Home > Research > Publications & Outputs > The CALYMHA survey

Associated organisational unit

Electronic data

  • CALYMHa_v_revised_NO_BOLD

    Rights statement: This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version David Sobral, Jorryt Matthee, Philip Best, Andra Stroe, Huub Röttgering, Iván Oteo, Ian Smail, Leah Morabito, Ana Paulino-Afonso; The CALYMHA survey: Lyα luminosity function and global escape fraction of Lyα photons at z = 2.23. Mon Not R Astron Soc 2017; 466 (1): 1242-1258. doi: 10.1093/mnras/stw3090 is available online at: https://academic.oup.com/mnras/article/466/1/1242/2617718/

    Accepted author manuscript, 2.85 MB, PDF document

    Available under license: CC BY-NC: Creative Commons Attribution-NonCommercial 4.0 International License

Links

Text available via DOI:

View graph of relations

The CALYMHA survey: Lyα luminosity function and global escape fraction of Lyα photons at z = 2.23

Research output: Contribution to journalJournal article

Published
  • David Sobral
  • Jorryt Matthee
  • Philip N. Best
  • Andra Stroe
  • Huub J A Röttgering
  • Ivàn Oteo
  • Ian Smail
  • Leah Morabito
  • Ana Paulino-Afonso
Close
<mark>Journal publication date</mark>04/2017
<mark>Journal</mark>Monthly Notices of the Royal Astronomical Society
Issue number1
Volume466
Number of pages17
Pages (from-to)1242-1258
Publication statusPublished
Early online date30/11/16
Original languageEnglish

Abstract

We present the CAlibrating LYMan-α with Hα (CALYMHA) pilot survey and new results on Lyman α (Lyα) selected galaxies at z ∼ 2. We use a custom-built Lyα narrow-band filter at the Isaac Newton Telescope, designed to provide a matched volume coverage to the z = 2.23 Hα HiZELS survey. Here, we present the first results for the COSMOS and UDS fields. Our survey currently reaches a 3σ line flux limit of ∼4 × 10−17 erg s−1 cm−2, and a Lyα luminosity limit of ∼1042.3 erg s−1. We find 188 Lyα emitters over 7.3 × 105 Mpc3, but also find significant numbers of other line-emitting sources corresponding to He ii, C iii] and C iv emission lines. These sources are important contaminants, and we carefully remove them, unlike most previous studies. We find that the Lyα luminosity function at z = 2.23 is very well described by a Schechter function up to LLy α ≈ 1043 erg s−1 with
L∗=1042.59+0.16−0.08
L∗=1042.59−0.08+0.16

erg s−1,
ϕ∗=10−3.09+0.14−0.34
ϕ∗=10−3.09−0.34+0.14

Mpc−3 and α = −1.75 ± 0.25. Above LLy α ≈ 1043 erg s−1, the Lyα luminosity function becomes power-law like, driven by X-ray AGN. We find that Lyα-selected emitters have a high escape fraction of 37 ± 7 per cent, anticorrelated with Lyα luminosity and correlated with Lyα equivalent width. Lyα emitters have ubiquitous large (≈40 kpc) Lyα haloes, ∼2 times larger than their Hα extents. By directly comparing our Lyα and Hα luminosity functions, we find that the global/overall escape fraction of Lyα photons (within a 13 kpc radius) from the full population of star-forming galaxies is 5.1 ± 0.2 per cent at the peak of the star formation history. An extra 3.3 ± 0.3 per cent of Lyα photons likely still escape, but at larger radii.

Bibliographic note

This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The definitive publisher-authenticated version David Sobral, Jorryt Matthee, Philip Best, Andra Stroe, Huub Röttgering, Iván Oteo, Ian Smail, Leah Morabito, Ana Paulino-Afonso; The CALYMHA survey: Lyα luminosity function and global escape fraction of Lyα photons at z = 2.23. Mon Not R Astron Soc 2017; 466 (1): 1242-1258. doi: 10.1093/mnras/stw3090 is available online at: https://academic.oup.com/mnras/article/466/1/1242/2617718/