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You are cordially invited to afternoon ~~tea and biscuits~~ wine and chocolate

Astronomy Tea Talks at Caltech

Mondays, Robinson 106
Tea: 4.00pm
Talk: 4.15pm

Organised by:

2007 - 2008 season:
15 October 2007	David Rapetti (KIPAC/Stanford) "Probing cosmology with X-ray galaxy clusters" Most of the energy density of the Universe appears to be in the form of dark matter and dark energy, and yet these two components are the most intriguing mysteries in current cosmology. Using two complementary X-ray galaxy cluster studies we present new constraints on the mean matter density of the Universe, dark energy density, normalization of the density fluctuation power spectrum, and dark energy equation of state. First, using Chandra measurements of the X-ray gas mass fraction in 42 hot, X-ray luminous, dynamically relaxed galaxy clusters spanning the redshift range 0.05 constant, H_0, and the mean baryon density, w_bh^2, we obtain tight constraint on the mean matter density and a detection of the effects of dark energy on the distances to the clusters comparable in significance to recent type Ia supernovae (SNIa) studies. Second, using the X-ray luminosity function of the Massive Cluster Survey (MACS) in combination with the local BCS and REFLEX galaxy cluster samples, the mass function predictions of Jenkins et al. (2001), a mass-luminosity relation calibrated using the data of Reiprich and Bohringer (2002), and standard priors on H_0 and w_bh^2, we obtain the first precise determination of the dark energy equation of state from measurements of the growth of cosmic structure in galaxy clusters. Combining our results with independent constraints from cosmic microwave background and SNIa studies removes the need for priors on H_0 and w_bh^2 and leads to tighter constraints. Both of our results represent strong, independent evidences for cosmic acceleration.

2007 - 2008 season:

15 October 2007

"Probing cosmology with X-ray galaxy clusters"

Most of the energy density of the Universe appears to be in the form of dark matter and dark energy, and yet these two components
are the most intriguing mysteries in current cosmology. Using two complementary X-ray galaxy cluster studies we present new
constraints on the mean matter density of the Universe, dark energy density, normalization of the density fluctuation power
spectrum, and dark energy equation of state. First, using Chandra measurements of the X-ray gas mass fraction in 42 hot, X-ray
luminous, dynamically relaxed galaxy clusters spanning the redshift range 0.05 constant, H_0, and the mean baryon density, w_bh^2, we obtain tight constraint on the mean matter density and a detection of the
effects of dark energy on the distances to the clusters comparable in significance to recent type Ia supernovae (SNIa) studies.
Second, using the X-ray luminosity function of the Massive Cluster Survey (MACS) in combination with the local BCS and REFLEX
galaxy cluster samples, the mass function predictions of Jenkins et al. (2001), a mass-luminosity relation calibrated using the
data of Reiprich and Bohringer (2002), and standard priors on H_0 and w_bh^2, we obtain the first precise determination of the
dark energy equation of state from measurements of the growth of cosmic structure in galaxy clusters. Combining our results with
independent constraints from cosmic microwave background and SNIa studies removes the need for priors on H_0 and w_bh^2 and leads
to tighter constraints. Both of our results represent strong, independent evidences for cosmic acceleration.

More astronomy-related talks
CalTech Today calendar. CalTech astronomy colloquia (3:45pm Wednesdays, Robinson library). IPAC lunch talks (12:15pm Wednesdays, IPAC Conference Room 102). Theoretical Astrophysics and Relativity Seminars (2pm Fridays, 114 E. Bridge). Carnegie Observatories colloquia and lunches (4pm Tuesdays & 12:15pm Fridays, OCIW). Solange Ramírez's weekly compilation of astro talks in Pasadena.
Archives
2006, 2005, 2004, 2003, 2002, 2001, 2000, 1999, 1998
Last modified on 20th Jul 2011 by Johan Richard.

Astronomy Tea Talks at Caltech

Mondays, Robinson 106 Tea: 4.00pm Talk: 4.15pm

Mondays, Robinson 106
Tea: 4.00pm
Talk: 4.15pm