J/ApJ/808/19 Megasecond Chandra XVP obs. of NGC3115. II. (Lin+, 2015)
The Megasecond Chandra X-ray Visionary Project observation of NGC 3115.
II. Properties of point sources.
Lin D., Irwin J.A., Wong K.-W., Jennings Z.G., Homan J., Romanowsky A.J.,
Strader J., Sivakoff G.R., Brodie J.P., Remillard R.A.
<Astrophys. J., 808, 19 (2015)>
=2015ApJ...808...19L 2015ApJ...808...19L (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, X-ray ; Clusters, globular ; Galaxies, nearby
Keywords: Galaxy: stellar content; globular clusters: general; X-rays: binaries;
X-rays: individual: NGC 3115
Abstract:
We carried out an in-depth study of low-mass X-ray binaries (LMXBs)
detected in the nearby lenticular galaxy NGC 3115 using the Megasecond
Chandra X-ray Visionary Project observation (total exposure time
1.1Ms). In total we found 136 candidate LMXBs in the field and 49 in
globular clusters (GCs) above 2σ detection, with 0.3-8keV
luminosity LX∼1036-1039erg/s. Other than 13 transient
candidates, the sources overall have less long-term variability at
higher luminosity, at least at LX≳2x1037erg/s. In order to
identify the nature and spectral state of our sources, we compared
their collective spectral properties based on single-component models
(a simple power law or a multicolor disk) with the spectral evolution
seen in representative Galactic LMXBs. We found that in the LX
versus photon index ΓPL and LXversus disk temperature
kTMCD plots, most of our sources fall on a narrow track in which the
spectral shape hardens with increasing luminosity below
LX∼7x1037erg/s, but is relatively constant (ΓPL∼1.5 or
kTMCD∼1.5keV) above this luminosity, which is similar to the
spectral evolution of Galactic neutron star (NS) LMXBs in the soft
state in the Chandra bandpass. Therefore, we identified the track as
the NS LMXB soft-state track and suggested sources with
LX≲7x1037erg/s as atolls in the soft state and those with
LX≳7x1037erg/s as Z sources. Ten other sources (five are
transients) displayed significantly softer spectra and are probably
black hole X-ray binaries in the thermal state. One of them
(persistent) is in a metal-poor GC.
Description:
The 11 Chandra observations of NGC 3115 were made during three epochs:
one in 2001 Jun 14, two in 2010 (Jan 27 and 29), and nine in 2012 (Jan
18 to Apr 06). All observations used the imaging array of the AXAF CCD
Imaging Spectrometer (ACIS).
Accompanying the Chandra X-ray Visionary Project (XVP) observation, a
six pointing Hubble Space Telescope (HST) mosaic observation in the
F475W and F850LP filters (hereafter g and z) using the Advanced Camera
for Surveys (ACS) was also acquired in the field of NGC 3115.
In Paper III (Lin+, 2014ApJ...780...39L 2014ApJ...780...39L) we cross-correlated our X-ray
sources with the 360 globular clusters (GCs) from the HST/ACS mosaic
imaging and the 421 ones from the Subaru/Suprime-Cam imaging (Arnold
et al. 2011ApJ...736L..26A 2011ApJ...736L..26A; Jennings et al. 2014, J/AJ/148/32).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 92 48 The globular cluster LMXBs and candidates
table3.dat 172 482 The Master Source Catalog
table4.dat 306 496 The source counts, flux, and hardness ratio
in the merged observation for the 482 master source
table5.dat 237 4188 The source counts and flux in individual observations
for the 482 master sources
table6.dat 169 396 *Spectral fit results
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Note on table6.dat: the spectral models consist of two main continuum
components: a standard thermal multicolor disk (MCD, diskbb in XSPEC,
Arnaud 1996ASPC..101...17A 1996ASPC..101...17A) and a Comptonized component (often modeled with
a single power law, PL, or the Comptonization model comptt in XSPEC).
