arXiv subjects

Samuel Goldstein

Publications and source records attributed to Samuel Goldstein.

At least 19 recordsLinked to original sources

arXiv2026

Engineered broadband Purcell protection using a shared $\Pi$-filter for multiplexed superconducting qubits

We propose a broadband Purcell-protection scheme based on a single shared filter integrated directly into the feedline, enabling simultaneous protection of multiple qubits in a compact architecture with minimal hardware overhead. The filter consists of two open-ended stubs connected by an in-line transmission line, forming a $\Pi$ geometry, and operates via engineered passive microwave interference that suppresses the real part of the environmental admittance over a wide frequency window. Circuit simulations and finite-element modeling show strong suppression of transmission within the target band (the qubit's frequencies) while preserving the readout and reset modes of the multiplexed architecture. For realistic device parameters, the proposed design yields Purcell-limited relaxation times exceeding $1$ ms over a frequency span of approximately $1.5$ GHz, which can be further extended with straightforward modifications of the design. Our results establish the $\Pi$-filter as a compact and scalable solution for broadband impedance engineering in superconducting quantum circuits, compatible with standard dispersive readout protocols.

quant-ph↗

arXiv2026

If at First You Don't Succeed, Trispectrum: I. Estimating the Matter Power Spectrum Covariance with Higher-Order Statistics

We present a method to estimate non-Gaussian power spectrum covariance matrices by directly measuring the response of the small-scale power spectrum to long-wavelength perturbations via bispectrum and trispectrum estimators. Specifically, we derive estimators for the complete non-Gaussian matter power spectrum covariance, including the super-sample contribution, in terms of the squeezed bispectrum and collapsed trispectrum of the underlying density field. We apply these estimators to the Quijote simulations, and recover unbiased estimates of the small-scale ($k\gtrsim 0.15~h/{\rm Mpc}$) matter power spectrum covariance at the percent level using only 25 simulations - comparable to the precision of the sample covariance estimated using 5,000 simulations. This technique significantly reduces the number of simulations needed to estimate power spectrum covariances and opens the possibility of inferring power spectrum covariances directly from survey data, enabling stringent tests of simulations and, potentially, power spectrum analyses that do not rely on external covariance matrices.

astro-ph.CO↗

arXiv2026

A 2% determination of $N_{\rm eff}$ from primordial element abundance, cosmic microwave background, and baryon acoustic oscillation measurements

We present a new constraint on the effective number of relativistic species in the early universe, $N_{\rm eff}$, by combining recent primordial helium abundance measurements from the Large Binocular Telescope $Y_p$ Project with primordial deuterium abundance data, cosmic microwave background (CMB) observations from $\it{Planck}$, the Atacama Cosmology Telescope, and the South Pole Telescope, and baryon acoustic oscillation (BAO) data from the Dark Energy Spectroscopic Instrument, yielding $N_{\rm eff}=2.990\pm0.070$ (68% C.L.). This is the tightest constraint on $N_{\rm eff}$ to date, and is in excellent agreement with the standard model prediction of $N_{\rm eff}=3.044$. Furthermore, we constrain excess contributions to $N_{\rm eff}$ beyond the three neutrino species, finding $\Delta N_{\rm eff}<0.107$ (95% C.L.). This bound nearly approaches the minimum contribution to $\Delta N_{\rm eff}$ from a light spin-3/2 particle that decoupled at any time after inflation ended. Our baseline analysis does not include large-scale $\it{Planck}$ polarization information, enabling a fully consistent combination of state-of-the-art CMB and BAO measurements. As a byproduct, we show that current $N_{\rm eff}$ bounds are essentially insensitive to the inclusion or exclusion of optical depth constraints inferred from large-scale CMB polarization data, making $N_{\rm eff}$ highly robust in this regard. Our constraints place stringent limits on light particles in the early Universe and on a broad range of models aimed at increasing the CMB-inferred value of the Hubble constant.

