JWST’s PEARLS: Temperatures of Nine Highly Magnified Stars in a Galaxy at Redshift 0.94 and Simulated Stellar Population Dependence on Stellar Metallicity and the Initial Mass Function
Year: 2025
Type: article
Abstract: We present stellar atmosphere modeling of JWST NIRCam photometry of nine highly magnified individual stars in a single galaxy at redshift z = 0.94 known as the Warhol arc, which is strongly lensed by the galaxy cluster MACS J0416. Seven of these transients were identified by Yan et al. The nine sources are likely red supergiants with temperatures T eff ≈ 4000 K. We present new long-slit spectroscopy of the Warhol arc acquired with Keck I telescope and the Large Binocular Telescope, and use these data to help constrain the arc’s oxygen abundance to be 12 + log ( O / H ) = 8.45 ± 0.08 . A microlensing simulation is performed on synthetic stellar populations using a range of stellar metallicities and initial mass function (IMF) slopes. The temperature distribution of the simulated detectable stars is sensitive to the choice of stellar metallicity, and setting the stellar metallicity equal to the arc’s nebular metallicity ( log ( Z * / Z ⊙ ) = − 0.24 ) produces a simulated temperature distribution that is consistent with the observations, while lower stellar metallicities ( log ( Z * / Z ⊙ ) < – 0.75 ) produce simulated temperatures that are inconsistent with the observations. The expected detection rate is strongly anticorrelated with the IMF slope for α > 1.2. For the canonical IMF slope α = 2.35, the simulation yields expected transient detection rates that agree with the observed detection rates in the Hubble Space Telescope Flashlights filters, but overpredicts the detection rate by a factor of ∼3–12 (<2 σ tension) in the JWST filters. The simulated detection rate is sensitive to the choice of stellar metallicity, with lower metallicities ( log ( Z * / Z ⊙ ) < – 0.75 ) yielding a significantly lower simulated detection rate that further reduces the modest tension with the observations.
Source: The Astrophysical Journal
Authors: Hayley Williams, Patrick L. Kelly, Rogier A. Windhorst, Alexei V. Filippenko, Amruth Alfred, Tom Broadhurst, Wenlei Chen, Christopher J. Conselice, Seth H. Cohen, José M. Diego, Benne W. Holwerda, Anton M. Koekemoer, Sung Kei Li, Ashish Kumar Meena, José M. Palencia, Massimo Ricotti, Clayton D. Robertson, Bangzheng Sun, Haojing Yan, Adi Zitrin
Institutions: University of Minnesota, Arizona State University, University of California, Berkeley, University of Hong Kong, Ikerbasque, University of the Basque Country, Donostia International Physics Center, Oklahoma State University, University of Manchester, Instituto de Física de Cantabria, University of Louisville, Space Telescope Science Institute, Ben-Gurion University of the Negev, University of Maryland, College Park, University of Missouri
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Funders: National Science Foundation, National Aeronautics and Space Administration, W. M. Keck Foundation, United States - Israel Binational Science Foundation, California Institute of Technology, Space Telescope Science Institute, United States-Israel Binational Science Foundation, Israel Science Foundation, Goddard Space Flight Center
Awards: G103270039, G1055883707, G256731684, G3077354795, G4096137220, G433322167, G5568641063, G58316358, G6273510985, Luminous High-Redshift Stars and Dark Matter Substructure Using Galaxy Cluster Lenses, NEXT GENERATION FRONTIER STUDIES OF GALAXY FORMATI ON AND EVOLUTION WITH NEXT GENERATION SPACE TELES, G6608474652, G6909262500, THE PROPOSAL SEEKS TO ACCOMPLISH SEVERAL INVESTIGATIONS TO SIMULATE THE PERFORMANCE OF JWST DEEP FIELD SURVEYS, VARYING AS-YET-POORLY CHARACTERIZED P, NSF-BSF: Galaxies in the Reionization Era, G8067020961, IN 2002 WE WERE GRANTED 110 HOURS GTO TIME FOR A JWST MEDIUM-DEEP SURVEY. WITH HST AND SPITZER EXPERIENCE 14 YEARS LATER WE REDEFINE THIS SURVEY TO IMAGE~18 NIRCAM FIELDS IN 7 FILTERS TO AB<~ 29 29.3 MAG YIELDING 140 000 GALAXIES AT 0<~ Z<~ 12 15 IN 0.05 DEG2 (>~ 30 HUDFS!). WE WILL STUDY GALAXY ASSEMBLY + SUPER-MASSIVE BLACK-HOLE GROWTH AT Z 0 7 INCLUDING OBJECT VARIABILITY ON MONTHS YEARS TIMESCALES. WE STUDY THE REIONIZING POPULATION AT Z 2 8 AND USE THE BEST LENSING TARGETS TO OPTIMIZE OUR STUDY OF FIRST LIGHT OBJECTS AT Z 10 15. OUR SCIENCE GOALS ARE: 1. GALAXY ASSEMBLY; 2. SUPER-MASSIVE BLACK-HOLE GROWTH; 3. REIONIZATION; 4. FIRST LIGHT; 5. STUDY THE BEST LENSING CLUSTERS TO FIND JWST OBJECTS. MAP&REMOVE STRAYLIGHT GRADIENTS AND QUANTIFY SAMPLE COMPLETENESS IN RANDOM FIELD&CLUSTER IMAGES: WE WILL: A) USE HUDF AND HFF DATA TO SIMULATE MAP AND REMOVE A RANGE OF STRAYLIGHT AMPLITUDES AND GRADIENTS THAT COULD AFFECT RANDOM DEEP FIELDS (DFS) AND CLUSTER FIELDS WITH JWST; B) DETERMINE ACCURATE COMPLETENESS CORRECTIONS VS. GALAXY FLUX SIZE WAVELENGTH AND LOCATION IN JWST DFS OF VARIOUS DEPTH AND IN CLUSTER FIELDS WITH THEIR KNOWN GALAXY CLUSTER+ICL FOREGROUND; C) DETERMINE THE CLUSTER SELECTION FUNCTIONS BY FOLDING LENSING MAPS WITH SIMULATED BACKGROUND IMAGES YIELDING SIMULATED LENSED IMAGES AND THEIR COMPLETENESS CORRECTIONS FOR LENSED SOURCES WHICH WE SHOW CAN BE FACTORS 2 3; AND D) MODEL COSMIC VARIANCE IN HIERARCHICAL MODELS AT Z 6 15. WE WILL CORRECT THE LFS FOR THESE COMPLETENESS FUNCTIONS. WE WILL THEN USE A BAYESIAN CODE TO DETERMINE THE OPTIMAL SET OF LF EVOLUTION PARAMETERS FROM THE AVAILABLE JWST DATA TO QUANTIFY HOW GALAXIES ASSEMBLED SINCE Z<~ 15., G8380842850, G8401272922, G8552695075, G8835071962
OpenAlex ID: W7117659828