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

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studying extragalactic extinction using type ia supernovae
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Studying extragalactic extinction using Type Ia Supernovae Rahman - - PowerPoint PPT Presentation

Oct 24, 2022 457 likes •601 views

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)

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Studying extragalactic extinction using Type Ia Supernovae

Rahman Amanullah, The Oskar Klein Centre, Stockholm University

rahman@fysik.su.se

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2013-02-05 / Cosmology for all, Lund

Combining SNe + WMAP + BAO + H

0 and assuming a time-independent

w and a flat Universe.

w=-0.977−0.054−0.082

0.0500.077 

w=- 1.013−0.073

+0.068

Union 2 (R.A et al., 2010) Union 2.1 (Suzuki et al., 2012)

Current constraints on dark energy

statistical (systematic) systematic

The largest systematic uncertainty, besides calibration, comes from uncertainties in colour corrections. SNe Ia are standardisable candles and the largest correction to the brightness is the redder-fainter correction.

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2013-02-05 / Cosmology for all, Lund

SN1994D NASA/ESA

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2013-02-05 / Cosmology for all, Lund

Flickr: lrargerich

MW LMC SMC

Gordon et al. (2003)

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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 RV = 3.1) was assumed for all host galaxies (Riess et al. 1999, Knop et al. 2003) Nobili & Goobar (2008) fitted CCM with RV = 1.75 ± 0.27 from 80 optical SNe Ia lightcurves. Guy et al. (2005,2007) constructed a colour law and let “RV” simultaneously be determined with cosmology (β = “RV + 1” = 2.5; R.A et al., 2010) SNe Ia seem to prefer a low RV

Light source Dust Observer

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2013-02-05 / Cosmology for all, Lund

The origin of SN Ia extinction?

MW SN Circumstellar? Host galaxy Intergalactic?

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2013-02-05 / Cosmology for all, Lund

Circumstellar Dust

SN Circumstellar Dust

Could CS dust explain SN colours (Wang 2005, Goobar, 2008)?

RA & Goobar (2011)

E(B-V) = 0.12

The existence of CS dust has implication on the progenitor scenario!

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2013-02-05 / Cosmology for all, Lund

Na I D

Patat et al. (2008) Host Sternberg et al. (2011)

SN 2006X

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2013-02-05 / Cosmology for all, Lund

Thermal reemission from circum- stellar dust?

We have used Herschel PACS 70 μm and 160 μm to study reddened SNe Ia to search for re-emission.

Johansson, RA & Goobar (2013)

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2013-02-05 / Cosmology for all, Lund

The reddening law of two SNe Ia

Folatelli et al. (2010)

UV – NIR data are called for!

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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 Analysis in progress! F225W-B ~ 2.5 mag (without reddening)

Expected uncertainty (Ellis et al. 2008)

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2013-02-05 / Cosmology for all, Lund

SN2012cg

Preliminary!

NOT/FIES high-res spectroscopy

Pete Challis

We have seen no evidence of evolution in our high-res spectroscopy!

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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 μm for 6 SNe Ia.