astro-ph.CO↗

arXiv2025

Evidence of galaxy cluster rotation in the cosmic microwave background

We report the first robust evidence for the rotational kinematic Sunyaev-Zel'dovich (rkSZ) effect, produced by the Thomson scattering of cosmic microwave background (CMB) photons off rotating intracluster gas. By combining CMB intensity and polarization measurements from the $\it{Planck}$ satellite with spectroscopic member-galaxy redshifts from the Sloan Digital Sky Survey in a sample of 25 X-ray cross-matched, low-redshift ($0.02< z< 0.09)$, massive ($10^{13.9}\lesssim M_{\rm 500c}/M_\odot \lesssim 10^{14.6}$) galaxy clusters, we detect a dipolar rkSZ signature aligned with the estimated rotation direction of each cluster, ruling out a chance fluctuation at 99.98% confidence (3.6$\sigma$). The significance of this measurement is enhanced by several new methodological improvements for isolating the rkSZ signal from primary CMB fluctuations and noise. The amplitude and shape of the signal are qualitatively consistent with predictions from state-of-the-art hydrodynamical simulations. These results establish a new tool with which to probe the dynamical state of galaxy clusters using CMB data.

astro-ph.CO↗

arXiv2025

Monodromic Dark Energy and DESI

Recent baryon acoustic oscillation (BAO) measurements from the Dark Energy Spectroscopic Instrument (DESI) collaboration have renewed interest in dynamical dark energy models, particularly those that cross the "phantom divide" ($w_{\rm DE} = -1$). We present the first observational constraints on monodromic k-essence, a physically motivated scalar field dark energy scenario capable of realizing rapid oscillations about the phantom divide. Using cosmic microwave background (CMB) information, DESI DR2 BAO measurements, and Type Ia supernovae observations, we constrain the amplitude, frequency, phase, and power-law index describing the monodromic k-essence scenario at the background level. We find that the monodromic dark energy scenario can fit these datasets with a $\chi^2$ that is comparable to the phenomenological $w_0$-$w_a$ parametrization. While the CMB and BAO data alone are consistent with the standard $\Lambda$CDM model, the inclusion of DESY5 supernovae shows a preference for a non-zero amplitude, $A=0.44^{+0.16}_{-0.12}$ (fully marginalized 68% C.L.). Conversely, inclusion of the Pantheon-Plus supernovae provides no evidence for monodromic k-essence, with $A<0.43$ (95% C.L.). We show that constraints on both monodromic dark energy and $w_0$-$w_a$ models are sensitive to the DESI DR2 LRG2 BAO distance, especially in the absence of supernovae data.

astro-ph.CO↗

arXiv2025

The Atacama Cosmology Telescope: DR6 Power Spectrum Foreground Model and Validation

We discuss the model of astrophysical emission at millimeter wavelengths used to characterize foregrounds in the multi-frequency power spectra of the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6), expanding on Louis et al. (2025). We detail several tests to validate the capability of the DR6 parametric foreground model to describe current observations and complex simulations, and show that cosmological parameter constraints are robust against model extensions and variations. We demonstrate consistency of the model with pre-DR6 ACT data and observations from Planck and the South Pole Telescope. We evaluate the implications of using different foreground templates and extending the model with new components and/or free parameters. In all scenarios, the DR6 $\Lambda$CDM and $\Lambda$CDM+$N_{\rm eff}$ cosmological parameters shift by less than $0.5\sigma$ relative to the baseline constraints. Some foreground parameters shift more; we estimate their systematic uncertainties associated with modeling choices. From our constraint on the kinematic Sunyaev-Zel'dovich power, we obtain a conservative limit on the duration of reionization of $\Delta z_{\rm rei} < 4.4$, assuming a reionization midpoint consistent with optical depth measurements and a minimal low-redshift contribution, with varying assumptions for this component leading to tighter limits. Finally, we analyze realistic non-Gaussian, correlated microwave sky simulations containing Galactic and extragalactic foreground fields, built independently of the DR6 parametric foreground model. Processing these simulations through the DR6 power spectrum and likelihood pipeline, we recover the input cosmological parameters of the underlying cosmic microwave background field, a new demonstration for small-scale CMB analysis. These tests validate the robustness of the ACT DR6 foreground model and cosmological parameter constraints.

