Nobel Prize for Physics 2011 Supernovae explosions and the Accelerating Universe Institute for Astronomy University of Vienna Since 09/2010: ouniprof University of Vienna 12/2008-08/10: Staff member European Southern Observatory 2008: Prof. University of Bonn 2002-2007: Volkswagen Foundation Young Research Group Göttingen Before: Heidelberg, Los Angeles, Munich, Durham (UK)
: Main research fields: Galaxy formation & evolution Morphology Cluster MS0451 z=0.5 FORS Deep Field Rotation Curv e Velocity Field
Nobel Prize for Physics 2011 For the discovery of the accelerating expansion of the Universe through observations of distant supernovae. Saul Perlmutter Brian Schmidt Adam Riess
Overview Basic Cosmology Stellar Evolution & Supernovae Ia The accelerating Universe Current & future research Material: nobelprize.org (Royal Swedish Academy of Sciences); my own lecture notes; Riess et al. 1998 AJ 116, 1009; Perlmutter et al. 1999 ApJ 517, 565 Dr. A Böhm (Innsbruck), Dr. M. Kenn (Vienna), Dr. B. Leibundgut (ESO)
Big Bang Evidence: Hubble expansion Primordial Nucleosynthesis Cosmic background radiation Structure formation
Cosmic Microwave Background Nobel Prize 2006 (Mather & Smoot) using COBE data: CMB uniform blackbody with variations T/T~10-5!
Structure Formation Early fl uctuations enable galaxy assembly (but: Dark Matter needed!)
Expanding Universe Hubble: brightness & size decrease with increasing redshift
Redshift & Look-back time Defi nition Redshift z : for v << c: z = v/c 13.5 Gyr 8 Gyr 5 Gyr S&W
Expanding Universe Hubble 1929: Sandage 1986: Velocity - Distance Relation: at high z relativistic corrections needed vrad = H0 D and dependance on matter content [H0]=km/s/Mpc
Dynamics of Universe Einstein's General Relativity Rij Ricci-Tensor, Tij Energy-momentum tensor, gij Metric, cosmological constant Cosmological Principle: Universe is homogenous and isotropic Robertson-Walker metric: Friedmann equations: R: scale radius : energy density p: pressure k: curvature
Observable quantities normalized densities 3H2/8 G critical density of 10-30 g/cm If cosm. constant form of vacuum energy: with equation-of-state: p = w. = / 8 G (energy density)
Standard Candles
Elliptical Galaxies as Standard Candles Bender et al. 1998 Ziegler&Bender 1997
Supernovae at high z
Supernovae at high z
Supernovae at high z
Supernovae Type Ia Hamuy et al. 1996: SN Ia: standard candles with absolute magnitude MB=-19.1±0.3m
Supernovae Type Ia Hamuy et al. 1996: SN Ia: standard candles with absolute magnitude MB=-19.1±0.3m
Supernovae Type Ia Evolution binary star system with differing masses: more massive star evolves faster becoming White Dwarf WD exhaust of H, He etc., no nuclear fusion > degenerate core Secondary star evolves to Red Giant phase exceeding Roche lobe WD extracts mass from RG, accumulates via accretion disk WD's mass exceeds Chandrasekhar limit of 1.4M0 WD explodes completely as supernova
Stellar Evolution radiative convective H He pp M<1.2-1.5 M
Stellar Evolution 100 R 1R L~R 2 T 4eff 0.01 R Hertzsprung Russel diagram
Stellar Evolution Red Giant phase
Stellar Evolution Assymptotic Giant Branch phase: degenerate CO core
Supernovae Type Ia Wikipedia
Calculation Distance Modulus Dependance on cosmo. distance (distance luminosity) analytic expression for fl at Universe with deceleration parameter q0 (Mattig 1958)
Effects on Distance Modulus + k X + Ag + Ai + k e Intrinsic absorption (dust in observed galaxy) K-correction (trafo to rest-frame) Galactic extinction (dust in Milky Way)
Effects on Distance Modulus + k X + Ag + Ai + k e Evolutionary effects Intrinsic absorption (dust in observed galaxy) K-correction (trafo to rest-frame) Galactic extinction (dust in Milky Way)
SCP's Hubble diagram Distant SNe are dimmer than expected in fl at or closed Universe!
Accelerating Universe SCP HZT
Concordance Cosmology Supernovae Cosmic Microwave Background Baryonic Acoustic Oscillations
Accelerating Universe
Slide by B. Leibundgut, ESO
Slide by B. Leibundgut, ESO
Constraining Dark Energy: CLASH Observes 25 massive galaxy clusters with HST (WFC3, ACS) in 15 fi lters. Among primary goal: detect SNe Ia out to z~2 to test constancy of DE. CLASH-VLT: spectroscopic follow-up using ESO's telescopes on Paranal. PhD project U. Kuchner utilizes CLASH VIMOS spectra
Synergy ground-based / space-based measurements
Cosmic History