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OATS-UNI/TS SEMINAR
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Speaker: Antonella Garzilli (SISSA - Trieste)

Title: Measuring the intergalactic medium thermal history with wavelets filtering
Date: Wednesday, May 30th, 2012
Time: 11:30
Venue: Villa Bazzoni
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Abstract: We describe our recent measurement of the thermal state of the intergalactic medium (IGM) in the redshift interval z=1.7-3.2 by studying the small-scale fluctuations in the Lyman-alpha forest transmitted flux. We applied a wavelet filtering technique to eighteen high resolution quasar spectra obtained with the Ultraviolet and Visual Echelle Spectrograph (UVES), and compare these data to synthetic spectra drawn from a suite of hydrodynamical simulations in which the IGM thermal state and cosmological parameters are varied. We obtain estimates of the IGM thermal state that are in good agreement with other recent, independent wavelet-based measurements. We also perform a reanalysis of the same data set using the Lyman-alpha forest flux probability distribution function (PDF), which has previously been used to measure the IGM temperature-density relation. We find the constraints obtained from wavelets and the flux PDF are formally consistent with each other, although in agreement with previous studies, the flux PDF constraints favour an isothermal or inverted IGM temperature-density relation. We also perform a joint analysis by combining our wavelet and flux PDF measurements. Our results are consistent with previous observations that indicate there may be additional sources of heating in the IGM at z < 4.
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Contact: Matteo Viel (OATS)