1 / 16

SDSS-II SN survey: Constraining Dark Energy with intermediate- redshift probes

SN survey. SDSS-II SN survey: Constraining Dark Energy with intermediate- redshift probes. Hubert Lampeitl University Portsmouth, ICG. In collaboration with:

becka
Download Presentation

SDSS-II SN survey: Constraining Dark Energy with intermediate- redshift probes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SN survey SDSS-II SN survey:Constraining Dark Energy with intermediate-redshift probes Hubert Lampeitl University Portsmouth, ICG In collaboration with: H.J. Seo, T. Giannantonio, C. Shapiro, R.C. Nichol, B. Bassett, W.J. Percival, T. Davis, B.Dilday, J. Frieman, P. Garnavich, M. Sako, M. Smith, J. Sollerman

  2. Why intermediate-redshiftprobes? In most cosmological analysis several different probes are combined in order To derive the most constraining parameters on cosmology Most popular: SN + BAO + CMB but GS & ISW Stretch over a very wide redshift range (in case of CMB z=1089) In case of Supernova Ia combinations from Several Instruments (Nearby, ESSENCE, SNLS, HST): eg. Davis et al. 2007, Kowalski et al. 2008, Hicken et al, 2009, Kessler et al. 2009) Kowalski et al. 2008 Eisenstein et al. 2005 Komatsu et al., 2009 Systematic and statistical uncertainties for SN are now on same level! Increasing the sample doesn’t help! Cross check: Are the results consistent if we limit ourself to one redshift range? - Less prone for systematic effects, but less stringent limits

  3. Why intermediate-redshiftprobes? In most cosmological analysis several different probes are combined in order To derive the most constraining parameters on cosmology Most popular: SN + BAO + CMB but GS & ISW Stretch over a very wide redshift range (in case of CMB z=1089) In case of Supernova Ia combinations from Several Instruments (Nearby, ESSENCE, SNLS, HST): eg. Davis et al. 2007, Kowalski et al. 2008, Hicken et al, 2009, Kessler et al. 2009) Kessler et al, 2009 Kowalski et al. 2008 Systematic and statistical uncertainties for SN are now on same level! Increasing the statistic doesn’t help! Cross check: Are the results consistent if we limit our self to one redshift range? - Less prone for systematic effects, but less stringent limits

  4. Possible and identified problemswith Supernova • Restframeu-band (UV lightcurve ~ 10%) • evolution of SN spectra over redshift • and progenitor type • SN demographics • -> k-corrections • Dust in host galaxy (RV=3.1 vs. 2.2) • local peculiar velocities (Hubble bubble) • selection effects • photometric cross survey calibration • . • . • . Foley et al., 2008 Nugent Hasiao

  5. SDSS-II SNe Survey Goals:

  6. 484 confirmed SN with IAU designation Hubert Lampeitl, ICG, 29/5/2008

  7. Z = 0.013 Z = 0.47 Hubert Lampeitl, ICG

  8. Additional spectroscopic observation time awarded on BOSS spectrograph to follow up and get redshifts for SN candidates without confirmed redshift

  9. SDSS-II SN survey: 1st year • - 103 spectroscopically confirmed • SN with z=[0.045;0.42] from 2005 • after stringent quality cuts • - All fit with MLCS2k2 for various • LC fitter choices (evaluation • of LC fitter systematic, • Kessler et al, 2009) • Fiducialmodel chosen to reflect • current understanding Scatter ~0.14 mag LCDM q0=-0.33 z=0.34 z=0.13

  10. Case for acceleration (C. Shapiro) Independent of matter content content for q0 = constant and flat universe Principal components: a1<0 only if the universe has accelerated at one point: P=96%

  11. Baryon Acoustic Oscillations (BAO) Eisenstein et al., 2005 Percival et al., 2007 DV(0.35)/DV(0.2) = 1.812 ± 0.062 SDSS/2dF 1:1 scaling wit a(t) z = 0.35 z = 0.2 z=1089 BAO provides a ‘standard ruler’ Hubert Lampeitl, ICG

  12. Distance Duality Phase space density of photons must be conserved in all metric theories of gravity (Etherington 1933, Ellis 1971) ! BAO SN LCDM More, Bovy, &Hogg 2009 Avgoustidis, Verde, & Jimenez 2009

  13. Constraining wwith ISW Giannantonio et al., astro-ph/0801.4380 private communication SDSS DR6 Main galaxy sample & LRG ISW detected on with ~3s & growth of structure Kaiser Effect: 2dFGRS (Hawkins, 2003) Including bias Linder, PhRvD 72 (2005) Peacock, Nature 410, 169 (2001)

  14. Constraining Cosmological Parameters flat curved ISW SDSS-SN GS BAO Curvature constrained by WMAP: (1 sigma errors)

  15. Systematic uncertainties Hard to quantify and easily underestimated! • Main uncertainty: U-band anomaly caused by uncertainties in spectral library -0.41 (sys) in w • Combining other identified systematic effects uncertainty results in +/- 0.16 (sys) in w

  16. Summary Supernova drawn from SDSS-II SN survey finds under the Assumption of a flat universe indication of an accelerating universe with a probability>97% No compelling evidence for a violation of distance duality found using SN & BAO. Possible indication of systematic effect in one of the probes. Combining the SDSS SN data with either ISW or GS gives Limits on w:

More Related