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Supernova Cosmology - a status report

Supernova Cosmology - a status report. Marek Kowalski Physikalisches Institut Universität Bonn 2 nd BTCP Workshop 4.10.2010, Bad Honnef. Content. Introduction Current surveys Systematic errors C urrent constraints Future projects. Supernova Type Ia.

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Supernova Cosmology - a status report

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  1. Supernova Cosmology- a statusreport Marek KowalskiPhysikalischesInstitutUniversität Bonn 2nd BTCP Workshop 4.10.2010, Bad Honnef

  2. Content • Introduction • Currentsurveys • Systematicerrors • Currentconstraints • Future projects

  3. Supernova Type Ia • White dwarf in binarysystem • Masstransfer up to „critical“ Chandrasekharmass of 1.4 M • Thermonuclearexplosion • Explosion of similarenergies • Visiblein cosmicdistances

  4. Stretching the timescale: Correcting the brightness SNeIa as “standard” Candles • Nearby supernovae used to studySNelight curve (z<0.1) • Intrinsically brighter SNe have widerlightcurves.

  5. Simulation of thewidth-brightnessrelation Kasen, Roepke, Woosley, Nature 2009 Kasen, Roepke, Woosley, Nature 2009

  6. Simulation of thewidth-brightnessrelation Kasen, Roepke, Woosley, Nature 2009

  7. Dust Extinction Excesscolor (B-V) Extinction coefficient At least 4 (possible) sources of dust (1) MW dust (β=RB≈4.1) (2)  Host galaxy dust (3)  Intergalactic dust (4)  Dust shell around SN Empiracle approach: fit for β β≈2.5 ≠ RB (i.e. MW dust)

  8. A bit brighter M fainterthen expected normalization SNeIa Hubble Diagram •  M • 1 0 0.72 0.28 0 1 Supernova Cosmology Project (SCP)Kowalski et al. (2008) fainter

  9. SNeIa Hubble Diagram •  M • 1 0 0.72 0.28 0 1 HST Supernova Cosmology Project (SCP)Kowalski et al. (2008) SNLS Essence fainter SDSS PanStarrs PTF SNF CfA

  10. Reference new picture difference Searchingfor Supernovae • One example - the SNLS: • Canadian-French-Hawaii Telescope: 3.6 m • MegaCam Camera: 3.6 108 pixels • four 1 sq deg fields observed every ~4 d • 5-year program finding about 500 SNeIa SN-Candidate

  11. SNLS-Lightcurves

  12. SloanDigitial Sky Survey (SDSS) First year papers: arXiv:0908.4274, arXiv:0908.4276

  13. Sloan Digital Sky Survey

  14. SNe at large Redshifts (z>1) Observations from Space with the Hubble Space Telescopes: + NIR sensitivity

  15. HST Surveyof Clusters with z ≥ 1 Motivation: Large SNe rate dueoverdensities of Galaxies — in particular of nearlydust-freeEarly-types • Cycle 14, 219 orbits (PI S. Perlmutter) 24 clusters fromRCS,RDCS,IRAC, XMM Dawson et al. (SCP), ApJ (2009)

  16. HST Surveyof Clusters with z ≥ 1 Suzuki et al., In preparation

  17. Systematicuncertainties Examplefrom Union2 compilation (Amanullah et al, 2010) Topic of project in B12

  18. Light-curvefitterdifference Kessler et al. (SDSS), 2009 • MLCS2K2: w = -0.76 ± 0.07 (stat) • Trained on low-zdata • Prior on extinction • SALT2: w = -0.96 ± 0.06 (stat) • Trained onlow-z + SNLS data • Empiraclemodelforextinction

  19. Light-curvefitterdifference Originsof the “discrepancy” now well identified • Model rest-frame UV calibration → disappearswithimprovedphotometriccalibration • Treatment of thecolorvariabilityof SNeIa → disappearswhenassumptions(i.e. priors) are dropped (SNLS, submitted 2010) Differencebetweenfitsshouldn‘tbetaken as measure of systematicuncertainty

  20. Host galaxydependence Evidence (4 sigma) forhost stellar massdependence of SN brightnessafterstretch & colorcorrection (Sullivan et al. 2010)

  21. Puttingit all together - the Union2 • 557 SNefrom17 datasets • Consistent lightcurve fits • (SALT2), including sample • dependent pass-band function • Error propagationleadsto • covariancetermsbetweenSNe

  22. CosmologicalParameters  Supernova Cosmology Project Amanullah et al. 2010 Combination of SNe with: BAO (Percival et. al., 2010) CMB (WMAP-7 year data, 2010) For a flat Universe: Ωm= 0.279±0.014(stat) ±0.009(sys) … and with curvature: Ωm= 0.281±0.014(stat) ±0.010(sys) Ωk= -0.004±0.006(stat) ±0.001(sys) M

  23. Equation of state: w=p/ w = -0.997±0.052 (stat) ±0.061 (sys) – flat universe w = -1.035±0.057 (stat) ±0.076 (sys) – curved universe

  24. Constraints as a function of redshift

  25. (Selected)Future Projects Project z-range # SNe Pan-STARRS 0.1-0.5 ~104 DES (2012) 0.1-0.9 ~10 LSST (2018) 0.1-0.9 ~106 JDEM/Euclid (2018?) 0.2-3.0 >3000

  26. The Large SynopticSurveyTelescope 8.4 m diameter 9.6 sq.deg FOV 3.2x109pixels 15 s exposures

  27. LSST: > 105 SNe Ia per year http://www.lsst.org/lsst/scibook

  28. SN Iaphotometricredshifts(fromsimulations) σz=0.007 σμ=0.16 http://www.lsst.org/lsst/scibook

  29. SN cosmology: BAO & DlExample: equation of state w(z)=w0+waxz(1+z)-1 http://www.lsst.org/lsst/scibook

  30. Euclid & Supernovae Astier, Guy & Pain, A&A, accepted (2010) Addingfilter-wheelforopticalchannelwouldallowforextraordinary SN survey 18 monthsurvey (10 & 50 sqdeg) wouldprovidecompetetiveconstraints on darkenergy

  31. Conclusion • Data consistent with cosmological constant • Systematic uncertainties are of similar size as statistical • No show stoppers identified (but lots of work) • Next generation surveys are designed to control systematic errors and can significantly improve on current constraints

  32. Currentsurveys HST SNLS Essence SDSS PanStarrs PTF SNF CfA redshift

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