The UV continua and inferred stellar populations of galaxies at z≃7-9 revealed by the Hubble Ultra-Deep Field 2012 campaign

J. S. Dunlop, A. B. Rogers, R. J. McLure, R. S. Ellis, Brant E Robertson, A. Koekemoer, P. Dayal, E. Curtis-Lake, V. Wild, S. Charlot, R. A A Bowler, M. A. Schenker, M. Ouchi, Y. Ono, M. Cirasuolo, S. R. Furlanetto, Daniel P Stark, T. A. Targett, E. Schneider

Research output: Contribution to journalArticle

102 Citations (Scopus)

Abstract

We use the new ultra-deep, near-infrared imaging of the Hubble Ultra-Deep Field (HUDF) provided by our UDF12 Hubble Space Telescope (HST)Wide Field Camera 3/IR campaign to explore the rest-frame ultraviolet (UV) properties of galaxies at redshifts z ≥ 6.5. We present the first unbiased measurement of the average UV power-law index, (β), (fλ α λβ) for faint galaxies at z≃7, the first meaningful measurements of (β) at z≃8, and tentative estimates for a new sample of galaxies at z≃9. Utilizing galaxy selection in the new F140W (J140) imaging to minimize colour bias, and applying both colour and power-law estimators of β, we find (β)= -2.1 ± 0.2 at z ≃7 for galaxies with MUV ≃-18. This means that the faintest galaxies uncovered at this epoch have, on average, UV colours no more extreme than those displayed by the bluest star-forming galaxies at low redshift. At z ≃ 8 we find a similar value, (β)= -1.9± 0.3. At z ≃ 9, we find (β)= -1.8± 0.6, essentially unchanged from z ≃ 6 to 7 (albeit highly uncertain). Finally, we show that there is as yet no evidence for a significant intrinsic scatter in β within our new, robust z ≃ 7 galaxy sample. Our results are most easily explained by a population of steadily star-forming galaxies with either ≃ solar metallicity and zero dust, or moderately sub-solar (≃10-20 per cent) metallicity with modest dust obscuration (AV ≃ 0.1-0.2). This latter interpretation is consistent with the predictions of a state-of-the-art galaxy-formation simulation, which also suggests that a significant population of very-low metallicity, dust-free galaxies with β ≃ -2.5 may not emerge until MUV > -16, a regime likely to remain inaccessible until the James Webb Space Telescope.

Original languageEnglish (US)
Pages (from-to)3520-3533
Number of pages14
JournalMonthly Notices of the Royal Astronomical Society
Volume432
Issue number4
DOIs
StatePublished - Oct 2013

Fingerprint

galaxies
continuums
dust
power law
near infrared
metallicity
color
prediction
simulation
blue stars
James Webb Space Telescope
occultation
galactic evolution
Hubble Space Telescope
estimators
cameras
time measurement
stars
estimates
predictions

Keywords

  • Evolution-galaxies
  • First stars
  • Formation-galaxies
  • Galaxies
  • High-redshift-galaxies
  • Reionization
  • Stellar content-dark ages

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

The UV continua and inferred stellar populations of galaxies at z≃7-9 revealed by the Hubble Ultra-Deep Field 2012 campaign. / Dunlop, J. S.; Rogers, A. B.; McLure, R. J.; Ellis, R. S.; Robertson, Brant E; Koekemoer, A.; Dayal, P.; Curtis-Lake, E.; Wild, V.; Charlot, S.; Bowler, R. A A; Schenker, M. A.; Ouchi, M.; Ono, Y.; Cirasuolo, M.; Furlanetto, S. R.; Stark, Daniel P; Targett, T. A.; Schneider, E.

In: Monthly Notices of the Royal Astronomical Society, Vol. 432, No. 4, 10.2013, p. 3520-3533.

