The RASS-SDSS Galaxy Cluster Survey

Popesso, P.; Böhringer, H.; Voges, W.

doi:10.1007/10995020_101

Cited by 2 publications

(1 citation statement)

References 189 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We will investigate the radio properties of BzK galaxies at all redshifts to see if there are any differences in the z < 1.4 populations which are contaminating the BzK space. We note that a spectroscopic study by Popesso et al (2008) also finds that 23 per cent of sBzK lie at z < 1.4. The number of pBzK in their sample is too small to produce a reliable measure of the fraction at low redshift.…”

Section: Resultsmentioning

confidence: 71%

The star formation history ofK-selected galaxies

Dunne

Ivison

Maddox

et al. 2009

Monthly Notices of the Royal Astronomical Society

148

134

View full text Add to dashboard Cite

We have studied the μJy radio properties of K-selected galaxy populations detected in the Ultra-Deep Survey (UDS) portion of the United Kingdom Infrared Telescope (UKIRT) Deep Sky Survey using 610-and 1400-MHz images from the Very Large Array and the Giant Metre-wave Telescope. These deep radio mosaics, combined with the largest and deepest K-band image currently available, allow high signal-to-noise ratio (S/N) detections of many K-selected subpopulations, including sBzK and pBzK star-forming and passive galaxies. We find a strong correlation between the radio and K-band fluxes and a linear relationship between star formation rate (SFR) and K-band luminosity. We find no evidence, either from radio spectral indices or a comparison with submm-derived SFRs, that the full sample is strongly contaminated by active galactic nuclei (AGN) at these low flux densities, though this is very difficult to determine from this data set. The photometric redshift distributions for the BzK galaxies place 37 (29) per cent of pBzK (sBzK) galaxies at z < 1.4, implying that location on the BzK diagram alone is not sufficient to select samples at 1.4 < z < 2.5. The sBzK and pBzK galaxies have similar levels of radio flux density, SFR and specific SFR (SSFR -SFR per unit stellar mass) at z < 1.4, suggesting there is strong contamination of the pBzK sample by star-forming galaxies. At z > 1.4, the pBzK galaxies become difficult to detect in the radio stack, though the implied SFRs are still much higher than expected for passively evolving galaxies. It may be that their radio emission comes from low-luminosity AGN. Extremely red objects (EROs) straddle the passive and star-forming regions of the BzK diagram and also straddle the two groups in terms of their radio properties. We find that K-bright ERO samples are dominated by passive galaxies and faint ERO samples contain more star-forming galaxies. The star formation history (SFH) from stacking all K-band sources in the UDS agrees well with that derived for other wavebands and other radio surveys, at least out to z ∼ 2. The radio-derived SFH then appears to fall more steeply than that measured at other wavelengths. The SSFR for K-selected sources rises strongly with redshift at all stellar masses, and shows a weak dependence on stellar mass. High-and low-mass galaxies show a similar decline in SSFR since z ∼ 2.

show abstract

Section: Resultsmentioning

confidence: 71%

The star formation history ofK-selected galaxies

Dunne

Ivison

Maddox

et al. 2009

Monthly Notices of the Royal Astronomical Society

148

134

View full text Add to dashboard Cite

show abstract

Properties of Satellite Galaxies in the SDSS Photometric Survey: Luminosities, Colors, and Projected Number Density Profiles

Lares

Lambas

Dominguez

2011

The Astronomical Journal

View full text Add to dashboard Cite

We analyze photometric data in SDSS-DR7 to infer statistical properties of faint satellites associated to isolated bright galaxies (M r < −20.5) in the redshift range 0.03 < z < 0.1. The mean projected radial number density profile shows an excess of companions in the photometric sample around the primaries, with approximately a power law shape that extends up to ≃ 700 kpc. Given this overdensity signal, a suitable background subtraction method is used to study the statistical properties of the population of bound satellites, down to magnitude M r = −14.5, in the projected radial distance range 100 < r p /kpc < 3 < R vir >. The maximum projected distance corresponds is in the range 470 − 660 kpc for the different samples. We have also considered a colour cut consistent with the observed colours of spectroscopic satellites in nearby galaxies so that distant redshifted galaxies do not dominate the statistics. We have tested the implementation of this background subtraction procedure using a mock catalogue derived from the Millenium simulation SAM galaxy catalogue based on a ΛCDM model. We find that the method is effective in reproducing the true projected radial satellite number density profile and luminosity distributions, providing confidence in the results derived from SDSS data. We find that the spatial extent of satellite systems is larger for bright, red primaries. Also, we find a larger spatial distribution of blue satellites. For the different samples analyzed, we derive the average number of satellites and their luminosity distributions down to M r = −14.5. The mean number of satellites depends very strongly on host luminosity. Bright primaries (M r < −21.5) host on average ∼ 6 satellites with M r < −14.5. This number is reduced for primaries with lower luminosities (−21.5 < M r < −20.5) which have less than 1 satellites per host. We provide Schechter function fits to the luminosity distributions of satellite galaxies where the resulting faint end slopes equal to 1.3 ± 0.2, consistent with the universal value. This shows that satellites of bright primaries lack an excess population of faint objects, in agreement with the results in the Milky Way and nearby galaxies.

show abstract

The RASS-SDSS Galaxy Cluster Survey

Cited by 2 publications

References 189 publications

The star formation history ofK-selected galaxies

The star formation history ofK-selected galaxies

Properties of Satellite Galaxies in the SDSS Photometric Survey: Luminosities, Colors, and Projected Number Density Profiles

Contact Info

Product

Resources

About