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, 802-804 Roelofs, Bassa, Voss & Nelemans astro-ph/0802.2097 Nelemans, 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? We want to understand supernovae Type Ia supernovae are important for cosmology Type Ia supernovae produce the majority of iron

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

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

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)‏

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

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)‏

Archival data Feasibility 2006mr 2004W 2002cv NGC 1316 NGC 4649 18.1 Mpc 15.9 Mpc 22.4 Mpc <2.2 1038 erg/s <5.9 1037 erg/s <1.3 1038 erg/s

SN2007on November 5, 2007 NGC 1404 20 Mpc

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

SN2007on Chandra ACIS 75 ks Hardness: S 0.3-1.0 keV M 1.0-2.0 keV H 2.0-8.0 keV

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

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

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

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!

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

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)‏

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)‏

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