BibTeX

@article{2506.12130v1,
Author        = {Sabrina Berger and Madeline A. Marshall and J. Stuart B. Wyithe and Tiziana di Matteo and Yueying Ni and Stephen M. Wilkins and Minghao Yue},
Title         = {Biases in stellar masses of JWST high-z quasar host galaxies caused by
  quasar subtraction},
Eprint        = {2506.12130v1},
ArchivePrefix = {arXiv},
PrimaryClass  = {astro-ph.GA},
Abstract      = {JWST has enabled a new era of understanding high-z galaxy and black hole
evolution with more than 30 high-z quasar host galaxy detections. Many of these
observations imply galaxies with black holes that are overmassive compared to
their low-z counterparts. However, the bright quasar point source removal may
cause significant biases in these stellar mass measurements. We develop a
simulation-based inference method to disentangle the quasar host galaxy stellar
mass measurements from observational biases during the point source removal. We
use the BlueTides simulation to generate mock images and perform point source
removal on thousands of simulated high-z quasar host galaxies, constructing
corrected host magnitude posteriors. We find that JWST photometry tends to
either correctly recover or modestly misestimate host magnitudes, with a
maximum magnitude underestimate of 0.21 mag. With our corrected magnitude
posteriors, we perform SED fitting on each quasar host galaxy and compare the
stellar mass measurement before and after the correction. We find that stellar
mass estimates are generally robust, or overestimated by $\leq0.3$ dex. We also
find that the stellar masses of a subset of hosts (J1120+0641, J0844-0132,
J0911+0152, and J1146-0005) remain unconstrained, as key photometric bands
provide only flux upper limits. Understanding these biases is essential to
uncovering the evolutionary pathways of high-z quasars with their hosts.},
Year          = {2025},
Month         = {Jun},
Url           = {http://arxiv.org/abs/2506.12130v1},
File          = {2506.12130v1.pdf}
}