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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, 802-804 Roelofs, Bassa, Voss & Nelemans astro-ph/0802.2097
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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, 802-804 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) Progenitor wind with V~50 km/s Variable absorption lines 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 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
SN2007on November 5, 2007 NGC 1404 20 Mpc
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
SN2007on follow-up Chandra ACIS-S 40 ks 2-4 counts within 1” 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 Forandagainst 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 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