J/ApJ/763/128 Chandra Local Volume Survey: NGC 404 sources (Binder+, 2013)
The Chandra Local Volume Survey: the X-ray point-source population of NGC 404.
Binder B., Williams B.F., Eracleous M., Gaetz T.J., Kong A.K.H.,
Skillman E.D., Weisz D.R.
<Astrophys. J., 763, 128 (2013)>
=2013ApJ...763..128B 2013ApJ...763..128B
ADC_Keywords: Galaxies, nearby ; X-ray sources ; Photometry, HST ; Surveys ;
Binaries, X-ray
Keywords: binaries: general; galaxies: individual: NGC 404;
surveys; X-rays: galaxies
Abstract:
We present a comprehensive X-ray point-source catalog of NGC 404
obtained as part of the Chandra Local Volume Survey. A new 97ks
Chandra ACIS-S observation of NGC 404 was combined with archival
observations for a total exposure of ∼123ks. Our survey yields 74
highly significant X-ray point sources and is sensitive to a limiting
unabsorbed luminosity of ∼6x1035erg/s in the 0.35-8keV band. To
constrain the nature of each X-ray source, cross-correlations with
multi-wavelength data were generated. We searched overlapping Hubble
Space Telescope observations for optical counterparts to our X-ray
detections, but find only two X-ray sources with candidate optical
counterparts. We find 21 likely low-mass X-ray binaries (LMXBs),
although this number is a lower limit due to the difficulties in
separating LMXBs from background active galactic nuclei. The X-ray
luminosity functions (XLFs) in both the soft and hard energy bands are
presented. The XLFs in the soft band (0.5-2keV) and the hard band
(2-8keV) have a limiting luminosity at the 90% completeness limit of
1035erg/s and 1036erg/s, respectively, significantly lower than
previous X-ray studies of NGC 404. We find the XLFs to be consistent
with those of other X-ray populations dominated by LMXBs. However, the
number of luminous (>1037erg/s) X-ray sources per unit stellar mass
in NGC 404 is lower than is observed for other galaxies. The relative
lack of luminous XRBs may be due to a population of LMXBs with
main-sequence companions formed during an epoch of elevated star
formation ∼0.5Gyr ago.
Description:
NGC 404 was observed during Chandra X-Ray Observatory Cycle 12 on 2010
October 21-22 for 97ks using the ACIS-S array (Obs. ID 12339). We
additionally utilize archival observations: NGC 404 was observed on
1999 December 19 (Obs. ID 870) for ∼24ks and on 2000 August 30 (Obs.
ID 384) for ∼2ks, both using the ACIS-S array.
We created images in the following energy bands (keV): 0.35-8.0,
0.35-1.0, 1.0-2.0, 2.0-8.0 with bin sizes of 1, 2, 3, and 4.
Three HST fields were used to search for optical counterparts for each
of our X-ray sources. One field (labeled "DEEP") was taken as part of
the Advanced Camera for Surveys (ACS) Nearby Galaxy Survey Treasury
(ANGST, GO-10915; Dalcanton et al. 2009ApJS..183...67D 2009ApJS..183...67D), while the
other two shallowered fields (labeled "NE" and "SW") were obtained as
part of GO-11986. Details of the HST data acquisition and data
reduction are provided in Williams et al. (2010ApJ...716...71W 2010ApJ...716...71W).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 65 74 The NGC 404 source list
table4.dat 66 74 Merged log(pns) values for different energy bands
table5.dat 135 74 Total net counts in different energy bands
table6.dat 50 74 Photon flux in different energy bands
table10.dat 29 74 Hardness ratio
table12.dat 104 31 Multi-wavelength observations of NGC 404 X-ray
sources
table13.dat 62 74 X-Ray source properties and classification
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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)
II/312 : GALEX-DR5 (GR5) sources from AIS and MIS (Bianchi+ 2011)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/284 : The USNO-B1.0 Catalog (Monet+ 2003)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
J/ApJ/758/15 : Chandra X-ray point sources of NGC 300 (Binder+, 2012)
J/ApJ/737/45 : Variable 1.4GHz radio sources from NVSS & FIRST (Ofek+, 2011)
J/ApJ/734/L22 : ACS Nearby Galaxy Survey Treasury (Williams+, 2011)
J/ApJS/192/10 : Chandra ACIS survey in 383 nearby galaxies. I. (Liu, 2011)
J/ApJS/192/6 : A GALEX UV imaging survey of nearby galaxies (Lee+, 2011)
J/ApJS/181/444 : X-emitting stars identified from RASS/SDSS (Agueros+, 2009)
J/ApJS/179/19 : CDFS survey: 2 Ms source catalogs (Luo+, 2008)
J/MNRAS/382/1552 : Multiwavelength study of nearby galaxy nuclei (Lira+, 2007)
J/ApJS/157/59 : Ultraluminous X-ray sources in nearby galaxies (Liu+, 2005)
J/MNRAS/328/461 : Early-type galaxies X-ray luminosities (O'Sullivan+, 2001)
J/AJ/116/1626 : Spiral & lenticular galaxy brightness profiles (Baggett+,
1998)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/74] Running sequence number
4- 21 A18 --- ID Source identifier (HHMMSS.ss+DDMMSS.s; J2000)
23- 31 F9.6 deg RAdeg Right Ascension in decimal degrees (J2000)
33- 41 F9.6 deg DEdeg Declination in decimal degrees (J2000)
43- 46 F4.2 arcsec ePos [0.02/1.1] Positional error circle around source
48- 54 E7.4 s.cm2 Expmap Total exposure map value in source region
56- 60 F5.2 pix Rsrc [1.5/36.3] Average radius of extraction region (1)
62- 65 F4.1 arcmin theta [0/14] Off-axis angle θ
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Note (1): In units of sky pixels, (1 sky pixel = 0.392").