Research output: Contribution to journalArticle

Dunlop, JS, Rogers, AB, McLure, RJ, Ellis, RS, Robertson, BE, Koekemoer, A, Dayal, P, Curtis-Lake, E, Wild, V, Charlot, S, Bowler, RAA, Schenker, MA, Ouchi, M, Ono, Y, Cirasuolo, M, Furlanetto, SR, Stark, DP, Targett, TA & Schneider, E 2013, 'The UV continua and inferred stellar populations of galaxies at z≃7-9 revealed by the Hubble Ultra-Deep Field 2012 campaign', Monthly Notices of the Royal Astronomical Society, vol. 432, no. 4, pp. 3520-3533. https://doi.org/10.1093/mnras/stt702
Dunlop, J. S. ; Rogers, A. B. ; McLure, R. J. ; Ellis, R. S. ; Robertson, Brant E ; Koekemoer, A. ; Dayal, P. ; Curtis-Lake, E. ; Wild, V. ; Charlot, S. ; Bowler, R. A A ; Schenker, M. A. ; Ouchi, M. ; Ono, Y. ; Cirasuolo, M. ; Furlanetto, S. R. ; Stark, Daniel P ; Targett, T. A. ; Schneider, E. / The UV continua and inferred stellar populations of galaxies at z≃7-9 revealed by the Hubble Ultra-Deep Field 2012 campaign. In: Monthly Notices of the Royal Astronomical Society. 2013 ; Vol. 432, No. 4. pp. 3520-3533.
@article{24404844f47c4b1c9aabbffc4e4dea9c,
title = "The UV continua and inferred stellar populations of galaxies at z≃7-9 revealed by the Hubble Ultra-Deep Field 2012 campaign",
abstract = "We use the new ultra-deep, near-infrared imaging of the Hubble Ultra-Deep Field (HUDF) provided by our UDF12 Hubble Space Telescope (HST)Wide Field Camera 3/IR campaign to explore the rest-frame ultraviolet (UV) properties of galaxies at redshifts z ≥ 6.5. We present the first unbiased measurement of the average UV power-law index, (β), (fλ α λβ) for faint galaxies at z≃7, the first meaningful measurements of (β) at z≃8, and tentative estimates for a new sample of galaxies at z≃9. Utilizing galaxy selection in the new F140W (J140) imaging to minimize colour bias, and applying both colour and power-law estimators of β, we find (β)= -2.1 ± 0.2 at z ≃7 for galaxies with MUV ≃-18. This means that the faintest galaxies uncovered at this epoch have, on average, UV colours no more extreme than those displayed by the bluest star-forming galaxies at low redshift. At z ≃ 8 we find a similar value, (β)= -1.9± 0.3. At z ≃ 9, we find (β)= -1.8± 0.6, essentially unchanged from z ≃ 6 to 7 (albeit highly uncertain). Finally, we show that there is as yet no evidence for a significant intrinsic scatter in β within our new, robust z ≃ 7 galaxy sample. Our results are most easily explained by a population of steadily star-forming galaxies with either ≃ solar metallicity and zero dust, or moderately sub-solar (≃10-20 per cent) metallicity with modest dust obscuration (AV ≃ 0.1-0.2). This latter interpretation is consistent with the predictions of a state-of-the-art galaxy-formation simulation, which also suggests that a significant population of very-low metallicity, dust-free galaxies with β ≃ -2.5 may not emerge until MUV > -16, a regime likely to remain inaccessible until the James Webb Space Telescope.",
keywords = "Evolution-galaxies, First stars, Formation-galaxies, Galaxies, High-redshift-galaxies, Reionization, Stellar content-dark ages",
author = "Dunlop, {J. S.} and Rogers, {A. B.} and McLure, {R. J.} and Ellis, {R. S.} and Robertson, {Brant E} and A. Koekemoer and P. Dayal and E. Curtis-Lake and V. Wild and S. Charlot and Bowler, {R. A A} and Schenker, {M. A.} and M. Ouchi and Y. Ono and M. Cirasuolo and Furlanetto, {S. R.} and Stark, {Daniel P} and Targett, {T. A.} and E. Schneider",
year = "2013",
month = "10",
doi = "10.1093/mnras/stt702",
language = "English (US)",
volume = "432",
pages = "3520--3533",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "4",

}

TY - JOUR

T1 - The UV continua and inferred stellar populations of galaxies at z≃7-9 revealed by the Hubble Ultra-Deep Field 2012 campaign

AU - Dunlop, J. S.

AU - Rogers, A. B.

AU - McLure, R. J.

AU - Ellis, R. S.

AU - Robertson, Brant E

AU - Koekemoer, A.

AU - Dayal, P.

AU - Curtis-Lake, E.

AU - Wild, V.

AU - Charlot, S.

AU - Bowler, R. A A

AU - Schenker, M. A.

