Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 0911.3151

The propagation of uncertainties in stellar population synthesis modeling III: model calibration, comparison, and evaluation

Charlie Conroy·James E. Gunn
View original source ↗Read source document ↗Export metadata ↓

Abstract

Stellar population synthesis (SPS) provides the link between the stellar and dust content of galaxies and their observed spectral energy distributions. In the present work we perform a comprehensive calibration of our own flexible SPS (FSPS) model against a suite of data. Several public SPS models are intercompared, including the models of Bruzual & Charlot (BC03), Maraston (M05) and FSPS. The relative strengths and weaknesses of these models are evaluated, with the following conclusions: 1) The FSPS and BC03 models compare favorably with MC data at all ages, whereas M05 colors are too red and the age-dependence is incorrect; 2) All models yield similar optical and near-IR colors for old metal-poor systems, and yet they all provide poor fits to the integrated J-K and V-K colors of both MW and M31 star clusters; 4) All models predict ugr colors too red, D4000 strengths too strong and Hdelta strengths too weak compared to massive red sequence galaxies, under the assumption that such galaxies are composed solely of old metal-rich stars; 5) FSPS and, to a lesser extent, BC03 can reproduce the optical and near-IR colors of post-starburst galaxies, while M05 cannot. Reasons for these discrepancies are explored. The failure at predicting the ugr colors, D4000, and Hdelta strengths can be explained by some combination of a minority population of metal-poor stars, young stars, blue straggler and/or blue horizontal branch stars, but not by appealing to inadequacies in either theoretical stellar atmospheres or canonical evolutionary phases (e.g., the main sequence turn-off). We emphasize that due to a lack of calibrating star cluster data in regions of the metallicity-age plane relevant for galaxies, all of these models continue to suffer from serious uncertainties that are difficult to quantify. (ABRIDGED)

Explore related subjects

astro-ph.CO

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Charlie Conroy, James E. Gunn. 2009-11-17. The propagation of uncertainties in stellar population synthesis modeling III: model calibration, comparison, and evaluation. https://doi.org/10.1088/0004-637x%2F712%2F2%2F833

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

CHEX-MATE: AMALGAM weak-lensing analysis of 41 Planck Sunyaev-Zel'dovich-selected galaxy clusters

We present a weak-lensing shear analysis of 41 Planck SZ-selected galaxy clusters at $0.11\le z\le 0.55$ from the CHEX-MATE sample, using wide-field Subaru/Suprime-Cam and CFHT/MegaPrime imaging from the AMALGAM project. We detect the azimuthally averaged weak-lensing signal around the X-ray peak of each cluster, achieving a median S/N of 6.5 per cluster. The $45^\circ$-rotated component has a median S/N of -0.1 and ranges from -1.8 to +1.8, consistent with zero. We model the excess surface mass density profile of each cluster with an NFW profile to infer weak-lensing mass and concentration constraints. The total systematic uncertainty in the weak-lensing mass calibration is assessed to be $8\%$. Using a hierarchical Bayesian framework, we then derive weak-lensing-calibrated scaling relations for the halo concentration, $c_{200}$, as a function of $M_{200}$ and redshift, and for the Planck SZ mass proxy, $M_{SZ}$, as a function of $M_{500}$ and redshift, while accounting for sample selection effects, weak-lensing modelling biases, and residual calibration uncertainty. At $M_{200}=10^{15}M_\odot$ and $z=0.25$, we find $c_{200}=3.53\pm0.71$ with an intrinsic scatter of $0.22\pm0.04$ dex. The inferred normalisation and scatter are consistent with recent $Λ$CDM predictions for massive haloes, with no significant mass or redshift dependence over the probed range. For the Planck mass proxy, our baseline regression yields $M_{SZ}/M_{500}=0.83\pm0.09$ at $M_{500}=7\times10^{14}M_\odot$ and $z=0.25$, with an intrinsic scatter of $0.10\pm0.02$ dex. A restricted model with fixed unit mass slope and no redshift evolution gives $1-b=0.72\pm0.11$. We also provide weak-lensing-calibrated posterior estimates of $M_{500}$ for the sample based on the baseline $M_{SZ}$--$M_{500}$--$z$ relation. These results provide an initial weak-lensing mass calibration for CHEX-MATE multi-probe cluster studies.

astro-ph.CO↗
arXiv2026

Dynamics of Biased Domain Walls: The Rocket Effect

We investigate the dynamics of domain walls in scalar field theories with degenerate vacua (i.e., vacua of equal energy density) in which the scalar field mass depends on the vacuum state. Using analytical arguments and numerical simulations, we show that this vacuum dependence of the scalar field mass renders the emission of scalar radiation from domain walls anisotropic, preferentially toward regions with smaller scalar field mass. We further show that the resulting recoil (rocket) effect biases the evolution of cosmological domain wall networks in favor of the lower-mass vacuum, thereby promoting network decay. We also demonstrate that the biased evolution of domain walls in theories with degenerate vacua, previously attributed to asymmetries of the potential barrier near the local maximum, is instead primarily controlled by the vacuum dependence of the scalar field mass. More generally, in theories with non-degenerate vacua, this recoil mechanism constitutes an additional source of dynamical bias that can either hasten or delay network decay relative to the standard expectation based solely on differences in vacuum energy density.

astro-ph.CO↗
arXiv2026

Multi-tracer mass bias in matched cosmic voids from SDSS DR7 and the ELUCID constrained simulation

Cosmic voids provide a unique environment for studying the relationship between galaxies, subhaloes, and dark matter in the underdense Universe. Using the SDSS galaxy catalogue and the ELUCID constrained simulation, we establish an observationally anchored framework for measuring multi-tracer mass bias within matched cosmic voids. A sample of 102 matched void pairs is constructed to directly compare galaxy, subhalo, and dark matter mass distributions within an observationally constrained realisation of the local Universe. We find that both the galaxy-to-dark matter and subhalo-to-dark matter mass ratios decrease toward void centres, indicating that luminous and halo tracers become increasingly depleted relative to the underlying matter distribution in the deepest underdensities. In contrast, the galaxy-to-subhalo mass ratio exhibits substantially larger statistical uncertainties within the inner void regions ($r/R_{\rm v}\lesssim0.5$). By comparing measurements obtained using independent and common coordinate frameworks, we show that coordinate offsets contribute to the observed scatter but cannot fully account for the large uncertainties. The remaining uncertainty primarily arises from the severe scarcity of massive subhaloes ($\log_{10}(M_{\rm sub}/h^{-1}M_\odot)\ge11.8$) within void interiors, which greatly reduces the number of statistically valid measurements near void centres. Our results provide an empirical characterization of multi-tracer mass bias in observationally constrained cosmic environments and demonstrate the importance of accounting for coordinate consistency and tracer scarcity when interpreting such measurements in extreme underdense regions.

astro-ph.CO↗