Search

We present three separate void catalogs created using a volume-limited sample of the DESI Year 1 Bright Galaxy Survey. We use the algorithms VoidFinder and V2 to construct void catalogs out to a redshift of z=0.24. We obtain 1,461 interior voids with VoidFinder, 420 with V2 using REVOLVER pruning, and 295 with V2 using VIDE pruning. Comparing our catalog with an overlapping SDSS void catalog, we find generally consistent void properties but significant differences in the void volume overlap, which we attribute to differences in the galaxy selection and survey masks. These catalogs are suitable for studying the variation in galaxy properties with cosmic environment and for cosmological studies., Comment: 17 pages, 6 figures

We measure the growth of cosmic density fluctuations on large scales and across the redshift range $0.3

The Dark Energy Spectroscopic Instrument (DESI) collaboration measured a tight relation between the Hubble constant ($H_0$) and the distance to the Coma cluster using the fundamental plane (FP) relation of the deepest, most homogeneous sample of early-type galaxies. To determine $H_0$, we measure the distance to Coma by several independent routes each with its own geometric reference. We measure the most precise distance to Coma from 12 Type Ia Supernovae (SNe Ia) in the cluster with mean standardized brightness of $m_B^0=15.712\pm0.041$ mag. Calibrating the absolute magnitude of SNe Ia with the HST distance ladder yields $D_{\textrm Coma}=98.5\pm2.2$ Mpc, consistent with its canonical value of 95--100 Mpc. This distance results in $H_0=76.5 \pm 2.2$ km/s/Mpc from the DESI FP relation. Inverting the DESI relation by calibrating it instead to the Planck+$\Lambda$CDM value of $H_0=67.4$ km/s/Mpc implies a much greater distance to Coma, $D_{\textrm Coma}=111.8\pm1.8$ Mpc, $4.6\sigma$ beyond a joint, direct measure. Independent of SNe Ia, the HST Key Project FP relation as calibrated by Cepheids, Tip of the Red Giant Branch from JWST, or HST NIR surface brightness fluctuations all yield $D_{\textrm Coma}<$ 100 Mpc, in joint tension themselves with the Planck-calibrated route at $>3\sigma$. From a broad array of distance estimates compiled back to 1990, it is hard to see how Coma could be located as far as the Planck+$\Lambda$CDM expectation of $>$110 Mpc. By extending the Hubble diagram to Coma, a well-studied location in our own backyard whose distance was in good accord well before the Hubble Tension, DESI indicates a more pervasive conflict between our knowledge of local distances and cosmological expectations. We expect future programs to refine the distance to Coma and nearer clusters to help illuminate this new, local window on the Hubble Tension., Comment: v2 - team name fixed

At the low-redshift end ($z<0.05$) of the Hubble diagram with Type Ia Supernovae (SNe Ia), the contribution to Hubble residual scatter from peculiar velocities is of similar size to that due to the standardization of the SN Ia light curve. A way to improve the redshift measurement of the SN host galaxy is to utilize the average redshift of the galaxy group, effectively averaging over small-scale/intracluster peculiar velocities. One limiting factor is the fraction of SN host galaxies in galaxy groups, previously found to be 30% using (relatively incomplete) magnitude-limited galaxy catalogs. Here, we do the first analysis of N-body simulations to predict this fraction, finding $\sim$66% should have associated groups and group averaging should improve redshift precision by $\sim$120 km s$^{-1}$. Furthermore, using spectroscopic data from the Anglo-Australian Telescope, we present results from the first pilot program to evaluate whether or not 23 previously unassociated SN Ia hosts belong in groups. We find that 91% of these candidates can be associated with groups, consistent with predictions from simulations given the sample size. Combining with previously assigned SN host galaxies in Pantheon+, we demonstrate improvement in Hubble residual scatter equivalent to 145 km s$^{-1}$, also consistent with simulations. For new and upcoming low-$z$ samples from, for example, the Zwicky Transient Facility and the Rubin Observatory's Legacy Survey of Space and Time, a separate follow-up program identifying galaxy groups of SN hosts is a highly cost-effective way to enhance their constraining power., Comment: 17 pages, 12 figures. Submitted to ApJ

The Dark Energy Spectroscopic Instrument (DESI) Peculiar Velocity Survey aims to measure the peculiar velocities of early and late type galaxies within the DESI footprint using both the Fundamental Plane and Tully-Fisher relations. Direct measurements of peculiar velocities can significantly improve constraints on the growth rate of structure, reducing uncertainty by a factor of approximately 2.5 at redshift 0.1 compared to the DESI Bright Galaxy Survey's redshift space distortion measurements alone. We assess the quality of stellar velocity dispersion measurements from DESI spectroscopic data. These measurements, along with photometric data from the Legacy Survey, establish the Fundamental Plane relation and determine distances and peculiar velocities of early-type galaxies. During Survey Validation, we obtain spectra for 6698 unique early-type galaxies, up to a photometric redshift of 0.15. 64\% of observed galaxies (4267) have relative velocity dispersion errors below 10\%. This percentage increases to 75\% if we restrict our sample to galaxies with spectroscopic redshifts below 0.1. We use the measured central velocity dispersion, along with photometry from the DESI Legacy Imaging Surveys, to fit the Fundamental Plane parameters using a 3D Gaussian maximum likelihood algorithm that accounts for measurement uncertainties and selection cuts. In addition, we conduct zero-point calibration using the absolute distance measurements to the Coma cluster, leading to a value of the Hubble constant, $H_0 = 76.05 \pm 0.35$(statistical) $\pm 0.49$(systematic FP) $\pm 4.86$(statistical due to calibration) $\mathrm{km \ s^{-1} Mpc^{-1}}$. This $H_0$ value is within $2\sigma$ of Planck Cosmic Microwave Background results and within $1\sigma$, of other low redshift distance indicator-based measurements., Comment: 18 pages, 9 figures, 2 tables. Submitted for publication in MNRAS

We explore correlations between the orientations of small galaxy groups, or "multiplets", and the large-scale gravitational tidal field. Using data from the Dark Energy Spectroscopic Instrument (DESI) Y1 survey, we detect the intrinsic alignment (IA) of multiplets to the galaxy-traced matter field out to separations of 100 Mpc/h. Unlike traditional IA measurements of individual galaxies, this estimator is not limited by imaging of galaxy shapes and allows for direct IA detection beyond redshift z = 1. Multiplet alignment is a form of higher-order clustering, for which the scale-dependence traces the underlying tidal field and amplitude is a result of small-scale (< 1 Mpc/h) dynamics. Within samples of bright galaxies (BGS), luminous red galaxies (LRG) and emission-line galaxies (ELG), we find similar scale-dependence regardless of intrinsic luminosity or colour. This is promising for measuring tidal alignment in galaxy samples that typically display no intrinsic alignment. DESI's LRG mock galaxy catalogues created from the AbacusSummit N-body simulations produce a similar alignment signal, though with a 33% lower amplitude at all scales. An analytic model using a non-linear power spectrum (NLA) only matches the signal down to 20 Mpc/h. Our detection demonstrates that galaxy clustering in the non-linear regime of structure formation preserves an interpretable memory of the large-scale tidal field. Multiplet alignment complements traditional two-point measurements by retaining directional information imprinted by tidal forces, and contains additional line-of-sight information compared to weak lensing. This is a more effective estimator than the alignment of individual galaxies in dense, blue, or faint galaxy samples., Comment: For an accessible summary of this paper, see https://cmlamman.github.io/doc/multipletIA_summary.pdf