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See also:
B/chandra : The Chandra Archive Log (CXC, 1999-2014)
B/hst : HST Archived Exposures Catalog (STScI, 2007)
IX/45 : The Chandra Source Catalog, Release 1.1 (Evans+ 2012)
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
J/AJ/148/32 : Globular cluster candidates in NGC 3115 (Jennings+, 2014)
J/ApJ/766/88 : Chandra obs. of X-ray binaries in Cen A (Burke+, 2013)
J/MNRAS/428/389 : SLUGGS globular clusters in early-type galaxies (Pota+, 2013)
J/ApJ/756/27 : Class. of sources from the 2XMMi-DR3 cat. (Lin+, 2012)
J/ApJS/179/360 : Thermonuclear X-ray bursts observed by RXTE (Galloway+, 2008)
J/ApJS/169/401 : ChaMP X-ray point source catalog (Kim+, 2007)
J/ApJ/586/814 : NGC 4472 Chandra/HST study (Maccarone+, 2003)
J/other/NewA/5.137 : Supersoft X-ray sources catalog (Greiner+, 2000)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Type Object type (1)
5- 7 I3 --- MSID [4/451] The master source unique index
9- 12 A4 --- GC GC in Jennings et al. (2014, J/AJ/148/32;
<[JSR2014] ANNN> in Simbad)
14- 17 F4.2 arcsec dXO [0.01/1] The offset between the GC center
and our X-ray source
19- 24 F6.3 mag gmag [19.9/24.4]? HST/ACS g-band magnitude
26- 30 F5.3 mag e_gmag [0.002/0.07]? gmag uncertainty
32- 37 F6.3 mag zmag [18.7/23.2]? HST/ACS z-band magnitude
39- 43 F5.3 mag e_zmag [0.002/0.07]? zmag uncertainty
45- 50 F6.3 mag gSmag [19.5/24.6]? Subaru/Suprime-Cam g-band magnitude
52- 56 F5.3 mag e_gSmag [0.003/0.3]? gSCmag uncertainty
58- 63 F6.3 mag rSmag [18.8/23.6]? Subaru/Suprime-Cam r-band magnitude
65- 69 F5.3 mag e_rSmag [0.003/0.2]? rSCmag uncertainty
71- 76 F6.3 mag iSmag [18.4/23.6]? Subaru/Suprime-Cam i-band magnitude
78- 82 F5.3 mag e_iSmag [0.003/0.3]? iSCmag uncertainty
84- 87 F4.2 pc Rh [0.2/4.8]? Half-light radius
89- 92 I4 km/s Vel [238/1123]? Heliocentric velocity from
Pota et al. (2013, J/MNRAS/428/389)
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Note (1): Type as follows:
GC = LMXBs coincident with HST/ACS GCs (37 sources).
GCc = LMXBs coincident with GCs detected/covered only in the
Subaru/Suprime-Cam images, but not in the HST/ACS images (7 sources).
GCp = GC LMXB candidates whose optical matches were not classified as GCs by
Jennings et al. (2014, J/AJ/148/32) but were assumed to be GCs by us
(there is another similar source, S65, which is not included in the
table because the photometry is not available due to being too close to
the bright galaxy center; see the text for details).
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- MSID [1/482] The master source unique index
5- 20 A16 --- CXOU CXOU Name (JHHMMSS.s+DDMMSS)
22- 31 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000; ICRS)
33- 42 F10.6 deg DEdeg Declination in decimal degrees (J2000; ICRS)
44- 47 F4.2 arcsec PU [0.03/8] The 1σ statistical positional
uncertainty in each coordinate
49- 54 F6.3 arcmin Sep [0.003/22] Angular separation from galaxy center
56- 61 F6.3 --- SepR Ratio of angular separation to D25 isophote
elliptical radius
63- 67 F5.2 arcsec psf50 The 50% PSF radius at the source position in
merged observation
69- 73 F5.2 arcsec psf90 The 90% PSF radius at the source position in
merged observation
75- 79 I5 --- ObsID Observation ID in which the source is
detected; 0 for the merged observation
81- 86 F6.1 --- SNR [2/95.2] Signal-to-noise ratio (1)
88- 92 F5.1 --- Vvar [1/127] Flux variation factor in 0.5-7keV band
94- 97 F4.1 --- Svar [1/46] Significance of flux variation; equation 1
99-106 E8.2 10-7W Lmax Maximum 0.5-7keV luminosity (2)
108-115 E8.2 10-7W b_Lmax Lower limit on Lmax at 68% confidence level (2)
117-124 E8.2 10-7W B_Lmax Upper limit of Lmax at 68% confidence level (2)
126-130 A5 --- OLmax Corresponding observation ID of Lmax
132-139 E8.2 10-7W Lmin Minimum 0.5-7 keV luminosity (2)
141-148 E8.2 10-7W b_Lmin Lower limit on Lmin at 68% confidence level (2)
150-157 E8.2 10-7W B_Lmin Upper limit of Lmin at 68% confidence level (2)
159-163 A5 --- OLmin Corresponding observation ID of Lmin
165 I1 --- GLmax Maximum Gregory-Loredo short-term
variability index (6-10 = variable) (3)
167-172 A6 --- Type Source type (4)
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Note (1): The 0.5-7keV net counts divided by the error in the observation the
source was detected.
