README web version of /home/usg/OPS/MTS/readme_xml/readme_60943000

Principal Investigator Email Address

• j.m.gelbord@durham.ac.uk

Estimated Total Execution Time (hours, including overheads)

• 1 hour

General Description

• Scientific background:
  
  Our target appears to be a z = 0.22 starburst galaxy, based upon the
  optical spectrum from SDSS, yet it has an X-ray luminosity (L_x) of
  2 times 10^{43} erg/s.  It is one of a sample of objects we have
  discovered that have the optical spectra of pure starburst galaxies
  but have L_x 10 to 100 times more powerful than the most X-ray
  luminous star forming galaxies known in the local universe.  These
  galaxies either represent a new extreme of the starburst luminosity
  function or they are composite galaxies that harbour active nuclei so
  deeply buried that they leave no trace in the optical band.  In deep
  surveys where the information about individual objects is often
  limited, objects with such high L_x values are generally assumed to be
  AGN.  We intend to test this assumption by measuring or putting limits
  on the AGN contribution to our extreme L_x starbursts.
  
  Science goals:
  
  We will use the wider spectral coverage and the higher sensitivity of
  X-shooter to look for optical AGN signatures that were not detectable
  with SDSS or NIR features that are less affected by reddening.  One
  signature would be broad hydrogen lines.  If the observed X-rays are
  due to a buried AGN, then there should be a broad Pa alpha line that
  would be detectable with at least 5-sigma significance unless it is
  buried by more than 20 magnitudes of A_v extinction.  If we detect
  broad Pa alpha we can look for corresponding components of Pa beta or
  H alpha, which would allow us to measure or put limits on the amount
  of reddening.
  
  Another signature of AGN would be emission from forbidden
  high-ionization lines (FHILs, with ionization potentials > 100 eV).
  These lines are found throughout the X-Shooter bandpass, but the most
  prominent FHILs are [Fe VII] 6087A, [Fe X] 6374A, [Fe XI] 7892A, and
  [Si VI] 1.96um.
  
  If we are able to detect any of these spectral signatures, then we
  will confirm the presence of an AGN in our target galaxy.  Moreover,
  both broad lines and FHILs scale with AGN power so if we are able to
  measure their fluxes and combine these with constraints on the
  reddening, then we will be able to estimate the fraction of the X-ray
  power that is driven by the AGN.  Conversely, if no AGN signatures are
  found, then we will use the flux limits to put strong limits on the
  contribution of a AGN to the high L_x of our target.
  
  We want to flux calibrate in order to quantify the strength of any AGN
  contribution.  However, if we are forced to accept non-photometric
  clear conditions, we can at least try to detect AGN signatures.

Waiver Requests

• No Waiver Request was submitted

Critical Observing Condition Constraints

• We requested photometric conditions because flux calibration is required
   to quantify any contribution from a buried AGN and to measure the extinction along
   the line of sight to the nucleus.
  
  If necessary, we could make due with clear but not photometric conditions.  We would
   still be able to test whether there are detectable AGN signatures, which would provide
   some result and would demonstrate what we could do with X-shooter observations in
   the future.
  
  We can tolerate scattered light from the moon because we can achieve our science
   goals entirely with lines observed at 743 nm ([Fe VII] 6087 at z=0.2204) and longer
   wavelengths.  However, if the shorter wavelength background is not too high, there
   are other high-ionization lines that could further enhance our results.

Time-Critical Aspects

• None.

Special Execution Requirements

• None.

Special Calibration Information

• The default calibration plan is sufficient.

ToO Information

• Not applicable.

ToO Activators List

• Not applicable.

Do all your OBs comply with the instrument-specific requirements listed
 on the instrument-specific Phase 2 web page ?

• YES

Do all your finding charts comply with both the general and instrument-specific
 Phase 2 Web Pages ?

• YES

If you submitted OBs for standard stars, did you specify the magnitude
 and spectral type of all standard stars in the OBs ?

• N/A

Have you specified the S/N ratio at given wavelength in the User Comments
 field of each OB?

• YES

Have you included OBs for any calibrations that you need but which are
 not part of the Calibration Plan ?

• N/A

If you are observing Moving Targets, have you attached suitable ephemeris
 files to your OBs?

• N/A

If you have preferences which OBs should be executed first, did you make
 use of the User Priority field in the OBs ?

• N/A

If this is a run that requires coordinated observations with other facilities,
 did you give proper instructions in the Time-Critical Aspects Section ?

• N/A