Detection of far-infrared and polycyclic aromatic hydrocarbon emission from the cosmic eye: Probing the dust and star formation of lyman break galaxies

B. Siana, Ian Smail, A. M. Swinbank, J. Richard, H. I. Teplitz, K. E K Coppin, R. S. Ellis, Daniel P Stark, J. P. Kneib, A. C. Edge

Research output: Contribution to journalArticle

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Abstract

We report the results of a Spitzer infrared (IR) study of the Cosmic Eye, a strongly lensed, L*UV Lyman break galaxy (LBG) at z = 3.074. We obtained Spitzer mid-IR spectroscopy as well as MIPS 24 and 70 μm photometry. The Eye is detected with high significance at both 24 and 70 μm and, when including a flux limit at 3.5 mm, we estimate an IR luminosity of L IR = 8.3+4.7 -4.4 × 1011 L assuming a magnification of 28 3. This L IR is eight times lower than that predicted from the rest-frame ultraviolet properties assuming a Calzetti reddening law. This has also been observed in other young LBGs, and indicates that the dust reddening law may be steeper in these galaxies. The mid-IR spectrum shows strong polycyclic aromatic hydrocarbon (PAH) emission at 6.2 and 7.7 μm, with equivalent widths near the maximum values observed in star-forming galaxies at any redshift. The L PAH-to-L IR ratio lies close to the relation measured in local starbursts. Therefore, L PAH or L MIR may be used to estimate L IR, and thus star formation rate, of LBGs, whose fluxes at longer wavelengths are typically below current confusion limits. We also report the highest redshift detection of the 3.3 μm PAH emission feature. The PAH ratio, L 6.2/L 3.3 = 5.1 2.7, and the PAH-to-LIR ratio, L 3.3/L IR = 8.5 4.7 × 10-4, are both in agreement with measurements in local starbursts and ultraluminous infrared galaxies (ULIRGs), suggesting that this line may serve as a good proxy for L PAH or L IR at z > 3 with the James Webb Space Telescope.

Original languageEnglish (US)
Pages (from-to)1273-1281
Number of pages9
JournalAstrophysical Journal
Volume698
Issue number2
DOIs
StatePublished - 2009
Externally publishedYes

Fingerprint

polycyclic aromatic hydrocarbons
star formation
PAH
dust
galaxies
James Webb Space Telescope
confusion
estimates
star formation rate
detection
magnification
infrared spectroscopy
photometry
infrared spectra
luminosity
wavelength
stars
wavelengths

Keywords

  • Galaxies: high-redshift
  • Galaxies: individual (J213512.73-010143, Cosmic Eye)
  • Infrared: galaxies

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Detection of far-infrared and polycyclic aromatic hydrocarbon emission from the cosmic eye : Probing the dust and star formation of lyman break galaxies. / Siana, B.; Smail, Ian; Swinbank, A. M.; Richard, J.; Teplitz, H. I.; Coppin, K. E K; Ellis, R. S.; Stark, Daniel P; Kneib, J. P.; Edge, A. C.

In: Astrophysical Journal, Vol. 698, No. 2, 2009, p. 1273-1281.

Research output: Contribution to journalArticle

Siana, B. ; Smail, Ian ; Swinbank, A. M. ; Richard, J. ; Teplitz, H. I. ; Coppin, K. E K ; Ellis, R. S. ; Stark, Daniel P ; Kneib, J. P. ; Edge, A. C. / Detection of far-infrared and polycyclic aromatic hydrocarbon emission from the cosmic eye : Probing the dust and star formation of lyman break galaxies. In: Astrophysical Journal. 2009 ; Vol. 698, No. 2. pp. 1273-1281.
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abstract = "We report the results of a Spitzer infrared (IR) study of the Cosmic Eye, a strongly lensed, L*UV Lyman break galaxy (LBG) at z = 3.074. We obtained Spitzer mid-IR spectroscopy as well as MIPS 24 and 70 μm photometry. The Eye is detected with high significance at both 24 and 70 μm and, when including a flux limit at 3.5 mm, we estimate an IR luminosity of L IR = 8.3+4.7 -4.4 × 1011 L assuming a magnification of 28 3. This L IR is eight times lower than that predicted from the rest-frame ultraviolet properties assuming a Calzetti reddening law. This has also been observed in other young LBGs, and indicates that the dust reddening law may be steeper in these galaxies. The mid-IR spectrum shows strong polycyclic aromatic hydrocarbon (PAH) emission at 6.2 and 7.7 μm, with equivalent widths near the maximum values observed in star-forming galaxies at any redshift. The L PAH-to-L IR ratio lies close to the relation measured in local starbursts. Therefore, L PAH or L MIR may be used to estimate L IR, and thus star formation rate, of LBGs, whose fluxes at longer wavelengths are typically below current confusion limits. We also report the highest redshift detection of the 3.3 μm PAH emission feature. The PAH ratio, L 6.2/L 3.3 = 5.1 2.7, and the PAH-to-LIR ratio, L 3.3/L IR = 8.5 4.7 × 10-4, are both in agreement with measurements in local starbursts and ultraluminous infrared galaxies (ULIRGs), suggesting that this line may serve as a good proxy for L PAH or L IR at z > 3 with the James Webb Space Telescope.",
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T1 - Detection of far-infrared and polycyclic aromatic hydrocarbon emission from the cosmic eye