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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- 2 I2 --- Seq [1/74] Running sequence number
4 A1 --- l_logP0 Limit flag on logP0
5- 10 F6.2 [-] logP0 [-10/0] Non-source probability, 0.5-8keV (2)
12 A1 --- l_logP2 Limit flag on logP2
13- 18 F6.2 [-] logP2 [-10/0] Non-source probability, 0.5-2keV (2)
20 A1 --- l_logP3 Limit flag on logP3
21- 26 F6.2 [-] logP3 [-10/0] Non-source probability, 2-8keV (2)
28 A1 --- l_logP4 Limit flag on logP4
29- 34 F6.2 [-] logP4 [-10/0] Non-source probability, 0.35-8keV (2)
36 A1 --- l_logP5 Limit flag on logP5
37- 42 F6.2 [-] logP5 [-10/0] Non-source probability, 0.35-1.1keV (2)
44 A1 --- l_logP6 Limit flag on logP6
45- 50 F6.2 [-] logP6 [-10/0] Non-source probability, 1.1-2.6keV (2)
52 A1 --- l_logP7 Limit flag on logP7 (G1)
53- 58 F6.2 [-] logP7 [-10/0] Non-source probability, 2.6-8keV (2)(G1)
60 A1 --- l_logP1 Limit flag on logP1 (G1)
61- 66 F6.2 [-] logP1 [-10/0] Non-source probability, 0.35-2keV (2)(G1)
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Note (2): Of not being a source. Values smaller than -10 have been replaced
with lower limits. All these cases are highly significant detections.
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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- 2 I2 --- Seq [1/74] Running sequence number
4- 8 F5.1 ct Net0 [2.5/697] Net counts in the 0.5-8keV energy band
10- 13 F4.1 ct E_Net0 Upper limit uncertainty in Net0
15- 18 F4.1 ct e_Net0 Lower limit uncertainty in Net0
20- 24 F5.1 ct Net2 [0.8/687] Net counts in the 0.5-2keV energy band
26- 29 F4.1 ct E_Net2 Upper limit uncertainty in Net2
31- 34 F4.1 ct e_Net2 Lower limit uncertainty in Net2
36 A1 --- l_Net3 Limit flag on Net3
37- 41 F5.1 ct Net3 [-12/205.5] Net counts in the 2-8keV energy band
43- 46 F4.1 ct E_Net3 ? Upper limit uncertainty in Net3
48- 51 F4.1 ct e_Net3 ? Lower limit uncertainty in Net3
53- 57 F5.1 ct Net4 [4.5/713] Net counts in the 0.35-8keV energy band
59- 62 F4.1 ct E_Net4 Upper limit uncertainty in Net4
64- 67 F4.1 ct e_Net4 Lower limit uncertainty in Net4
69 A1 --- l_Net5 Limit flag on Net5
70- 74 F5.1 ct Net5 [-0.3/555] Net counts in the 0.35-1.1keV energy
band
76- 79 F4.1 ct E_Net5 ? Upper limit uncertainty in Net5
81- 84 F4.1 ct e_Net5 ? Lower limit uncertainty in Net5
86 A1 --- l_Net6 Limit flag on Net6
87- 91 F5.1 ct Net6 [0.9/342] Net counts in the 1.1-2.6keV energy band
93- 96 F4.1 ct E_Net6 ? Upper limit uncertainty in Net6
98-101 F4.1 ct e_Net6 ? Lower limit uncertainty in Net6
103 A1 --- l_Net7 Limit flag on Net7 (G1)
104-108 F5.1 ct Net7 [-11/148] Net counts in the 2.6-8keV energy
band (G1)
110-113 F4.1 ct E_Net7 ? Upper limit uncertainty in Net7 (G1)
115-118 F4.1 ct e_Net7 ? Lower limit uncertainty in Net7 (G1)
120 A1 --- l_Net1 Limit flag on Net1 (G1)
121-125 F5.1 ct Net1 [-11/148] Net counts in the 0.35-2keV energy
band (G1)
127-130 F4.1 ct E_Net1 ? Upper limit uncertainty in Net1 (G1)
132-135 F4.1 ct e_Net1 ? Lower limit uncertainty in Net1 (G1)
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/74] Running sequence number
4- 8 F5.2 [cm-2/s] logF0 [-7/-4] Log of 0.5-8keV energy band photon flux (4)
10- 14 F5.2 [cm-2/s] logF2 Log of 0.5-2keV energy band photon flux (4)
16- 20 F5.2 [cm-2/s] logF3 Log of 2-8keV energy band photon flux (4)
22- 26 F5.2 [cm-2/s] logF4 Log of 0.35-8keV energy band photon flux (4)
28- 32 F5.2 [cm-2/s] logF5 Log of 0.35-1.1keV energy band photon flux (4)
34- 38 F5.2 [cm-2/s] logF6 Log of 1.1-2.6keV energy band photon flux (4)
40- 44 F5.2 [cm-2/s] logF7 Log of 2.6-8keV energy band photon flux (4) (G1)
46- 50 F5.2 [cm-2/s] logF1 Log of 0.35-2keV energy band photon flux (4) (G1)
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Note (4): In units of photons/cm2/s.
