This page summarizes the results from GO-20456 which was a medium size Spitzer IRS Spectroscopy program in GOODS-N. There are four main papers which came out of this effort:

  • Pope et al. 2008 Presented the IRS Spectra of Submillimeter Galaxies. Demonstrated that the majority of them are PAH dominated. Provided more accurate estimates on their star-formation rates and AGN content, ruling out the possibility, based on the PAH equivalent widths that AGN dominate the energetics of these galaxies.

  • Alexander et al. 2008 Utilized the IRS Spectra in conjunction with the X-ray data to definitively demonstrate the presence of Compton-thick AGN activity.

  • Magnelli et al. 2008 Used the multiwavelength photometric data in GOODS to assess the presence of the 3.3 micron PAH feature in the SED of high redshift galaxies. The excess in the IRAC passbands where the 3.3 micron PAH should be present was found to correlate with the ~11 micron PAH emission which is obtained from the spectra. Since both features arise from C-H bending and stretching modes, the correlation between the two favors the existence of the 3.3 micron PAH feature.

  • Murphy et al. 2009 Provides a comprehensive analysis of all the sources, their AGN content and their SFR. Demonstrates that UV derived SFR are incorrect for many objects and that obscured AGN are not responsible for the discrepancy between high-z galaxies and SED in the local Universe. Instead, PAH EW at high redshift seems to be higher in high bolometric luminosity sources while local analogs of such extreme luminosity sources do not exist. This is probably due to the increased gas content of the galaxies at high redshift.

  • Other papers which utilized some of the data from this program were Frayer et al. and Pope et al.

  • Final data products will be posted here soon.