From Supernovae to Baryon acoustic Oscillations來自新星的重子聲學(xué)振蕩

1、from supernovae to baryon acoustic oscillationspatrice okoumasupervisor : prof. bruce a. bassettuctdec. 2008ska postgraduate bursary conferenceoverviewtheoretical workobservational workdata analysisadiabatic & isocurvature modeson baotype-ia supernovae meerkat /skasalta type-ia supernovae (sne i

2、a) - explosion of a white dwarf having accreted mass from a companion star, beyond a critical threshold known as the chandrasekhar limit ( 1.4 solar masses).a remindersilicon linefolatelli (2004) sne ia as standardizable candlekrisciunas et al., 2005spectral characterization of type-ia supernovae vi

3、a chi-squared based techniques and cross- correlation approach (snid by blondin et al. 2006) - m.sc. a past workchi-squared approachcross-correlation approach (snid code) 2-week campaign for infra red light curves of sne ia (irsf, sutherland, sa) work with ariel goobar & al. (sweden) extinctions

4、 corrections for optical observations - major uncertainty inusing sne ia for cosmology in nir, sne-ia are still standardizable candles ( krisciunas et al., 2005 ) smaller extinction corrections strong evidence for a weaker lightcurve width-brightnesscorrection lower error budget better constraints o

5、n the cosmology2-week campaign for optical spectra of sne (1.9-m telescope, sutherland, sa) work with . y. fang & al. (michigan,us); a. goobar et al. (sweden) goals :training;testing simultaneous identification of transients from rotse (http:/ gamsberg (southern namibia).theoretical workobservat

6、ional workdata analysisadiabatic & isocurvature modeson baosupernovaemeerkat / skasaltnumber density and/or energy density characterize cosmological species in the early universe.linear perturbations of these quantities are the early universe through baryon acoustic oscillations work with k. moo

7、dley et al. (ukzn,sa) & c. zunckel (princeton, us) metric perturbationseqs. for evolution of perturbationsthenadiabatic modes are perturbations affecting cosmological species such that :isocurvature modes :cmb (for flat universe) = adiabatic modes are dominant 10% isocurvature modes are allowed

8、(in early universe).s. white (2008) therefore, if we assume adiabatic fluctuations, what do we get wrong about dark energy . and . by how much ?baryon acoustic oscillations (b.a.o) = pathfinderinitial fluctuations in density and gravitational potential drive acoustic waves in the fluid:compressions

9、and rarefactions.at early times the universe was hot, dense and ionized. photons and matter were tightly coupled by thomson scattering.an (adiab.) evolution in a spherically symmetric shell of plasma another prediction verified !eisenstein et al . (2005) detect the theorized “bump” in the 2-point co

10、rrelation function of the sdss -lrg at z 0.35r0theory/modelcontrol with datafeedbacksimulation(classical) programsimulations using camb (code ) mixturecross-correlation pkcorrelation coeff.= -1 : anti-correlation= 1 : full correlationelse : partial correlationdivide bothtotally correlatedpartially correlatedzoomstrong “degeneracy” with dark energyvia baoimmediate perspective perspective (contd) : fisher formalism on pkseo & eisenstein (2007) approach huge collaboration opportunities.hi