Hidden Activity in High-redshift Spheroidal Galaxies
Rodighiero, Gruppioni, Civano, Comastri, Franceschini, Mignoli, Fritz, Vignali
We exploit very deep mid-IR and X-ray observations by Spitzer and Chandra in the HDFN to identify signs of hidden activity in spheroidal galaxies between z~0.3 to 1.
The nature of the mid-IR emission in these sources is analyzed through their SEDs based on the available multi-wavelength photometry and optical spectroscopy.
We conclude that 20% of the original sample of spheroidal
galaxies in HDFN are detected during phases of prominent activity, of both stellar and quasar origin.