We analyze the spectra of 300,000 luminous red galaxies (LRGs) with stellar masses \(M_* \gtrsim 10^{11} M_{\odot}\) from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). By studying ...their star-formation histories, we find two main evolutionary paths converging into the same quiescent galaxy population at \(z\sim0.55\). Fast-growing LRGs assemble \(80\%\) of their stellar mass very early on (\(z\sim5\)), whereas slow-growing LRGs reach the same evolutionary state at \(z\sim1.5\). Further investigation reveals that their clustering properties on scales of \(\sim\)1-30 Mpc are, at a high level of significance, also different. Fast-growing LRGs are found to be more strongly clustered and reside in overall denser large-scale structure environments than slow-growing systems, for a given stellar-mass threshold. Our results imply a dependence of clustering on stellar-mass assembly history (naturally connected to the mass-formation history of the corresponding halos) for a homogeneous population of similar mass and color, which constitutes a strong observational evidence of galaxy assembly bias.
We have developed an analytical method based on forward-modeling techniques to characterize the high-mass end of the red sequence (RS) galaxy population at redshift \(z\sim0.55\), from the DR10 BOSS ...CMASS spectroscopic sample, which comprises \(\sim600,000\) galaxies. The method, which follows an unbinned maximum likelihood approach, allows the deconvolution of the intrinsic CMASS colour-colour-magnitude distributions from photometric errors and selection effects. This procedure requires modeling the covariance matrix for the i-band magnitude, g-r colour and r-i colour using Stripe 82 multi-epoch data. Our results indicate that the error-deconvolved intrinsic RS distribution is consistent, within the photometric uncertainties, with a single point (\(<0.05~{\rm{mag}}\)) in the colour-colour plane at fixed magnitude, for a narrow redshift slice. We have computed the high-mass end (\(^{0.55}M_i \lesssim -22\)) of the \(^{0.55}i\)-band RS Luminosity Function (RS LF) in several redshift slices within the redshift range \(0.52<z<0.63\). In this narrow redshift range, the evolution of the RS LF is consistent, within the uncertainties in the modeling, with a passively-evolving model with \(\Phi_* = (7.248 \pm 0.204) \times10^{-4}\) Mpc\(^{-3}\) mag\(^{-1}\), fading at a rate of \(1.5\pm0.4\) mag per unit redshift. We report RS completeness as a function of magnitude and redshift in the CMASS sample, which will facilitate a variety of galaxy-evolution and clustering studies using BOSS. Our forward-modeling method lays the foundations for future studies using other dark-energy surveys like eBOSS or DESI, which are affected by the same type of photometric blurring/selection effects.
We model the luminosity-dependent projected and redshift-space two-point correlation functions (2PCFs) of the Sloan Digital Sky Survey (SDSS) DR7 Main galaxy sample, using the halo occupation ...distribution (HOD) model and the subhalo abundance matching (SHAM) model and its extension. All the models are built on the same high-resolution \(N\)-body simulations. We find that the HOD model generally provides the best performance in reproducing the clustering measurements in both projected and redshift spaces. The SHAM model with the same halo-galaxy relation for central and satellite galaxies (or distinct haloes and subhaloes), when including scatters, has a best-fitting \(\chi^2/\rm{dof}\) around \(2\)--\(3\). We therefore extend the SHAM model to the subhalo clustering and abundance matching (SCAM) by allowing the central and satellite galaxies to have different galaxy--halo relations. We infer the corresponding halo/subhalo parameters by jointly fitting the galaxy 2PCFs and abundances and consider subhaloes selected based on three properties, the mass \(M_{\rm acc}\) at the time of accretion, the maximum circular velocity \(V_{\rm acc}\) at the time of accretion, and the peak maximum circular velocity \(V_{\rm peak}\) over the history of the subhaloes. The three subhalo models work well for luminous galaxy samples (with luminosity above \(L_*\)). For low-luminosity samples, the \(V_{\rm acc}\) model stands out in reproducing the data, with the \(V_{\rm peak}\) model slightly worse, while the \(M_{\rm acc}\) model fails to fit the data. We discuss the implications of the modeling results.
We study the galaxy clustering dependence on the \(\left\mathrm{O\scriptsize{II}}\right\) emission line luminosity in the SDSS DR7 Main galaxy sample at mean redshift \(z\sim0.1\). We select ...volume-limited samples of galaxies with different \(\left\mathrm{O\scriptsize{II}}\right\) luminosity thresholds and measure their projected, monopole and quadrupole two-point correlation functions. We model these observations using the 1\(h^{-1}\rm{Gpc}\) MultiDark Planck cosmological simulation and generate light-cones with the SUrvey GenerAtoR algorithm. To interpret our results, we adopt a modified (Sub)Halo Abundance Matching scheme, accounting for the stellar mass incompleteness of the emission line galaxies. The satellite fraction constitutes an extra parameter in this model and allows to optimize the clustering fit on both small and intermediate scales (i.e. \(r_p\lesssim 30h^{-1}\rm{Mpc})\), with no need of any velocity bias correction. We find that, in the local Universe, the \(\left\mathrm{O\scriptsize{II}}\right\) luminosity correlates with all the clustering statistics explored and with the galaxy bias. This latter quantity correlates more strongly with the SDSS \(r\)-band magnitude than \(\left\mathrm{O\scriptsize{II}}\right\) luminosity. In conclusion, we propose a straightforward method to produce reliable clustering models, entirely built on the simulation products, which provides robust predictions of the typical ELG host halo masses and satellite fraction values. The SDSS galaxy data, MultiDark mock catalogues and clustering results are made publicly available.