Note (2): Assuming a source distance of 9.7Mpc. In units of erg/s
Note (3): A higher value indicates variability of a higher degree of
confidence; sources with indices of 6-10 are definitely variable.
Note (4): Source type as follows:
BH = black hole X-ray binary;
GC = low-mass X-ray binary in a (candidate) globular cluster; those not
designated as BH are most likely neutron star low-mass
X-ray binaries;
F = low-mass X-ray binary in the field; those not designated as BH are
most likely neutron star low-mass X-ray binaries;
SSS = supersoft X-ray source;
AGN = background active galactic nucleus;
Star = coronally active star in our Galaxy;
G = hot gas emission in a galaxy
T = Transient
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- MSID [1/482] The master source unique index
5 A1 --- Obs Observation (G1)
7- 12 F6.1 ks Exp [35/1131] Exposure time
14- 19 F6.1 --- Cb Counts in the broad band; 0.5-7.0keV
21- 26 F6.1 --- b_Cb Lower limit of Cb at 68% confidence level
28- 33 F6.1 --- B_Cb Upper limit of Cb at 68% confidence level
35- 42 E8.2 mW/m2 Fb Flux in the broad band; 0.5-7.0keV (2)
44- 51 E8.2 mW/m2 b_Fb Lower limit of Fb at 68% confidence level
53- 60 E8.2 mW/m2 B_Fb Upper limit of Fb at 68% confidence level
62- 67 F6.1 --- Cu Counts in the ultra-soft band; 0.2-0.5keV
69- 74 F6.1 --- b_Cu Lower limit of Cu at 68% confidence level
76- 81 F6.1 --- B_Cu Upper limit of Cu at 68% confidence level
83- 90 E8.2 mW/m2 Fu Flux in the ultra-soft band; 0.2-0.5keV (2)
92- 99 E8.2 mW/m2 b_Fu Lower limit of Fu at 68% confidence level
101-108 E8.2 mW/m2 B_Fu Upper limit of Fu at 68% confidence level
110-115 F6.1 --- Cs Counts in the soft band; 0.5-1.2keV
117-122 F6.1 --- b_Cs Lower limit of Cs at 68% confidence level
124-129 F6.1 --- B_Cs Upper limit of Cs at 68% confidence level
131-138 E8.2 mW/m2 Fs Flux in the soft band; 0.5-1.2keV (2)
140-147 E8.2 mW/m2 b_Fs Lower limit of Fs at 68% confidence level
149-156 E8.2 mW/m2 B_Fs Upper limit of Fs at 68% confidence level
158-163 F6.1 --- Cm Counts in the medium band; 1.2-2.0keV
165-170 F6.1 --- b_Cm Lower limit of Cm at 68% confidence level
172-177 F6.1 --- B_Cm Upper limit of Cm at 68% confidence level
179-186 E8.2 mW/m2 Fm Flux in the medium band; 1.2-2.0keV (2)
188-195 E8.2 mW/m2 b_Fm Lower limit of Fm at 68% confidence level
197-204 E8.2 mW/m2 B_Fm Upper limit of Fm at 68% confidence level
206-211 F6.1 --- Ch Counts in the hard band; 2.0-7.0keV
213-218 F6.1 --- b_Ch Lower limit of Ch at 68% confidence level
220-225 F6.1 --- B_Ch Upper limit of Ch at 68% confidence level
227-234 E8.2 mW/m2 Fh Flux in the hard band; 2.0-7.0keV (2)
236-243 E8.2 mW/m2 b_Fh Lower limit of Fh at 68% confidence level
245-252 E8.2 mW/m2 B_Fh Upper limit of Fh at 68% confidence level
254-258 F5.2 --- HR1 ? Hardness Ratio using the 0.5-1.2keV and
the 1.2-2.0 keV fluxes (3)