astro-ph.CO↗

arXiv2025

Wonderings on Wiggly Bispectra: Non-linear Evolution and Reconstruction of Oscillations in the Squeezed Bispectrum

Oscillations in the primordial bispectrum are sourced by a range of inflationary phenomena, including features in the inflaton potential and interactions with massive fields through the Cosmological Collider scenario. These signatures offer a powerful window into early-universe physics. In this work, we study how oscillations of the form $\lim_{q\ll k}B(q,k)\propto \cos(\mu \ln(q/k))$ impact the non-linear squeezed matter bispectrum. Using a suite of $N$-body simulations with non-Gaussian initial conditions, we show that non-linear evolution significantly damps these oscillations, effectively erasing the signal on scales $k \gtrsim 0.3~h/{\rm Mpc}$ at redshift $z=0$. This damping is well-described by the Zel'dovich approximation and can be modeled deep into the non-linear regime using non-perturbative separate universe simulations. Promisingly, we show that reconstruction techniques developed for baryon acoustic oscillation (BAO) analyses can largely undo this damping, improving constraints on the amplitude (phase) of oscillations in the primordial squeezed bispectrum by up to a factor of five (four) at $z=0$. We also discuss several challenges with modeling the non-linear evolution of the squeezed bispectrum in the Cosmological Collider scenario, where the bispectrum is suppressed by a factor of $(q/k)^{3/2}$ relative to the template studied here. Our findings pave the way for future searches for oscillatory bispectra using large-scale structure data.

astro-ph.CO↗

arXiv2025

The Atacama Cosmology Telescope: DR6 Power Spectra, Likelihoods and $\Lambda$CDM Parameters

We present power spectra of the cosmic microwave background (CMB) anisotropy in temperature and polarization, measured from the Data Release 6 maps made from Atacama Cosmology Telescope (ACT) data. These cover 19,000 deg$^2$ of sky in bands centered at 98, 150 and 220 GHz, with white noise levels three times lower than Planck in polarization. We find that the ACT angular power spectra estimated over 10,000 deg$^2$, and measured to arcminute scales in TT, TE and EE, are well fit by the sum of CMB and foregrounds, where the CMB spectra are described by the $\Lambda$CDM model. Combining ACT with larger-scale Planck data, the joint P-ACT dataset provides tight limits on the ingredients, expansion rate, and initial conditions of the universe. We find similar constraining power, and consistent results, from either the Planck power spectra or from ACT combined with WMAP data, as well as from either temperature or polarization in the joint P-ACT dataset. When combined with CMB lensing from ACT and Planck, and baryon acoustic oscillation data from DESI DR1, we measure a baryon density of $\Omega_b h^2=0.0226\pm0.0001$, a cold dark matter density of $\Omega_c h^2=0.118\pm0.001$, a Hubble constant of $H_0=68.22\pm0.36$ km/s/Mpc, a spectral index of $n_s=0.974\pm0.003$, and an amplitude of density fluctuations of $\sigma_8=0.813\pm0.005$. Including the DESI DR2 data tightens the Hubble constant to $H_0=68.43\pm0.27$ km/s/Mpc; $\Lambda$CDM parameters agree between the P-ACT and DESI DR2 data at the $1.6\sigma$ level. We find no evidence for excess lensing in the power spectrum, and no departure from spatial flatness. The contribution from Sunyaev-Zel'dovich (SZ) anisotropy is detected at high significance; we find evidence for a tilt with suppressed small-scale power compared to our baseline SZ template spectrum, consistent with hydrodynamical simulations with feedback.