We infer the growth of large scale structure over the redshift range $0.4\lesssim z \lesssim 1$ from the cross-correlation of spectroscopically calibrated Luminous Red Galaxies (LRGs) selected from the Dark Energy Spectroscopic Instrument (DESI) legacy imaging survey with CMB lensing maps reconstructed from the latest Planck and ACT data. We adopt a hybrid effective field theory (HEFT) model that robustly regulates the cosmological information obtainable from smaller scales, such that our cosmological constraints are reliably derived from the (predominantly) linear regime. We perform an extensive set of bandpower- and parameter-level systematics checks to ensure the robustness of our results and to characterize the uniformity of the LRG sample. We demonstrate that our results are stable to a wide range of modeling assumptions, finding excellent agreement with a linear theory analysis performed on a restricted range of scales. From a tomographic analysis of the four LRG photometric redshift bins we find that the rate of structure growth is consistent with $\Lambda$CDM with an overall amplitude that is $\simeq5-7\%$ lower than predicted by primary CMB measurements with modest $(\sim2\sigma)$ statistical significance. From the combined analysis of all four bins and their cross-correlations with Planck we obtain $S_8 = 0.765\pm0.023$, which is less discrepant with primary CMB measurements than previous DESI LRG cross Planck CMB lensing results. From the cross-correlation with ACT we obtain $S_8 = 0.790^{+0.024}_{-0.027}$, while when jointly analyzing Planck and ACT we find $S_8 = 0.775^{+0.019}_{-0.022}$ from our data alone and $\sigma_8 = 0.772^{+0.020}_{-0.023}$ with the addition of BAO data. These constraints are consistent with the latest Planck primary CMB analyses at the $\simeq 1.6-2.2\sigma$ level, and are in excellent agreement with galaxy lensing surveys., Comment: 60 pages, 26 figures, comments welcome

We present a high-significance cross-correlation of CMB lensing maps from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) with spectroscopically calibrated luminous red galaxies (LRGs) from the Dark Energy Spectroscopic Instrument (DESI). We detect this cross-correlation at a significance of 38$\sigma$; combining our measurement with the Planck Public Release 4 (PR4) lensing map, we detect the cross-correlation at 50$\sigma$. Fitting this jointly with the galaxy auto-correlation power spectrum to break the galaxy bias degeneracy with $\sigma_8$, we perform a tomographic analysis in four LRG redshift bins spanning $0.4 \le z \le 1.0$ to constrain the amplitude of matter density fluctuations through the parameter combination $S_8^\times = \sigma_8 \left(\Omega_m / 0.3\right)^{0.4}$. Prior to unblinding, we confirm with extragalactic simulations that foreground biases are negligible and carry out a comprehensive suite of null and consistency tests. Using a hybrid effective field theory (HEFT) model that allows scales as small as $k_{\rm max}=0.6$ $h/{\rm Mpc}$, we obtain a 3.3% constraint on $S_8^\times = \sigma_8 \left(\Omega_m / 0.3\right)^{0.4} = 0.792^{+0.024}_{-0.028}$ from ACT data, as well as constraints on $S_8^\times(z)$ that probe structure formation over cosmic time. Our result is consistent with the early-universe extrapolation from primary CMB anisotropies measured by Planck PR4 within 1.2$\sigma$. Jointly fitting ACT and Planck lensing cross-correlations we obtain a 2.7% constraint of $S_8^\times = 0.776^{+0.019}_{-0.021}$, which is consistent with the Planck early-universe extrapolation within 2.1$\sigma$, with the lowest redshift bin showing the largest difference in mean. The latter may motivate further CMB lensing tomography analyses at $z<0.6$ to assess the impact of potential systematics or the consistency of the $\Lambda$CDM model over cosmic time., Comment: Prepared for submission to JCAP (47 pages, 13 figures)

Gravitational waves (GWs) have revealed surprising properties of binary black hole (BBH) populations, but there is still mystery surrounding how these compact objects evolve. We apply Bayesian inference and an efficient method to calculate the BBH merger rates in the Shark host galaxies, to determine the combination of COMPAS parameters that outputs a population most like the GW sources from the LVK transient catalogue. For our COMPAS models, we calculate the likelihood with and without the dependence on the predicted number of BBH merger events. We find strong correlations between hyper-parameters governing the specific angular momentum (AM) of mass lost during mass transfer, the mass-loss rates of Wolf-Rayet stars via winds and the chemically homogeneous evolution (CHE) formation channel. We conclude that analysing the marginalised and unmarginalised likelihood is a good indicator of whether the population parameters distribution and number of observed events reflect the LVK data. In doing so, we see that the majority of the models preferred in terms of the population-level parameters of the BBHs greatly overpredict the number of events we should have observed to date. Looking at the smaller number of models which perform well with both likelihoods, we find that those with no CHE, AM loss occurring closer to the donor during the first mass-transfer event, and/or higher rates of mass-loss from Wolf-Rayet winds are generally preferred by current data. We find these conclusions to be robust to our choice of selection criteria., Comment: 27 pages, 19 figures, 6 tables, Accepted by MNRAS

Dark Energy Spectroscopic Instrument (DESI) uses more than 2.4 million Emission Line Galaxies (ELGs) for 3D large-scale structure (LSS) analyses in its Data Release 1 (DR1). Such large statistics enable thorough research on systematic uncertainties. In this study, we focus on spectroscopic systematics of ELGs. The redshift success rate ($f_{\rm goodz}$) is the relative fraction of secure redshifts among all measurements. It depends on observing conditions, thus introduces non-cosmological variations to the LSS. We, therefore, develop the redshift failure weight ($w_{\rm zfail}$) and a per-fibre correction ($\eta_{\rm zfail}$) to mitigate these dependences. They have minor influences on the galaxy clustering. For ELGs with a secure redshift, there are two subtypes of systematics: 1) catastrophics (large) that only occur in a few samples; 2) redshift uncertainty (small) that exists for all samples. The catastrophics represent 0.26\% of the total DR1 ELGs, composed of the confusion between O\,\textsc{ii} and sky residuals, double objects, total catastrophics and others. We simulate the realistic 0.26\% catastrophics of DR1 ELGs, the hypothetical 1\% catastrophics, and the truncation of the contaminated $1.31

We use the forward modeling pipeline, Obiwan, to study the imaging systematics of the Luminous Red Galaxies (LRGs) targeted by the Dark Energy Spectroscopic Instrument (DESI). We update the Obiwan pipeline, which had previously been developed to simulate the optical images used to target DESI data, to further simulate WISE images in the infrared. This addition makes it possible to simulate the DESI LRGs sample, which utilizes WISE data in the target selection. Deep DESI imaging data combined with a method to account for biases in their shapes is used to define a truth sample of potential LRG targets. We simulate a total of 15 million galaxies to obtain a simulated LRG sample (Obiwan LRGs) that predicts the variations in target density due to imaging properties. We find that the simulations predict the trends with depth observed in the data, including how they depend on the intrinsic brightness of the galaxies. We observe that faint LRGs are the main contributing power of the imaging systematics trend induced by depth. We also find significant trends in the data against Galactic extinction that are not predicted by Obiwan. These trends depend strongly on the particular map of Galactic extinction chosen to test against, implying Large-Scale Structure systematic contamination (e.g. Cosmic-Infrared Background) in the Galactic extinction maps is a likely root cause. We additionally observe that the DESI LRGs sample exhibits a complex dependency on a combination of seeing, depth, and intrinsic galaxy brightness, which is not replicated by Obiwan, suggesting discrepancies between the current simulation settings and the actual observations. The detailed findings we present should be used to guide any observational systematics mitigation treatment for the clustering of the DESI LRG sample., Comment: 46 pages, 26 figures

Empirical correlations connecting starlight to galaxy dynamics (e.g., the fundamental plane (FP) of elliptical/quiescent galaxies and the Tully--Fisher relation of spiral/star-forming galaxies) provide cosmology-independent distance estimation and are central to local Universe cosmology. In this work, we introduce the mass hyperplane (MH), which is the stellar-to-dynamical mass relation $(M_\star/M_\mathrm{dyn})$ recast as a linear distance indicator. Building on recent FP studies, we show that both star-forming and quiescent galaxies follow the same empirical MH, then use this to measure the peculiar velocities (PVs) for a sample of 2496 galaxies at $z<0.12$ from GAMA. The limiting precision of MH-derived distance/PV estimates is set by the intrinsic scatter in size, which we find to be $\approx$0.1~dex for both quiescent and star-forming galaxies (when modeled independently) and $\approx$0.11~dex when all galaxies are modeled together; showing that the MH is as good as the FP. To empirically validate our framework and distance/PV estimates, we compare the inferred distances to groups as derived using either quiescent or star-forming galaxies. A good agreement is obtained with no discernible bias or offset, having a scatter of $\approx$0.05~dex $\approx$12\% in distance. Further, we compare our PV measurements for the quiescent galaxies to the previous PV measurements of the galaxies in common between GAMA and the Sloan Digital Sky Survey (SDSS), which shows similarly good agreement. Finally, we provide comparisons of PV measurements made with the FP and the MH, then discuss possible improvements in the context of upcoming surveys such as the 4MOST Hemisphere Survey (4HS)., Comment: Accepted: 15th May 2024