260-264 F5.2 --- bHR1 ? Lower limit of HR1 at 68% confidence level
266-270 F5.2 --- BHR1 ? Upper limit of HR1 at 68% confidence level
272-276 F5.2 --- HR2 Hardness Ratio using the 1.2-2.0keV and
the 2.0-7.0 keV fluxes (3)
278-282 F5.2 --- bHR2 Lower limit of HR2 at 68% confidence level
284-288 F5.2 --- BHR2 Upper limit of HR2 at 68% confidence level
290-294 F5.2 --- HR3 Hardness Ratio using the 0.5-2.0keV and
the 2.0-7.0 keV fluxes (3)
296-300 F5.2 --- bHR3 Lower limit of HR3 at 68% confidence level
302-306 F5.2 --- BHR3 Upper limit of HR3 at 68% confidence level
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Note (2): In units of erg/s/cm2.
Note (3): HR is defined as (H-S)/(H+S), where S and H are the energy fluxes
in the soft and hard energy bands, respectively.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- MSID [1/482] The master source unique index
5- 9 I5 --- ObsID The observation ID
11- 16 F6.1 --- Cb Counts in the broad band; 0.5-7.0keV
18- 23 F6.1 --- b_Cb Lower limit of Cb at 68% confidence level
25- 30 F6.1 --- B_Cb Upper limit of Cb at 68% confidence level
32- 39 E8.2 mW/m2 Fb Flux in the broad band; 0.5-7.0keV (1)
41- 48 E8.2 mW/m2 b_Fb Lower limit of Fb at 68% confidence level
50- 57 E8.2 mW/m2 B_Fb Upper limit of Fb at 68% confidence level
59- 63 F5.1 --- Cu Counts in the ultra-soft band; 0.2-0.5keV
65- 69 F5.1 --- b_Cu Lower limit of Cu at 68% confidence level
71- 75 F5.1 --- B_Cu Upper limit of Cu at 68% confidence level
77- 84 E8.2 mW/m2 Fu Flux in the ultra-soft band; 0.2-0.5keV (1)
86- 93 E8.2 mW/m2 b_Fu Lower limit of Fu at 68% confidence level
95-102 E8.2 mW/m2 B_Fu Upper limit of Fu at 68% confidence level
104-108 F5.1 --- Cs Counts in the soft band; 0.5-1.2keV
110-114 F5.1 --- b_Cs Lower limit of Cs at 68% confidence level
116-120 F5.1 --- B_Cs Upper limit of Cs at 68% confidence level
122-129 E8.2 mW/m2 Fs Flux in the soft band; 0.5-1.2keV (1)
131-138 E8.2 mW/m2 b_Fs Lower limit of Fs at 68% confidence level
140-147 E8.2 mW/m2 B_Fs Upper limit of Fs at 68% confidence level
149-153 F5.1 --- Cm Counts in the medium band; 1.2-2.0keV
155-159 F5.1 --- b_Cm Lower limit of Cm at 68% confidence level
161-165 F5.1 --- B_Cm Upper limit of Cm at 68% confidence level
167-174 E8.2 mW/m2 Fm Flux in the medium band; 1.2-2.0keV (1)
176-183 E8.2 mW/m2 b_Fm Lower limit of Fm at 68% confidence level
185-192 E8.2 mW/m2 B_Fm Upper limit of Fm at 68% confidence level
194-198 F5.1 --- Ch Counts in the hard band; 2.0-7.0keV
200-204 F5.1 --- b_Ch Lower limit of Ch at 68% confidence level
206-210 F5.1 --- B_Ch Upper limit of Ch at 68% confidence level
212-219 E8.2 mW/m2 Fh Flux in the hard band; 2.0-7.0keV (1)
221-228 E8.2 mW/m2 b_Fh Lower limit of Fh at 68% confidence level
230-237 E8.2 mW/m2 B_Fh Upper limit of Fh at 68% confidence level
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Note (1): In units of erg/s/cm2.
