SDSS Globular Cluster Candidates Around M31 S.A. Bates J.A. Holtzman R.A.M. Walterbos NMSUAPO May 2004

Scientific Motivation SDSS scanned 2.6 x 18 degrees around M31 in Fall 2002 SDSS scanned 2.6 x 18 degrees around M31 in Fall 2002 To use the large extent of the SDSS scan to locate new globular clusters at large radii To use the large extent of the SDSS scan to locate new globular clusters at large radii Recent INT survey found clusters Recent INT survey found clusters Halo clusters can help to better constrain the mass and chemical composition of M31 and the origin of clusters Halo clusters can help to better constrain the mass and chemical composition of M31 and the origin of clusters

Procedure Matched known clusters to SDSS objects Matched known clusters to SDSS objects 2 arcsec distance 2 arcsec distance magnitude range r~(v-0.25) or brightest magnitude range r~(v-0.25) or brightest Plot clusters in multi-dimensional space Plot clusters in multi-dimensional space object type, Petrosian radius, magnitude, color, ellipticity, r90/r50 object type, Petrosian radius, magnitude, color, ellipticity, r90/r50 Choose candidates based upon concentration of clusters Choose candidates based upon concentration of clusters Final list of candidates Final list of candidates eliminate objects scan ends and cluster duplicates eliminate objects scan ends and cluster duplicates visual inspection visual inspection FWHM FWHM Spectra taken of two candidates last month at APO Spectra taken of two candidates last month at APO

Selection Criteria Criteria GALAXY classification GALAXY classification 2 < Petrosian radius < 5 2 < Petrosian radius < 5 2 < r90/r50 < 3 2 < r90/r50 < 3 ellipticity > 0.8 ellipticity > 0.8 r < 18 r < 18

Selection Color Criteria Color Criteria |(g-r)-2(r-i)| < 0.5 |(g-r)-2(r-i)| < 0.5 |(u-r-1)-4(r-i)| < 0.75 |(u-r-1)-4(r-i)| < 0.75

Previously Confirmed Clusters

New Clusters 3367-r r velocity velocity large Balmer absorption lines large Balmer absorption lines

New Clusters 3366-r r velocity velocity

New Clusters 3367-r r velocity velocity

Positions New clusters at large projected galactocentric radii New clusters at large projected galactocentric radii

Future Work Follow-up spectroscopy at APO next fall Follow-up spectroscopy at APO next fall Bruzual & Charlot stellar population synthesis models Bruzual & Charlot stellar population synthesis models