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 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:
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FileName Lrecl Records Explanations
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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
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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
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Bytes Format Units Label Explanations
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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")
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Note (1): Facilities: C, Chandra; X, XMM; H, ROSAT; S, Swift.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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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)
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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 2008ApJ...672.1137R).
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 23-Apr-2012