MAMMOTH-Subaru. V. Effects of Cosmic Variance on Lyα Luminosity Functions at z = 2.2–2.3
Cosmic variance introduces significant uncertainties into galaxy number density properties when surveying the high-redshift Universe with a small volume. Such uncertainties produce the field-to-field variance σ _g of galaxy numbers in observational astronomy, which significantly affects the luminosi...
Saved in:
| Main Authors: | , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2024-01-01
|
| Series: | The Astrophysical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-4357/ad04da |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1846143789412909056 |
|---|---|
| author | Ke Ma Haibin Zhang Zheng Cai Yongming Liang Nobunari Kashikawa Mingyu Li Yunjing Wu Qiong Li Xiaohui Fan Sean D. Johnson Masami Ouchi |
| author_facet | Ke Ma Haibin Zhang Zheng Cai Yongming Liang Nobunari Kashikawa Mingyu Li Yunjing Wu Qiong Li Xiaohui Fan Sean D. Johnson Masami Ouchi |
| author_sort | Ke Ma |
| collection | DOAJ |
| description | Cosmic variance introduces significant uncertainties into galaxy number density properties when surveying the high-redshift Universe with a small volume. Such uncertainties produce the field-to-field variance σ _g of galaxy numbers in observational astronomy, which significantly affects the luminosity function (LF) measurement of Ly α emitters (LAEs). For most previous Ly α LF studies, σ _g is often adopted from predictions by cosmological simulations, but barely confirmed by observations. Measuring cosmic variance requires a huge sample over a large volume, exceeding the capabilities of most astronomical instruments. In this study, we demonstrate an observational approach for measuring the cosmic variance contribution for z ≈ 2.2 Ly α LFs. The LAE candidates are observed using the narrow band and broad band of the Subaru/Hyper Suprime-Cam in eight independent fields, making the total survey area ≃11.62 deg ^2 and a comoving volume of ≃8.71 × 10 ^6 Mpc ^3 . We report a best-fit Schechter function with parameters α = −1.75 (fixed), ${L}_{\mathrm{Ly}\alpha }^{* }={5.95}_{-0.96}^{+1.22}\times {10}^{42}$ erg s ^−1 , and ${\phi }_{\mathrm{Ly}\alpha }^{* }={5.26}_{-1.27}^{+1.65}$ × 10 ^−4 Mpc ^−3 for the overall Ly α LFs. After clipping out the regions that may bias the cosmic variance measurements, we calculate σ _g by sampling LAEs within multiple pointings on the field image. We investigate the relation between σ _g and survey volume V , and fit a simple power-law ${\sigma }_{g}=k\times {\left(\tfrac{V}{{10}^{5}\,{\mathrm{Mpc}}^{3}}\right)}^{\beta }$ . We find best-fit values of $-{1.399}_{-0.156}^{+0.160}$ for β and ${1.249}_{-0.193}^{+0.213}$ for k . We compare our measurements with predictions from simulations and find that the cosmic variance of LAEs is likely larger than that of general star-forming galaxies. |
| format | Article |
| id | doaj-art-670fb4ab2dfb4a04940ac7a7b04b0b14 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-670fb4ab2dfb4a04940ac7a7b04b0b142024-12-02T10:10:35ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01961110210.3847/1538-4357/ad04daMAMMOTH-Subaru. V. Effects of Cosmic Variance on Lyα Luminosity Functions at z = 2.2–2.3Ke Ma0https://orcid.org/0000-0002-0564-891XHaibin Zhang1https://orcid.org/0000-0003-2273-9415Zheng Cai2https://orcid.org/0000-0001-8467-6478Yongming Liang3https://orcid.org/0000-0002-2725-302XNobunari Kashikawa4https://orcid.org/0000-0003-3954-4219Mingyu Li5https://orcid.org/0000-0001-6251-649XYunjing Wu6https://orcid.org/0000-0003-0111-8249Qiong Li7Xiaohui Fan8https://orcid.org/0000-0003-3310-0131Sean D. Johnson9https://orcid.org/0000-0001-9487-8583Masami Ouchi10https://orcid.org/0000-0002-1049-6658Department of Astronomy, Tsinghua University , Beijing 100084, People's Republic of China ; markma501x@gmail.com, hbz@icrr.u-tokyo.ac.jp, zcai@mail.tsinghua.edu.cn; School of Physics and Astronomy, University of Nottingham , University Park, Nottingham, NG7 2RD, UKDepartment of Astronomy, Tsinghua University , Beijing 100084, People's Republic of China ; markma501x@gmail.com, hbz@icrr.u-tokyo.ac.jp, zcai@mail.tsinghua.edu.cnDepartment of Astronomy, Tsinghua University , Beijing 100084, People's Republic of China ; markma501x@gmail.com, hbz@icrr.u-tokyo.ac.jp, zcai@mail.tsinghua.edu.cnInstitute for Cosmic Ray Research, The University of Tokyo , Kashiwa, Chiba 277-8582, Japan ; ymliang@icrr.u-tokyo.ac.jpNational Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Department of Astronomy, School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Research Center for the Early Universe, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, JapanDepartment