We present the MOST Hosts survey (Multi-Object Spectroscopy of Transient Hosts). The survey is planned to run throughout the five years of operation of the Dark Energy Spectroscopic Instrument (DESI) and will generate a spectroscopic catalog of the hosts of most transients observed to date, in particular all the supernovae observed by most public, untargeted, wide-field, optical surveys (PTF/iPTF, SDSS II, ZTF, DECAT, DESIRT). Scientific questions for which the MOST Hosts survey will be useful include Type Ia supernova cosmology, fundamental plane and peculiar velocity measurements, and the understanding of the correlations between transients and their host galaxy properties. Here, we present the first release of the MOST Hosts survey: 21,931 hosts of 20,235 transients. These numbers represent 36% of the final MOST Hosts sample, consisting of 60,212 potential host galaxies of 38,603 transients (a transient can be assigned multiple potential hosts). Of these galaxies, 40% do not appear in the DESI primary target list and therefore require a specific program like MOST Hosts. Of all the transients in the MOST Hosts list, only 26.7% have existing classifications, and so the survey will provide redshifts (and luminosities) for nearly 30,000 transients. A preliminary Hubble diagram and a transient luminosity-duration diagram are shown as examples of future potential uses of the MOST Hosts survey. The survey will also provide a training sample of spectroscopically observed transients for photometry-only classifiers, as we enter an era when most newly observed transients will lack spectroscopic classification. The MOST Hosts DESI survey data will be released through the Wiserep platform on a rolling cadence and updated to match the DESI releases. Dates of future releases and updates are available through the https://mosthosts.desi.lbl.gov website., Comment: Submitted to ApJS

This paper provides a comprehensive overview of how fitting of Baryon Acoustic Oscillations (BAO) is carried out within the upcoming Dark Energy Spectroscopic Instrument's (DESI) 2024 results using its DR1 dataset, and the associated systematic error budget from theory and modelling of the BAO. We derive new results showing how non-linearities in the clustering of galaxies can cause potential biases in measurements of the isotropic ($\alpha_{\mathrm{iso}}$) and anisotropic ($\alpha_{\mathrm{ap}}$) BAO distance scales, and how these can be effectively removed with an appropriate choice of reconstruction algorithm. We then demonstrate how theory leads to a clear choice for how to model the BAO and develop, implement and validate a new model for the remaining smooth-broadband (i.e., without BAO) component of the galaxy clustering. Finally, we explore the impact of all remaining modelling choices on the BAO constraints from DESI using a suite of high-precision simulations, arriving at a set of best-practices for DESI BAO fits, and an associated theory and modelling systematic error. Overall, our results demonstrate the remarkable robustness of the BAO to all our modelling choices and motivate a combined theory and modelling systematic error contribution to the post-reconstruction DESI BAO measurements of no more than $0.1\%$ ($0.2\%$) for its isotropic (anisotropic) distance measurements. We expect the theory and best-practices laid out to here to be applicable to other BAO experiments in the era of DESI and beyond., Comment: 30 pages, 18 figures, 1 table, updated to match version accepted by MNRAS

Theory of the physics of the early hot universe leads to a prediction of baryon acoustic oscillations that has received confirmation from the pair-wise separations of galaxies in samples of hundreds of thousands of objects. Evidence is presented here for the discovery of a remarkably strong individual contribution to the baryon acoustic oscillation (BAO) signal at z=0.068, an entity that is given the name Ho'oleilana. The radius of the 3D structure is 155/h_{75} Mpc. At its core is the Bootes supercluster. The Sloan Great Wall, CfA Great Wall, and Hercules complex all lie within the BAO shell. The interpretation of Ho'oleilana as a BAO structure with our preferred analysis implies a value of the Hubble constant of 76.9+8.2-4.8 km/s/Mpc., Comment: One video and two interactive models. 14 pages, 14 figures

More precise measurements of galaxy clustering will be provided by the next generation of galaxy surveys such as DESI, WALLABY and SKA. To utilize this information to improve our understanding of the Universe, we need to accurately model the distribution of galaxies in their host dark matter halos. In this work we present a new galaxy number density profile of haloes, which makes predictions for the positions of galaxies in the host halo, different to the widely adopted Navarro-Frenk-White (NFW) profile, since galaxies tend to be found more in the outskirts of halos (nearer the virial radius) than an NFW profile. The parameterised galaxy number density profile model of haloes is fit and tested using the DARKSAGE semi-analytic model of galaxy formation. We find that our galaxy number density profile model of haloes can accurately reproduce the halo occupation distribution and galaxy two-point correlation function of the DARKSAGE simulation. We also derive the analytic expressions for the circular velocity and gravitational potential energy for this profile model. We use the SDSS DR10 galaxy group catalogue to validate this galaxy number density profile model of haloes. Compared to the NFW profile, we find that our model more accurately predicts the positions of galaxies in their host halo and the galaxy two-point correlation function., Comment: 13 pages. 10 figures. Appear on ApJ

$ $Future surveys could obtain tighter constraints on the cosmological parameters with the galaxy power spectrum than with the Cosmic Microwave Background. However, the inclusion of multiple overlapping tracers, redshift bins, and more non-linear scales means that generating the necessary ensemble of simulations for model-fitting presents a computational burden. In this work, we combine full-shape fitting of galaxy power spectra, analytical covariance matrix estimates, the MOPED (Massively Optimised Parameter Estimation and Data compression) method, and the Taylor expansion interpolation of the power spectrum for the first time to constrain the cosmological parameters directly from a state-of-the-art set of galaxy clustering measurements. We find it takes less than a day to compute the analytical covariance while it takes several months to calculate the simulated ones. Combining MOPED with the Taylor expansion interpolation of the power spectrum, we can constrain the cosmological parameters in just a few hours instead of a few days. We also find that even without a priori knowledge of the best-fit cosmological or galaxy bias parameters, the analytical covariance matrix with the MOPED compression still gives consistent cosmological constraints to within 0.1$\sigma$ after two iterations. Therefore, the pipeline we have developed here can significantly speed up the analysis for future surveys such as DESI and Euclid., Comment: Revised version for MNRAS submission. 5 figures, 6 tables, and 13 pages. Comments are welcome

How does the appearance of a strongly lensed system change if a gravitational wave is produced by the lens? In this work we address this question by considering a supermassive black hole binary at the center of the lens emitting gravitational waves propagating either colinearly or orthogonally to the line of sight. Specializing to an Einstein ring configuration (where the source, the lens and the observer are aligned), we show that the gravitational wave induces changes on the ring's angular size and on the optical path of photons. The changes are the same for a given pair of antipodal points on the ring, but maximally different for any pair separated by $90^{\circ}$. For realistic lenses and binaries, we find that the change in the angular size of the Einstein ring is dozens of orders of magnitude smaller than the precision of current experiments. On the other hand, the difference in the optical path induced on a photon by a gravitational wave propagating \textit{orthogonally} to the line of sight triggers, at peak strain, time delays in the range $\sim 0.01 - 1$ seconds, making the chance of their detection (and thus the use of Einstein rings as gravitational wave detectors) less hopeless., Comment: v2. Version accepted for publication in the Open Journal of Astrophysics. 8 pages, four figures. Comments are welcome!

