Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2303.11024

Mass Metallicity Relationship of SDSS Star Forming Galaxies: Population Synthesis Analysis and Effects of Star Burst Length, Extinction Law, Initial Mass Function and Star Formation Rate

Eva Sextl·Rolf-Peter Kudritzki·H. Jabran Zahid·I-Ting Ho
View original source ↗Read source document ↗Export metadata ↓

Abstract

We investigate the mass-metallicity relationship of star forming galaxies by analysing the absorption line spectra of $\sim$200,000 galaxies in the Sloan Digital Sky Survey. The galaxy spectra are stacked in bins of stellar mass and a population synthesis technique is applied yielding metallicities, ages and star formation history of the young and old stellar population together with interstellar reddening and extinction. We adopt different lengths of the initial starbursts and different initial mass functions for the calculation of model spectra of the single stellar populations contributing to the total integrated spectrum. We also allow for deviations of the ratio of extinction to reddening RV from 3.1 and determine the value from the spectral fit. We find that burst length and RV have a significant influence on the determination of metallicities whereas the effect of the initial mass function is small. RV values are larger than 3.1. The metallicities of the young stellar population agree with extragalactic spectroscopic studies of individual massive supergiant stars and are significantly higher than those of the older stellar population. This confirms galaxy evolution models where metallicity depends on the ratio of gas to stellar mass and where this ratio decreases with time. Star formation history is found to depend on galaxy stellar mass. Massive galaxies are dominated by stars formed at early times.

Explore related subjects

astro-ph.GA

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Eva Sextl, Rolf-Peter Kudritzki, H. Jabran Zahid, I-Ting Ho. 2023-03-20. Mass Metallicity Relationship of SDSS Star Forming Galaxies: Population Synthesis Analysis and Effects of Star Burst Length, Extinction Law, Initial Mass Function and Star Formation Rate. https://doi.org/10.3847/1538-4357%2Facc579

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

KEEP EXPLORING

Related papers

arXiv2026

An extensive universe avoids phantom dark energy

A major challenge in cosmology and astrophysics is the phantom dark energy used to explain the data of DESI DR2 BAO. Assuming that the degrees of freedom of the universe are (d=3) extensive, we find that the linearised Hubble parameter in Tsallis Entropic cosmology is consistent with Cosmic Chronometers (CC) and DESI DR2 data upto z<2.33, avoiding the need for phantom energy while keeping the observed CMB acoustic angular scale constraint. It also obviates the need for a significant density of CDM.

astro-ph.GA↗
arXiv2026

Optimizing Photometric Redshift Training Sets I: Efficient Compression of the Galaxy Color-Redshift Relation with UMAP

Spectroscopic datasets are essential for training and calibrating photometric redshift (photo-$z$) methods. However, spectroscopic redshifts (spec-$z$'s) constitute a biased and sparse sampling of the photometric galaxy population, which creates difficulties for the common grid-based approach for mapping color to redshift using self-organizing maps (SOMs). Instead, we utilized the uniform manifold approximation and projection (UMAP) algorithm to compress a Rubin--Roman-like $ugrizyJH$ color space into a thin and densely-sampled manifold. Crucially, the manifold varies continuously and monotonically in redshift and specific star formation rate in roughly orthogonal directions. Using COSMOS2020 many-band photo-$z$'s and compiled spec-$z$'s as representative and non-representative samples, respectively, we trained and tested redshift prediction from a SOM, from nearest neighbors in UMAP coordinates (UMAP-$k$NN-$z$), and directly from nearest neighbors in the color space to assess how well location in each space maps to redshift. For the representative training set, UMAP-$k$NN-$z$ exhibited smaller photo-$z$ scatter and fraction of outliers than SOM-based methods. When training with the highly-biased spec-$z$ sample, UMAP-$k$NN-$z$ maintained similar performance while SOM- and color-based methods predictions were significantly degraded, especially at $z>1.5$ where training sets are the most sparse. The physically-meaningful trends across the UMAP manifold allow for accurate redshift prediction even in such poorly-sampled regions of color space. This suggests that representative, spectroscopically-anchored training sets can be produced by interpolating between spectroscopic sources at the UMAP coordinates of photometric objects, maximizing the performance of photo-$z$ algorithms.

astro-ph.GA↗
arXiv2026

Characterization of Orbits in Bars in Disc Galaxies Using Fourier Frequencies

Bars are among the most prominent dynamical structures in disc galaxies, yet their long-term evolution and the orbital families that sustain them remain only partially understood. In this work, we introduce a new methodology based on frozen potentials combined with Fourier analysis of particle trajectories to identify regular and sticky orbits in self-consistent $N$-body simulations. This approach allows us to isolate particles belonging to the $x_1$ family, directly associated with the bar, and the $x_2$ family, linked to a secondary perpendicular structure. Tracking these orbits across multiple snapshots enables us to quantify the time evolution of key bar properties, including its mass fraction, semi-axes, and density profile. Compared with established used diagnostics, our method provides the closest match to the temporal behaviour of the Fourier bar-strength parameter $A_2$, while offering a direct dynamical interpretation and full three-dimensional characterization that Fourier-based approaches cannot provide. Our analysis further reveals that the indices $n_x$, $n_y$, and $n_z$ describing the bar density distribution are anisotropic and rarely equal to the canonical $n=2$ assumed in Ferrers profiles, highlighting the limitations of standard analytical approximations. We also find strong correlations between bar growth, orbital chaoticity, and angular momentum redistribution, with the bar acting both as a sink and as a driver of angular momentum transfer. A comparison between the two models analysed shows that rapidly forming bars are weaker and less stable than those that grow more gradually. Altogether, our methodology provides a robust framework for linking orbital structure to the dynamical evolution of barred galaxies.

astro-ph.GA↗