X-ray nondetection of the Lyα emitters at z ∼ 4.5

J. X. Wang; J. E. Rhoads; S. Malhotra; S. Dawson; D. Stern; A. Dey; T. M. Heckman; C. A. Norman; H. Spinrad

doi:10.1086/422311

X-ray nondetection of the Lyα emitters at z ∼ 4.5

J. X. Wang, J. E. Rhoads, S. Malhotra, S. Dawson, D. Stern, A. Dey, T. M. Heckman, C. A. Norman, H. Spinrad

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58 Scopus citations

Abstract

The Lyα emitters found at z ∼ 4.5 by the Large Area Lyman Alpha (LALA) survey have high equivalent widths in the Lyα line, which can be produced by either narrow-lined active galactic nuclei (AGNs) or by stellar populations with a very high proportion of young, massive stars. To investigate the AGN scenario, we obtained two deep Chandra exposures to study the X-ray nature of the Lyα emitters. The 172 ks deep Chandra image on the LALA Boötes field was presented in a previous paper, and in this Letter we present a new Chandra deep exposure (174 ks) on the LALA Cetus field, which doubled our sample of X-ray-imaged Lyα sources and imaged the brightest source among our Lyα emitters. None of the 101 Lyα sources covered by two Chandra exposures were detected individually in X-rays, with a 3 σ limiting X-ray flux of F_{0.5-10.0 keV} < 3.3 × 10 ^-16 ergs cm^-2 s^-1 for on-axis targets. The sources remain undetectable in the stacked image, implying a 3 σ limit to the average luminosity of L_{2-8 keV} < 2.8 × 10⁴² ergs s^-1. The resulting X-ray to Lyα ratio is greater than 21 times lower than the ratios for known high-redshift type II quasars. Together with optical spectra obtained at Keck, we conclude that no evidence of AGN activity was found among our Lyα emitters at z ∼ 4.5.

Original language	English (US)
Pages (from-to)	L21-L24
Journal	Astrophysical Journal
Volume	608
Issue number	1 II
DOIs	https://doi.org/10.1086/422311
State	Published - Jun 10 2004
Externally published	Yes

Keywords

Galaxies: active
Galaxies: high-redshift
Galaxies: starburst
X-rays: galaxies

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1086/422311

Cite this

@article{59f360a3d3c74c6e80281ec819664b8b,

title = "X-ray nondetection of the Lyα emitters at z ∼ 4.5",

abstract = "The Lyα emitters found at z ∼ 4.5 by the Large Area Lyman Alpha (LALA) survey have high equivalent widths in the Lyα line, which can be produced by either narrow-lined active galactic nuclei (AGNs) or by stellar populations with a very high proportion of young, massive stars. To investigate the AGN scenario, we obtained two deep Chandra exposures to study the X-ray nature of the Lyα emitters. The 172 ks deep Chandra image on the LALA Bo{\"o}tes field was presented in a previous paper, and in this Letter we present a new Chandra deep exposure (174 ks) on the LALA Cetus field, which doubled our sample of X-ray-imaged Lyα sources and imaged the brightest source among our Lyα emitters. None of the 101 Lyα sources covered by two Chandra exposures were detected individually in X-rays, with a 3 σ limiting X-ray flux of F0.5-10.0 keV < 3.3 × 10 -16 ergs cm-2 s-1 for on-axis targets. The sources remain undetectable in the stacked image, implying a 3 σ limit to the average luminosity of L2-8 keV < 2.8 × 1042 ergs s-1. The resulting X-ray to Lyα ratio is greater than 21 times lower than the ratios for known high-redshift type II quasars. Together with optical spectra obtained at Keck, we conclude that no evidence of AGN activity was found among our Lyα emitters at z ∼ 4.5.",

keywords = "Galaxies: active, Galaxies: high-redshift, Galaxies: starburst, X-rays: galaxies",

author = "Wang, {J. X.} and Rhoads, {J. E.} and S. Malhotra and S. Dawson and D. Stern and A. Dey and Heckman, {T. M.} and Norman, {C. A.} and H. Spinrad",

note = "Funding Information: This work was supported by Chandra X-Ray Center grants GO2-3152x and GO3-4148X and has benefited from images provided by the National Optical Astronomy Observatory (NOAO) Deep Wide-Field Survey (Jannuzi & Dey 1999; Brown et al. 2003), which is supported by NOAO. NOAO is operated by AURA, Inc., under a cooperative agreement with the National Science Foundation. We would like to thank B. T. Jannuzi for his help on narrowband imaging observations and L. Kewley for checking the Lya flux of CDF-S 202 in the observed frame. The work of S. D. was supported by IGPP-LLNL University Collaborative Research Program grant 03-AP-015. The work of D. S. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). This work includes observations made at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA.",

year = "2004",

month = jun,

day = "10",

doi = "10.1086/422311",

language = "English (US)",

volume = "608",

pages = "L21--L24",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "1 II",

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T1 - X-ray nondetection of the Lyα emitters at z ∼ 4.5

AU - Wang, J. X.

