Strong polycyclic aromatic hydrocarbon emission from z ≈ 2 ulirgs

Vandana Desai, B. T. Soifer, Arjun Dey, Emeric Le Floc'H, Lee Armus, Kate Brand, Michael J I Brown, Mark Brodwin, Buell Tomasson Jannuzi, James R. Houck, Daniel W. Weedman, Matthew L N Ashby, Anthony Gonzalez, Jiasheng Huang, Howard A. Smith, Harry Teplitz, Steve P. Willner, Jason Melbourne

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

Using the Infrared Spectrograph on board the Spitzer Space Telescope, we present low-resolution (64 < λ/δλ < 124), mid-infrared (20-38 μm) spectra of 23 high-redshift ULIRGs detected in the Boötes field of the NOAO Deep Wide-Field Survey. All of the sources were selected to have (1) f ν(24 μm)>0.5 mJy; (2) R - [24]>14 Vega mag; and (3) a prominent rest frame 1.6 μm stellar photospheric feature redshifted into Spitzer's 3-8 μm IRAC bands. Of these, 20 show emission from polycyclic aromatic hydrocarbons (PAHs), usually interpreted as signatures of star formation. The PAH features indicate redshifts in the range 1.5 < z < 3.0, with a mean of 〈z〉 = 1.96 and a dispersion of 0.30. Based on local templates, these sources have extremely large infrared luminosities, comparable to that of submillimeter galaxies. Our results confirm previous indications that the rest-frame 1.6 μm stellar bump can be efficiently used to select highly obscured star-forming galaxies at z 2, and that the fraction of starburst-dominated ULIRGs increases to faint 24 μm flux densities. Using local templates, we find that the observed narrow redshift distribution is due to the fact that the 24 μm detectability of PAH-rich sources peaks sharply at z = 1.9. We can analogously use observed spectral energy distributions to explain the broader redshift distribution of Spitzer-detected ULIRGs that are dominated by an active galactic nucleus (AGN). Finally, we conclude that z 2 sources with a detectable 1.6 μm stellar opacity feature lack sufficient AGN emission to veil the 7.7 μm PAH band.

Original languageEnglish (US)
Pages (from-to)1190-1204
Number of pages15
JournalAstrophysical Journal
Volume700
Issue number2
DOIs
StatePublished - 2009
Externally publishedYes

Fingerprint

polycyclic aromatic hydrocarbons
PAH
active galactic nuclei
templates
galaxies
Space Infrared Telescope Facility
spectral energy distribution
opacity
spectrographs
star formation
indication
flux density
luminosity
signatures
stars
energy
distribution

Keywords

  • Galaxies: active
  • Galaxies: evolution
  • Galaxies: formation
  • Galaxies: starburst
  • Infrared: galaxies

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Desai, V., Soifer, B. T., Dey, A., Le Floc'H, E., Armus, L., Brand, K., ... Melbourne, J. (2009). Strong polycyclic aromatic hydrocarbon emission from z ≈ 2 ulirgs. Astrophysical Journal, 700(2), 1190-1204. https://doi.org/10.1088/0004-637X/700/2/1190

Strong polycyclic aromatic hydrocarbon emission from z ≈ 2 ulirgs. / Desai, Vandana; Soifer, B. T.; Dey, Arjun; Le Floc'H, Emeric; Armus, Lee; Brand, Kate; Brown, Michael J I; Brodwin, Mark; Jannuzi, Buell Tomasson; Houck, James R.; Weedman, Daniel W.; Ashby, Matthew L N; Gonzalez, Anthony; Huang, Jiasheng; Smith, Howard A.; Teplitz, Harry; Willner, Steve P.; Melbourne, Jason.

In: Astrophysical Journal, Vol. 700, No. 2, 2009, p. 1190-1204.

Research output: Contribution to journalArticle

Desai, V, Soifer, BT, Dey, A, Le Floc'H, E, Armus, L, Brand, K, Brown, MJI, Brodwin, M, Jannuzi, BT, Houck, JR, Weedman, DW, Ashby, MLN, Gonzalez, A, Huang, J, Smith, HA, Teplitz, H, Willner, SP & Melbourne, J 2009, 'Strong polycyclic aromatic hydrocarbon emission from z ≈ 2 ulirgs', Astrophysical Journal, vol. 700, no. 2, pp. 1190-1204. https://doi.org/10.1088/0004-637X/700/2/1190
Desai V, Soifer BT, Dey A, Le Floc'H E, Armus L, Brand K et al. Strong polycyclic aromatic hydrocarbon emission from z ≈ 2 ulirgs. Astrophysical Journal. 2009;700(2):1190-1204. https://doi.org/10.1088/0004-637X/700/2/1190
Desai, Vandana ; Soifer, B. T. ; Dey, Arjun ; Le Floc'H, Emeric ; Armus, Lee ; Brand, Kate ; Brown, Michael J I ; Brodwin, Mark ; Jannuzi, Buell Tomasson ; Houck, James R. ; Weedman, Daniel W. ; Ashby, Matthew L N ; Gonzalez, Anthony ; Huang, Jiasheng ; Smith, Howard A. ; Teplitz, Harry ; Willner, Steve P. ; Melbourne, Jason. / Strong polycyclic aromatic hydrocarbon emission from z ≈ 2 ulirgs. In: Astrophysical Journal. 2009 ; Vol. 700, No. 2. pp. 1190-1204.
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abstract = "Using the Infrared Spectrograph on board the Spitzer Space Telescope, we present low-resolution (64 < λ/δλ < 124), mid-infrared (20-38 μm) spectra of 23 high-redshift ULIRGs detected in the Bo{\"o}tes field of the NOAO Deep Wide-Field Survey. All of the sources were selected to have (1) f ν(24 μm)>0.5 mJy; (2) R - [24]>14 Vega mag; and (3) a prominent rest frame 1.6 μm stellar photospheric feature redshifted into Spitzer's 3-8 μm IRAC bands. Of these, 20 show emission from polycyclic aromatic hydrocarbons (PAHs), usually interpreted as signatures of star formation. The PAH features indicate redshifts in the range 1.5 < z < 3.0, with a mean of 〈z〉 = 1.96 and a dispersion of 0.30. Based on local templates, these sources have extremely large infrared luminosities, comparable to that of submillimeter galaxies. Our results confirm previous indications that the rest-frame 1.6 μm stellar bump can be efficiently used to select highly obscured star-forming galaxies at z 2, and that the fraction of starburst-dominated ULIRGs increases to faint 24 μm flux densities. Using local templates, we find that the observed narrow redshift distribution is due to the fact that the 24 μm detectability of PAH-rich sources peaks sharply at z = 1.9. We can analogously use observed spectral energy distributions to explain the broader redshift distribution of Spitzer-detected ULIRGs that are dominated by an active galactic nucleus (AGN). Finally, we conclude that z 2 sources with a detectable 1.6 μm stellar opacity feature lack sufficient AGN emission to veil the 7.7 μm PAH band.",
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AU - Soifer, B. T.

AU - Dey, Arjun

AU - Le Floc'H, Emeric

AU - Armus, Lee

AU - Brand, Kate

AU - Brown, Michael J I

AU - Brodwin, Mark

AU - Jannuzi, Buell Tomasson

AU - Houck, James R.

AU - Weedman, Daniel W.

AU - Ashby, Matthew L N

AU - Gonzalez, Anthony

AU - Huang, Jiasheng

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KW - Galaxies: starburst

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