2000 (IPP)

Permanent URI for this collectionhttp://localhost:4000/handle/11007/629

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Subject: search.filters.subject.Cosmology

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    Observing high-redshift Supernovae in lensed galaxies
    (2000-01-28) Saini, Tarun Deep; Raychaudhury, Somak; Shchekinov, Yuri A.
    Supernovae in distant galaxies that are grav- tationally lensed by foreground galaxy clusters make ex- cellent cosmological candles for measuring quantities like the density of the Universe in its various components and the Hubble constant. Distant supernovae will be more eas- ly detectable since foreground cluster lenses would mag- nify such supernovae by up to 3–4 magnitudes. We show that in the case of the lens cluster Abell 2218, the de- tectability of high-redshift supernovae is significantly en- hanced due to the lensing effects of the cluster. Since ensed supernovae will remain point images even when their host galaxies are stretched into arcs, the signal-to- noise ratio for their observation will be further enhanced, typically by an order of magnitude. We recommend moni- toring well-modelled clusters with several known arclets for the detection of cosmologically useful SNe around z = 1 and beyond.
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    Living with Lambda
    (2000-10-24) Sahni, Varun
    This talk presents a brief overview of recent results pertaining to the cosmological con- stant ‘ ’. I summarize the observational situation focussing on observations of high redshift Type Ia supernovae which suggest > 0. Observations of small angular anisotropies in the cosmic mi- crowave background complement Type Ia supernovae observations and both CMB and Sn can be combined to place strong constraints on the value of . The presence of a small -term increases the age of the universe and slows down the formation of large scale structure. I also review recent the- oretical attempts to generate a small -term at the current epoch and a model independent approach for determining the cosmic equation of state.