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IR S pectral Diagnostics of z=2 Dust Obscured Galaxies (DOGs)

IR S pectral Diagnostics of z=2 Dust Obscured Galaxies (DOGs). Jason Melbourne (Caltech) B.T. Soifer, Lee Armus, Keith Matthews, Vandana Desai, Arjun Dey, Shane Bussmann. Melbourne et al. 2008. DOGs are Defined by Very Red Optical to Mid-IR Colors . R-[24] > 14 (Vega mag)

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IR S pectral Diagnostics of z=2 Dust Obscured Galaxies (DOGs)

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  1. IR Spectral Diagnostics of z=2 Dust Obscured Galaxies (DOGs) Jason Melbourne (Caltech) B.T. Soifer, Lee Armus, Keith Matthews, Vandana Desai, Arjun Dey, Shane Bussmann Melbourne et al. 2008

  2. DOGs are Defined by Very Red Optical to Mid-IR Colors • R-[24] > 14 (Vega mag) • F[24]/F[R] > 1000 • Significant amounts of warm dust. • Total IR energy densities great than ULIRGs. Dey et al. 2008

  3. Over 2000 DOGs Identified in the NOAO Deep Wide Field Survey of Bootes • 10 square degrees • BRI ground based imaging • Spitzer IRAC imaging • Spitzer MIPS imaging

  4. The Redshift Distribution of DOGs is Centered About z=2 • Median redshift of z = 1.99 • z = 0.5 Dey et al. 2008

  5. Spectral Energy Distributions Vary with 24 micron Flux • Brighter DOGs tend to show power-law SEDs. • Fainter DOGs tend to show a “bump” in the observed mid-IR. Dey et al. 2008

  6. IRS Spectra of Power-Law DOGs Suggest AGN Activity Weedman et al. 2005

  7. IRS Spectra of “Bump” DOGs Suggest Star Formation Desai et al. 2009

  8. TripleSpec: 5 Orders in the Near-IR, Including J, H, and K in One Spectrum

  9. Spectra of Power-Law DOGs Reveal Broad H H Melbourne et al. in prep

  10. Spectra of “Bump” DOGs Reveal Narrow H H Melbourne et al. in prep

  11. Broad Ha from AGN dominates, but narrow Ha suggests star formation Broad H Narrow H

  12. OSIRIS Sample is AGN Dominated

  13. These look different

  14. Summary • A simple optical to mid-IR color selection identifies extreme z=2 ULIRGs. • These Dust Obscured Galaxies (DOGs) may evolve into massive the ellipticals of today. • DOGs are powered by a combination of SF and AGN activity. • OSIRIS observations pinpoint the location of the AGN and constrain SFR.

  15. Spectra of Power-Law DOGs Reveal Broad H Counts 1.5 1.6 1.7 1.8 Observed Wavelength (m)

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