AU - Rhoads, J. E.

AU - Malhotra, S.

AU - Dawson, S.

AU - Stern, D.

AU - Dey, A.

AU - Heckman, T. M.

AU - Norman, C. A.

AU - Spinrad, H.

N1 - Funding Information: This work was supported by Chandra X-Ray Center grants GO2-3152x and GO3-4148X and has benefited from images provided by the National Optical Astronomy Observatory (NOAO) Deep Wide-Field Survey (Jannuzi & Dey 1999; Brown et al. 2003), which is supported by NOAO. NOAO is operated by AURA, Inc., under a cooperative agreement with the National Science Foundation. We would like to thank B. T. Jannuzi for his help on narrowband imaging observations and L. Kewley for checking the Lya flux of CDF-S 202 in the observed frame. The work of S. D. was supported by IGPP-LLNL University Collaborative Research Program grant 03-AP-015. The work of D. S. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). This work includes observations made at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA.

PY - 2004/6/10

Y1 - 2004/6/10

N2 - The Lyα emitters found at z ∼ 4.5 by the Large Area Lyman Alpha (LALA) survey have high equivalent widths in the Lyα line, which can be produced by either narrow-lined active galactic nuclei (AGNs) or by stellar populations with a very high proportion of young, massive stars. To investigate the AGN scenario, we obtained two deep Chandra exposures to study the X-ray nature of the Lyα emitters. The 172 ks deep Chandra image on the LALA Boötes field was presented in a previous paper, and in this Letter we present a new Chandra deep exposure (174 ks) on the LALA Cetus field, which doubled our sample of X-ray-imaged Lyα sources and imaged the brightest source among our Lyα emitters. None of the 101 Lyα sources covered by two Chandra exposures were detected individually in X-rays, with a 3 σ limiting X-ray flux of F0.5-10.0 keV < 3.3 × 10 -16 ergs cm-2 s-1 for on-axis targets. The sources remain undetectable in the stacked image, implying a 3 σ limit to the average luminosity of L2-8 keV < 2.8 × 1042 ergs s-1. The resulting X-ray to Lyα ratio is greater than 21 times lower than the ratios for known high-redshift type II quasars. Together with optical spectra obtained at Keck, we conclude that no evidence of AGN activity was found among our Lyα emitters at z ∼ 4.5.

AB - The Lyα emitters found at z ∼ 4.5 by the Large Area Lyman Alpha (LALA) survey have high equivalent widths in the Lyα line, which can be produced by either narrow-lined active galactic nuclei (AGNs) or by stellar populations with a very high proportion of young, massive stars. To investigate the AGN scenario, we obtained two deep Chandra exposures to study the X-ray nature of the Lyα emitters. The 172 ks deep Chandra image on the LALA Boötes field was presented in a previous paper, and in this Letter we present a new Chandra deep exposure (174 ks) on the LALA Cetus field, which doubled our sample of X-ray-imaged Lyα sources and imaged the brightest source among our Lyα emitters. None of the 101 Lyα sources covered by two Chandra exposures were detected individually in X-rays, with a 3 σ limiting X-ray flux of F0.5-10.0 keV < 3.3 × 10 -16 ergs cm-2 s-1 for on-axis targets. The sources remain undetectable in the stacked image, implying a 3 σ limit to the average luminosity of L2-8 keV < 2.8 × 1042 ergs s-1. The resulting X-ray to Lyα ratio is greater than 21 times lower than the ratios for known high-redshift type II quasars. Together with optical spectra obtained at Keck, we conclude that no evidence of AGN activity was found among our Lyα emitters at z ∼ 4.5.

KW - Galaxies: active

KW - Galaxies: high-redshift

KW - Galaxies: starburst

KW - X-rays: galaxies

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U2 - 10.1086/422311

DO - 10.1086/422311

M3 - Article

AN - SCOPUS:3142756550

SN - 0004-637X

VL - 608

SP - L21-L24

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1 II

ER -

X-ray nondetection of the Lyα emitters at z ∼ 4.5

Abstract

Keywords

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