Directory
Jun Ji
Contact Information
n/a 500 Church St. Ann Arbor, Mi 48109 Department Phone: (734) 764-3440 Fax: (734) 763-6317Email: jijun (append "@umich.edu" to send email)
Research Statement:
There are usually diffuse gases surrounding the elliptical galaxies. They are in the temperature of from 6 to 10 million Kelvins, which are hot enough to peak at soft X-ray emission region (from 0.5 keV to 1 keV). They are thought to be originated from the mass loss of normal stars in terms of stellar winds and planetary nebulae, type II supernova explosion from collapsing of massive stars, and type I supernova explosion from an accreting white dwarf that exceed its Chandrasecha limit. Each enrichment mechanism contribute different portions of metal to the gas,thus the matallicity of the hot gases actually tells us the history of the host galaxy.
The matallicity of hot gases could be measured by their soft X-ray spectra, because a bunch of emission lines (such as FeXVII,FeXVIII, OVII and OVIII) are in the soft X-ray region which contribute most of the soft X-ray emissions. But in the past, due to the low spectral resolution and sensitivity, it was very hard to constrain the metallicity of hot gases.With the powerful X-ray telescope of XMM-Newton, we have much larger photon collecting areas and higher spectral resolution in the soft X-ray band. Thus it should give a better constrain on metallicity of hot gases.
I am focusing on analysing the archived data of 11 bright elliptical galaxies observed by the XMM-Newton X-ray telescope. The data consist of moderate resolution CCD spectra of EPIC instrument as well as high resolution spectra of RGS instrument on board of XMM-Newton. Our goal is to constrain the metallicity of hot gases by fitting the their X-ray spectra.