We explore the connection between the gravitational wave (GW) merger rates of stellar-mass binary black holes (BBH) and galaxy properties. We do this by generating populations of stars using the binary population synthesis code COMPAS and evolving them in galaxies from the semi-analytic galaxy formation model Shark, to determine the number of mergers occurring in each simulation time-step. We find that metal-rich and massive galaxies with star formation rate (SFR) greater than $1M_{\odot}/ \rm yr$ are 10 times more likely to have GW events compared to younger, less massive and metal poor galaxies. Our simulation with the default input parameters predicts a higher local merger rate density compared to the third GW transient catalogue (GWTC-3) prediction from LIGO, VIRGO and KAGRA, due to short coalescence times, low metallicities and a high SFR at low redshift in the simulation, which produces more BBHs that merge within the age of the Universe compared to observations. We identify alternate remnant mass models that more accurately reproduce the volumetric rate and provide updated fits to the merger rate as a function of redshift. We then investigate the relative fraction of GW events in our simulation that are in observable host galaxies from upcoming galaxy surveys, determining which of those are ideal for tracing host galaxies with high merger rates. The implications of this work can be utilised for constraining stellar evolution models, better informing follow-up programs, and placing informative priors on host galaxies when measuring cosmological parameters such as the Hubble constant., Comment: 20 pages, 16 figures - Accepted by MNRAS

We study, for the first time, the cross correlation between the angular distribution of radial peculiar velocities (PV) and the lensing convergence of cosmic microwave background (CMB) photons. We derive theoretical expectations for the signal and its covariance and assess its detectability with existing and forthcoming surveys. We find that such cross-correlations are expected to improve constraints on different gravitational models by partially breaking degeneracies with the matter density. We identify in the distance-scaling dispersion of the peculiar velocities the most relevant source of noise in the cross correlation. For this reason, we also study how the above picture changes assuming a redshift-independent scatter for the PV, obtained for example using a reconstruction technique. Our results show that the cross correlation might be detected in the near future combining PV measurements from DESI and the convergence map from CMB-S4. Using realistic direct PV measurements we predict a cumulative signal-to-noise ratio of approximately $3.8 \sigma$ using data on angular scales $3 \leq \ell \leq 200$. For an idealized reconstructed peculiar velocity map extending up to redshift $z=0.15$ and a smoothing scale of $4$ Mpc $h^{-1}$ we predict a cumulative signal-to-noise ratio of approximately $ 27 \sigma$ from angular scales $3 \leq \ell \leq200 $. We conclude that currently reconstructed peculiar velocities have more constraining power than directly observed ones, even though they are more cosmological-model dependent., Comment: v2, minor changes to match the published version. two figures added. Comments are welcome!

The WALLABY pilot survey has been conducted using the Australian SKA Pathfinder (ASKAP). The integrated 21-cm HI line spectra are formed in a very different manner compared to usual single-dish spectra Tully-Fisher measurements. It is thus extremely important to ensure that slight differences (e.g. biases due to missing flux) are quantified and understood in order to maximise the use of the large amount of data becoming available soon. This article is based on four fields for which the data are scientifically interesting by themselves. The pilot data discussed here consist of 614 galaxy spectra at a rest wavelength of 21cm. Of these spectra, 472 are of high enough quality to be used to potentially derive distances using the Tully-Fisher relation. We further restrict the sample to the 251 galaxies whose inclination is sufficiently close to edge-on. For these, we derive Tully-Fisher distances using the deprojected WALLABY velocity widths combined with infrared (WISE W1) magnitudes. The resulting Tully-Fisher distances for the Eridanus, Hydra, Norma and NGC 4636 clusters are 21.5, 53.5, 69.4 and 23.0 Mpc respectively, with uncertainties of 5--10\%, which are better or equivalent to the ones obtained in studies using data obtained with giant single dish telescopes. The pilot survey data show the benefits of WALLABY over previous giant single-dish telescope surveys. WALLABY is expected to detect around half a million galaxies with a mean redshift of $z = 0.05 (200 Mpc)$. This study suggests that about 200,000 Tully-Fisher distances might result from the survey., Comment: 21 pages, 12 Figures, 6 Tables, accepted for publication in the MNRAS

With Cosmicflows-4, distances are compiled for 55,877 galaxies gathered into 38,065 groups. Eight methodologies are employed, with the largest numbers coming from the correlations between the photometric and kinematic properties of spiral galaxies (TF) and elliptical galaxies (FP). Supernovae that arise from degenerate progenitors (type Ia Sne) are an important overlapping component. Smaller contributions come from distance estimates from the surface brightness fluctuations of elliptical galaxies and the luminosities and expansion rates of core collapse supernovae (SNII). Cepheid period-luminosity relation and tip of the red giant branch observations founded on local stellar parallax measurements along with the geometric maser distance to NGC 4258 provide the absolute scaling of distances. The assembly of galaxies into groups is an important feature of the study in facilitating overlaps between methodologies. Merging between multiple contributions within a methodology and between methodologies is carried out with Bayesian Markov chain Monte Carlo procedures. The final assembly of distances is compatible with a value of the Hubble constant of $H_0=74.6$ km s$^{-1}$ Mpc$^{-1}$ with the small statistical error of $\pm 0.8$ km s$^{-1}$ Mpc$^{-1}$ but a large potential systematic error of ~3 km s$^{-1}$ Mpc$^{-1}$. Peculiar velocities can be inferred from the measured distances. The interpretation of the field of peculiar velocities is complex because of large errors on individual components and invites analyses beyond the scope of this study., Comment: 38 pages, 24 figures. catalogs available at edd.ifa.hawaii.edu. Revised version, accepted to ApJ

Amongst the most popular explanations for dark energy are modified theories of gravity. The galaxy overdensity and peculiar velocity fields help us to constrain the growth rate of structure and distinguish different models of gravity. We introduce an improved method for constraining the growth rate of structure with the galaxy overdensity and peculiar velocity fields. This method reduces the modelling systematic error by accounting for the wide-angle effect and the zero-point calibration uncertainty during the modelling process. We also speed up the posterior sampling by around 30 times by first calculating the likelihood at a small number of fiducial points and then interpolating the likelihood values during MCMC sampling. We test the new method on mocks and we find it is able to recover the fiducial growth rate of structure. We applied our new method to the SDSS PV catalogue, which is the largest single peculiar velocity catalogue to date. Our constraint on the growth rate of structure is \(f\sigma_8 = 0.405_{-0.071}^{+0.076}\) (stat) \(\pm 0.009\) (sys) at the effective redshift of 0.073. Our constraint is consistent with a Planck 2018 cosmological model, \(f\sigma_8 = 0.448\), within one standard deviation. Our improved methodology will enable similar analysis on future data, with even larger sample sizes and covering larger angular areas on the sky., Comment: 18 pages, 11 figures and 2 tables. Accepted by MNRAS. You can find the code https://github.com/YanxiangL/Peculiar_velocity_fitting and data https://zenodo.org/record/6640513. Comments are welcome

The next generation of galaxy surveys will provide more precise measurements of galaxy clustering than have previously been possible. The 21-cm radio signals that are emitted from neutral atomic hydrogen (HI) gas will be detected by large-area radio surveys such as WALLABY and the SKA, and deliver galaxy positions and velocities that can be used to measure galaxy clustering statistics. But, to harness this information to improve our cosmological understanding, and learn about the physics of dark matter and dark energy, we need to accurately model the manner in which galaxies detected in HI trace the underlying matter distribution of the Universe. For this purpose, we develop a new HI-based Halo Occupation Distribution (HOD) model, which makes predictions for the number of galaxies present in dark matter halos conditional on their HI mass. The parameterised HOD model is fit and validated using the Dark Sage semi-analytic model, where we show that the HOD parameters can be modelled by simple linear and quadratic functions of HI mass. However, we also find that the clustering predicted by the HOD depends sensitively on the radial distributions of the HI galaxies within their host dark matter halos, which does not follow the NFW profile in the Dark Sage simulation. As such, this work enables -- for the first time -- a simple prescription for placing galaxies of different HI mass within dark matter halos in a way that is able to reproduce the HI mass-dependent galaxy clustering and HI mass function simultaneously and without requiring knowledge of the optical properties of the galaxies. Further efforts are required to demonstrate that this model can be used to produce large ensembles of mock galaxy catalogues for upcoming surveys., Comment: 18 pages, 13 figures, 1 table. Published in ApJ

