Galaxy clusters offer scientists a window to study the chemical evolution and gas properties of the universe through examining the hot intra-cluster medium (ICM). The ICM is an element rich region between the galaxies in clusters, which gives information on the chemistry and gas dynamics of the galaxy cluster. It is continually enriched by metals synthesized in Type la (SN1a) and core-collapse (SNcc) supernovae. The goal of this research is to examine the cross calibration using the HIghest x-ray FLUX Galaxy Cluster Sample (HIFLUGCS), which consists of 63 of the brightest, low redshift (2) galaxy clusters, between the MOS-I/II instruments onboard the X-ray Multi-Mirror Mission (XMM Newton) and the Advanced CCD Imaging Spectrometer (ACIS)-1/S instruments onboard Chandra, and their influence on elemental abundances and plasma temperature of the ICM.

Using the Chandra Interactive Analysis of Observations (CIAO) Tools ver. 4.11, I reduce X-ray images for the clusters from the ACIS-1/S instruments before extracting X-ray spectra from the isothermal source regions on the images. I also use the XMM-Newton Science Analysis System (SAS) ver. 17.0.0 to collect pre-processed x-ray spectra extracted from the same isothermal source regions as from Chandra. The spectra from both telescopes are fitted using a photoelectric absorption (phabs) model and thermal plasma emission (apec) model. XMM-Newton spectra use (XSPEC) ver. 12.0.1, while Chandra x-ray spectra use Sherpa fitting package in CIAO Tools ver, 4.11. I utilize the xa statistic to ensure the accuracy of the model to the X-ray spectra, and obtain the elemental abundances for Al, Si, Ca, Ni, and Fe and the plasma temperature (KT) because these are widely used in scientific journals.

After obtaining elemental abundances and KT, I graphed the ACIS-I/S and MOS-1/II abundances and KT against each other using Microsoft Excel. My initial hypothesis was that the data would follow a y=x trendline, but I found no relationship amongst the elemental abundance values and temperature for both instruments. After observing some of the data points concentrated in certain regions of the graphs, I created boxplots for the elemental abundance and temperature values for each instrument to visualize the distribution of abundance values and noticed for Fe and Ni, the distribution of abundance values was greater for ACIS-I/S than MOS-I/II, while MOS-I/II had a larger distribution of abundance values for Al and Si than ACIS-I/S. Because of MOS-1/S's unmatched photon gathering power, its ability to obtain more precise measurements for Fe and Ni with less instrumental contribution is better than Chandra. The greater distribution of Al and Si abundances for the MOS-I/II instruments confirm the contribution of AI and Si lines in the spectra when charged particles excite Al atoms in the camera housing and when Si atoms in the substrate of the CCD are excited and slightly overlapping each other as noted from D. H. Lumb et al. 2002. I found that certain instruments are better at taking more accurate measurements than others for specific elements.

Assessing the implications of these elemental abundance distributions on the radial profiles of galaxy clusters, which comprise the models for understanding the chemistry of the universe is the next step in assessing the biases of each instrument towards specific elements.