or Deflagration

• Relevance to Cosmology:– Bias, evolution, “Secondary Parameters”

Burning Physics: Deflagration

• Propagates via thermal conduction

• Subsonic

• Unburned layers have time to react=> expand– quenches burning

• RT unstable– Plumes, mixing of

chemical layers

• Large unburned massGamezo et al. 2004

Burning Physics: Detonation• Propagates via

compression

• Supersonic– No time to react

• Pure detonation=> complete burning to Ni

• “Delayed Detonation”– Early phase of slow

burning; expansion

• Layered structure

• Nearly complete burning

C/O

Burning Physics: Detonation• Propagates via

compression

• Supersonic– No time to react

• Pure detonation=> complete burning to Ni

• “Delayed Detonation”– Early phase of slow

burning; expansion

• Layered structure

• Nearly complete burning

C/O

Ni

Burning Physics: Detonation• Propagates via

compression

• Supersonic– No time to react

• Pure detonation=> complete burning to Ni

• “Delayed Detonation”– Early phase of slow

burning; expansion

• Layered structure

• Nearly complete burning

Ni

Si/S

C/OMg/O/Ne

Why NIR observations?

• Probe different chemical species– Particularly C I for SNe Ia

• Clean line profiles– Large Vel.– Severe blending in

UV/Optical

Filippenko 1997, ARA&A, 35, 309

Why NIR observations?

• Probe different chemical species– Particularly C I for SNe Ia

• Clean line profiles– Large Vel.– Severe blending in

UV/Optical– NIR: Fewer strong

lines, less blendingGerardy, 2002

NIRI Spectroscopy

NIRI Spectroscopy

• SN 2002fk:– No C I

NIRI Spectroscopy

• SN 2002fk:– No C I– MgII velocities

10500-14500 km/s

NIRI Spectroscopy

• SN 2002fk:– No C I– MgII velocities

10500-14500 km/s– >90% of the WD

mass has undergone nuclear burning

– No large mass of unburned C/O

NIRI Spectroscopy

NIRI Spectroscopy

• SN 2003hv:

– Fe-edge velocity ~13,000 km/s

– Sharp rise; sawtooth shaped line profile. Only highest Fe/Ni/Co emission seen

– Abrupt Fe-Si interface

– No Plumes

Future Prospects• Time-series

– Combined constraints from “full scan” through ejecta envelope

• High S/N– Detailed examination of line-profiles– Small-scale structure

• Multi-wavelength– NIR: Fe,Mg,C/O; Opt: Si/S, CSM; UV:opacity,

clumping, metallically; MIR: Isotopes, IR catastrophe?

• Late-epoch observations

Late-Epoch Observations• @ late-epoch (>200 d)

NIR Fe II becomes optically thin

• Probe global distribution of 56Ni

• Kinematic Offset from off-center detonation

• Signature of high-density burning– New physics

– Will affect LC (~0.1mag)

Subaru/OHS

SN 2003du~+300d

Summary

• NIR spectroscopy is a powerful tool for probing the physics of Type Ia SNe

– More detonation-like, not very deflagration-like– New physics in early phases of explosion– “Secondary Parameters?”

• Coming soon to Gemini?– GNIRS key project– Optical/NIR coordinated w/Spitzer MIR obs.