AU - Ouchi, M.

AU - Ono, Y.

AU - Cirasuolo, M.

AU - Furlanetto, S. R.

AU - Stark, Daniel P

AU - Targett, T. A.

AU - Schneider, E.

PY - 2013/10

Y1 - 2013/10

N2 - We use the new ultra-deep, near-infrared imaging of the Hubble Ultra-Deep Field (HUDF) provided by our UDF12 Hubble Space Telescope (HST)Wide Field Camera 3/IR campaign to explore the rest-frame ultraviolet (UV) properties of galaxies at redshifts z ≥ 6.5. We present the first unbiased measurement of the average UV power-law index, (β), (fλ α λβ) for faint galaxies at z≃7, the first meaningful measurements of (β) at z≃8, and tentative estimates for a new sample of galaxies at z≃9. Utilizing galaxy selection in the new F140W (J140) imaging to minimize colour bias, and applying both colour and power-law estimators of β, we find (β)= -2.1 ± 0.2 at z ≃7 for galaxies with MUV ≃-18. This means that the faintest galaxies uncovered at this epoch have, on average, UV colours no more extreme than those displayed by the bluest star-forming galaxies at low redshift. At z ≃ 8 we find a similar value, (β)= -1.9± 0.3. At z ≃ 9, we find (β)= -1.8± 0.6, essentially unchanged from z ≃ 6 to 7 (albeit highly uncertain). Finally, we show that there is as yet no evidence for a significant intrinsic scatter in β within our new, robust z ≃ 7 galaxy sample. Our results are most easily explained by a population of steadily star-forming galaxies with either ≃ solar metallicity and zero dust, or moderately sub-solar (≃10-20 per cent) metallicity with modest dust obscuration (AV ≃ 0.1-0.2). This latter interpretation is consistent with the predictions of a state-of-the-art galaxy-formation simulation, which also suggests that a significant population of very-low metallicity, dust-free galaxies with β ≃ -2.5 may not emerge until MUV > -16, a regime likely to remain inaccessible until the James Webb Space Telescope.

AB - We use the new ultra-deep, near-infrared imaging of the Hubble Ultra-Deep Field (HUDF) provided by our UDF12 Hubble Space Telescope (HST)Wide Field Camera 3/IR campaign to explore the rest-frame ultraviolet (UV) properties of galaxies at redshifts z ≥ 6.5. We present the first unbiased measurement of the average UV power-law index, (β), (fλ α λβ) for faint galaxies at z≃7, the first meaningful measurements of (β) at z≃8, and tentative estimates for a new sample of galaxies at z≃9. Utilizing galaxy selection in the new F140W (J140) imaging to minimize colour bias, and applying both colour and power-law estimators of β, we find (β)= -2.1 ± 0.2 at z ≃7 for galaxies with MUV ≃-18. This means that the faintest galaxies uncovered at this epoch have, on average, UV colours no more extreme than those displayed by the bluest star-forming galaxies at low redshift. At z ≃ 8 we find a similar value, (β)= -1.9± 0.3. At z ≃ 9, we find (β)= -1.8± 0.6, essentially unchanged from z ≃ 6 to 7 (albeit highly uncertain). Finally, we show that there is as yet no evidence for a significant intrinsic scatter in β within our new, robust z ≃ 7 galaxy sample. Our results are most easily explained by a population of steadily star-forming galaxies with either ≃ solar metallicity and zero dust, or moderately sub-solar (≃10-20 per cent) metallicity with modest dust obscuration (AV ≃ 0.1-0.2). This latter interpretation is consistent with the predictions of a state-of-the-art galaxy-formation simulation, which also suggests that a significant population of very-low metallicity, dust-free galaxies with β ≃ -2.5 may not emerge until MUV > -16, a regime likely to remain inaccessible until the James Webb Space Telescope.

KW - Evolution-galaxies

KW - First stars

KW - Formation-galaxies

KW - Galaxies

KW - High-redshift-galaxies

KW - Reionization

KW - Stellar content-dark ages

UR - http://www.scopus.com/inward/record.url?scp=84880003387&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84880003387&partnerID=8YFLogxK

U2 - 10.1093/mnras/stt702

DO - 10.1093/mnras/stt702

M3 - Article

AN - SCOPUS:84880003387

VL - 432

SP - 3520

EP - 3533

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -