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J/A+A/311/384       ROSAT observations of BL Lacertae objects (lamer+ 1996)
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ROSAT observations of BL Lacertae objects.
      Lamer G., Brunner H., Staubert R.
     <Astron. Astrophys. 311, 384 (1996)>
     =1996A&A...311..384L      (SIMBAD/NED BibCode)
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ADC_Keywords: BL Lac objects ; X-ray sources
Keywords: galaxies: active - BL Lacertae objects: general -
          radio continuum: galaxies - X-rays: galaxies
Mission_Name: ROSAT

Description:
    We present soft X-ray spectra of 74 BL Lacertae objects observed with
    the PSPC detector on board of the ROSAT satellite. The sample contains
    all BL Lac objects detected during the pointed observation phase as a
    target or serendipitously. We have investigated the soft X-ray and
    broad band spectral properties and discuss the consequences for the
    X-ray emission processes. For the first time a clear dependence of the
    X-ray spectral steepness on the radio to X-ray spectral energy
    distribution is found: {alpha}_rx_ and {alpha}_x_ are correlated in
    the X-ray selected (XBL) subsample and anticorrelated in the radio
    selected (RBL) subsample. The objects with intermediate {alpha}_rx_
    values thus do have the steepest soft X-ray spectra. Simulated PSPC
    spectra based on a set of simple two component multifrequency spectra
    are in good agreement with the measurements and suggest a broad range
    of synchrotron cutoff energies. We have calculated synchrotron
    self-Compton beaming factors for a subsample of radio bright objects
    and find a correlation of the beaming factors {delta}_IC_ with
    {alpha}_rx_ and {alpha}_x_. The most extreme RBL objects are very
    similar to flat spectrum radio quasars in all their broad band and
    X-ray properties.

File Summary:
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  FileName  Lrecl  Records   Explanations
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ReadMe         80        .   This file
table2         56       73   List of PSPC observations
table3         63       74   X-ray and broad band spectra
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Byte-by-byte Description of file: table2
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   Bytes Format Units   Label     Explanations
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   1- 11  A11   ---     Name      Object name
  13- 18  I6    ---     ROR       ROSAT observation request (ROR) number
      19  A1    ---   n_ROR       [-] '-' when two ROR numbers
  20- 25  I6    ---     ROR2      ? Second ROR number
  27- 35  A9    ---     Date      Completed date
  39- 43  I5    s       Exp       Exposition time
  46- 53  E8.0  ---     Counts    Net counts
  54- 56  I3    ---   e_Counts    ? rms uncertainty on Counts
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Byte-by-byte Description of file: table3
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   Bytes Format   Units     Label     Explanations
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   1- 12  A12     ---       Name      Object name
  14- 18  F5.2  10+20cm-2   NH,gal    Galactic hydrogen column density
      19  A1      ---     n_NH,gal    Note on NH,gal (1)
  22- 26  F5.2  10+20cm-2   NH,fit    ? Fitted hydrogen column density
  29- 33  F5.2  10+20cm-2 e_NH,fit    ? rms uncertainty on NH,fit
  35- 40  F6.2    uJy       F1keV     Flux at 1 keV
  42- 45  F4.2    ---       alpha     Spectral index between .1kev and 2.4keV
  49- 52  F4.2    ---     e_alpha     rms uncertainty on alpha
  54- 57  F4.2    ---       alpha_rx_ X-ray spectral index
  59- 63  F5.2    ---       delta_IC_ ? Inverse Compton beaming factor
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Note (1): a: Elvis et al. 1989, other values: Stark et al. 1992
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References:
   Elvis M. et al., 1989, AJ, 97, 777     =1989AJ.....97..777E
   Stark A.A. et al., 1992, ApJS, 79, 77  =1992ApJS...79...77S
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(End)                                         Patricia Bauer [CDS]   26-Mar-1996