Home > Research > Publications & Outputs > Spectroscopic confirmation of a Coma Cluster pr...

Associated organisational unit

Electronic data

  • protocluster-v4

    Rights statement: This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: 10.3847/1538-4357/ab75c3

    Accepted author manuscript, 20.5 MB, PDF document

Links

Text available via DOI:

View graph of relations

Spectroscopic confirmation of a Coma Cluster progenitor at z~2.2

Research output: Contribution to journalJournal article

Published
  • Behnam Darvish
  • Nicholas Scoville
  • Christopher Martin
  • David Sobral
  • Bahram Mobasher
  • Alessandro Rettura
  • Jorryt Matthee
  • Peter Capak
  • Nima Chartab
  • Shoubaneh Hemmati
  • Daniel Masters
  • Hooshang Nayyeri
  • Donal O'Sullivan
  • Ana Paulino-Afonso
  • Zahra Sattari
  • Abtin Shahidi
  • Mara Salvato
Close
Article number8
<mark>Journal publication date</mark>19/03/2020
<mark>Journal</mark>The Astrophysical Journal
Issue number1
Volume892
Number of pages10
Publication StatusPublished
<mark>Original language</mark>English

Abstract

We report the spectroscopic confirmation of a new protocluster in the COSMOS field at z ∼ 2.2, originally identified as an overdensity of narrow-band selected Hα emitting candidates. With only two masks of Keck/MOSFIRE near-IR spectroscopy in both H (∼ 1.47-1.81 μm) and K (∼ 1.92- 2.40 μm) bands (∼ 1.5 hour each), we confirm 35 unique protocluster members with at least two emission lines detected with S/N > 3. Combined with 12 extra members from the zCOSMOS-deep spectroscopic survey (47 in total), we estimate a mean redshift, line-of-sight velocity dispersion, and total mass of zmean=2.23224 ± 0.00101, σlos=645 ± 69 km s−1, and Mvir ∼ (1 − 2)×10^14 M⊙ for this protocluster, respectively. We estimate a number density enhancement of δg ∼ 7 for this system and we argue that the structure is likely not virialized at z ∼ 2.2. However, in a spherical collapse model, δg is expected to grow to a linear matter enhancement of ∼ 1.9 by z=0, exceeding the collapse threshold of 1.69, and leading to a fully collapsed and virialized Coma-type structure with a total mass of Mdyn(z=0) ∼ 9.2×10^14 M⊙ by now. This observationally efficient confirmation suggests that large narrow-band emission-line galaxy surveys, when combined with ancillary photometric data, can be used to effectively trace the large-scale structure and protoclusters at a time when they are mostly dominated by star-forming galaxies.

Bibliographic note

This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi: 10.3847/1538-4357/ab75c3