A Link to the Past: Using Markov Chain Monte Carlo Fitting to Constrain Fundamental Parameters of High-Redshift Galaxies

Abstract

We have a developed a new method for fitting spectral energy distributions (SEDs) to identify and constrain the physical properties of high-redshift (4 < z < 8) galaxies. Our approach uses an implementation of Bayesian based Markov Chain Monte Carlo (PiMC^2) that allows us to compare observations to arbitrarily complex models and to compute 95% credible intervals that provide robust constraints for the model parameters. The work is presented in 2 sections. In the first, we test PiMC^2 using simulated SEDs to not only confirm the recovery of the known inputs but to assess the limitations of the method and identify potential hazards of SED fitting when applied specifically to high redshift (z>4) galaxies. Our tests reveal five critical results: 1) the ability to confidently constrain metallicity, population ages, and Av all require photometric accuracy better than what is currently achievable (i.e. less than a few percent); 2) the ability to confidently constrain stellar masses (within a factor of two) can be achieved without the need for high-precision photometry; 3) the addition of IRAC photometry does not guarantee that tighter constraints of the stellar masses and ages can be defined; 4) different assumptions about the star formation history can lead to significant biases in mass and age estimates; and 5) we are able to constrain stellar age and Av of objects that are both young and relatively dust free. In the second part of the paper we apply PiMC^2 to 17 4<z<8 objects, including the GRAPES Ly alpha sample (4<z<6), supplemented by HST/WFC3 near-IR observations, and several broad band selected z>6 galaxies. Using PiMC^2, we are able to constrain the stellar mass of these objects and in some cases their stellar age and find no evidence that any of these sources formed at a redshift much larger than z_f=8, a time when the Universe was ~ 0.6 Gyr old.

Submitted to ApJ (Full abstract, 47 pages, 17 figures, 7 tables)

References in corpus (30)

• Stellar population synthesis at the resolution of 2003
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• Starburst99: Synthesis Models for Galaxies with Active Star Formation
• The Optical and Near-Infrared Properties of Galaxies: I. Luminosity and Stellar Mass Functions
• Evolutionary population synthesis: models, analysis of the ingredients and application to high-z galaxies
• Bayes in the sky: Bayesian inference and model selection in cosmology
• The Hubble Ultra Deep Field
• The Evolution of the Global Stellar Mass Density at 0 < z < 3
• Evidence for TP-AGB stars in high redshift galaxies, and their effect on deriving stellar population parameters
• Rest-frame ultraviolet-to-optical spectral characteristics of extremely metal-poor and metal-free galaxies
• The impact of nebular emission on the ages of z~6 galaxies
• Star formation rates and stellar masses of z=7-8 galaxies from IRAC observations of the WFC3/IR ERS and the HUDF field
• The luminosity function, halo masses and stellar masses of luminous Lyman-break galaxies at redshifts 5<z<6
• Evidence for a Massive Post-Starburst Galaxy at z ~ 6.5
• Optical to mid-IR observations of Lyman-alpha galaxies at redshift 5 in the HUDF: a young and low mass population
• Discovery of a Very Bright Strongly-Lensed Galaxy Candidate at z ~ 7.6
• GRAPES, Grism Spectroscopy of the Hubble Ultra Deep Field: Description and Data Reduction
• A multi-wavelength study of z = 3.15 Lyman-alpha emitters in the GOODS South Field
• The 1-1000 micron SEDs of far-infrared galaxies
• Discovery of a possibly old galaxy at $z=6.027$, multiply imaged by the massive cluster Abell 383
• The Importance of Nebular Continuum and Line Emission in Observations of Young Massive Star Clusters
• SED fitting with Markov Chain Monte Carlo: Methodology and Application to z=3.1 Lyman Alpha Emitting Galaxies
• CIGALEMC: Galaxy Parameter Estimation using a Markov Chain Monte Carlo Approach with Cigale
• The Stellar Population of Lyman-alpha Emitting Galaxies at z ~ 5.7
• The impact of nebular emission on the broadband fluxes of high-redshift galaxies
• Bright Strongly Lensed Galaxies at Redshift z~ 6-7 behind the Clusters Abell 1703 and CL0024+161
• The nature of z ~ 2.3 Lyman-alpha emitters
• On Lya emission in z~3-6 UV-selected galaxies
• Unveiling the Sigma-Discrepancy in IR-Luminous Mergers I: Dust & Dynamics
• Ly-alpha emitters in the GOODS-S field: a powerful pure nebular SED with N IV] emission at z=5.563

Cited by in corpus (20)

• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• CLASH: Three Strongly Lensed Images of a Candidate z ~ 11 Galaxy
• The mass evolution of the first galaxies: stellar mass functions and star formation rates at $4<z<7$ in the CANDELS GOODS-South field
• The spectral evolution of the first galaxies. II. Spectral signatures of Lyman continuum leakage from galaxies in the reionization epoch
• AGNfitter: A Bayesian MCMC approach to fitting spectral energy distributions of AGN
• Physical Properties of Spectroscopically-Confirmed Galaxies at z >= 6. I. Basic Characteristics of the Rest-Frame UV Continuum and Lyman-alpha emission
• Emission-Line Galaxies from the Hubble Space Telescope Probing Evolution and Reionization Spectroscopically (PEARS) Grism Survey. II: The Complete Sample
• Learning the Relationship between Galaxies Spectra and their Star Formation Histories using Convolutional Neural Networks and Cosmological Simulations
• SATMC: Spectral Energy Distribution Analysis Through Markov Chains
• A Comprehensive Bayesian Discrimination of the Simple Stellar Population Model, Star Formation History and Dust Attenuation Law in the Spectral Energy Distribution Modeling of Galaxies
• Physical Properties of Spectroscopically-Confirmed Galaxies at $z\ge 6$. III. Stellar Populations from SED Modeling with Secure Ly$\alpha$ Emission and Redshifts
• Metallicities of Emission-Line Galaxies from HST ACS PEARS and HST WFC3 ERS Grism Spectroscopy at 0.6 < z < 2.4
• JWST/MIRI Simulated Imaging: Insights into Obscured Star-Formation and AGN for Distant Galaxies in Deep Surveys
• An embedded active nucleus in the OH megamaser galaxy IRAS16399-0937
• Evidence for Reduced Specific Star Formation Rates in the Centers of Massive Galaxies at z = 4
• Real or Interloper? The Redshift Likelihoods of z>8 Galaxies in the HUDF12
• Probing the Physical Properties of z=4.5 Lyman Alpha Emitters with Spitzer
• Not In Our Backyard: Spectroscopic Support for the CLASH z=11 Candidate MACS0647-JD
• Physical and Morphological Properties of [O II] Emitting Galaxies in the HETDEX Pilot Survey
• Survey design for Spectral Energy Distribution fitting: a Fisher Matrix approach