Laura Tomas

Mission Planner for the XMM-Newton Users' Support Group.

Main research interests: Cosmic X-ray Background, Active Galactic
Nuclei

The CXB is mainly due to the integrated emission of many discrete
sources: a mixture of absorbed and unabsorbed Active Galactic
Nuclei, folded with their corresponding luminosity function and
its cosmological evolution.

The objective of my current research work is to use some deep
XMM-Newton observations to:

- Detect the discrete sources that make up the Cosmic X-ray
  Background
- For the moderately faint detected sources: study their individual
  spectral properties directly from spectral fitting.
- For the very faint detected sources: obtain their spectral
  properties by means of the analysis of hardness ratio diagrams
  and stacked spectra.
- Find the optical counterparts to study the correlation between
  optical and X-ray properties.
- Compare the observed properties with the predictions of the
  theoretical models for the X-ray background (in particular, the
  fraction of absorbed and unabsorbed AGNs, density of AGN with
  redshift)