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Dust-Obscured Galaxies (DOGs)

Dust-Obscured Galaxies (DOGs). Vandana Desai Spitzer Science Center with Lee Armus, Colin Borys, Mark Brodwin, Michael Brown, Shane Bussmann, Arjun Dey, Buell Jannuzzi, Emeric Le Floc’h, Jason Melbourne, Alexandra Pope, Tom Soifer. The role of high-z ULIRGs. Quasar. Starburst. Merger.

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Dust-Obscured Galaxies (DOGs)

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  1. Dust-Obscured Galaxies (DOGs) Vandana Desai Spitzer Science Center with Lee Armus, Colin Borys, Mark Brodwin, Michael Brown, Shane Bussmann, Arjun Dey, Buell Jannuzzi, Emeric Le Floc’h, Jason Melbourne, Alexandra Pope, Tom Soifer

  2. The role of high-z ULIRGs Quasar Starburst Merger AGN “on” Massive Galaxy Dey et al. 2009 after Sanders et al. 1988 and their relation to mergers, star formation, AGN, and the formation of massive galaxies

  3. The z=2 ULIRG zoo Caitlin’s MIPS-70 ULIRGs Alejo’s Host-obscured Quasars SMGs DOGs

  4. NOAO Deep Wide-Field Survey Ground-based Data for Bootes Field 9 deg2 Bw, R, I, K ~ 27.1, 26.1, 25.4, 19.0 mag (Vega) MIPS-24 ~0.3 mJy PIs: A. Dey & B. Jannuzi

  5. Dust-Obscured Galaxies (DOGs) Fraction Most extreme 10% R-[24] (Vega mag)

  6. DOG Selection Warning: Need better data on UV emission from local ULIRGs. R-[24] (Vega mag) Redshift Dey+08

  7. Papovich et al. 2004 increasingly significant numbers at fainter fluxes... Papovich +04 Euclid Norm # Counts DOG Fraction Dey +08 24 micron flux (mJy) 24 micron flux (mJy) ...where we find the peak of the 24m counts! 24 micron flux (mJy)

  8. The DOG criterion selects for z = 2 • LIR = ULIRGs (large error) • Space density = (2.82+-0.05)x10-5h70Mpc-3 • (like 4L* galaxies) • Log(IRLD) = • 8.23+0.18-0.30 Lsun Mpc-3 • 60% of all z=2 ULIRGs • 25% of IRLD at z = 2 Dey+08

  9. Power Laws and Bumps Faint “Bump” starforming Bright Power-Law AGN

  10. Spectroscopy of Power-Law DOGs IRS Houck+05, also Weedman+06, Yan+06 NIRSPEC Brand+07 • 7/10 are broad-line AGN • Extinction to narrow and broad-lines high – host obscured? • AGN-like: • silicate absorption • Weak PAHs

  11. Spitzer/IRS spectra of bump DOGs Desai+09, Huang+09, Farrah08

  12. NIR spectra of bump DOGs No NIR spectra of bump sources due to inconvenient redshift. 70 micron selection? Casey+09, Farrah+09 Desai+09

  13. Morphology - HST rest-UV rest-optical rest-UV rest-optical • Extended emission dominates • Few on-going mergers Morphologies of power-law DOGs 2” Bussmann et al. 2009a; See also Dasyra et al. 2009

  14. Morphology - HST Morphologies of bump DOGs • On-going interactions more common • More similar to SMGs (Borys et al., in prep) rest-optical 2” Bussmann et al. 2010, in prep.

  15. Morphology – Keck AO Fainter (bump/SF) DOGs are more diffuse than bright (PL/AGN) DOGs. Melbourne et al. 2009

  16. 1.4<z<2 QSOs (Shen et al. 2008) 2<z<2.5 QSOs (Shen et al. 2008) Brodwin et al. 2008, Magliocchetti+08, Farrah+06 Clustering • Strong clustering • Comparable to SMGs & QSOs • Large uncertainties 2<z<2.5 QSOs (Shen et al. 2008) R0 (h-1 Mpc) Fn(24) [mJy]

  17. FIR SEDs of PL DOGs • 5/12 detected at 350m with CSO • 0/2 of these detected at 1.3mm with CARMA • Preferred SED:Mrk231 • Tdust > 45 K (Warmer than SMGs) • Mdust ~ 3x108 Msun Bussmann et al. 2009b

  18. FIR SEDs of bump DOGs • 70 faint DOGs in GOODs-N • Stack 70, 160, 850, 1.2mm • TBDOG ~ TSMG • Need some extra hot dust (10% of LIR) compared to SMGs • SFR = 200 Msun/yr • Stacked X-rays consistent with SF, but see Fiore+08 PACS 110 mm SCUBA-2 450 mm Pope+08, see also Lonsdale+09,Fiolet09

  19. Herschel GTO observations of Bootes • Herschel probes peak of DOG SED! • Bright, rare Bootes DOGs likely detected in L5 250 mm data depending on: • confusion • the power of priors • FIR SEDs • Bulk properties attainable through stacking

  20. Herschel Key Program in GOODS PACS 110 mm SCUBA-2 450 mm PACS and SCUBA-2 will detect most (fainter) DOGs in GOODs. Pope et al. 2008

  21. The role of high-z ULIRGs Quasar SMG – bump DOG Merger PL DOG Massive Galaxy Dey et al. 2009 after Sanders et al. 1988 and their relation to mergers, star formation, AGN, and the formation of massive galaxies

  22. Summary • ~Half of z = 2 ULIRGs are DOGs • Contribute a ~quarter of the total IR luminosity density at z~2 • Space density + clustering => ~3-4L* elliptical at z=0 • Bright DOGs ~ Power-Law ~ compact ~ (obscured) AGN • Faint DOGs ~ Bump ~ diffuse, interacting ~ SF • Herschel will help pin down FIR SED, which is a major existing uncertainty. Need FIR SEDs to reassess!

  23. What is a DOG? A ULIRG at z = 2, selected at 24 micron

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