With recent evidence for a possible "curvature tension" among early and late universe cosmological probes, Effective Field Theories of Large Scale Structure (EFTofLSS) have emerged as a promising new framework to generate constraints on $\Omega_k$ that are independent of both CMB measurements, and some of the assumptions of flatness that enter into other large-scale structure analyses. In this work we use EFTofLSS to simultaneously constrain measurements from the 6dFGS, BOSS, and eBOSS catalogues, representing the most expansive full-shape investigation of curvature to date. Fitting the full-shape data with a BBN prior on $\Omega_b h^2$ and fixed $n_s$, we measure $\Omega_k = -0.089^{+0.049}_{-0.046}$, corresponding to a $\sim 2 \sigma$ preference for curvature. We argue that this result cannot be biased towards flatness by assumptions in the fitting methodology. Using the Bayesian evidence ratio our full-shape data assigns betting odds of 2:1 in favour of curvature, indicating present measurements remain broadly compatible with both flat and curved cosmological models. When our full-shape sample is combined with Planck 2018 CMB measurements, we break the geometric degeneracy and recover a joint fit on $\Omega_k$ of $-0.0041^{+0.0026}_{-0.0021}$. Using the suspiciousness statistic (built on the standard Bayes factor), we find evidence for a moderate tension between Planck 2018 and our suite of full-shape measurements, at a significance of $1.76 ^{+0.14}_{-0.11} \sigma$ ($p \sim 0.08 \pm 0.02$). These results demonstrate the usefulness of full-shape clustering measurements as a CMB independent probe of curvature in the ongoing curvature tension debate., Comment: 14 pages, 7 figures, 7 tables

We present a new catalogue of distances and peculiar velocities (PVs) of $34,059$ early-type galaxies derived from Fundamental Plane (FP) measurements using data from the Sloan Digital Sky Survey (SDSS). This $7016\,\mathrm{deg}^{2}$ homogeneous sample comprises the largest set of peculiar velocities produced to date and extends the reach of PV surveys up to a redshift limit of $z=0.1$. Our SDSS-based FP distance measurements have a mean uncertainty of 23%. Alongside the data, we produce an ensemble of 2,048 mock galaxy catalogues that reproduce the data selection function, and are used to validate our fitting pipelines and check for systematic errors. We uncover a significant trend between group richness and mean surface brightness within the sample, which may hint at an environmental dependence within the FP or the presence of unresolved systematics, and can result in biased peculiar velocities. This is removed using multiple FP fits as function of group richness, a procedure made tractable through a new analytic derivation for the integral of a 3D Gaussian over non-trivial limits. Our catalogue is calibrated to the zero-point of the CosmicFlows-III sample with an uncertainty of $0.004$ dex (not including cosmic variance or the error within CosmicFlows-III itself), which is validated using independent cross-checks with the predicted zero-point from the 2M++ reconstruction of our local velocity field. Finally, as an example of what is possible with our new catalogue, we obtain preliminary bulk flow measurements up to a depth of $135\,h^{-1}\mathrm{Mpc}$. We find a slightly larger-than-expected bulk flow at high redshift, although this could be caused by the presence of the Shapley supercluster which lies outside the SDSS PV footprint., Comment: 25 pages, 19 figures, 3 tables. Accepted for publication in MNRAS. The SDSS PV catalogue, associated data products and simulations are available on Zenodo at https://zenodo.org/record/6640513

The presence of massive neutrinos in the early Universe is expected to have influenced the observed distribution of galaxies, and their observed motions. In this work, we explore whether measurements of galaxy peculiar velocities could allow us to improve upon neutrino mass constraints from galaxy redshift surveys alone. Using Fisher matrix forecasts, we show that the galaxy peculiar motions $\textit{do}$ contain information on the sum of the masses of neutrinos $\sum m_{\nu}$, and that this information can be used to improve upon constraints that may be obtained from low-redshift galaxy surveys ($z<0.5$) combined with $\textit{Planck}$ measurements of the Cosmic Microwave Background. Compared to the full constraining power offered by $\textit{Planck}$ and higher redshift DESI data, we find that the benefit of including peculiar velocities only marginally improves neutrino mass constraints. However, when one does not include information from $\textit{Planck}$, our results show that the inclusion of peculiar velocity measurements can substantially improve upon the constraints from redshift surveys alone, and that in some cases the addition of further data from high density peculiar velocity surveys is more successful at overcoming the sample variance than adding further data from redshifts only. We demonstrate that it may be possible to achieve upper bounds of $\sum m_{\nu} \approx $0.14 eV (68% confidence limit), from upcoming spectroscopic galaxy surveys alone, as long as the peculiar velocity data is available, an improvement of $\sim$14% over redshift surveys alone, but not as strong as when CMB data is included., Comment: After the original version of our paper was published we identified an error in our analysis that changes a number of figures and conclusions in the published version of the paper. The results are updated to correct for this error here

Measurements of cosmic flows enable us to test whether cosmological models can accurately describe the evolution of the density field in the nearby Universe. In this paper, we measure the low-order kinematic moments of the cosmic flow field, namely bulk flow and shear moments, using the Cosmicflows-4 Tully-Fisher catalogue (CF4TF). To make accurate cosmological inferences with the CF4TF sample, it is important to make realistic mock catalogues. We present the mock sampling algorithm of CF4TF. These mock can accurately realize the survey geometry and luminosity selection function, enabling researchers to explore how these systematics affect the measurements. These mocks can also be further used to estimate the covariance matrix and errors of power spectrum and two-point correlation function in future work. In this paper, we use the mocks to test the cosmic flow estimator and find that the measurements are unbiased. The measured bulk flow in the local Universe is 376 $\pm$ 23 (error) $\pm$ 183 (cosmic variance) km s$^{-1}$ at depth $d_{\text{MLE}}=35$ Mpc $h^{-1}$, to the Galactic direction of $(l,b)=(298\pm 3^{\circ}, -6\pm 3^{\circ})$. Both the measured bulk and shear moments are consistent with the concordance $\Lambda$ Cold Dark Matter cosmological model predictions., Comment: 15 pages, 13 figures, 2 tables. Appear in ApJ

With the remarkable increase in scale and precision provided by upcoming galaxy redshift surveys, systematic errors that were previously negligible may become significant. In this paper, we explore the potential impact of low-magnitude systematic redshift offsets on measurements of the Baryon Acoustic Oscillation (BAO) feature, and the cosmological constraints recovered from such measurements. Using 500 mock galaxy redshift surveys as our baseline sample, we inject a series of systematic redshift biases (ranging from +/-0.2% to +/-2%), and measure the resulting shift in the recovered isotropic BAO scale. When BAO measurements are combined with CMB constraints (in both {\Lambda}CDM and wCDM cosmologies), plausible systematics introduce a negligible offset on combined fits of H0 and {\Omega}m, and systematics must be an order of magnitude greater than this plausible baseline to introduce a 1-{\sigma} shift on such combined fits. We conclude that systematic redshift biases are very unlikely to bias constraints on parameters such as H0 provided by BAO cosmology, either now or in the near future. We also detail a theoretical model that predicts the impact of uniform redshift systematics on {\alpha}, and show this model is in close alignment with the results of our mock survey analysis., Comment: 12 pages, 10 figures, submitted to MNRAS

We determine the upper limit on the mass of the lightest neutrino from the most robust recent cosmological and terrestrial data. Marginalizing over possible effective relativistic degrees of freedom at early times ($N_\mathrm{eff}$) and assuming normal mass ordering, the mass of the lightest neutrino is less than 0.037 eV at 95% confidence; with inverted ordering, the bound is 0.042 eV. These results improve upon the strength and robustness of other recent limits and constrain the mass of the lightest neutrino to be barely larger than the largest mass splitting. We show the impacts of realistic mass models, and different sources of $N_\mathrm{eff}$., Comment: 5 pages, 2 figures + Appendix. Full dataset available at https://doi.org/10.5281/zenodo.4005381 (v3: Matches version published in PRD)

