SPECTROSCOPIC CONFIRMATION of A PROTOCLUSTER at z ≈ 3.786

Dey Arjun Dey, Arjun Dey, Kyoung Soo Lee, Naveen Reddy, Michael Cooper, Hanae Inami, Sungryong Hong, Anthony H. Gonzalez, Buell Tomasson Jannuzi

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

We present new observations of the field containing the z = 3.786 protocluster PC 217.96+32.3. We confirm that it is one of the largest known and most overdense high-redshift structures. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1.°2 0.°6 area (≈150 75 comoving Mpc) surrounding the protocluster's core and discovered 165 candidate Lyα emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least two overdense regions traced by the LAEs, the largest of which shows an areal overdensity in its core (i.e., within a radius of 2.5 comoving Mpc) of 14 ± 7 relative to the average LAE spatial density () in the imaged field. Further, is twice that derived by other field LAE surveys. Spectroscopy with Keck/DEIMOS yielded redshifts for 164 galaxies (79 LAEs and 85 LBGs); 65 lie at a redshift of 3.785 ± 0.010. The velocity dispersion of galaxies near the core is σ = 350 ± 40 km s-1, a value robust to selection effects. The overdensities are likely to collapse into systems with present-day masses of >1015 M o and >6 1014 M o. The low velocity dispersion may suggest a dynamically young protocluster. We find a weak trend between narrow-band (Lyα) luminosity and environmental density: the Lyα luminosity is enhanced on average by 1.35 within the protocluster core. There is no evidence that the Lyα equivalent width depends on environment. These suggest that star formation and/or active galactic nucleus (AGN) activity is enhanced in the higher-density regions of the structure. PC 217.96+32.3 is a Coma cluster analog, witnessed in the process of formation.

Original languageEnglish (US)
Article number11
JournalAstrophysical Journal
Volume823
Issue number1
DOIs
StatePublished - May 20 2016

Fingerprint

galaxies
field survey
luminosity
spectroscopy
coma
active galactic nuclei
low speed
narrowband
star formation
simulation
cameras
analogs
trends
radii
effect
young
trend

Keywords

  • cosmology: observations
  • galaxies: clusters: individual
  • galaxies: distances and redshifts
  • galaxies: evolution
  • galaxies: formation
  • galaxies: high-redshift

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Arjun Dey, D., Dey, A., Lee, K. S., Reddy, N., Cooper, M., Inami, H., ... Jannuzi, B. T. (2016). SPECTROSCOPIC CONFIRMATION of A PROTOCLUSTER at z ≈ 3.786. Astrophysical Journal, 823(1), [11]. https://doi.org/10.3847/0004-637X/823/1/11

SPECTROSCOPIC CONFIRMATION of A PROTOCLUSTER at z ≈ 3.786. / Arjun Dey, Dey; Dey, Arjun; Lee, Kyoung Soo; Reddy, Naveen; Cooper, Michael; Inami, Hanae; Hong, Sungryong; Gonzalez, Anthony H.; Jannuzi, Buell Tomasson.

In: Astrophysical Journal, Vol. 823, No. 1, 11, 20.05.2016.

Research output: Contribution to journalArticle

Arjun Dey, D, Dey, A, Lee, KS, Reddy, N, Cooper, M, Inami, H, Hong, S, Gonzalez, AH & Jannuzi, BT 2016, 'SPECTROSCOPIC CONFIRMATION of A PROTOCLUSTER at z ≈ 3.786', Astrophysical Journal, vol. 823, no. 1, 11. https://doi.org/10.3847/0004-637X/823/1/11
Arjun Dey D, Dey A, Lee KS, Reddy N, Cooper M, Inami H et al. SPECTROSCOPIC CONFIRMATION of A PROTOCLUSTER at z ≈ 3.786. Astrophysical Journal. 2016 May 20;823(1). 11. https://doi.org/10.3847/0004-637X/823/1/11
Arjun Dey, Dey ; Dey, Arjun ; Lee, Kyoung Soo ; Reddy, Naveen ; Cooper, Michael ; Inami, Hanae ; Hong, Sungryong ; Gonzalez, Anthony H. ; Jannuzi, Buell Tomasson. / SPECTROSCOPIC CONFIRMATION of A PROTOCLUSTER at z ≈ 3.786. In: Astrophysical Journal. 2016 ; Vol. 823, No. 1.
@article{be04a7742b03468e8d3a559b39f36cc2,
title = "SPECTROSCOPIC CONFIRMATION of A PROTOCLUSTER at z ≈ 3.786",
abstract = "We present new observations of the field containing the z = 3.786 protocluster PC 217.96+32.3. We confirm that it is one of the largest known and most overdense high-redshift structures. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1.°2 0.°6 area (≈150 75 comoving Mpc) surrounding the protocluster's core and discovered 165 candidate Lyα emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least two overdense regions traced by the LAEs, the largest of which shows an areal overdensity in its core (i.e., within a radius of 2.5 comoving Mpc) of 14 ± 7 relative to the average LAE spatial density () in the imaged field. Further, is twice that derived by other field LAE surveys. Spectroscopy with Keck/DEIMOS yielded redshifts for 164 galaxies (79 LAEs and 85 LBGs); 65 lie at a redshift of 3.785 ± 0.010. The velocity dispersion of galaxies near the core is σ = 350 ± 40 km s-1, a value robust to selection effects. The overdensities are likely to collapse into systems with present-day masses of >1015 M o and >6 1014 M o. The low velocity dispersion may suggest a dynamically young protocluster. We find a weak trend between narrow-band (Lyα) luminosity and environmental density: the Lyα luminosity is enhanced on average by 1.35 within the protocluster core. There is no evidence that the Lyα equivalent width depends on environment. These suggest that star formation and/or active galactic nucleus (AGN) activity is enhanced in the higher-density regions of the structure. PC 217.96+32.3 is a Coma cluster analog, witnessed in the process of formation.",
keywords = "cosmology: observations, galaxies: clusters: individual, galaxies: distances and redshifts, galaxies: evolution, galaxies: formation, galaxies: high-redshift",
author = "{Arjun Dey}, Dey and Arjun Dey and Lee, {Kyoung Soo} and Naveen Reddy and Michael Cooper and Hanae Inami and Sungryong Hong and Gonzalez, {Anthony H.} and Jannuzi, {Buell Tomasson}",
year = "2016",
month = "5",
day = "20",
doi = "10.3847/0004-637X/823/1/11",
language = "English (US)",
volume = "823",
journal = "Astrophysical Journal",
issn = "0004-637X",
publisher = "IOP Publishing Ltd.",
number = "1",

