supernovae explosions and the accelerating universe...

Bodo Ziegler VERA seminar Wien 27.10.2011

2011 Nobel Prize in Physics: Supernovae explosions and the Accelerating Universe

Bodo Ziegler

Nobel Prize for Physics 2011

Institute for AstronomyUniversity of Vienna

Supernovae explosions and the Accelerating Universe

● 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)



FORS Deep Field Velocity FieldRotation Curve

Morphology

Cluster MS0451z=0.5

Bodo Ziegler:Main research fields:Galaxy formation & evolution



For the discovery of the accelerating expansion of the Universe through observations of distant supernovae.

Saul Perlmutter Brian Schmidt Adam Riess

Nobel Prize for Physics 2011



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, 565Dr. 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

S&W

Defi nition Redshift z :

for v << c: z = v/c

5 Gyr

8 Gyr

13.5 Gyr



Expanding Universe

Hubble 1929:

Velocity - Distance Relation:

vrad

= H0 D [H

0]=km/s/Mpc

Sandage 1986:

at high z relativistic corrections needed

and dependance on matter content



Dynamics of Universe

Einstein's General Relativity

Rij Ricci-Tensor, T

ij Energy-momentum tensor, g

ij Metric, � cosmological constant

Cosmological Principle: Universe is homogenous and isotropic

Robertson-Walker metric:

Friedmann equations:

R: scale radius� : energy densityp: pressurek: curvature



Observable quantities

normalized densities

3H2/8G critical densityof 10-30 g/cm

If cosm. constant form of vacuum energy: �� = � / 8� G (energy density)

with equation-of-state: p� = w

� �

� .



Standard Candles



Elliptical Galaxies as Standard Candles

Ziegler&Bender 1997 Bender et al. 1998



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

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

H→He

pp

M<1.2-1.5 M

radiative

convective



Stellar Evolution

L~R2 T4eff

100 R

1 R

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 Universewith deceleration parameter q

0 (Mattig 1958)



Effects on Distance Modulus

+ kX + Ag + Ai + ke

K-correction(trafo to rest-frame)

Intrinsic absorption(dust in observed galaxy)

Galactic extinction(dust in Milky Way)



Effects on Distance Modulus

+ kX + Ag + Ai + ke

K-correction(trafo to rest-frame)

Intrinsic absorption(dust in observed galaxy)

Galactic extinction(dust in Milky Way)

Evolutionary effects



SCP's Hubble diagram

Distant SNe are dimmer than expected in fl at or closed Universe!



Accelerating Universe

SCP HZT



Concordance Cosmology

Cosmic MicrowaveBackground

Supernovae

BaryonicAcousticOscillations



Accelerating Universe



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

supernovae explosions and the accelerating universe...

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