SED measurements of radio galaxies 1 < z < 5

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SED measurements of radio galaxies 1 lt z lt 5

• Bob Fosbury (ST-ECF) on behalf of the SHzRGS team
• Daniel Stern - PI, Peter Eisenhardt (JPL)
• Carlos De Breuck - Co-PI, Joel Vernet, Alessandro
  Rettura (ESO)
• Bob Fosbury (ST-ECF)
• Andrew Zirm (STSCI)
• Brigitte Rocca-Volmerange (IAP)
• Nick Seymour, Mark Lacy, Harry Teplitz (SSC)
• Arjun Dey, Mark Dickinson (NOAO)
• Wil van Breugel, Adam Stanford (UCLLNL)
• George Miley, Huub Rottgering (Leiden)
• Partick McCarthy (OCIW)
• Dave Alexander (IoA)

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Objective

• The hosts of powerful radio galaxies represent
  the most massive galaxies at their epoch
• By observing the SED through the restframe H-band
  with Spitzer, we measure the stellar masses
• The Spitzer images allow us to investigate the
  (proto)-cluster environment
• The SMBH is characterised from X-ray and radio
  measurements

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Evidence

• gE and cD galaxies in the local universe
• r(1/4) light profiles in distant sources
  (NICMOS)
• HzRG reside in (proto-)cluster environments
• Large, luminous Ly-a halos
• sub-mm detections gt high star formation rates
• NIR Hubble diagram (K-z Rocca-Volmerange et al.
  2004)
• Correlation of stellar bulge and BH masses

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Sample

• The objective is to cover the radio luminosity -
  redshift plane as uniformly as possible in the
  range 1 lt z lt 4, covering two orders of magnitude
  in radio luminosity
• Sample chosen to maximise number of supporting
  observation (but no bias towards cold dust
  properties - 850micron Obs not Det)

Solid symbols - HzRGs in our Spitzer sample with
IRAC/IRS imaging Large circles - MIPS
observations as well Filled circles - HzRGs with
HST data Filled squares - HzRGs with SCUBA
data Plusses - parent sample of 225 HzRGs from
which our sample of 70 was drawn
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Spitzer observations

• 3-camera programme GO 3329 (Stern)
• IRAC 4x30s in all 4 bands gt 5-sigma at m_AB22
  for ch 1 2 and at m_AB20 for ch 3 4
• IRS 16 micron imaging (peak-up) mode 2x60s gt
  5_sigma at 0.17mJy
• MIPS subset of 21 sources with low 24 micron
  background all three bands 24 (30s), 70 (30s),
  160 (50s) but most detections at 24

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Supporting observations

• 48/70 have HST imaging total exposure of 1.5Ms
• 16 have Chandra/XMM-Newton data
• 43 have published sub-mm data
• 22 have deep optical polarimetric observations
  from Keck/VLT
• Use to construct broadband SED and characterise
  AGN and dust re-radiation in addition to the
  evolved stellar population
• Also use to study galaxy morphology and
  environment

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WFPC2 - IRAC

• HST/WFPC2 top and Spitzer/IRAC bottom images
  of 5 HzRGs
• From left to right, galaxies shown are 3C266 (z
  1.275), MRC 0152-209 (z 1.920), USS 1707105 (z
  2.349), MRC 0406-244 (z 2.427), and 4C41.17
  (z 3792)
• Images are 30 arcsec on a side, oriented with
  North up and East to the left. Note that a number
  of the fields show overdensities of
  infrared-bright, optically-faint galaxies

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Supporting proposals

• ESO and Palomar imaging (for 4000Å-break)
• IRS mid-IR spectroscopy (Silicate, PAH and
  continuum)
• MIPS - to extend subset
• ESO imaging polarimetry (removal of AGN
  component)
• MAMBO and SCUBA sub-mm
• VLA 4.8 and 8.4 GHz to extend 3 GHz restframe
  depth polarimetry to measure RM environment
• HST archive

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4C23.56

• This is our initial example object with very
  complete observational coverage.

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Keck spectropolarimetry

• Showing the dominance of the scattered quasar in
  the restframe ultraviolet(Cimatti et al.
  1998Vernet et al. 2001)

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Composite SED
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SED modelling

• Initial modelling with stellar population
  (PEGASE.2), hot and cold dust (Siebenmorgen), and
  synchrotron components
• Will add the scattered AGN
• We need deeper sum-mm observations for most of
  this sample

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Restframe H-band estimates

• By Nick Seymour (elliptical templates warm dust)
• Full SED fitting tbd by Alessandro Rettura

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Restframe H-band vs. z

• Derived from best-fit models to the multi-band
  photometry
• Sources with large error bars lack MIPS 24micron
  observations, making the decomposition of stellar
  and dust/AGN components of the SED less secure.
• The error bars for these sources show that the
  range of reasonable stellar luminosities given
  (1) the total H-band luminosity and (2) that the
  stellar emission typically dominates at observed
  3.6micron (as seen in the modelling of sources
  with MIPS data) and hence can predict a
  reasonable lower value to the H-band luminosity.
• The red line shows the expected H-band luminosity
  of a passively evolving 1012M_sun elliptical
  galaxy from the PEGASE.2 models (see
  Rocca-Volmerange et al., 2004)

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First cut at M-z for Radio Galaxy hosts
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BH mass vs. stellar mass

• Local galaxies with measured kinematic and
  stellar masses (blue stars)
• HzRG with measured X-ray luminosities (red
  squares)
• Implications for BH growth at early epochs

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• Nick Seymours status pages