astro-ph.CO↗

arXiv2025

The Atacama Cosmology Telescope: DR6 Constraints on Extended Cosmological Models

We use new cosmic microwave background (CMB) primary temperature and polarization anisotropy measurements from the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6) to test foundational assumptions of the standard cosmological model and set constraints on extensions to it. We derive constraints from the ACT DR6 power spectra alone, as well as in combination with legacy data from Planck. To break geometric degeneracies, we include ACT and Planck CMB lensing data and baryon acoustic oscillation data from DESI Year-1, and further add supernovae measurements from Pantheon+ for models that affect the late-time expansion history. We verify the near-scale-invariance (running of the spectral index $d n_s/d\ln k = 0.0062 \pm 0.0052$) and adiabaticity of the primordial perturbations. Neutrino properties are consistent with Standard Model predictions: we find no evidence for new light, relativistic species that are free-streaming ($N_{\rm eff} = 2.86 \pm 0.13$, which combined with external BBN data becomes $N_{\rm eff} = 2.89 \pm 0.11$), for non-zero neutrino masses ($\sum m_\nu < 0.082$ eV at 95% CL), or for neutrino self-interactions. We also find no evidence for self-interacting dark radiation ($N_{\rm idr} < 0.134$), early-universe variation of fundamental constants, early dark energy, primordial magnetic fields, or modified recombination. Our data are consistent with standard BBN, the FIRAS-inferred CMB temperature, a dark matter component that is collisionless and with only a small fraction allowed as axion-like particles, a cosmological constant, and the late-time growth rate predicted by general relativity. We find no statistically significant preference for a departure from the baseline $\Lambda$CDM model. In general, models introduced to increase the Hubble constant or to decrease the amplitude of density fluctuations inferred from the primary CMB are not favored by our data.

astro-ph.CO↗

arXiv2024

Constraints on axions from patchy screening of the cosmic microwave background

The resonant conversion of cosmic microwave background (CMB) photons into axions within large-scale structure induces an anisotropic spectral distortion in CMB temperature maps. Applying state-of-the-art foreground cleaning techniques to $\textit{Planck}$ CMB observations, we construct maps of axion-induced "patchy screening" of the CMB. We cross-correlate these maps with data from the $\textit{unWISE}$ galaxy survey and find no evidence of axions. We constrain the axion-photon coupling, $g_{a\gamma\gamma} \lesssim 2 \times 10^{-12}~{\rm GeV}^{-1}$, at the 95% confidence level for axion masses in the range $10^{-13}~{\rm eV} \lesssim m_a \lesssim 10^{-12}~{\rm eV}$. These constraints are competitive with the tightest astrophysical axion limits in this mass range and are inferred from robust population-level statistics, which makes them complementary to existing searches that rely on modeling of individual systems.

astro-ph.CO↗

arXiv2024

Massive-ish Particles from Small-ish Scales: Non-Perturbative Techniques for Cosmological Collider Physics from Large-Scale Structure Surveys

Massive particles produced during inflation impact soft limits of primordial correlators. Searching for these signatures presents an exciting opportunity to uncover the particle spectrum in the inflationary epoch. We present non-perturbative methods to constrain intermediate-mass scalars ($0\leq m/H<3/2$, where $H$ is the inflationary Hubble scale) produced during inflation, which give rise to a power-law scaling in the squeezed primordial bispectrum. Exploiting the large-scale structure consistency relations and the separate universe approach, we derive models for the late-time squeezed matter bispectrum and collapsed matter trispectrum sourced by these fields. To validate our models, we run $N$-body simulations with the "Cosmological Collider" squeezed bispectrum for two different particle masses. Our models yield unbiased constraints on the amplitude of non-Gaussianity, $f_{\rm NL}^{\Delta}$, from the squeezed bispectrum and collapsed trispectrum deep into the non-linear regime ($k_{\rm max}\approx 2~h/{\rm Mpc}$ at $z=0$). We assess the information content of these summary statistics, emphasizing the importance of sample variance cancellation in the matter sector. We also study the scale-dependent halo bias in our simulations. For mass-selected halos, the non-Gaussian bias estimated from our simulations agrees with predictions based on (i) separate universe simulations and (ii) universal mass functions. With further work, these results can be used to search for inflationary massive particle production with upcoming galaxy surveys.

