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13 October 2006ESO Science Day1 / 7 E-ELT Spectropolarimetry of Type Ia Supernovae in the Coma Supercluster Dietrich Baade – ESO, Garching Lifan Wang – Texas Ferdinando Patat – ESO, Garching Others - Welcome
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13 October 2006ESO Science Day2 / 7 The case for E-ELT spectropolarimetry An E-ELT should want to have a high (higher than AO) spatial-resolution mode There will be no E-ELTI facility Polarimetry attains a spatial resolution of ~3 Spectropolarimetry measures the shape of regions with different velocity and/or composition separately Contrary to E-ELTI and AO, this resolution does not depend on angular size (distance) but on flux only Spectropolarimetry requires TONS of photons Current E-ELT design permits polarimetry at no extra cost Cash expenditures at the instrument level below the noise
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13 October 2006ESO Science Day3 / 7 SNe Ia are (used as) standard candles Justification by physical models is patchy SNe Ia are polarized (in lines and continuum) ► Calibration depends on aspect angle Type Ia SNe
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13 October 2006ESO Science Day4 / 7 A relation between structure and absolute luminosity 17 SNe Ia observed well before V max (the outliers are `special΄) Trend: slower (brighter) SNe seem to be less polarized in Si II 635.5 Delayed detonation as kind of an after-burner may a) smooth out clumpy structures b) burn more fuel and so make SNe brighter ► Want to observe SNe at same distance: go to massive clusters Wang et al. 2006
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13 October 2006ESO Science Day5 / 7 SNe Ia in the Coma supercluster (I) Distance modulus:-34.5 mag Absolute magnitude at maximum:-18.5 mag Apparent magnitude at maximum: 16 mag VLT (FORS1) limit for spectropolarimetry at m=16: 0.2% accuracy in 80 minutes ► Observations just barely possible at maximum E-ELT limit (@42m): can go 3.5 mag fainter
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13 October 2006ESO Science Day6 / 7 SNe in the Coma supercluster (II) Stellar mass of Abell 1667:~0.2 10 15 M ☺ Supernova rate: ~0.05/century/10 10 M ☺ ► Expect >1 SN/year One wide-angle camera can easily monitor many clusters and still detect SNe well before maximum light. ► Enough SNe to schedule flexibly with normal priority
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13 October 2006ESO Science Day7 / 7 Immediate objectives Quantitative measurement of effects of asphericity on luminosity calibration of SNe Ia Radial and angular chemical structure of ejecta Constraints on explosion mechanism (deflagration vs. delayed detonation)
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