RASSCNDINS - ROSAT All-Sky Survey Candidate Isolated Neutron Stars

Overview

Using new and archival observations made with the Swift satellite and other facilities, the authors 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 (kT_eff < 200 eV), non-variable X-ray sources - as in a previous study - yields an all-sky limit of <= 31 INSs. In the course of their analysis, the authors identify 5 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.

Following selection of the INS candidates, short (~ 1 ks) follow-up observations with Swift/XRT were obtained for 92 of the candidates; these observations decreased the X-ray positional uncertainty (the systematic positional error associated with Swift blind pointing observations is on the order of 3.5"). The authors obtained (where possible) contemporaneous UV observations with Swift/UVOT for counterpart identification with off-band objects.

Catalog Bibcode

2010ApJ...714.1424T

References

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    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in May 2012 based on CDS Catalog J/ApJ/714/1424 files table1.dat and table2.dat.

Parameters

Name
The standard RASS/BSC source identification, i.e., '1RXS JHHMMSS.s+DDMMSS'.

RA
The Right Ascension of the RASS/BSC source in the selected equinox. This was given (implicitly via the name) in J2000.0 equatorial coordinates to a precision of 0.1 seconds of time in the original table.

Dec
The Declination of the RASS/BSC source in the selected equinox. This was given (implicitly via the name) in J2000.0 equatorial coordinates to a precision of 1 arcsecond in the original table.

LII
The Galactic Longitude of the RASS/BSC source.

BII
The Galactic Latitude of the RASS/BSC source.

Prob_No_ID
The probability P_no-id that the RASS/BSC X-ray source is not associated with any off-band counterparts in the catalogs considered (USNO-A2, NVSS and IRAS). The selection criterion for sources in this table is P_no-id >= 0.8.

Source_Type
The source type for the RASS/BSC source using a self-explanatory classification scheme.

Alt_Name
An alternative name for the RASS/BSC source.

Xray_Follow_Up
The observation facility(ies) with which follow-up higher spatial-resolution X-ray observations were performed, using the following codes:

    C: Chandra;
    X: XMM-Newton;
    H: ROSAT HRI;
    S: Swift XRT.

Hardness_Ratio
The PSPC hardness ratio HR1 of the RASS/BSC source.

INS_Category
The final object categorization of the RASS/BSC source as to whether it is an INS, not an INS, or its INS status is still undetermined. The HEASARC notes that two objects (1RXS J044048.0+292440 and 1RXS J142644.1+500633) were contradictorally categorized as 'Undetermined' in Table 1 of the published paper but as 'Not an INS' in Table 2 of the published paper. The latter categorization appears to be erroneous and both these objects are 'Undetermined' in this HEASARC table.

Swift_ObsID
The Swift observation identifier for the relevant Swift follow-up observation.

XRT_Name
The Swift/XRT identification of the counterpart to the RASS/BSC source, i.e., 'Swift XRT JHHMMSS.s+DDMMSS.s'. The HEASARC notes that this is a non-CDS standard name.

RASS_XRT_Offset
The angular separation, in arcseconds, between the RASS/BSC source and the Swift/XRT source.

UVOT_Name
The Swift/UVOT identification of the counterpart to the RASS/BSC source, i.e., 'Swift UVOT JHHMMSS.s+DDMMSS.s'. The HEASARC notes that this is a non-CDS standard name.

Log_Chance_Prob_Ux
The logarithm of the probability of a chance association between the Swift/UVOT and the Swift/XRT sources.

TwoMASS_Name
The 2MASS identification of the counterpart to the RASS/BSC source, i.e., '2MASS JHHMMSS.s+DDMMSS.s'. The HEASARC notes that this is a non-CDS standard name.

Log_Chance_Prob_2mx
The logarithm of the probability of a chance association between the 2MASS and the Swift/XRT sources.

Log_Chance_Prob_2mu
The logarithm of the probability of a chance association between the 2MASS and the Swift/UVOT sources.

USNO_Name
The USNO identification of the counterpart to the RASS/BSC source, i.e., 'USNO JHHMMSS.s+DDMMSS.s'. The HEASARC notes that this is a non-CDS standard name.

Log_Chance_Prob_Usx
The logarithm of the probability of a chance association between the USNO and the Swift/XRT sources.

Log_Chance_Prob_Usu
The logarithm of the probability of a chance association between the USNO and the Swift/UVOT sources.

Source_Flag
This parameter flags 3 special cases, as follows:

     h = XRT source found to be extended.
     i = XRT source saturated.
     j = During the process of this work, 1RXS J141256.0+792204 was identified
         as an INS, 'Calvera' (Rutledge et al. 2008ApJ...672.1137R).

Class
The HEASARC Browse object classification, based on the ins_category value if it is 'INS', else based on the source_type value.

Contact Person

Questions regarding the RASSCNDINS database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:33:22 EDT