}

TY - JOUR

T1 - SPECTROSCOPIC CONFIRMATION of A PROTOCLUSTER at z ≈ 3.786

AU - Arjun Dey, Dey

AU - Dey, Arjun

AU - Lee, Kyoung Soo

AU - Reddy, Naveen

AU - Cooper, Michael

AU - Inami, Hanae

AU - Hong, Sungryong

AU - Gonzalez, Anthony H.

AU - Jannuzi, Buell Tomasson

PY - 2016/5/20

Y1 - 2016/5/20

N2 - We present new observations of the field containing the z = 3.786 protocluster PC 217.96+32.3. We confirm that it is one of the largest known and most overdense high-redshift structures. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1.°2 0.°6 area (≈150 75 comoving Mpc) surrounding the protocluster's core and discovered 165 candidate Lyα emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least two overdense regions traced by the LAEs, the largest of which shows an areal overdensity in its core (i.e., within a radius of 2.5 comoving Mpc) of 14 ± 7 relative to the average LAE spatial density () in the imaged field. Further, is twice that derived by other field LAE surveys. Spectroscopy with Keck/DEIMOS yielded redshifts for 164 galaxies (79 LAEs and 85 LBGs); 65 lie at a redshift of 3.785 ± 0.010. The velocity dispersion of galaxies near the core is σ = 350 ± 40 km s-1, a value robust to selection effects. The overdensities are likely to collapse into systems with present-day masses of >1015 M o and >6 1014 M o. The low velocity dispersion may suggest a dynamically young protocluster. We find a weak trend between narrow-band (Lyα) luminosity and environmental density: the Lyα luminosity is enhanced on average by 1.35 within the protocluster core. There is no evidence that the Lyα equivalent width depends on environment. These suggest that star formation and/or active galactic nucleus (AGN) activity is enhanced in the higher-density regions of the structure. PC 217.96+32.3 is a Coma cluster analog, witnessed in the process of formation.

AB - We present new observations of the field containing the z = 3.786 protocluster PC 217.96+32.3. We confirm that it is one of the largest known and most overdense high-redshift structures. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1.°2 0.°6 area (≈150 75 comoving Mpc) surrounding the protocluster's core and discovered 165 candidate Lyα emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least two overdense regions traced by the LAEs, the largest of which shows an areal overdensity in its core (i.e., within a radius of 2.5 comoving Mpc) of 14 ± 7 relative to the average LAE spatial density () in the imaged field. Further, is twice that derived by other field LAE surveys. Spectroscopy with Keck/DEIMOS yielded redshifts for 164 galaxies (79 LAEs and 85 LBGs); 65 lie at a redshift of 3.785 ± 0.010. The velocity dispersion of galaxies near the core is σ = 350 ± 40 km s-1, a value robust to selection effects. The overdensities are likely to collapse into systems with present-day masses of >1015 M o and >6 1014 M o. The low velocity dispersion may suggest a dynamically young protocluster. We find a weak trend between narrow-band (Lyα) luminosity and environmental density: the Lyα luminosity is enhanced on average by 1.35 within the protocluster core. There is no evidence that the Lyα equivalent width depends on environment. These suggest that star formation and/or active galactic nucleus (AGN) activity is enhanced in the higher-density regions of the structure. PC 217.96+32.3 is a Coma cluster analog, witnessed in the process of formation.

KW - cosmology: observations

KW - galaxies: clusters: individual

KW - galaxies: distances and redshifts

KW - galaxies: evolution

KW - galaxies: formation

KW - galaxies: high-redshift

UR - http://www.scopus.com/inward/record.url?scp=84971516668&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84971516668&partnerID=8YFLogxK

U2 - 10.3847/0004-637X/823/1/11

DO - 10.3847/0004-637X/823/1/11

M3 - Article

VL - 823

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 1

M1 - 11

ER -