Rasmus Voss (MPE)and

Gijs Nelemans (Nijmegen)and also

Gijs Roelofs (Cfa)Cees Bassa (McGill)

Detection of a SNIa progenitor?

SN2007on in the X-rays

Voss & Nelemans (2008), Nature, 451, 802-804Roelofs, Bassa, Voss & Nelemans astro-ph/0802.2097Nelemans, Voss, Roelofs & Bassa astro-ph/0802.2239

Outline

Original idea (should be something)

SN2007on (there is something)

Follow-up (but is it real?)

SN2007sr (for this one there is nothing)

Progenitors of type Ia SNae

Why?Why?

We want to understand supernovae

Type Ia supernovae are important for cosmologyType Ia supernovae produce the majority of iron

Progenitors of type Ia SNae

Single degenerate:Single degenerate:

Double degenerate:Double degenerate:

Exploding white dwarfs

Accretion onto a WD by a non-degenerate starcauses it to exceed the Chandrasekhar mass

Two WDs with a combined mass above the Chandrasekhar mass merge

Progenitors of type Ia SNae

Single degenerate:Single degenerate:

Double degenerate:Double degenerate:

Exploding white dwarfs

Accretion onto a WD by a non-degenerate starcauses it to exceed the Chandrasekhar mass

Two WDs with a combined mass above the Chandrasekhar mass merge

Maybe both worksDella Valle & Livio (1994)Scannapieco & Bildsten (2005)Manucci et al. (2006)Sullivan et al. (2006)

Progenitors of type Ia SNae

Previous workPrevious work

Optical upper limits -5.5 in the V-bandMaoz & Manucci (2008)

Hydrogen and helium in the spectrum

Mass loss rate of progenitor below ~10-5M

sol/yearMattila et al. (2005)

Surviving star G star at Tychos supernovaRuiz-Lapuente et al. (2004)

Variable absorption lines Progenitor wind with V~50 km/sPatat et al. (2007)

Progenitors of type Ia SNae

Single degenerate:Single degenerate:

Double degenerate:Double degenerate:

Exploding white dwarfs

Accretion onto a WD by a non-degenerate starcauses it to exceed the Chandrasekhar mass

Two WDs with a combined mass above the Chandrasekhar mass merge

Progenitors of type Ia SNae

Single degenerate:Single degenerate:

Double degenerate:Double degenerate:

Exploding white dwarfs

Accretion onto a WD by a non-degenerate starcauses 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)

Archival data

FeasibilityFeasibility

2006mr

2004W

2002cv

NGC 1316

NGC 4649

NGC 3190

18.1 Mpc

15.9 Mpc

22.4 Mpc

<2.2 1038 erg/s

<5.9 1037 erg/s

<1.3 1038 erg/s

November 5, 2007November 5, 2007

NGC 1404 20 Mpc

SN2007on

SN2007on

21 counts within 2”Background expectation 6.9

Chandra ACISChandra ACIS75 ks 75 ks

SN2007on

Hardness:

S 0.3-1.0 keV

M 1.0-2.0 keV

H 2.0-8.0 keV

Chandra ACISChandra ACIS75 ks 75 ks

SN2007on follow-up

Chandra ACIS-SChandra ACIS-S40 ks 40 ks

2-4 counts within 1”Background expectation 1.4

SN2007on follow-up

Chandra ACIS-SChandra ACIS-S40 ks 40 ks

2-4 counts within 1”Background expectation 1.4

Luminosity decreased with 90-95% probability

Might be a source 50-95%

SN2007on follow-up

Optical offsetOptical offset1.18” 1.18”

Probability of 1-5%

SN2007on progenitor

For and against

Chance coincidence probability0.3% (but 4 trials)

SoftnessLess than 10%

Upper limits on source shows that it has weakenedwith 90-95% probability

Probability of off-set1-5%

Might actually be a source afterwards50-95%

Don't make up your mind yetWait for more Chandra data!

SN2007sr

Chandra ACISChandra ACIS450 ks450 ks

December 7, 2007December 7, 2007

Antennae 13-20 Mpc

Saviane et al. (2008)

H0=75 km/s/Mpc

SN2007sr

(But off-axis)

But sub-luminous?(25 Mpc)

13-20 Mpc

Saviane et al. (2008)

H0=75 km/s/Mpc

December 7, 2007December 7, 2007

Antennae

Bloom et al. (2007)Pojmanski et al. (2008)

Chandra ACISChandra ACIS450 ks450 ks

SN2007sr

Galactic, LMC & SMC supersoft sourcesGreiner (2000)

Supersoft sources in M31Di Stefano et al. (2004)In M101, M51, M83 & NGC 4967Di Stefano & Kong (2004)

Conclusions

Detection of a bright X-ray progenitor of SN2007on?

Interesting upper limits on the progenitor of SN2007sr