Environmental impacts on molecular gas in protocluster galaxies at z ∼ 2

PASJ: Publications of the Astronomical Society of Japan

Kodama, Tadayuki¹  Lee, Minju²  Umehata, Hideki²  Matsuda, Yuichi²  Tanaka, Ichi³  Iono, Daisuke⁴  Suzuki, Tomoko L⁴  Tadaki, Ken-ichi⁵  Hayashi, Masao⁵  Toshikawa, Jun⁵  Kohno, Kotaro⁵  Tamura, Yoichi⁶  Shimakawa, Rhythm⁷  Hatsukade, Bunyo⁷  Koyama, Yusei⁷ 

[1] Astronomical Institute, Tohoku University, Aoba-ku, Sendai, Miyagi, 980-8578, Japan;Department of Astronomical Science, SOKENDAI (The Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan;Division of Particle and Astrophysical Science, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8602, Japan;Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan;National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan;Research Center for the Early Universe, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;Subaru Telescope, National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 650 North A’ohoku Place, Hilo, HI 96720, USA

关键词: galaxies: ISM;    galaxies: clusters: general;    galaxies: high-redshift;   

DOI  :  10.1093/pasj/psz005

学科分类：天文学(综合)

来源: Oxford University Press

【 摘 要 】

We present the results from ALMA CO(3–2) observations of 66 Hα-selected galaxies in three protoclusters around radio galaxies: PKS 1138−262 (⁠|$z$| = 2.16), USS 1558−003 (⁠|$z$| = 2.53), and 4C 23.56 (⁠|$z$| = 2.49). The pointing areas have an overdensity of ∼100 compared to the mean surface number density of galaxies in field environments. We detect the CO emission line in 16 star-forming galaxies, including six previously published galaxies, to measure the molecular gas mass. In the stellar mass range of 10.5 < log (Mstar/M⊙) < 11.0, the protocluster galaxies have larger gas mass fractions and longer gas depletion timescales compared to the scaling relations established for field galaxies. On the other hand, the amounts of molecular gas in more massive galaxies with log (Mstar/M⊙) > 11.0 are comparable in mass to the scaling relation, or smaller. Our results suggest that the environmental effects on gas properties are mass dependent: in high-density environments, gas accretion through cosmic filaments is accelerated in less massive galaxies, while this is suppressed in the most massive system.

【 授权许可】

CC BY