GHOSTS - Bulges, Halos, and the Resolved Stellar Outskirts of Massive Disk Galaxies

Understand

Our GHOSTS survey measures the stellar envelope properties of 14 nearby disk galaxies by imaging their resolved stellar populations with HST/ACS&WFPC2.

• Most of the massive galaxies in the sample (Vrot >200 km/s) have very extended stellar envelopes with Sersic law profiles or mu(r)~r^-2.5 power law profiles in the outer regions.
• For these massive galaxies we can fit the central bulge light and the outer halo out to 30 kpc with one and the same Sersic profile and the stellar surface density of the profiles correlate with Hubble type and bulge- to-disk ratio.
• This suggests that the central bulges and inner halos are created in the same process.