astro-ph.CO↗

arXiv2023

Consistently constraining $f_{\rm NL}$ with the squeezed lensing bispectrum using consistency relations

We introduce a non-perturbative method to constrain the amplitude of local-type primordial non-Gaussianity ($f_{\rm NL}$) using squeezed configurations of the CMB lensing convergence and cosmic shear bispectra. First, we use cosmological consistency relations to derive a model for the squeezed limit of angular auto- and cross-bispectra of lensing convergence fields in the presence of $f_{\rm NL}$. Using this model, we perform a Fisher forecast with specifications expected for upcoming CMB lensing measurements from the Simons Observatory and CMB-S4, as well as cosmic shear measurements from a Rubin LSST/Euclid-like experiment. Assuming a minimum multipole $\ell_{\rm min}=10$ and maximum multipole $\ell_{\rm max}=1400$, we forecast $\sigma_{f_{\rm NL}}=175$ ($95$) for Simons Observatory (CMB-S4). Our forecasts improve considerably for an LSST/Euclid-like cosmic shear experiment with three tomographic bins and $\ell_{\rm min}=10$ and $\ell_{\rm max}=1400$ ($5000$) with $\sigma_{f_{\rm NL}}=31$ ($16$). A joint analysis of CMB-S4 lensing and LSST/Euclid-like shear yields little gain over the shear-only forecasts; however, we show that a joint analysis could be useful if the CMB lensing convergence can be reliably reconstructed at larger angular scales than the shear field. The method presented in this work is a novel and robust technique to constrain local primordial non-Gaussianity from upcoming large-scale structure surveys that is completely independent of the galaxy field (and therefore any nuisance parameters such as $b_\phi$), thus complementing existing techniques to constrain $f_{\rm NL}$ using the scale-dependent halo bias.

astro-ph.CO↗

arXiv2023

Canonical Hubble-Tension-Resolving Early Dark Energy Cosmologies are Inconsistent with the Lyman-$\alpha$ Forest

Current cosmological data exhibit discordance between indirect and some direct inferences of the present-day expansion rate, $H_0$. Early dark energy (EDE), which briefly increases the cosmic expansion rate prior to recombination, is a leading scenario for resolving this "Hubble tension" while preserving a good fit to cosmic microwave background (CMB) data. However, this comes at the cost of changes in parameters that affect structure formation in the late-time universe, including the spectral index of scalar perturbations, $n_s$. Here, we present the first constraints on axion-like EDE using data from the Lyman-$\alpha$ forest, i.e., absorption lines imprinted in background quasar spectra by neutral hydrogen gas along the line of sight. We consider two independent measurements of the one-dimensional Ly$\alpha$ forest flux power spectrum, from the Sloan Digital Sky Survey (SDSS eBOSS) and from the MIKE/HIRES and X-Shooter spectrographs. We combine these with a baseline dataset comprised of Planck CMB data and baryon acoustic oscillation (BAO) measurements. Combining the eBOSS Ly$\alpha$ data with the CMB and BAO dataset reduces the 95% confidence level (CL) upper bound on the maximum fractional contribution of EDE to the cosmic energy budget, $f_{\rm EDE}$, from 0.07 to 0.03 and constrains $H_0=67.9_{-0.4}^{+0.4}$ km/s/Mpc (68% CL), with maximum a posteriori value $H_0=67.9$ km/s/Mpc. Similar results are obtained for the MIKE/HIRES and X-Shooter Ly$\alpha$ data. Our Ly$\alpha$-based EDE constraints yield $H_0$ values that are in $>4\sigma$ tension with the SH0ES distance-ladder measurement and are driven by the preference of the Ly$\alpha$ forest data for $n_s$ values lower than those required by EDE cosmologies that fit Planck CMB data. Taken at face value, the Ly$\alpha$ forest severely constrains canonical EDE models that could resolve the Hubble tension.