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Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- MSID [1/481] Master source unique index
5- 5 A1 --- Obs Observation (G1)
7- 12 F6.1 10+20/cm2 NH-PL Intrinsic column density from PL fit
14- 19 F6.1 10+20/cm2 e_NH-PL ? Lower uncertainty on NH at 90%
confidence level
21- 26 F6.1 10+20/cm2 E_NH-PL ? Upper uncertainty on NH at 90%
confidence level
28- 31 F4.2 --- Gamma-PL Photon index
33- 37 F5.2 --- e_Gamma-PL Lower uncertainty on Gamma_PL at 90%
confidence level
39- 42 F4.2 --- E_Gamma-PL Upper uncertainty on Gamma_PL at 90%
confidence level
44- 49 F6.2 10-6 N-PL Normalization of the PL fit
51- 56 F6.2 10-6 e_N-PL Lower uncertainty on N-PL at 90%
confidence level
58- 63 F6.2 10-6 E_N-PL Upper uncertainty on N-PL at 90%
confidence level
65- 69 F5.1 10+30W L-PL Luminosity in 0.3-8.0keV from PL fit (2)
71- 75 F5.1 10+30W e_L-PL Lower uncertainty on L-PL at 90%
confidence level (2)
77- 81 F5.1 10+30W E_L-PL Upper uncertainty on L-PL at 90%
confidence level (2)
83- 88 F6.1 10+20/cm2 NH-MCD Intrinsic column density from MCD fit
90- 95 F6.1 10+20/cm2 e_NH-MCD ? Lower uncertainty on NH-MCD at 90%
confidence level
97-102 F6.1 10+20/cm2 E_NH-MCD ? Upper uncertainty on NH-MCD at 90%
confidence level
104-107 F4.2 keV kT-MCD MCD fit apparent inner disk temperature
109-113 F5.2 keV e_kT-MCD Lower uncertainty on kT-MCD at 90%
confidence level
115-118 F4.2 keV E_kT-MCD Upper uncertainty on kT-MCD at 90%
confidence level
120-129 F10.2 km R-MCD Apparent inner disk radius from MCD fit (3)
131-140 F10.2 km e_R-MCD Lower uncertainty on R-MCD at 90%
confidence level
142-151 F10.2 km E_R-MCD Upper uncertainty on R-MCD at 90%
confidence level
153-157 F5.1 10+30W L-MCD Luminosity in 0.3-8.0keV from MCD fit (2)
159-163 F5.1 10+30W e_L-MCD Lower uncertainty on L-MCD at 90%
confidence level (2)
165-169 F5.1 10+30W E_L-MCD Upper uncertainty on L-MCD at 90%
confidence level (2)
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Note (2): Assume a source distance of 9.7Mpc and isotropic emission for
the PL fit or an inclination of 60 degree for the MCD fit.
The units are 1e37erg/s.
Note (3): From the MCD normalization (R-MCD/km)/(D/10kpc))2 cos(theta), where
D is the source distance assumed to be 9.7Mpc and theta is the disk
inclination assumed to be 60 degrees.
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Global notes:
Note (G1): Observations as follows:
0 = combination of all observations in which the source is covered;
h = combination of observations in the high state (for the 13
transients in Figure 3 a-d);
l = combination of observations in the low state (for source 198
only, referred to Figure 3c).
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History:
From electronic version of the journal
References:
Wong et al. Paper I. 2014ApJ...780....9W 2014ApJ...780....9W
Lin et al. Paper III. 2015ApJ...808...20L 2015ApJ...808...20L
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-Nov-2015