We introduce $\sf{CosmoBit}$, a module within the open-source $\sf{GAMBIT}$ software framework for exploring connections between cosmology and particle physics with joint global fits. $\sf{CosmoBit}$ provides a flexible framework for studying various scenarios beyond $\Lambda$CDM, such as models of inflation, modifications of the effective number of relativistic degrees of freedom, exotic energy injection from annihilating or decaying dark matter, and variations of the properties of elementary particles such as neutrino masses and the lifetime of the neutron. Many observables and likelihoods in $\sf{CosmoBit}$ are computed via interfaces to $\sf{AlterBBN}$, $\sf{CLASS}$, $\sf{DarkAges}$, $\sf{MontePython}$, $\sf{MultiModeCode}$, and $\sf{plc}$. This makes it possible to apply a wide range of constraints from large-scale structure, Type Ia supernovae, Big Bang Nucleosynthesis and the cosmic microwave background. Parameter scans can be performed using the many different statistical sampling algorithms available within the $\sf{GAMBIT}$ framework, and results can be combined with calculations from other $\sf{GAMBIT}$ modules focused on particle physics and dark matter. We include extensive validation plots and a first application to scenarios with non-standard relativistic degrees of freedom and neutrino temperature, showing that the corresponding constraint on the sum of neutrino masses is much weaker than in the standard scenario., Comment: 44 pages (including executive summary), 11 figures + appendices. Code available at https://github.com/GambitBSM/gambit_1.5 and all datasets available at https://doi.org/10.5281/zenodo.3975642 . V3: minor revisions, matches published version

We show that correlations between the phases of the galaxy density field in redshift space provide additional information about the growth rate of large-scale structure that is complementary to the power spectrum multipoles. In particular, we consider the multipoles of the line correlation function (LCF), which correlates phases between three collinear points, and use the Fisher forecasting method to show that the LCF multipoles can break the degeneracy between the measurement of the growth rate of structure $f$ and the amplitude of perturbations $\sigma_8$ that is present in the power spectrum multipoles at large scales. This leads to an improvement in the measurement of $f$ and $\sigma_8$ by up to 220 per cent for $k_{\rm max} = 0.15 \, h\mathrm{Mpc}^{-1}$ and up to 50 per cent for $k_{\rm max} = 0.30 \, h\mathrm{Mpc}^{-1}$ at redshift $z=0.25$, with respect to power spectrum measurements alone for the upcoming generation of galaxy surveys like DESI and Euclid. The average improvements in the constraints on $f$ and $\sigma_8$ for $k_{\rm max} = 0.15 \, h\mathrm{Mpc}^{-1}$ are $\sim 90$ per cent for the DESI BGS sample with mean redshift $\overline{z}=0.25$, $\sim 40$ per cent for the DESI ELG sample with $\overline{z}=1.25$, and $\sim 40$ per cent for the Euclid H$\alpha$ galaxies with $\overline{z}=1.3$. For $k_{\rm max} = 0.30 \, h\mathrm{Mpc}^{-1}$, the average improvements are $\sim 40$ per cent for the DESI BGS sample and $\sim 20$ per cent for both the DESI ELG and Euclid H$\alpha$ galaxies., Comment: 28 pages, 13 figures, 2 tables. v2 has additional discussion on model-independence of the forecasts. v3 matches the MNRAS accepted version

We compare the performance of four state-of-the-art models for extracting isotropic measurements of the Baryon Acoustic Oscillation (BAO) scale. To do this, we created a new, public, modular code Barry, which contains datasets, model fitting tools, and model implementations incorporating different descriptions of non-linear physics and algorithms for isolating the BAO feature. These are then evaluated for bias, correlation, and fitting strength using mock power spectra and correlation functions developed for the Sloan Digital Sky Survey Data Release 12. Our main findings are as follows: 1) All of the models can recover unbiased constraints when fit to the pre- and post-reconstruction simulations. 2) Models that provide physical descriptions of the damping of the BAO feature (using e.g., standard perturbation or effective-field theory arguments) report smaller errors on average, although the distribution of mock $\chi^{2}$ values indicates these are underestimated. 3) Allowing the BAO damping scale to vary can provide tighter constraints for some mocks, but is an artificial improvement that only arises when noise randomly sharpens the BAO peak. 4) Unlike recent claims in the literature when utilising a BAO Extractor technique, we find no improvement in the accuracy of the recovered BAO scale. 5) We implement a procedure for combining all models into a single consensus result that improves over the standard method without obviously underestimating the uncertainties. Overall, Barry provides an excellent framework for performing the cosmological analyses for upcoming surveys, and for rapidly testing and validating new models., Comment: 17 pages, 13 figures

We model the large-scale linear galaxy bias $b_g(x,z)$ as a function of redshift $z$ and observed absolute magnitude threshold $x$ for broadband continuum emission from the far infrared to ultra-violet, as well as for prominent emission lines, such as the H$\alpha$, H$\beta$, Lya and [OII] lines. The modelling relies on the semi-analytic galaxy formation model GALFORM, run on the state-of-the-art $N$-body simulation SURFS with the Planck 2015 cosmology. We find that both the differential bias at observed absolute magnitude $x$ and the cumulative bias for magnitudes brighter than $x$ can be fitted with a five-parameter model: $b_g(x,z)=a + b(1+z)^e(1 + \exp{[(x-c)d]})$. We also find that the bias for the continuum bands follows a very similar form regardless of wavelength due to the mixing of star-forming and quiescent galaxies in a magnitude limited survey. Differences in bias only become apparent when an additional colour separation is included, which suggest extensions to this work could look at different colours at fixed magnitude limits. We test our fitting formula against observations, finding reasonable agreement with some measurements within $1\sigma$ statistical uncertainties, and highlighting areas of improvement. We provide the fitting parameters for various continuum bands, emission lines and intrinsic galaxy properties, enabling a quick estimation of the linear bias in any typical survey of large-scale structure., Comment: Revised manuscript accepted for publication in MNRAS

We re-analyze data from the gravitational-wave event GW170817 and its host galaxy NGC4993 to demonstrate the importance of accurate total and peculiar velocities when measuring the Hubble constant using this nearby Standard Siren. We show that a number of reasonable choices can be made to estimate the velocities for this event, but that systematic differences remain between these measurements depending on the data used. This leads to significant changes in the Hubble constant inferred from GW170817. We present Bayesian Model Averaging as one way to account for these differences, and obtain $H_{0}=66.8^{+13.4}_{-9.2}\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$. Adding additional information on the viewing angle from high resolution imaging of the radio counterpart refines this to $H_{0}=64.8^{+7.3}_{-7.2}\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$. During this analysis we also present an alternative Bayesian model for the posterior on $H_{0}$ from Standard Sirens that works more closely with observed quantities from redshift and peculiar velocity surveys. Our results more accurately capture the true uncertainty on the total and peculiar velocities of NGC4993 and show that exploring how well different datasets characterize galaxy groups and the velocity field in the local Universe could improve this measurement further. These considerations impact any low-redshift distance measurement, and the improvements we suggest here can also be applied to standard candles like type Ia supernovae. GW170817 is particularly sensitive to peculiar velocity uncertainties because it is so close. For future standard siren measurements the importance of this error will decrease as (a) we will measure more distant standard sirens, and (b) the random direction of peculiar velocities will average out with more detections., Comment: 13 pages, 5 figures. Updated to match accepted version in MNRAS; textual changes only (results/figures unchanged)

Redshifts have been so easy to measure for so long that we tend to neglect the fact that they too have uncertainties and are susceptible to systematic error. As we strive to measure cosmological parameters to better than 1% it is worth reviewing the accuracy of our redshift measurements. Surprisingly small systematic redshift errors, as low as 0.0001, can have a significant impact on the cosmological parameters we infer, such as $H_0$. Here we investigate an extensive (but not exhaustive) list of ways in which redshift estimation can go systematically astray. We review common theoretical errors, such as adding redshifts instead of multiplying by (1+z); using v=cz; and using only cosmological redshift in the estimates of luminosity and angular-diameter distances. We consider potential observational errors, such as rest wavelength precision, air to vacuum conversion at altitude, and spectrograph wavelength calibration. Finally, we explore physical effects, such as peculiar velocity corrections, galaxy internal velocities, gravitational redshifts, and overcorrecting within a bulk flow. We conclude that it would be quite easy for small systematic redshift errors to have infiltrated our data and be impacting our cosmological results. While it is unlikely that these errors are large enough to resolve the current $H_0$ tension, it remains possible, and redshift accuracy may become a limiting factor in near future experiments. With the enormous efforts going into calibrating the vertical axis of our plots (standard candles, rulers, clocks, and sirens) we argue that it is now worth paying a little more attention to the horizontal axis (redshifts)., Comment: 11 pages, 8 figures, accepted by MNRAS

