J/MNRAS/472/3706 Globular cluster 47 Tuc Chandra studies (Bhattacharya+, 2017)
Chandra studies of the globular cluster 47 Tucanae: a deeper X-ray source
catalogue, five new X-ray counterparts to millisecond radio pulsars and new
constraints to r-mode instability window.
Bhattacharya S., Heinke C.O., Chugunov A.I., Freire P.C.C., Ridolfi A.,
Bogdanov S.
<Mon. Not. R. Astron. Soc., 472, 3706-3721 (2017)>
=2017MNRAS.472.3706B 2017MNRAS.472.3706B (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; X-ray sources
Keywords: stars: neutron - pulsars: general -
globular clusters: individual: NGC 104
Abstract:
We combined Chandra ACIS observations of the globular cluster 47
Tucanae (47 Tuc) from 2000, 2002 and 2014-2015 to create a deeper
X-ray source list, and study some of the faint radio millisecond
pulsars (MSPs) present in this cluster. We have detected 370 X-ray
sources within the half-mass radius (2.79 arcsec) of the cluster, 81
of which are newly identified, by including new data and using
improved source detection techniques. The majority of the newly
identified sources are in the crowded core region, indicating cluster
membership. We associate five of the new X-ray sources with
chromospherically active BY Dra or W UMa variables identified by
Albrow et al. We present alternative positions derived from two
methods, centroiding and image reconstruction, for faint, crowded
sources. We are able to extract X-ray spectra of the recently
discovered MSPs 47 Tuc aa, 47 Tuc ab, the newly timed MSP 47 Tuc Z,
and the newly resolved MSPs 47 Tuc S and 47 Tuc F. Generally, they are
well fitted by blackbody or neutron star atmosphere models, with
temperatures, luminosities and emitting radii similar to those of
other known MSPs in 47 Tuc, though 47 Tuc aa and 47 Tuc ab reach lower
X-ray luminosities. We limit X-ray emission from the full surface of
the rapidly spinning (542 Hz) MSP 47 Tuc aa, and use this limit to put
an upper bound for amplitude of r-mode oscillations in this pulsar as
α<2.5x10-9 and constrain the shape of the r-mode
instability window.
Description:
We combined 180ks of new Chandra ACIS data on 47 Tuc with 370ks
of archival data, and used improved algorithms to generate a new
source catalogue, finding 81 new sources for a total of 370 within the
half-mass region.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 127 370 47 Tuc basic X-ray source properties,
combined data set
table3.dat 30 28 Alternative positions of crowded sources,
obtained from image reconstruction
table4.dat 40 21 Deviations in X-ray positions of individual MSPs
from their known radio positions
table5.dat 45 5 New optical counterpart identifications
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See also:
J/ApJ/559/1060 : Variables in 47 Tuc (Albrow+, 2001)
J/A+A/372/85 : Detected sources at 12µm in 47 Tuc (Ramdani+, 2001)
J/other/Sci/292.2290 : Chandra compact binaries in 47 Tuc (Grindlay+, 2001)
J/ApJ/625/796 : X-ray sources in globular cluster 47 Tuc (Heinke+, 2005)
J/A+A/537/A2 : 8.6um imaging of 47 Tuc (Momany+, 2012)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- W Label (wavdetect number),
will be [GHE2001] WNNN in Simbad
5- 19 A15 --- CXOGlb CXOGlb J designation (HHMMSS.s+DDMMSS)
21- 22 I2 h RAh Right ascension (J2000) (1)
24- 25 I2 min RAm Right ascension (J2000) (1)
27- 32 F6.3 s RAs Right ascension (J2000) (1)
34 A1 --- DE- Declination sign (J2000) (1)
35- 36 I2 deg DEd Declination (J2000) (1)
38- 39 I2 arcmin DEm Declination (J2000) (1)
41- 46 F6.3 arcsec DEs Declination (J2000) (1)
48- 52 F5.3 arcsec ePos rms uncertainty on position (2)
54- 57 F4.2 --- fPSF PSF fraction
59- 62 F4.2 --- fExpo Fractional exposure time
64- 70 F7.1 ct ncts0.5-2 0.5-2keV net counts
72- 76 F5.1 ct e_ncts0.5-2 Error on ncts0.5-2 (lower value)
78- 82 F5.1 ct E_ncts0.5-2 Error on ncts0.5-2 (upper value)
84- 90 F7.1 ct ncts0.5-6 0.5-6keV net counts
92- 96 F5.1 ct e_ncts0.5-6 Error on ncts0.5-2 (lower value)
98-102 F5.1 ct E_ncts0.5-6 Error on ncts0.5-2 (upper value)
104-109 F6.1 10+23W lum0.5-6 0.5-6keV luminosity
111-114 F4.1 10+23W e_lum0.5-6 Error on lum0.5-6 (lower value)
116-119 F4.1 10+23W E_lum0.5-6 Error on lum0.5-6 (upper value)
121-127 A7 --- Notes Notes (3)
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Note (1): The source positions have been adjusted to place them on to the radio
frame, using the X-ray detections of 19 radio MSPs.
Note (2): Positional errors are quoted in arcseconds for both RA and DE, and
are the 95 per cent error circles, as calculated by Heinke et al.
(2005, Cat. J/ApJ/625/796).
Note (3): The Notes column indicates c for sources which appear confused,
and m for sources added manually, and includes other reported names
(X for ROSAT sources, MSP-* for MSPs).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- W Label (wavdetect number)
5- 6 I2 h RAh Right ascension (J2000)
8- 9 I2 min RAm Right ascension (J2000)
11- 16 F6.3 s RAs Right ascension (J2000)
18 A1 --- DE- Declination sign (J2000)
19- 20 I2 deg DEd Declination (J2000)
22- 23 I2 arcmin DEm Declination (J2000)
25- 30 F6.3 arcsec DEs Declination (J2000)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- W Label (wavdetect number)
5- 7 A3 --- MSP MSP radio detection name (e.g. 47 Tuc E),
9- 13 F5.2 arcsec DRA Deviation in right ascension
14 A1 --- --- [,]
15- 17 F3.1 arcsec DRA2 ? Second deviation in right ascension,
if two possibilities
19- 23 F5.2 arcsec DDE Deviation in declination
24 A1 --- --- [,]
25- 29 F5.2 arcsec DDE2 ? Second deviation in declination,
if two possibilities
31- 34 F4.2 arcsec Xerr 95 per cent confidence error circle radius
on the X-ray position (following
Heinke et al., 2005, Cat. J/ApJ/625/796)
36 A1 --- l_D/Xerr Limit flag on D/Xerr
37- 40 F4.2 --- D/Xerr Total deviation divided by the X-ray error
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- W Label (wavdetect number)
5- 11 A7 --- A01Name Albrow et al. (2001, Cat. J/ApJ/559/1060) name
13- 18 F6.3 arcsec DRA Chandra minus HST right ascension
20- 25 F6.3 arcsec DDE Chandra minus HST declination
27- 38 A12 --- Type Type
(from Albrow et al., 2001, Cat. J/ApJ/559/1060)
40- 45 F6.4 d Per Period
(from Albrow et al., 2001, Cat. J/ApJ/559/1060)
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 26-Jun-2020