Studying extragalactic extinction using Type Ia Supernovae Rahman - PowerPoint PPT Presentation

Studying extragalactic extinction using Type Ia Supernovae Rahman Amanullah, The Oskar Klein Centre, Stockholm University rahman@fysik.su.se

Current constraints on dark energy Union 2 (R.A et al., 2010) Union 2.1 (Suzuki et al., 2012)  0.050  0.077  + 0.068 w =-0.977 − 0.054 − 0.082  w =- 1.013 − 0.073 statistical (systematic) systematic Combining SNe + WMAP + BAO + H 0 and assuming a time-independent w and a flat Universe. SNe Ia are standardisable candles and the largest correction to the brightness is the redder-fainter correction. The largest systematic uncertainty, besides calibration, comes from uncertainties in colour corrections. 2013-02-05 / Cosmology for all, Lund

NASA/ESA SN1994D 2013-02-05 / Cosmology for all, Lund

Flickr: lrargerich SMC LMC MW Gordon et al. (2003) 2013-02-05 / Cosmology for all, Lund

SN Ia reddening and cosmology Historically no reddening correction was applied (Perlmutter et al., 1998, 1999) or MW reddening (CCM with R V = 3.1) was assumed for all host galaxies (Riess et al. 1999, Knop et al. 2003) Dust Light source Observer Nobili & Goobar (2008) fitted CCM with R V = 1.75 ± 0.27 from 80 optical SNe Ia lightcurves. Guy et al. (2005,2007) constructed a colour law and let “ R V ” simultaneously be determined with cosmology (β = “ R V + 1” = 2.5; R.A et al., 2010) SNe Ia seem to prefer a low R V 2013-02-05 / Cosmology for all, Lund

The origin of SN Ia extinction? MW Intergalactic? Circumstellar? SN Host galaxy 2013-02-05 / Cosmology for all, Lund

Circumstellar Dust RA & Goobar (2011) Could CS dust explain SN colours (Wang 2005, Goobar, 2008)? E(B-V) = 0.12 Circumstellar Dust SN The existence of CS dust has implication on the progenitor scenario! 2013-02-05 / Cosmology for all, Lund

Na I D SN 2006X Host Patat et al. (2008) Sternberg et al. (2011) 2013-02-05 / Cosmology for all, Lund

Thermal reemission from circum- stellar dust? We have used Herschel PACS 70 μ m and 160 μ m to study reddened SNe Ia to search for re-emission. Johansson, RA & Goobar (2013) 2013-02-05 / Cosmology for all, Lund

The reddening law of two SNe Ia Folatelli et al. (2010) UV – NIR data are called for! 2013-02-05 / Cosmology for all, Lund

HST Cycle 19 program 6 nearby Type Ia SNe were followed E(B-V) = 0.0 – 1.0 D = 15 – 85 Mpc F225W-B ~ 2.5 mag (without reddening) Expected uncertainty (Ellis et al. 2008) Analysis in progress! 2013-02-05 / Cosmology for all, Lund

SN2012cg NOT/FIES high-res spectroscopy Preliminary! Pete Challis We have seen no evidence of evolution in our high-res spectroscopy! 2013-02-05 / Cosmology for all, Lund

Summary Reddening correction for SN Ia is the most important ● astrophysical systematic uncertainty for SN Ia cosmology The measured extinction law does not appear to follow ● any of the known laws (SMC, LMC, MW). CS dust provides an interesting extinction law and ● implications for SN Ia observables Our Herschel programme puts stringent limits on CS ● mass/temperature Stay tuned for our HST C19 results, measuring ● extinction law from 0.2 – 1.2 μ m for 6 SNe Ia. 2013-02-05 / Cosmology for all, Lund