Measurements of the growth rate of structure, $f\sigma_8$ in the low-redshift Universe allow stringent tests of the cosmological model. In this work, we provide new constraints on $f\sigma_{8}$ at an effective redshift of $z=0.03$ using the combined density and velocity fields measured by the 2MTF and 6dFGSv surveys. We do this by applying a new estimator of the redshift-space density and momentum (density-weighted velocity) power spectra, developed in the first paper of this series, to measured redshifts and peculiar velocities from these datasets. We combine this with models of the density and momentum power spectra in the presence of complex survey geometries and with an ensemble of simulated galaxy catalogues that match the survey selection functions and galaxy bias. We use these simulations to estimate the errors on our measurements and identify possible systematics. In particular, we are able to identify and remove biases caused by the non-Gaussianity of the power spectra by applying the Box-Cox transformation to the power spectra prior to fitting. After thorough validation of our methods we recover a constraint of $f\sigma_8(z_{\mathrm{eff}}=0.03)=0.404^{+0.082}_{-0.081}$ from the combined 2MTF and 6dFGSv data. This measurement is fully consistent with the expectations of General Relativity and the $\Lambda$ Cold Dark Matter cosmological model. It is also comparable and complementary to constraints using different techniques on similar data, affirming the usefulness of our method for extracting cosmology from velocity fields., Comment: 15 pages, 9+1 figures, published in MNRAS, Jun/2019. This is the second in "The Redshift-Space Momentum Power Spectrum" series of papers; Paper I develops the methods used in this work

Low redshift surveys of galaxy peculiar velocities provide a wealth of cosmological information. We revisit the idea of extracting this information by directly measuring the redshift-space momentum power spectrum from such surveys. We provide a comprehensive theoretical and practical framework for estimating and fitting this from data, analogous to well understood techniques used to measure the galaxy density power spectrum from redshift surveys. We formally derive a new estimator, which includes the effects of shot noise and survey geometry; we evaluate the variance of the estimator in the Gaussian regime; we compute the optimal weights for the estimator; we demonstrate that the measurements are Gaussian distributed, allowing for easy extraction of cosmological parameters; and we explore the effects of peculiar velocity measurement errors. We finish with a proof-of-concept using realistic mock galaxy catalogues, which demonstrates that we can measure and fit both the redshift-space galaxy density and momentum power spectra from peculiar velocity surveys and that including the latter substantially improves our constraints on the growth rate of structure. We also provide theoretical descriptions for modelling the non-linear redshift-space density and momentum power spectrum multipoles, and forecasting the constraints on cosmological parameters using the Fisher information contained in these measurements for arbitrary weights. These may be useful for measurements of the galaxy density power spectrum even in the absence of peculiar velocities., Comment: 22+3 Pages, 14 Figures. Accepted for publication in MNRAS. This is the first in "The Redshift-Space Momentum Power Spectrum" series of papers; Paper II applies this work to current data

We present the final distance measurements for the 2MASS Tully-Fisher (2MTF) survey. The final 2MTF catalogue contains 2,062 nearby spiral galaxies in the CMB frame velocity range of 600 km s$^{-1}$ $< cz < 10,000$ km s$^{-1}$ with a mean velocity of 4,805 km s$^{-1}$. The main update in this release is the replacement of some archival HI data with newer ALFALFA data. Using the 2MTF template relation, we calculate the distances and peculiar velocities of all 2MTF galaxies. The mean uncertainties of the linear distance measurements are around 22\% in all three infrared bands. 2MTF measurements agree well with the distances from the Cosmicflows-3 compilation, which contains 1,117 common galaxies, including 28 with SNIa distance measurements. Using distances estimated from the `3-bands combined' 2MTF sample and a $\chi^2$ minimization method, we find best-fit bulk flow amplitudes of $308 \pm 26$ km s$^{-1}$, $318 \pm 29$ km s$^{-1}$, and $286 \pm 25$ km s$^{-1}$ at depths of $R_I = $ 20, 30 and 40 $h^{-1}{\rm Mpc}$, respectively, which is consistent with the $\Lambda$CDM model and with previous 2MTF results with different estimation techniques and a preliminary catalogue., Comment: 8 pages, 6 figures, 2 tables, accepted for publication in MNRAS

(Abridged) The Maunakea Spectroscopic Explorer (MSE) is an end-to-end science platform for the design, execution and scientific exploitation of spectroscopic surveys. It will unveil the composition and dynamics of the faint Universe and impact nearly every field of astrophysics across all spatial scales, from individual stars to the largest scale structures in the Universe. Major pillars in the science program for MSE include (i) the ultimate Gaia follow-up facility for understanding the chemistry and dynamics of the distant Milky Way, including the outer disk and faint stellar halo at high spectral resolution (ii) galaxy formation and evolution at cosmic noon, via the type of revolutionary surveys that have occurred in the nearby Universe, but now conducted at the peak of the star formation history of the Universe (iii) derivation of the mass of the neutrino and insights into inflationary physics through a cosmological redshift survey that probes a large volume of the Universe with a high galaxy density. MSE is positioned to become a critical hub in the emerging international network of front-line astronomical facilities, with scientific capabilities that naturally complement and extend the scientific power of Gaia, the Large Synoptic Survey Telescope, the Square Kilometer Array, Euclid, WFIRST, the 30m telescopes and many more., Comment: 9 chapters, 301 pages, 100 figures. This version of the DSC is a comprehensive update of the original version, released in 2016, which can be downloaded at arXiv:1606.00043. A detailed summary of the design of MSE is available in the MSE Book 2018, available at arXiv:1810.08695

This document summarizes the science cases related to cosmology studies with the MaunaKea Spectroscopic Explorer (MSE), a highly-multiplexed (4332 fibers), wide FOV (1.5 sq deg), large aperture (11.25 m in diameter), optical/NIR (360nm to 1300nm) facility. The MSE High-z Cosmology Survey is designed to probe a large volume of the Universe with a galaxy density sufficient to measure the extremely-large-scale density fluctuations required to explore primordial non-Gaussianity and therefore inflation. We expect a measurement of the local parameter $f_{NL}$ to a precision $\sigma(f_{NL}) = 1.8$. Combining the MSE High-z Cosmology Survey data with data from a next generation CMB stage 4 experiment and existing DESI data will provide the first $5\sigma$ confirmation of the neutrino mass hierarchy from astronomical observations. In addition, the Baryonic Acoustic Oscillations (BAO) observed within the sample will provide measurements of the distance-redshift relationship in six different redshift bins between $z=1.6$ and 4.0, each with an accuracy of $\sim0.6\%$. The simultaneous measurements of Redshift Space Distortions (RSD) constrain the amplitude of the fluctuations, at a level ranging from $1.9\%$ to $3.6\%$. The proposed survey covers 10,000 ${\rm deg}^2$, measuring redshifts for three classes of target objects: Emission Line Galaxies (ELGs) with $1.6

The low-order kinematic moments of galaxies, namely bulk flow and shear, enables us to test whether theoretical models can accurately describe the evolution of the mass density field in the nearby Universe. We use the so-called etaMLE maximum likelihood estimator in logdistance space to measure thesemoments from a combined sample of the 2MASS Tully-Fisher (2MTF) survey and the COSMICFLOWS-3 (CF3) compilation. Galaxies common between 2MTF and CF3 demonstrate a small zero-point difference of -0.016+-0.002 dex.We test the etaMLE on 16 mock 2MTF survey catalogues in order to explore how well the etaMLE recovers the true moments, and the effect of sample anisotropy. On the scale size of 37 Mpc/h, we find that the bulk flow of the local Universe is 259 +- 15 km/h in the direction is (l,b)=(300+-4, 23+-3) (Galactic coordinates). The average shear amplitude is 1.7+-0.4 h km/s/Mpc. We use a variable window function to explore the bulk and shear moments as a function of depth. In all cases, the measurements are consistent with the predictions of the L cold dark matter (LCDM) model., Comment: 11 pages, 10+2 figures, published in MNRAS, Oct/2018