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/74] Running sequence number
4- 8 F5.2 --- HR1 [-0.8/0.7] The "soft" color (5)
10- 13 F4.2 --- e_HR1 Uncertainty in HR1
15- 19 F5.2 --- HR2 [-0.7/0.8] The "hard" color (5)
21- 24 F4.2 --- e_HR2 Uncertainty in HR2
26- 29 A4 --- Hcl Classification of source (G2)
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Note (5): Where HR1=(M-S)/(H+M+S) and HR2=(H-M)/(H+M+S).
S = 0.35-1.1keV;
M = 1.1-2.6keV;
H = 2.6-8keV.
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Byte-by-byte Description of file: table12.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/74] Running sequence number
4- 9 F6.3 mag NUV [15.1/24.5]? GALEX GR6 NUV magnitude
11- 15 F5.3 mag e_NUV [0.001/0.6]? NUV uncertainty
17- 22 F6.3 mag FUV [17/24.1]? GALEX GR6 FUV magnitude
24- 28 F5.3 mag e_FUV [0.003/0.4]? FUV uncertainty
30- 34 F5.2 mag F606W [21.6/25.4]? HST F606W band magnitude
36- 39 F4.2 mag e_F606W [0.01/0.02]? F606W uncertainty
41- 45 F5.2 mag F814W [19.2/24.3]? HST F814W band magnitude
47- 50 F4.2 mag e_F814W [0.01]? F814W uncertainty
52- 56 F5.2 mag Bmag [9/21]? USNO-B1 B-band magnitude
58- 62 F5.2 mag Rmag [8/21]? USNO-B1 R-band magnitude
64- 68 F5.2 mag Jmag [7.6/16.4]? 2MASS J-band magnitude
70- 73 F4.2 mag e_Jmag [0.02/0.2]? Jmag uncertainty
75- 79 F5.2 mag Hmag [7.5/15.9]? 2MASS H-band magnitude
81- 84 F4.2 mag e_Hmag [0.02/0.2]? Hmag uncertainty
86- 90 F5.2 mag Ksmag [7.4/15.5]? 2MASS Ks-band magnitude
92- 95 F4.2 mag e_Ksmag [0.02/0.3]? Ksmag uncertainty
97-100 F4.1 mJy S1.4 [3.4/53.7]? NVSS 1.4GHz flux density
102-104 F3.1 mJy e_S1.4 [0.4/2]? S1.4 uncertainty
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Byte-by-byte Description of file: table13.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/74] Running sequence number
4- 7 A4 --- Hcl Classification from hardness ratios (HRs) (G2)
9- 27 A19 --- Fit Spectral fit ("apec" = Astrophysical Plasma
Emission Code, Smith et al. 2001ApJ...556L..91S 2001ApJ...556L..91S)
29- 33 A5 --- Var Variability (long or rapid)
35- 37 F3.1 kpc d [0/6.3] Galactocentric distance
39- 54 A16 --- XID Wavelength counterpart(s)
56- 62 A7 --- Class Object classification (background AGN, XRB,
SSS:super-soft source or FS: forground star)
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Global Notes:
Note (G1): Note adde by CDS: columns for 2.6-8keV and 0.35-2keV have similar
values; they are not displayed in the VizieR database.
Note (G2): Classification as follows:
XRB = likely contaminated with background AGNs, given their X-ray similarities
to low-mass X-ray binaries (LMXBs),
BKG = likely background sources with an indeterminate spectral shape,
ABS = heavily absorbed sources,
SNR = these sources are likely to be foreground stars or super-soft sources
(SSSs), and not true supernova remnants
HARD = indeterminate hard-X source
SOFT = indeterminate soft-X source
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History:
From electronic version of the journal
References:
Binder et al. Paper I:NGC 300. 2012ApJ...758...15B 2012ApJ...758...15B Cat. J/ApJ/758/15
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 21-Oct-2014