astro-ph.CO↗

arXiv2022

Squeezing $f_{\rm NL}$ out of the matter bispectrum with consistency relations

We show how consistency relations can be used to robustly extract the amplitude of local primordial non-Gaussianity ($f_{\rm NL}$) from the squeezed limit of the matter bispectrum, well into the non-linear regime. First, we derive a non-perturbative relation between primordial non-Gaussianity and the leading term in the squeezed bispectrum, revising some results present in the literature. This relation is then used to successfully measure $f_{\rm NL}$ from $N$-body simulations. We discuss the dependence of our results on different scale cuts and redshifts. Specifically, the analysis is strongly dependent on the choice of the smallest soft momentum, $q_{\rm min}$, which is the most sensitive to primordial bispectrum contributions, but is largely independent of the choice of the largest hard momentum, $k_{\rm max}$, due to the non-Gaussian nature of the covariance. We also show how the constraints on $f_{\rm NL}$ improve at higher redshift, due to a reduced off-diagonal covariance. In particular, for a simulation with $f_{\rm NL} = 100$ and a volume of $(2.4 \text{ Gpc}/h)^3$, we measure $f_{\rm NL} = 98 \pm 12$ at redshift $z=0$ and $f_{\rm NL} = 97 \pm 8$ at $z=0.97$. Finally, we compare our results with a Fisher forecast, showing that the current version of the analysis is satisfactorily close to the Fisher error. We regard this as a first step towards the realistic application of consistency relations to constrain primordial non-Gaussianity using observations.

astro-ph.CO↗

arXiv2022

Beyond dark energy Fisher forecasts: how DESI will constrain LCDM and quintessence models

We baseline with current cosmological observations to forecast the power of the Dark Energy Spectroscopic Instrument (DESI) in two ways: 1. the gain in constraining power of parameter combinations in the standard $\Lambda$CDM model, and 2. the reconstruction of quintessence models of dark energy. For the former task we use a recently developed formalism to extract the leading parameter combinations constrained by different combinations of cosmological survey data. For the latter, we perform a non-parametric reconstruction of quintessence using the Effective Field Theory of Dark Energy. Using mock DESI observations of the Hubble parameter, angular diameter distance, and growth rate, we find that DESI will provide significant improvements over current datasets on $\Lambda$CDM and quintessence constraints. Including DESI mocks in our $\Lambda$CDM analysis improves constraints on $\Omega_m$, $H_0$, and $\sigma_8$ by a factor of two, where the improvement results almost entirely from the angular diameter distance and growth of structure measurements. Our quintessence reconstruction suggests that DESI will considerably improve constraints on a range of quintessence properties, such as the reconstructed potential, scalar field excursion, and the dark energy equation of state. The angular diameter distance measurements are particularly constraining in the presence of a non-$\Lambda$CDM signal in which the potential cannot be accounted for by shifts in $H_0$ and $\Omega_m$.

astro-ph.CO↗

arXiv2022

3D-printed stand, timing interface, and coil localization tools for concurrent TMS-fMRI experiments

