Xray selected starbursts: the midIR view

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X-ray selected starbursts the mid-IR view

• Antonis Georgakakis
• Imperial College
• M. Rowan-Robinson (IC), T. Babbedge (IC),
• I. Georgantopoulos (Athens)

Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
2
Starforming galaxies at X-ray wavelengths

• The only tool to study
• X-ray binaries
• Hot gas component
• Chandra and XMM-Newton detailed information for
  nearby galaxies (lt100Mpc)

Baldi et al. 2006a, b
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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Starforming galaxies at X-ray wavelengths

• Chandra and XMM the first X-ray selected galaxy
  samples outside the local Universe
• Chandra Deep Fields identify galaxies to z1
• Chandra XMM-Newton wide-angle shallow surveys
  find galaxies at z0.1
• Study X-ray galaxy evolution to z1

z 0.298
Hornschemeier et al. 2003
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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Georgakakis et al. 2006a, bGeorgantopoulos et
al. 2005
Starforming galaxies at X-ray wavelengths

• Chandra and XMM the first X-ray selected galaxy
  samples outside the local Universe
• Chandra Deep Fields identify galaxies to z1
• Chandra XMM-Newton wide-angle shallow surveys
  find galaxies at z0.1
• Study X-ray galaxy evolution to z1

z 0.07
Needles in the Haystack Survey
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
5
Ghosh White 2001
Starforming galaxies at X-ray wavelengths

• Chandra and XMM the first X-ray selected galaxy
  samples outside the local Universe
• Chandra Deep Fields identify galaxies to z1
• Chandra XMM-Newton wide-angle shallow surveys
  find galaxies at z0.1
• Study X-ray galaxy evolution to z1

SFR
X-rays
Norman et al. 2005 Georgantopoulos et a. 2005
Georgakakis et al. 2006a, b
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
6
Ghosh White 2001
Starforming galaxies at X-ray wavelengths

• Chandra and XMM the first X-ray selected galaxy
  samples outside the local Universe
• Chandra Deep Fields identify galaxies to z1
• Chandra XMM-Newton wide-angle shallow surveys
  find galaxies at z0.1
• Study X-ray galaxy evolution to z1

SFR
Evolution studies sensitive to normal galaxy
selection. Obscured or low-luminosity AGN
contamination may bias any results
conclusions This problem is more serious for
high-z sources Multi-wavelength data essential
X-rays
Norman et al. 2005 Georgantopoulos et a. 2005
Georgakakis et al. 2006a, b
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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X-ray selected galaxies at IR

• local SF galaxies tight LXLIR correlation
  (Ranalli et al. 2003)
• AGN deviate from the SF galaxy relation
• combined IRX-ray data can be used to identify
  contaminating AGN in X-ray selected galaxy samples

Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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The GOODS-North dataset

• ultra-deep X-ray data from CDF-N (Alexander et
  al. 2003)
• Spitzer 3.6-24?m (GOODS team)
• optical UBVRIz (Capak et al. 2004)
• spectroscopy (Barger et al. 2003 Team Keck
  Treasury redshift Survey)

Chandra Deep Field North team
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
9
The GOODS-North dataset

• ultra-deep X-ray data from CDF-N (Alexander et
  al. 2003)
• Spitzer 3.6-24?m (GOODS team)
• optical UBVRIz (Capak et al. 2004)
• spectroscopy (Barger et al. 2003 Team Keck
  Treasury redshift Survey)

• IR properties of CDF-N X-ray sources classified
  by Bauer et al. (2005)
• type-I AGN (19 in total)
• type-II AGN (85 in total)
• 56 secure normal galaxies
• 47 candidate normal galaxies (AGN
  contamination expected)
• Only X-ray sources with optical IDs that overlap
  with the Spitzer survey area

Chandra Deep Field North team
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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The method

• LIR estimation
• optical/mid-IR SED fitting method of
  Rowan-Robinson et al. 2005
• optical (UBVRIz)near-IR
• Galaxy (E/S0Sdm)
• AGN
• mid-IR (3.6-24?m) excess
• Starburst (M82, ARP220)
• Cirrus SED
• AGN torus

See poster by Babbedge et al.
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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Results LX-LIR

• secure normal galaxies
• z0.5
• consistent with SF LX-LIR
• BUT also few AGN

Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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Results LX-LIR

• secure normal galaxies
• z0.5
• consistent with SF LX-LIR
• BUT also few AGN
• candidate normal galaxies
• z0.5
• mostly AGN
• BUT also a few galaxies
• Normal galaxies
• 50 of galaxies LIRGs
• handful ULIRGs
• upper limit LX1042erg/s

Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
13
Results LX-LIR

• secure normal galaxies
• z0.5
• consistent with SF LX-LIR
• BUT also few AGN
• candidate normal galaxies
• z0.5
• mostly AGN
• BUT also a few galaxies
• Normal galaxies
• 50 of galaxies LIRGs
• handful ULIRGs
• upper limit LX1042erg/s

Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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Results LX-LIR

• secure normal galaxies
• z0.5
• consistent with SF LX-LIR
• BUT also few AGN
• candidate normal galaxies
• z0.5
• mostly AGN
• BUT also a few galaxies
• Normal galaxies
• 50 of galaxies LIRGs
• handful ULIRGs
• upper limit LX1042erg/s

Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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Galaxy fraction against LIR
HyLIRGs
LIRGs
ULIRGs

• AGN dominate ULIRG and HyLIRG IR luminosities.
• 35 of the X-ray selected LIRGs starbursts

Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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Conclusions

• X-rayIR powerful tool for discriminating normal
  galaxies from AGN
• X-ray selected starbursts 50 LIRGs, only a
  handful ULIRGs
• Upper limit in starburst X-ray luminosity
  LX1042erg/s
• Future clean sample to study X-ray galaxy
  evolution free of AGN contamination biases.

Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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X-ray selected galaxies at IR

• Early-type galaxies LXMstar correlation
• AGN deviate from this relation
• X-ray stellar masses (e.g. 3.6?m) can be used
  to identify AGN in early-type galaxies

Hornschemeier et al. 2005
LX?M1.8
AGN?
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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Results LX-Mstar
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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Results LX-Mstar
Early type galaxies only no mid-IR excess over
stellar cirrus mid-IR SEDs secure
normal galaxies candidate normal galaxies
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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Results LX-Mstar

• Early type galaxies only
• no mid-IR excess over stellar
• cirrus mid-IR SEDs
• secure normal galaxies
• candidate normal galaxies
• LX?Mstar1.8, consistent with local studies
  (Hornschemeier et al. 2005 Ellis O'Sullivan
  2005)

Galaxy Evolution?with?Spitzer and Herschel, Crete
2006
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AGN fraction against LIR
z1
Mirabel Sanders 1996 local Universe
Galaxy Evolution?with?Spitzer and Herschel, Crete
2006