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- Ancillary Targets
- Transient Universe in Stripe 82
- Host Galaxies of SDSS-II SNe
- BCGs in
Stripe 82 - High-Quality LRG spectra
- Reddened
Quasars - No Quasar Left Behind
- Variability-Selected Quasars
- K-band Selected Quasars
- Low-Mass Stars and Brown Dwarfs
- Low-Mass Binary Stars
- White Dwarfs and Hot Subdwarfs
- Distant Halo
Giants - Bright
Galaxies - High-Energy Blazars in Optical
- An X-Ray View Star Formation
- Remarkable X-Ray Sources
- Star-Forming Radio Galaxies
- Galaxies Near QSO Sight Lines
- Luminous Blue Galaxies
- BAL Quasar Variability
- Variable QSO Absorption
- Double-Lobed Radio QSOs
- High-Redshift Quasars
- High-z QSOs in SDSS/UKIDSS
- BOSS Targeting
- Algorithms
Brightest Cluster Galaxies in SDSS Stripe 82
Summary
Spectra of brightest cluster galaxies (BCGs) in the 220-square-degree stripe 82 survey area
Finding Targets
An object whose ANCILLARY_TARGET2 value includes one or more of the bitmasks
in the following table was targeted for spectroscopy as part of this
ancillary target program. See SDSS-III bitmasks to
learn how to use these values to identify objects in this ancillary target program.
| Program (bit name) |
Bit in ANCILLARY_TARGET2 | Target Description | Target density (deg–2) |
|---|---|---|---|
| STRIPE82BCG | 6 | Brightest cluster galaxy in stripe 82 survey area | 6.0 |
Description
Over 3,000 groups and clusters have been identified photometrically in SDSS Stripe 82 (Geach et al. 2011; Murphy et al. 2012). These clusters were identified from ugriz photometry generated from the coaddition of Stripe 82 images (Annis et al. 2011); this co-added image is ~ 2 mag deeper than imaging in the rest of the BOSS footprint. These clusters have photometric redshifts in the range 0 < z < 0.6 (median z = 0.32), and are expected to reside in dark matter halos with masses in excess of 2.5 x 1013 solar mass.
Each cluster is assigned a brightest cluster galaxy (BCG), which is simply defined as the brightest member associated with the cluster detection. To confirm the cluster redshifts, we obtained spectra of the likely BCGs with magnitudes 17 < ifib2 < 21.7 and colors that vary with redshift according to the cluster detection algorithm (Murphy et al. 2012). A sample of 1,505 BCGs was identified; the BOSS spectrograph obtained spectra of 1,345 of these galaxies. These 1,345 galaxies had not been previously included in the SDSS Data Release 7 main galaxy sample, or in the 2SLAQ or WiggleZ samples.
This new sample of spectroscopically confirmed galaxy clusters will enable a wide variety of science, including the weak lensing of groups and clusters, the link between star formation and AGN activity in BCGs, and the LRG population of dark matter halos.
Primary contact
| Alexie Leauthaud |
|---|
| University of Tokyo |
| alexie.leauthaud -at- ipmu.jp |
Other contacts
James Geach, David Murphy, Nic Ross, David Wake, Richard Bower, Kevin Bundy, Kyle Dawson, Matt George, Shirley Ho, Eric Huff, Jean-Paul Kneib, Yen-Ting Lin, Martin Makler, Rachel Mandelbaum, Daisuke Nagai, Nikhil Padmanabhan, Erin Sheldon, Jeremy Tinker, Frank van den Bosch, Martin White
REFERENCES
Annis, J.A., Soares-Santos, M., Strauss, M.A., Becker, A.C., Dodelson, S., Fan, X.,
Gunn, J.E., Hao, J., Ivezić, Ž, Jester, S., Jiang, L., Johnston, D.E.,
Kubo, J.M., Lampeitl, H., Lin, H., Lupton, R.H., Miknaitis, G., Seo, H-J.,
Simet, M., & Yanny, B., 2011, arXiv:1111.6619
Geach, J. E., Murphy, D. N. A., & Bower, R. G. 2011, MNRAS, 413, 3059,
doi:10.1111/j.1365-2966.2011.18380.x
Murphy, D. N. A., Geach, J. E., & Bower, R. G. 2012, MNRAS, 420, 1861,
doi:10.1111/j.1365-2966.2011.19782.x