J/PASJ/57/135 Chandra observation of NGC 2146 (Inui+, 2005)
Chandra observation of the starburst galaxy NGC 2146.
Inui T., Matsumoto H., Tsuru T.G., Koyama K., Matsushita S., Peck A.B.,
Tarchi A.
<Publ. Astron. Soc. Jap., 57, 135-145 (2005)>
=2005PASJ...57..135I 2005PASJ...57..135I
ADC_Keywords: Active gal. nuclei ; X-ray sources
Keywords: galaxies: active - galaxies: individual (NGC 2146) -
galaxies: starburst - X-rays: galaxies
Abstract:
We present six monitoring observations of the starburst galaxy
NGC 2146 using the Chandra X-ray Observatory. We detected 67 point
sources in the field of view of the ACIS-S detector. Six of these
sources were Ultra-Luminous X-ray Sources, the brightest of which had
a luminosity of 5x1039erg/s. One of them, with a luminosity of
∼1x1039erg/s, is coincident with the dynamical center location,
which may be a low-luminosity active galactic nucleus. We have
produced a table where the positions and main characteristics of the
detected sources are reported. A comparison between the positions of
the X-ray sources and those detected in NIR or radio indicates no
definite counterpart. We have derived a logN-logS relation and a
luminosity function. The luminosity function has a slope of 0.71 above
a detection limit, which is similar to those found in other starburst
galaxies. Diffuse emissions were detected in both soft (0.5-2.0keV)
and hard (2.0-10.0keV) energy bands. The spectra of the diffuse
component were fitted with two (hard and soft) components. The hard
power-law component, with a luminosity of ∼4x1039erg/s, is likely to
have originated by unresolved point sources.
Description:
NGC 2146 was observed six times through 2002 August to December, with
the Advanced CCD Imaging Spectrometer on board the Chandra X-ray
Observatory (CXO).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table8.dat 118 67 Main Chandra Point Source Catalog
--------------------------------------------------------------------------------
See also:
B/chandra : The Chandra Archive Log (CXC, 1999-)
J/ApJS/157/59 : Ultraluminous X-ray sources in nearby galaxies (Liu+, 2005)
Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- [IMT2005] Sequential number
4- 5 I2 h RAh Right ascension (J2000)
7- 8 I2 min RAm Right ascension (J2000)
10- 14 F5.2 s RAs Right ascension (J2000)
16 A1 --- DE- Declination sing (J2000)
17- 18 I2 deg DEd Declination (J2000)
20- 21 I2 arcmin DEm Declination (J2000)
23- 26 F4.1 arcsec DEs Declination (J2000)
28- 32 F5.1 ct NCt Net photon counts with background substracted
34- 37 F4.1 ct e_NCt rms uncertainty on NCt
39- 42 F4.1 --- Signi Significance
44- 47 F4.2 --- VTime Time variability given with the chi2 test
49- 53 F5.2 --- HR ? Hardness ratio (H-S)/(H+S)
(H:2-10keV, S:0.5-2keV)
54 A1 --- n_HR [c] Note on HR (1)
55- 59 F5.2 --- HRl ?=- Lower limit of hardness ratio interval
(90% confidence)
61- 65 F5.2 --- HRu ?=- Upper limit of hardness ratio interval
(90% confidence)
67- 70 F4.2 10-22cm-2 NH ? Absorption column density
71 A1 --- n_NH [b] Note on NH (1)
72- 75 F4.2 10-22cm-2 NHl ?=- Lower limit of NH interval
(90% confidence)
77- 80 F4.2 10-22cm-2 NHu ?=- Upper limit of NH interval
(90% confidence)
82- 85 F4.2 --- Gamma ? Photon-index
86 A1 --- n_Gamma [a] Note on Gamma (1)
87- 90 F4.2 --- Gammal ?=- Lower limit of Gamma interval
(90% confidence)
92- 95 F4.2 --- Gammau ?=- Upper limit of Gamma interval
(90% confidence)
97-100 F4.2 10-17W/m2 Fhard Observed flux in the hard 2-10keV band
102-106 F5.2 10-17W/m2 Ftot Observed flux in the total 0.5-10keV band
108-112 F5.2 [10-7W] logLhard X-ray luminosity in the hard 2-10keV band
114-118 F5.2 [10-7W] logLtot X-ray luminosity in the total 0.5-10keV band
--------------------------------------------------------------------------------
Note (1): Notes as follows:
a = Photon index fixed at 2.0 due to low number of counts (<180cts)
b = Absorption column density fixed at 0.4 (1022cm-2), the
best-fit value of the diffuse emission (<120cts).
c = Since a background-substracted hard band counts drop into minus,
HR shows less than -1.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 27-Jun-2006