1. Detection of a SNIa progenitor?
Rasmus Voss (MPE)‏
and
Gijs Nelemans (Nijmegen)‏
and also
Gijs Roelofs (Cfa)‏
Cees Bassa (McGill)‏
SN2007on in the X-rays
Voss & Nelemans (2008), Nature, 451,
Roelofs, Bassa, Voss & Nelemans astro-ph/
Nelemans, Voss, Roelofs & Bassa astro-ph/

2. Outline Original idea (should be something)
SN2007on (there is something)
Follow-up (but is it real?)
SN2007sr (for this one there is nothing)

3. Progenitors of type Ia SNae
Why?
We want to understand supernovae
Type Ia supernovae are important for cosmology
Type Ia supernovae produce the majority of iron

4. Progenitors of type Ia SNae
Exploding white dwarfs
Single degenerate:
Double degenerate:
Accretion onto a WD by a non-degenerate star
causes it to exceed the Chandrasekhar mass
Two WDs with a combined mass above the Chandrasekhar mass merge

5. Progenitors of type Ia SNae
Exploding white dwarfs
Single degenerate:
Double degenerate:
Accretion onto a WD by a non-degenerate star
causes it to exceed the Chandrasekhar mass
Two WDs with a combined mass above the Chandrasekhar mass merge
Della Valle & Livio (1994)‏
Scannapieco & Bildsten (2005)‏
Manucci et al. (2006)‏
Sullivan et al. (2006)‏
Maybe both works

6. Progenitors of type Ia SNae
Previous work
Optical upper limits
-5.5 in the V-band
Maoz & Manucci (2008)‏
Hydrogen and helium in the spectrum
Mass loss rate of progenitor below ~10-5Msol/year
Mattila et al. (2005)‏
Surviving star
G star at Tychos supernova
Ruiz-Lapuente et al. (2004)‏
Variable absorption lines
Progenitor wind with V~50 km/s
Patat et al. (2007)‏

7. Progenitors of type Ia SNae
Exploding white dwarfs
Single degenerate:
Double degenerate:
Accretion onto a WD by a non-degenerate star
causes it to exceed the Chandrasekhar mass
Two WDs with a combined mass above the Chandrasekhar mass merge

8. Progenitors of type Ia SNae
Exploding white dwarfs
Single degenerate:
Double degenerate:
Accretion onto a WD by a non-degenerate star
causes it to exceed the Chandrasekhar mass
The burning of the accreted matter on the surface of the WD causes strong X-ray emission!
Two WDs with a combined mass above the Chandrasekhar mass merge
No exchange of material before they touch, and therefore no X-rays (although models with the creation of an accretion disk exist)‏

9. Archival data Feasibility 2006mr 2004W 2002cv NGC 1316 NGC 4649
18.1 Mpc
15.9 Mpc
22.4 Mpc
< erg/s
< erg/s
< erg/s

10. SN2007on
November 5, 2007
NGC 1404
20 Mpc

11. Background expectation 6.9
SN2007on
Chandra ACIS
75 ks
21 counts within 2”
Background expectation 6.9

12. SN2007on Chandra ACIS 75 ks Hardness: S 0.3-1.0 keV M 1.0-2.0 keV
H keV

13. Background expectation 1.4
SN2007on follow-up
Chandra ACIS-S
40 ks
2-4 counts within 1”
Background expectation 1.4

14. Background expectation 1.4
SN2007on follow-up
Chandra ACIS-S
40 ks
2-4 counts within 1”
Background expectation 1.4
Might be a source 50-95%
Luminosity decreased with 90-95% probability

15. SN2007on follow-up
Optical offset
1.18”
Probability of 1-5%

16. SN2007on progenitor For and against Chance coincidence probability
0.3% (but 4 trials)‏
Probability of off-set
1-5%
Softness
Less than 10%
Might actually be a source afterwards
50-95%
Upper limits on source shows that it has weakened
with 90-95% probability
Don't make up your mind yet
Wait for more Chandra data!

17. SN2007sr December 7, 2007 Antennae 13-20 Mpc Saviane et al. (2008)‏
H0=75 km/s/Mpc
Chandra ACIS
450 ks

18. SN2007sr December 7, 2007 Antennae 13-20 Mpc Saviane et al. (2008)‏
H0=75 km/s/Mpc
Chandra ACIS
450 ks
(But off-axis)‏
But sub-luminous?
(25 Mpc)‏
Bloom et al. (2007)‏
Pojmanski et al. (2008)‏

19. SN2007sr Supersoft sources in M31 In M101, M51, M83 & NGC 4967
Di Stefano et al. (2004)‏
In M101, M51, M83 & NGC 4967
Di Stefano & Kong (2004)‏
Galactic, LMC & SMC supersoft sources
Greiner (2000)‏

20. Conclusions Detection of a bright X-ray progenitor of SN2007on?
Interesting upper limits on the progenitor of SN2007sr