Most statistical inference from cosmic large-scale structure relies on two-point statistics, i.e.\ on the galaxy-galaxy correlation function (2PCF) or the power spectrum. These statistics capture the full information encoded in the Fourier amplitudes of the galaxy density field but do not describe the Fourier phases of the field. Here, we quantify the information contained in the line correlation function (LCF), a three-point Fourier phase correlation function. Using cosmological simulations, we estimate the Fisher information (at redshift $z=0$) of the 2PCF, LCF and their combination, regarding the cosmological parameters of the standard $\Lambda$CDM model, as well as a Warm Dark Matter (WDM) model and the $f(R)$ and Symmetron modified gravity models. The galaxy bias is accounted for at the level of a linear bias. The relative information of the 2PCF and the LCF depends on the survey volume, sampling density (shot noise) and the bias uncertainty. For a volume of $1h^{-3}\rm Gpc^3$, sampled with points of mean density $\bar{n} = 2\times10^{-3} h^{3}\ \rm Mpc^{-3}$ and a bias uncertainty of 13\%, the LCF improves the parameter constraints by about 20\% in the $\Lambda$CDM cosmology and potentially even more in alternative models. Finally, since a linear bias only affects the Fourier amplitudes (2PCF), but not the phases (LCF), the combination of the 2PCF and the LCF can be used to break the degeneracy between the linear bias and $\sigma_8$, present in 2-point statistics., Comment: Accepted for Publication in MNRAS. 12 pages, 7 figures

In this short note we publish the analytic quantile function for the Navarro, Frenk & White (NFW) profile. All known published and coded methods for sampling from the 3D NFW PDF use either accept-reject, or numeric interpolation (sometimes via a lookup table) for projecting random Uniform samples through the quantile distribution function to produce samples of the radius. This is a common requirement in N-body initial condition (IC), halo occupation distribution (HOD), and semi-analytic modelling (SAM) work for correctly assigning particles or galaxies to positions given an assumed concentration for the NFW profile. Using this analytic description allows for much faster and cleaner code to solve a common numeric problem in modern astronomy. We release R and Python versions of simple code that achieves this sampling, which we note is trivial to reproduce in any modern programming language., Comment: 3 pages, 1 figure. R and Python versions of the code can be found at https://github.com/asgr/NFWdist and https://github.com/CullanHowlett/NFWdist respectively

We create a combined sample of 10,904 late and early-type galaxies from the 2MTF and 6dFGSv surveys in order to accurately measure bulk flow in the local Universe. Galaxies and groups of galaxies common between the two surveys are used to verify that the difference in zero-points is $<0.02$ dex. We introduce a maximum likelihood estimator ($\eta$MLE) for bulk flow measurements which allows for more accurate measurement in the presence non-Gaussian measurement errors. To calibrate out residual biases due to the subtle interaction of selection effects, Malmquist bias and anisotropic sky distribution, the estimator is tested on mock catalogues generated from 16 independent large-scale GiggleZ and SURFS simulations. The bulk flow of the local Universe using the combined data set, corresponding to a scale size of 40 h$^{-1}$ Mpc, is $288\pm24$ km s$^{-1}$ in the direction $(l,b)=(296\pm6^{\circ}, 21\pm5^{\circ})$. This is the most accurate bulk flow measurement to date, and the amplitude of the flow is consistent with the $\Lambda$CDM expectation for similar size scales., Comment: 17 pages, 14+6 figures, published in MNRAS, May/2018

We perform a detailed analysis of the covariance matrix of the spherically averaged galaxy power spectrum and present a new, practical method for estimating this within an arbitrary survey without the need for running mock galaxy simulations that cover the full survey volume. The method uses theoretical arguments to modify the covariance matrix measured from a set of small-volume cubic galaxy simulations, which are computationally cheap to produce compared to larger simulations and match the measured small-scale galaxy clustering more accurately than is possible using theoretical modelling. We include prescriptions to analytically account for the window function of the survey, which convolves the measured covariance matrix in a non-trivial way. We also present a new method to include the effects of supersample covariance and modes outside the small simulation volume which requires no additional simulations and still allows us to scale the covariance matrix. As validation, we compare the covariance matrix estimated using our new method to that from a brute force calculation using 500 simulations originally created for analysis of the Sloan Digital Sky Survey Main Galaxy Sample (SDSS-MGS). We find excellent agreement on all scales of interest for large scale structure analysis, including those dominated by the effects of the survey window, and on scales where theoretical models of the clustering normally break-down, but the new method produces a covariance matrix with significantly better signal-to-noise. Although only formally correct in real-space, we also discuss how our method can be extended to incorporate the effects of Redshift Space Distortions., Comment: 18 pages, 9 figures. Accepted for publication in MNRAS. Added new references to introduction and slightly updated text accordingly

We investigate measuring the peculiar motions of galaxies up to $z=0.5$ using Type Ia supernovae (SNe Ia) from LSST, and predict the subsequent constraints on the growth rate of structure. We consider two cases. Our first is based on measurements of the volumetric SNe Ia rate and assumes we can obtain spectroscopic redshifts and light curves for varying fractions of objects that are detected pre-peak luminosity by LSST (some of which may be obtained by LSST itself and others which would require additional follow-up). We find that these measurements could produce growth rate constraints at $z<0.5$ that significantly outperform those using Redshift Space Distortions (RSD) with DESI or 4MOST, even though there are $\sim4\times$ fewer objects. For our second case, we use semi-analytic simulations and a prescription for the SNe Ia rate as a function of stellar mass and star formation rate to predict the number of LSST SNe IA whose host redshifts may already have been obtained with the Taipan+WALLABY surveys, or with a future multi-object spectroscopic survey. We find $\sim 18,000$ and $\sim 160,000$ SN Ia with host redshifts for these cases respectively. Whilst this is only a fraction of the total LSST-detected SNe Ia, they could be used to significantly augment and improve the growth rate constraints compared to only RSD. Ultimately, we find that combining LSST SNe Ia with large numbers of galaxy redshifts will provide the most powerful probe of large scale gravity in the $z<0.5$ regime over the coming decades., Comment: 12 pages, 1 table, 5 figures. Accepted for publication in ApJ. The Fisher matrix forecast code used in this paper can be found at: https://github.com/CullanHowlett/PV_fisher. Updated to fix error in Eq. 1 (thanks to Eric Linder for pointing this out)

We present measurements of the velocity power spectrum and constraints on the growth rate of structure $f\sigma_{8}$, at redshift zero, using the peculiar motions of 2,062 galaxies in the completed 2MASS Tully-Fisher survey (2MTF). To accomplish this we introduce a model for fitting the velocity power spectrum including the effects of non-linear Redshift Space Distortions (RSD), allowing us to recover unbiased fits down to scales $k=0.2\,h\,{\rm Mpc}^{-1}$ without the need to smooth or grid the data. Our fitting methods are validated using a set of simulated 2MTF surveys. Using these simulations we also identify that the Gaussian distributed estimator for peculiar velocities of \cite{Watkins2015} is suitable for measuring the velocity power spectrum, but sub-optimal for the 2MTF data compared to using magnitude fluctuations $\delta m$, and that, whilst our fits are robust to a change in fiducial cosmology, future peculiar velocity surveys with more constraining power may have to marginalise over this. We obtain \textit{scale-dependent} constraints on the growth rate of structure in two bins, finding $f\sigma_{8} = [0.55^{+0.16}_{-0.13},0.40^{+0.16}_{-0.17}]$ in the ranges $k = [0.007-0.055, 0.55-0.150]\,h\,{\rm Mpc}^{-1}$. We also find consistent results using four bins. Assuming scale-\textit{independence} we find a value $f\sigma_{8} = 0.51^{+0.09}_{-0.08}$, a $\sim16\%$ measurement of the growth rate. Performing a consistency check of General Relativity (GR) and combining our results with CMB data only we find $\gamma = 0.45^{+0.10}_{-0.11}$, a remarkable constraint considering the small number of galaxies. All of our results are completely independent of the effects of galaxy bias, and fully consistent with the predictions of GR (scale-independent $f\sigma_{8}$ and $\gamma\approx0.55$)., Comment: 18 pages, 14 figures, 3 tables. Accepted for publication in MNRAS