Global Parameters of Type Ia Supernovae

1
Global Parameters of Type Ia Supernovae

• Bruno Leibundgut
• European Southern Observatory
• Max Stritzinger
• DARK Copenhagen

2
Global parameters

• What do we know from observations about
• total mass ?
• energy source, i.e. amount of fuel ?
• explosion energy ?
• density ?
• element distribution ?

Stritzinger Leibundgut, 2005, AA, 431,
423 Stritzinger, Leibundgut, Walch Contardo,
2006, AA, 450, 241 Blinnikov, et al., 2006, AA,
453, 229 Stritzinger, Mazzali, Sollerman
Benetti, 2006, AA, submitted
3
Usual procedure

• Take explosion model
• density and element distribution and
• explosion energy
• and calculate the emerging spectrum and SED
• ? always assume that you know the progenitor
• usually Chandrasekhar mass T0 white dwarf

4
Understanding SNe Ia
Assumes a progenitor!
5
Can we do better?

• Determine 56Ni from the peak luminosity
• Arnetts law
• Requires a bolometricluminosity
• multi-filter observations
• distance

6
Bolometric light curves
7
Ni masses from light curves
8
Check with a different method

• Ni masses from the emission line in nebular
  spectra (t300 days)

Stritzinger et al. 2006
9
Check with models

• Calculate the emission from explosion models
  (Röpke et al. 2004-2006) with a radiation
  transport code (STELLA Blinnikov et al. 1998)
  and then derive the parameters from these
  observations.

10
Comparison with real data
11
Check

• UVOIR light curve reproduced very well
  validation of procedure in Stritzinger
  Leibundgut
• True bolometric light curve offset by about 15

12
Not quite right

• Correction in SL05 insufficient
• ? total Ni mass underestimated by about 15-20

13
Determining H0 from models

• Hubbles law
• Luminosity distance
• Ni-Co decay

14
H0 from the nickel mass
a conversion of nickel energy into radiation
(LaENi) e(t) energy deposited in the supernova
ejecta
Stritzinger Leibundgut (2005)
15
Assumptions

• Rise time (15-25 days) ? about 10 uncertainty
• Arnetts rule
• energy input at maximum equals radiated energy
  (i.e. a1, e(tmax) 1)
• Nickel mass from models
• ? uniquely defines the bolometric peak luminosity

16
H0 and the Ni mass

• Problem
• Since SNe Ia have individual Ni masses it is not
  clear which one to apply!

17
Determine a lower limit for H0
18
Ejecta masses from light curves

• ?-ray escape depends on the total mass of the
  ejecta
• v expansionvelocity
• ? ?-ray opacity
• q distributionof nickel

19
Ejecta masses

• Large range in nickel and ejecta masses
• no ejecta mass at 1.4M?
• factor of 2 in ejecta masses
• some rather smalldifferences betweennickel and
  ejectamass

20
Dependence on explosion parameters

• case 1 (fiducial)v3000 km/s), ?0.0025 cm/g
  and q1/3
• case 2 v3625 km/s
• case 3 v3625 km/s, ?0.0084 cm/g and q1/2
• case 4 v3625 km/s, ?0.0084 cm/g and q1/3

21
Summary

• Arnetts rule is astonishingly good
• Determine the nickel mass in the explosion from
  the peak luminosity
• large variations (up to a factor of 10)
• upper limit on H0 based on models
• Ejecta masses appear to scatter considerably
• implications for progenitors?
• model too simple ? how can we improve?

22
Summary (cont.)

• SNe Ia may be more varied than we like
• Differences in the explosions?
• density
• ignition
• asymmetries
• progenitor mass
• metalicity