Massive neutrinos suppress the growth of structure below their free-streaming scale and leave an imprint on large-scale structure. Measuring this imprint allows us to constrain the sum of neutrino masses, M ν , a key parameter in particle physics beyond the Standard Model. However, degeneracies among cosmological parameters, especially between M ν and σ 8 , limit the constraining power of standard two-point clustering statistics. In this work, we investigate whether we can break these degeneracies and constrain M ν with the next higher-order correlation function -the bispectrum. We first examine the redshift-space halo bispectrum of 800 N -body simulations from the HADES suite and demonstrate that the bispectrum helps break the M ν -σ 8 degeneracy. Then using 22,000 N -body simulations of the Quijote suite, we quantify for the first time the full information content of the redshift-space halo bispectrum down to nonlinear scales using a Fisher matrix forecast of {Ω m , Ω b , h, n s , σ 8 , M ν }. For k max =0.5 h/Mpc, the bispectrum provides Ω m , Ω b , h, n s , and σ 8 constraints 1.9, 2.6, 3.1, 3.6, and 2.6 times tighter than the power spectrum. For M ν , the bispectrum improves the 1σ constraint from 0.2968 to 0.0572 eV -over 5 times tighter than the power spectrum. Even with priors from Planck, the bispectrum improves M ν constraints by a factor of 2.7. Although we reserve marginalizing over a more complete set of bias parameters to the next paper of the series, these constraints are derived for a (1 h −1 Gpc) 3 box, a substantially smaller volume than upcoming surveys. Thus, our results demonstrate that the bispectrum offers significant improvements over the power spectrum, especially for constraining M ν .

Massive neutrinos suppress the growth of structure on small scales and leave an imprint on large-scale structure that can be measured to constrain their total mass, M ν. With standard analyses of two-point clustering statistics, M ν constraints are severely limited by parameter degeneracies. Ref. [1] demonstrated that the bispectrum, the next higher-order statistic, can break these degeneracies and dramatically improve constraints on M ν and other cosmological parameters. In this paper, we present the constraining power of the redshift-space galaxy bispectrum monopole, Bg 0. We construct the Molino suite of 75,000 mock galaxy catalogs from the Quijote N-body simulations using the halo occupation distribution (HOD) model, which provides a galaxy bias framework well-suited for simulation-based approaches. Using these mocks, we present Fisher matrix forecasts for {Ωm, Ωb, h, ns , σ8, M ν} and quantify, for the first time, the information content of the Bg 0 down to nonlinear scales. For k max = 0.5 h/Mpc, Bg 0 improves constraints on Ωm, Ωb, h, ns , σ8, and M ν by 2.8, 3.1, 3.8, 4.2, 4.2, and 4.6× over the power spectrum, after marginalizing over HOD parameters. Even with priors from Planck, Bg 0 improves all of the cosmological constraints by ≳ 2×. In fact, for Pg 0+Pg 2 and Bg 0 out to k max = 0.5 h/Mpc with Planck priors, we achieve a 1σ M ν constraint of 0.048 eV, which is tighter than the current best cosmological constraint. While effects such as survey geometry and assembly bias will have an impact, these constraints are derived for (1 h-1 Gpc)3, a substantially smaller volume than upcoming surveys. Therefore, we conclude that the galaxy bispectrum will significantly improve cosmological constraints for upcoming galaxy surveys — especially for M ν.

Using group catalogs from the SDSS DR7, we attempt to measure galactic conformity in the local universe. We measure the quenched fraction of neighbor galaxies around isolated primary galaxies, dividing the isolated sample into star-forming and quiescent objects. We restrict our measurements to scales > 1 Mpc to probe the correlations between the formation histories of distinct halos. Over the stellar mass range 10 9.7 M * /M 10 10.9 , we find minimal statistical evidence for conformity. We further compare these data to predictions of the halo age-matching model, in which the oldest galaxies are associated with the oldest halos at fixed M * . For models with strong correlations between halo and stellar age, the conformity signal is too large to be consistent with the data. For weaker implementations of age-matching, galactic conformity is not a sensitive diagnostic of halo assembly bias, and would not produce a detectable signal in SDSS data. We reproduce the results of Kauffmann et al. (2013), in which the star formation rates of neighbor galaxies are significantly reduced around primary galaxies when the primaries are themselves low star formers. However, we find this result is mainly driven by contamination in the isolation criterion; when using our group catalog to remove the small fraction of satellite galaxies in the sample, the conformity signal largely goes away. Lastly, we show that small conformity signals, i.e., 2-5% differences in the quenched fractions of neighbor galaxies, can be produced by mechanisms other than halo assembly bias. For example, if passive galaxies occupy more massive halos than star forming galaxies of the same stellar mass, a conformity signal that is consistent with recent measurements from PRIMUS (Berti et al. 2016) can be produced.

In current and future surveys, quasars play a key role. The new data will extend our knowledge of the Universe as it will be used to better constrain the cosmological model at redshift z > 1 via baryon acoustic oscillation and redshift space distortion measurements. Here, we present the first clustering study of quasars observed by the extended Baryon Oscillation Spectroscopic Survey. We measure the clustering of ∼ 70, 000 quasars located in the redshift range 0.9 < z < 2.2 that cover 1,168 deg 2 . We model the clustering and produce high-fidelity quasar mock catalogues based on the BigMultiDark Planck simulation. Thus, we use a modified (Sub)Halo Abundance Matching model to account for the specificities of the halo population hosting quasars. We find that quasars are hosted by halos with masses ∼ 10 12.7 M and their bias evolves from 1.54 (z = 1.06) to 3.15 (z = 1.98). Using the current eBOSS data, we cannot distinguish between models with different fractions of satellites. The high-fidelity mock light-cones, including properties of halos hosting quasars, are made publicly available.