The KAGG survey: KCWI Analysis of Gas around Galaxies at z~3-5

@misc{oyarzun2026kagg,
  title = {{The KAGG survey: KCWI Analysis of Gas around Galaxies at z~3-5}},
  author = {Grecco A. Oyarzún and Marc Rafelski and J. Xavier Prochaska and Nissim Kanekar and Marcel Neeleman and Marie Wisz and Michele Fumagalli and Regina A. Jorgenson},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.25221},
  eprint = {2609.25221},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.25221},
}

TY  - UNPB
TI  - The KAGG survey: KCWI Analysis of Gas around Galaxies at z~3-5
AU  - Grecco A. Oyarzún
AU  - Marc Rafelski
AU  - J. Xavier Prochaska
AU  - Nissim Kanekar
AU  - Marcel Neeleman
AU  - Marie Wisz
AU  - Michele Fumagalli
AU  - Regina A. Jorgenson
PY  - 2026
DA  - 2026/09/21
PB  - arXiv
DO  - 10.48550/arxiv.2609.25221
UR  - https://arxiv.org/abs/2609.25221
AB  - We present the KCWI Analysis of Gas around Galaxies (KAGG) survey of Lyα emission around Damped Lyα Absorbers (DLAs) at z~3-5 with the Keck Cosmic Web Imager (KCWI) integral-field spectrograph. The KAGG survey is characterized by the sample of 36 DLAs spanning a wide metallicity range, the wide search area for associated Lyα emission (impact parameter b≲ 120kpc), and the high emission sensitivity, reaching Lyα luminosities ≲10^42 erg s^−1. We identify 7 DLA Lyα emitters that are likely DLA galaxy candidates due to the good match between the Lyα emission and DLA redshifts. Based on a composite sample of 11 DLA Lyα emitters from KAGG and MAGG (MUSE Analysis of Gas around Galaxies), we find that the impact parameters of DLA Lyα emitters decrease with DLA metallicity, from b>50kpc at [M/H]~-2 to b<50kpc at [M/H]~-1. Including Lyα emitters at larger velocity offsets and at larger impact parameters from the DLAs, we construct samples of 35 "Group" Lyα emitters and 17 "Large-scale" Lyα emitters. We find that their impact parameters and incidence rates also depend on DLA metallicity. Based on simulations of our survey and comparisons with models of galaxy formation, we conclude that higher DLA metallicities are associated with higher halo masses. The low Lyα emission detection rate at low impact parameters suggests that most DLA galaxies either have low stellar masses (M≲10^8M_⊙) or have their Lyα emission suppressed due to HI resonant scattering and/or dust absorption.
ER  -