Access to Astronomical Catalogues

J/ApJ/714/1424    Isolated neutron stars from Rosat and Swift   (Turner+, 2010)
A limit on the number of isolated neutron stars detected in the ROSAT
All-Sky-Survey Bright Source Catalog.
    Turner M.L., Rutledge R.E., Letcavage R., Shevchuk A.S.H., Fox D.B.
   <Astrophys. J., 714, 1424-1440 (2010)>
   =2010ApJ...714.1424T
ADC_Keywords: X-ray sources ; Cross identifications ; Pulsars

Keywords: stars: neutron - X-rays: stars


Abstract:
    Using new and archival observations made with the Swift satellite and
    other facilities, we examine 147 X-ray sources selected from the ROSAT
    All-Sky-Survey Bright Source Catalog (RASS/BSC) to produce a new limit
    on the number of isolated neutron stars (INSs) in the RASS/BSC, the
    most constraining such limit to date. Independent of X-ray spectrum
    and variability, the number of INSs is ≤48 (90% confidence).
    Restricting attention to soft (kTeff<200eV), non-variable X-ray
    sources -as in a previous study- yields an all-sky limit of ≤31
    INSs. In the course of our analysis, we identify five new high-quality
    INS candidates for targeted follow-up observations. A future all-sky
    X-ray survey with eROSITA, or another mission with similar
    capabilities, can be expected to increase the detected population of
    X-ray-discovered INSs from the 8-50 in the BSC, to (for a disk
    population) 240-1500, which will enable a more detailed study of
    neutron star population models.

Description:
    Following selection of the isolated neutron star (INS) candidates,
    short (∼1ks) follow-up observations with Swift/XRT were obtained on 92
    of the candidates; these observations decrease the X-ray positional
    uncertainty (the systematic positional error associated with Swift
    blind pointing observations is on the order of 3.5"), and obtain
    (where possible) contemporaneous UV observations with Swift/UVOT for
    counterpart identification with off-band objects.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat       109      147   Candidates RASS/BSC sources and identifications
table2.dat       149       77   Objects observed and detected with Swift/XRT


See also:
  IX/10 : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
  J/A+A/527/A139 : X-ray bursting neutron star atmosphere models (Suleimanov+,
                   2011)
  J/A+A/473/523  : Spectroscopic monitoring of 3 neutron stars (Van der Meer+,
                   2007)
  http://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/swift.pl : Swift mission archive


Byte-by-byte Description of file: table1.dat

   Bytes Format Units   Label     Explanations

   1- 16  A16   ---     1RXS      Source identification (JHHMMSS.s+DDMMSS)
  18- 22  F5.3  ---     Pnoid     The probability Pno-id that each RASS/BSC
                                  X-ray source was not associated with any of
                                  the off-band catalog sources (section 2.1)
  24- 55  A32   ---     Type      Source type
  57- 85  A29   ---     Name      Alternative Name
  87- 90  A4    ---     Obs       Observation facility (1)
  92- 96  F5.2  ---     HR        Hardness ratio
  98-109  A12   ---     Class     Object identification ("INS", "Not an INS", or
                                  "Undetermined")

Note (1): Facilities: C, Chandra; X, XMM; H, ROSAT; S, Swift.



Byte-by-byte Description of file: table2.dat

   Bytes Format Units   Label    Explanations

   1- 16  A16   ---     1RXS     Source identification (JHHMMSS.s+DDMMSS)
  18- 28  A11   ---     ObsID    Swift/XRT observation ID
  30- 47  A18   ---     XRT      XRT identification (JHHMMSS.s+DDMMSS.s)
  49- 53  F5.1  arcsec  R        Separation R between RASS/BSC source and
                                 Swift source
  55- 72  A18   ---     UVOT     UVOT identification (JHHMMSS.s+DDMMSS.s)
  74- 77  F4.1  [-]     Px       ? Log probability of chance association
                                 between UVOT and XRT source
  79- 96  A18   ---     2MASS    2MASS identification (JHHMMSS.s+DDMMSS.s)
  98-101  F4.1  [-]     Px2      ? Log probability of chance association
                                 between 2MASS and XRT source
 103-106  F4.1  [-]     PU       ? Log probability of chance association between
                                 2MASS and UVOT source
 108-125  A18   ---     USNO     USNO identification (JHHMMSS.s+DDMMSS.s)
 127-130  F4.1  [-]     PxU      ? Log probability of chance association between
                                 USNO and XRT source
 132-135  F4.1  [-]     PUU      ? Log probability of chance association between
                                 USNO and UVOT source
 137-148  A12   ---     Class    Object classification ("INS", "Not an INS", or
                                 "Undetermined")
     149  A1    ---     f_Class  [hij] Individual remarks (1)

Note (1): Flag as follows:
   h = XRT source found to be extended.
   i = XRT source saturated.
   j = During the process of this work, identified as an isolated neutron star
       (Calvera) (Rutledge et al. 2008ApJ...672.1137R).


History:
    From electronic version of the journal
(End)                                     Emmanuelle Perret [CDS]    23-Apr-2012