T2 - Probing the dust and star formation of lyman break galaxies

AU - Siana, B.

AU - Smail, Ian

AU - Swinbank, A. M.

AU - Richard, J.

AU - Teplitz, H. I.

AU - Coppin, K. E K

AU - Ellis, R. S.

AU - Stark, Daniel P

AU - Kneib, J. P.

AU - Edge, A. C.

PY - 2009

Y1 - 2009

N2 - We report the results of a Spitzer infrared (IR) study of the Cosmic Eye, a strongly lensed, L*UV Lyman break galaxy (LBG) at z = 3.074. We obtained Spitzer mid-IR spectroscopy as well as MIPS 24 and 70 μm photometry. The Eye is detected with high significance at both 24 and 70 μm and, when including a flux limit at 3.5 mm, we estimate an IR luminosity of L IR = 8.3+4.7 -4.4 × 1011 L assuming a magnification of 28 3. This L IR is eight times lower than that predicted from the rest-frame ultraviolet properties assuming a Calzetti reddening law. This has also been observed in other young LBGs, and indicates that the dust reddening law may be steeper in these galaxies. The mid-IR spectrum shows strong polycyclic aromatic hydrocarbon (PAH) emission at 6.2 and 7.7 μm, with equivalent widths near the maximum values observed in star-forming galaxies at any redshift. The L PAH-to-L IR ratio lies close to the relation measured in local starbursts. Therefore, L PAH or L MIR may be used to estimate L IR, and thus star formation rate, of LBGs, whose fluxes at longer wavelengths are typically below current confusion limits. We also report the highest redshift detection of the 3.3 μm PAH emission feature. The PAH ratio, L 6.2/L 3.3 = 5.1 2.7, and the PAH-to-LIR ratio, L 3.3/L IR = 8.5 4.7 × 10-4, are both in agreement with measurements in local starbursts and ultraluminous infrared galaxies (ULIRGs), suggesting that this line may serve as a good proxy for L PAH or L IR at z > 3 with the James Webb Space Telescope.

AB - We report the results of a Spitzer infrared (IR) study of the Cosmic Eye, a strongly lensed, L*UV Lyman break galaxy (LBG) at z = 3.074. We obtained Spitzer mid-IR spectroscopy as well as MIPS 24 and 70 μm photometry. The Eye is detected with high significance at both 24 and 70 μm and, when including a flux limit at 3.5 mm, we estimate an IR luminosity of L IR = 8.3+4.7 -4.4 × 1011 L assuming a magnification of 28 3. This L IR is eight times lower than that predicted from the rest-frame ultraviolet properties assuming a Calzetti reddening law. This has also been observed in other young LBGs, and indicates that the dust reddening law may be steeper in these galaxies. The mid-IR spectrum shows strong polycyclic aromatic hydrocarbon (PAH) emission at 6.2 and 7.7 μm, with equivalent widths near the maximum values observed in star-forming galaxies at any redshift. The L PAH-to-L IR ratio lies close to the relation measured in local starbursts. Therefore, L PAH or L MIR may be used to estimate L IR, and thus star formation rate, of LBGs, whose fluxes at longer wavelengths are typically below current confusion limits. We also report the highest redshift detection of the 3.3 μm PAH emission feature. The PAH ratio, L 6.2/L 3.3 = 5.1 2.7, and the PAH-to-LIR ratio, L 3.3/L IR = 8.5 4.7 × 10-4, are both in agreement with measurements in local starbursts and ultraluminous infrared galaxies (ULIRGs), suggesting that this line may serve as a good proxy for L PAH or L IR at z > 3 with the James Webb Space Telescope.

KW - Galaxies: high-redshift

KW - Galaxies: individual (J213512.73-010143, Cosmic Eye)

KW - Infrared: galaxies

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