Summary

This project generates and fits spectra from XMM observations of the COSMOS field to study the potential spatial variation of Emission Measure of Galactic Halo/ Circum-galactic medium.

Background

• The full 2 $deg^2$ COSMOS field is covered entirely by 56 XMM pointings for a total exposure ~ 1.5 Ms.
• To study the spatial variation of the GH/CGM EM, we divided the whole field into 10x10 regions, each with 10' in width and height.

The image of the COSMOS field. The white blocks at the center is Chandra C-COSMOS observations; the yellow circles are XMM-COSMOS pointings; the green boxes are the 10x10 regions that covers the whole field.

• We remove the point sources detected by Chandra and XMM, and generated spectra in each box region.

Goals

By fitting the spectra in each box region, we can visualize the variation of EM and determine quantitatively if the variation is real or simply due to statistics.

Proposed Solution

Data preparation

Data preparation phase aims to collect and clean data from XMM for spectra generation.

• Generate Chandra source list with 50% power diameters for source removal.

• Inspect and remove observations suffered from heavy soft proton flares.

• Generate spectra for 56 XMM pointings.

• Get temperature and EM for Local hot bubble from ROSAT map.

• Fit spectra in XMM circular pointings.

  

  

  GH/CGM EM distribution plot.

• EM seems to show clumpiness. Hard to tell from the distribution plot.