We present a study of the clustering and halo occupation distribution of BOSS CMASS galaxies in the redshift range 0.43 < z < 0.7 drawn from the Final SDSS-III Data Release. We compare the BOSS ...results with the predictions of a Halo Abundance Matching (HAM) clustering model that assigns galaxies to dark matter halos selected from the large BigMultiDark \(N\)-body simulation of a flat \(\Lambda\)CDM Planck cosmology. We compare the observational data with the simulated ones on a light-cone constructed from 20 subsequent outputs of the simulation. Observational effects such as incompleteness, geometry, veto masks and fiber collisions are included in the model, which reproduces within 1-\(\sigma\) errors the observed monopole of the 2-point correlation function at all relevant scales: from the smallest scales, 0.5 \(h^{-1}\) Mpc, up to scales beyond the Baryonic Acoustic Oscillation feature. This model also agrees remarkably well with the BOSS galaxy power spectrum (up to \(k\sim1\) \(h\) Mpc\(^{-1}\)), and the Three-point correlation function. The quadrupole of the correlation function presents some tensions with observations. We discuss possible causes that can explain this disagreement, including target selection effects. Overall, the standard HAM model describes remarkably well the clustering statistics of the CMASS sample. We compare the stellar to halo mass relation for the CMASS sample measured using weak lensing in the CFHT Stripe 82 Survey with the prediction of our clustering model, and find a good agreement within 1-\(\sigma\). The BigMD-BOSS light-cone including properties of BOSS galaxies and halo properties is made publicly available.
MNRAS (2016), 461, 3421 Current and future large redshift surveys, as the Sloan Digital Sky Survey IV
extended Baryon Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) or the Dark
Energy Spectroscopic ...Instrument (DESI), will use emission-line galaxies (ELG)
to probe cosmological models by mapping the large-scale structure of the
Universe in the redshift range $0.6 < z < 1.7$. With current data, we explore
the halo-galaxy connection by measuring three clustering properties of
$g$-selected ELGs as matter tracers in the redshift range $0.6 < z < 1$: (i)
the redshift-space two-point correlation function using spectroscopic redshifts
from the BOSS ELG sample and VIPERS; (ii) the angular two-point correlation
function on the footprint of the CFHT-LS; (iii) the galaxy-galaxy lensing
signal around the ELGs using the CFHTLenS. We interpret these observations by
mapping them onto the latest high-resolution MultiDark Planck N-body
simulation, using a novel (Sub)Halo-Abundance Matching technique that accounts
for the ELG incompleteness. ELGs at $z\sim0.8$ live in halos of $(1\pm
0.5)\times10^{12}\,h^{-1}$M$_{\odot}$ and 22.5$\pm2.5$% of them are satellites
belonging to a larger halo. The halo occupation distribution of ELGs indicates
that we are sampling the galaxies in which stars form in the most efficient
way, according to their stellar-to-halo mass ratio.
We present results on the clustering of 282,068 galaxies in the Baryon Oscillation Spectroscopic Survey (BOSS) sample of massive galaxies with redshifts 0.4<z<0.7 which is part of the Sloan Digital ...Sky Survey III project. Our results cover a large range of scales from ~0.5 to ~90 Mpc/h. We compare these estimates with the expectations of the flat LCDM cosmological model with parameters compatible with WMAP7 data. We use the MultiDark cosmological simulation together with a simple halo abundance matching technique, to estimate galaxy correlation functions, power spectra, abundance of subhaloes and galaxy biases. We find that the LCDM model gives a reasonable description to the observed correlation functions at z~0.5, which is a remarkably good agreement considering that the model, once matched to the observed abundance of BOSS galaxies, does not have any free parameters. However, we find a deviation (>~10%) in the correlation functions for scales less than ~1 Mpc/h and ~10-40 Mpc/h. A more realistic abundance matching model and better statistics from upcoming observations are needed to clarify the situation. We also estimate that about 12% of the "galaxies" in the abundance-matched sample are satellites inhabiting central haloes with mass M>~1e14 M_sun/h. Using the MultiDark simulation we also study the real space halo bias b(r) of the matched catalogue finding that b=2.00+/-0.07 at large scales, consistent with the one obtained using the measured BOSS projected correlation function. Furthermore, the linear large-scale bias depends on the number density n of the abundance-matched sample as b=-0.048-(0.594+/-0.02)*log(n/(h/Mpc)^3). Extrapolating these results to BAO scales we measure a scale-dependent damping of the acoustic signal produced by non-linear evolution that leads to ~2-4% dips at ~3 sigma level for wavenumbers k>~0.1 h/Mpc in the linear large-scale bias.
Current and future large redshift surveys, as the Sloan Digital Sky Survey IV extended Baryon Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) or the Dark Energy Spectroscopic Instrument (DESI), will ...use emission-line galaxies (ELG) to probe cosmological models by mapping the large-scale structure of the Universe in the redshift range \(0.6 < z < 1.7\). With current data, we explore the halo-galaxy connection by measuring three clustering properties of \(g\)-selected ELGs as matter tracers in the redshift range \(0.6 < z < 1\): (i) the redshift-space two-point correlation function using spectroscopic redshifts from the BOSS ELG sample and VIPERS; (ii) the angular two-point correlation function on the footprint of the CFHT-LS; (iii) the galaxy-galaxy lensing signal around the ELGs using the CFHTLenS. We interpret these observations by mapping them onto the latest high-resolution MultiDark Planck N-body simulation, using a novel (Sub)Halo-Abundance Matching technique that accounts for the ELG incompleteness. ELGs at \(z\sim0.8\) live in halos of \((1\pm 0.5)\times10^{12}\,h^{-1}\)M\(_{\odot}\) and 22.5\(\pm2.5\)% of them are satellites belonging to a larger halo. The halo occupation distribution of ELGs indicates that we are sampling the galaxies in which stars form in the most efficient way, according to their stellar-to-halo mass ratio.