of Astronomy, Tsinghua University , Beijing 100084, People's Republic of China ; markma501x@gmail.com, hbz@icrr.u-tokyo.ac.jp, zcai@mail.tsinghua.edu.cnDepartment of Astronomy, Tsinghua University , Beijing 100084, People's Republic of China ; markma501x@gmail.com, hbz@icrr.u-tokyo.ac.jp, zcai@mail.tsinghua.edu.cn; Steward Observatory, University of Arizona , 933 N. Cherry Avenue, Tucson, AZ 85721, USAJodrell Bank Centre for Astrophysics, University of Manchester , Oxford Road, Manchester, UKSteward Observatory, University of Arizona , 933 N. Cherry Avenue, Tucson, AZ 85721, USADepartment of Astronomy, University of Michigan , Ann Arbor, MI 48109, USAInstitute for Cosmic Ray Research, The University of Tokyo , Kashiwa, Chiba 277-8582, Japan ; ymliang@icrr.u-tokyo.ac.jp; National Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo , Kashiwa, Chiba 277-8583, JapanCosmic variance introduces significant uncertainties into galaxy number density properties when surveying the high-redshift Universe with a small volume. Such uncertainties produce the field-to-field variance σ _g of galaxy numbers in observational astronomy, which significantly affects the luminosity function (LF) measurement of Ly α emitters (LAEs). For most previous Ly α LF studies, σ _g is often adopted from predictions by cosmological simulations, but barely confirmed by observations. Measuring cosmic variance requires a huge sample over a large volume, exceeding the capabilities of most astronomical instruments. In this study, we demonstrate an observational approach for measuring the cosmic variance contribution for z ≈ 2.2 Ly α LFs. The LAE candidates are observed using the narrow band and broad band of the Subaru/Hyper Suprime-Cam in eight independent fields, making the total survey area ≃11.62 deg ^2 and a comoving volume of ≃8.71 × 10 ^6 Mpc ^3 . We report a best-fit Schechter function with parameters α = −1.75 (fixed), ${L}_{\mathrm{Ly}\alpha }^{* }={5.95}_{-0.96}^{+1.22}\times {10}^{42}$ erg s ^−1 , and ${\phi }_{\mathrm{Ly}\alpha }^{* }={5.26}_{-1.27}^{+1.65}$ × 10 ^−4 Mpc ^−3 for the overall Ly α LFs. After clipping out the regions that may bias the cosmic variance measurements, we calculate σ _g by sampling LAEs within multiple pointings on the field image. We investigate the relation between σ _g and survey volume V , and fit a simple power-law ${\sigma }_{g}=k\times {\left(\tfrac{V}{{10}^{5}\,{\mathrm{Mpc}}^{3}}\right)}^{\beta }$ . We find best-fit values of $-{1.399}_{-0.156}^{+0.160}$ for β and ${1.249}_{-0.193}^{+0.213}$ for k . We compare our measurements with predictions from simulations and find that the cosmic variance of LAEs is likely larger than that of general star-forming galaxies.https://doi.org/10.3847/1538-4357/ad04daLyα galaxiesCosmologyLuminosity function |
| spellingShingle | Ke Ma Haibin Zhang Zheng Cai Yongming Liang Nobunari Kashikawa Mingyu Li Yunjing Wu Qiong Li Xiaohui Fan Sean D. Johnson Masami Ouchi MAMMOTH-Subaru. V. Effects of Cosmic Variance on Lyα Luminosity Functions at z = 2.2–2.3 The Astrophysical Journal Lyα galaxies Cosmology Luminosity function |
| title | MAMMOTH-Subaru. V. Effects of Cosmic Variance on Lyα Luminosity Functions at z = 2.2–2.3 |
| title_full | MAMMOTH-Subaru. V. Effects of Cosmic Variance on Lyα Luminosity Functions at z = 2.2–2.3 |
| title_fullStr | MAMMOTH-Subaru. V. Effects of Cosmic Variance on Lyα Luminosity Functions at z = 2.2–2.3 |
| title_full_unstemmed | MAMMOTH-Subaru. V. Effects of Cosmic Variance on Lyα Luminosity Functions at z = 2.2–2.3 |
| title_short | MAMMOTH-Subaru. V. Effects of Cosmic Variance on Lyα Luminosity Functions at z = 2.2–2.3 |
| title_sort | mammoth subaru v effects of cosmic variance on lyα luminosity functions at z 2 2 2 3 |
| topic | Lyα galaxies Cosmology Luminosity function |
| url | https://doi.org/10.3847/1538-4357/ad04da |
| work_keys_str_mv | AT kema mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 AT haibinzhang mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 AT zhengcai mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 AT yongmingliang mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 AT nobunarikashikawa mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 AT mingyuli mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 AT yunjingwu mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 AT qiongli mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 AT xiaohuifan mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 AT seandjohnson mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 AT masamiouchi mammothsubaruveffectsofcosmicvarianceonlyaluminosityfunctionsatz2223 |