ACP Seminar (Astronomy - Cosmology - Particle Physics)

Speaker: Olivier Dore (NASA JPL)
Title: Planck Early Measurements of the Cosmic Infrared Background Anisotropies
Date (JST): Thu, Sep 01, 2011, 13:30 - 15:00
Place: Seminar Room A
Related File: 500.pdf
Abstract: Since it reached the Lagrange point L2 in august 2009, Planck has been observing the sky at frequencies ranging from 30 to 857 GHz, measuring not only the cosmic microwave background, but also everything else in the universe that radiates at these frequencies. The first scientific results from Planck cover a wide range of galactic and extragalactic astrophysics, including clusters, extragalactic radio sources, spinning and thermal dust in the Milky Way and Cosmic Infrared Background (CIB).

In this talk, after briefly introducing the Planck instrument, I will focus on Planck early measurements of the CIB. The CIB is the far-infrared relic emission from galaxies formed throughout cosmic history. It appears as a a cosmological, diffuse, background light. Being produced by the star heated dust within high redshift galaxies, it carries a wealth of information about the processes of star formation therein. Besides, the fluctuations detected in this background light trace the large-scale distribution of star-forming galaxies and, to some extent, the underlying distribution of the dark matter halos in which galaxies reside. The CIB is a thus direct probe of the interplay between baryon and dark matter throughout cosmic times and its unmatched redshift depth complements current and foreseeable optical or near infrared measurements.

Using six regions of the low galactic dust emission with a total area of about 140 deg2, Planck measured the angular power spectra of CIB anisotropies on angular scales ranging from half a degree to a few arcminutes at 217, 353, 545 and 857 GHz. At all these frequencies, we detect with high significance the clustering of high redshift dusty star-forming galaxies. Combining a new dusty galaxy parametric evolution model with a galaxy clustering model, we obtain a good fit to our data. I will discuss various aspects of these measurements and highlight the unique insights we expect to obtain from them in the coming years, combining Planck and other far-infrared measurements.