Concurrent TMS-fMRI involves administrating TMS while subjects are inside an MRI scanner and allows the study of the effects of neurostimulation on simultaneous brain activity. Despite its high promise, the technique has proven challenging to implement for at least three reasons. First, it is difficult to position and stabilize the TMS coil inside the MRI scanner in a way that precisely targets a pre-specified brain region. Second, standard task-presentation software suffers from imprecise timing, which can lead to TMS causing large image artifacts. Third, it is difficult to verify the exact TMS coil position during scanning. In this paper, we describe solutions to all three of these challenges. First, we develop a 3D-printed TMS stand that is fully adjustable and can reach most areas of the scalp. The stand is compatible with various MR coils and features an adjustable mirror holder. Second, we create an interface that can precisely time the TMS pulses with respect to the fMRI image acquisition with a variance of under 1 ms. Third, we develop software for precisely determining the TMS coil position inside the MRI scanner and computing the location of maximal stimulation. All three tools are either free or inexpensive. We provide detailed instructions for building and implementing these tools to facilitate an efficient and reliable concurrent TMS-fMRI setup.

q-bio.NC↗

arXiv2021

Connecting galaxy evolution in clusters with their radial profiles and phase space distribution: results from the IllustrisTNG hydrodynamical simulations

We study the population of galaxies around galaxy clusters in the hydrodynamic simulation suite IllustrisTNG 300-1 to study the signatures of their evolutionary history on observable properties. We measure the radial number density profile, phase space distribution, and splashback radius for galaxies of different masses and colors over the redshift range $z=0-1$. The three primary physical effects which shape the galaxy distribution within clusters are the galaxy quenching, angular momentum distribution and dynamical friction. We find three distinct populations of galaxies by applying a Gaussian mixture model to their distribution in color and mass. They have distinct evolutionary histories and leave distinct signatures on their distribution around cluster halos. We find that low-mass red galaxies show the most concentrated distribution in clusters and the largest splashback radius, while high-mass red galaxies show a less concentrated distribution and a smaller splashback radius. Blue galaxies, which mostly quench into the low-mass red population, have the shallowest distribution within the clusters, with those on radial orbits quenched rapidly before reaching pericenter. Comparison with the distribution of galaxies from the Dark Energy Survey (DES) survey around Sunyaev-Zeldovich (SZ) clusters from the Atacama Cosmology Telescope (ACT) and South Pole Telescope (SPT) surveys shows evidence for differences in galaxy evolution between simulations and data.

astro-ph.CO↗

arXiv2021

Perturbation theory models for LSST-era galaxy clustering: tests with sub-percent mock catalog measurements in Fourier and configuration space

We analyze the clustering of galaxies using the z=1.006 snapshot of the CosmoDC2 simulation, a high-fidelity synthetic galaxy catalog designed to validate analysis methods for the Large Synoptic Survey Telescope (LSST). We present sub-percent measurements of the galaxy auto-correlation and galaxy-dark matter cross correlations in Fourier space and configuration space for a magnitude-limited galaxy sample. At these levels of precision, the statistical errors of the measurement are comparable to the systematic effects present in the simulation and measurement procedure; nevertheless, using a hybrid-PT model, we are able to model non-linear galaxy bias with 0.5% precision up to scales of $k_{\rm max}= 0.5 \ h/{\rm Mpc}$ and $r_{\rm min}= 4 \ {\rm Mpc}/h$. While the linear bias parameter is measured with 0.01% precision, other bias parameters are determined with considerably weaker constraints and sometimes bimodal posterior distributions. We compare our fiducial model with lower dimensional models where the higher-order bias parameters are fixed at their co-evolution values and find that leaving these parameters free provides significant improvements in our ability to model small scale information. We also compare bias parameters for galaxy samples defined using different magnitude bands and find agreement between samples containing equal numbers of galaxies. Finally, we compare bias parameters between Fourier space and configuration space and find moderate tension between the two approaches. Although our model is often unable to fit the CosmoDC2 galaxy samples within the 0.1% precision of our measurements, our results suggest that the hybrid-PT model used in this analysis is capable of modeling non-linear galaxy bias within the percent level precision needed for upcoming galaxy surveys.

astro-ph.CO↗