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Notes for object NGC 6240

25 note(s) found in NED.


1. 2009ApJ...690.1322W
Re:NGC 6240
NGC 6240. This peculiar source hosts two active nuclei, as found by Chandra
(Komossa et al. 2003). Therefore, we do not include an analysis of this source.

2. 2008ApJS..178..189W
Re:NGC 6240
A9. NGC 6240 (IC 4625, UGC 10592, VV 617) Veilleux et al. (1995) classify the
optical spectrum as LINER. However, hard X-ray imaging has revealed two AGNs
separated by ~1" (Komossa et al. 2003). Armus et al. (2007) detect continuum
emission from dust hotter than 300 K, which also indicates the presence of an
AGN. High-resolution radio images from 2.3 to 8.4 GHz reveal two compact radio
sources with properties similar to Seyfert nuclei (Gallimore & Beswick 2004).
Near-infrared images also show two nuclei as well as bright extended emission
(Scoville et al. 2000). For a more complete discussion of the multiwavelength
properties of NGC 6240, see Iono et al. (2007).

3. 2007A&A...461.1209D
Re:NGC 6240
NGC 6240: Vignati et al. (1999), basing their analysis on this data set,
stated that the source is a Compton-thick Seyfert with a direct
component emerging at E >= 10 keV. Here their results are confirmed.
It is worth noting here that the source has been recognized to be in a
merging system with a binary black hole (Komossa et al. 2003).

4. 2006ApJ...651..835D
Re:NGC 6240
The two nuclei of this source are separated by 1.4 kpc and still show some
discrete velocity patterns. The velocity dispersion of the system peaks between
them; at the position of this peak the stellar kinematics may reflect localized
motions of self-gravitating gas (Tecza et al. 2000; Genzel et al. 2001). For the
velocity dispersion of this source we use the average of the values at two
nuclei and at the internuclear peak (229 km s^-1^), which is close to the
luminosity-averaged value, 225 km s^-1^ (Tecza et al. 2000).

5. 2006ApJ...651..835D
Re:NGC 6240
The two nuclei of this source are separated by 1.4 kpc and still show some
discrete velocity patterns. The velocity dispersion of the system peaks between
them; at the position of this peak the stellar kinematics may reflect localized
motions of self-gravitating gas (Tecza et al. 2000; Genzel et al. 2001). For the
velocity dispersion of this source we use the average of the values at two
nuclei and at the internuclear peak (229 km s^-1^), which is close to the
luminosity-averaged value, 225 km s^-1^ (Tecza et al. 2000).

6. 2006A&A...460...45G
Re:NGC 6240
NGC 6240 (IC 4625, UGC 10592, 4C 02.44). Komossa et al. (2003) discovered a
binary AGN in the galaxy coincident with the optical nucleus. They appear
compact-unresolved at energies between 2.5-8 keV. The spectroscopic analysis
shows a very hard radiation for both nuclei, with {GAMMA} = 0.2 for one to the
South and 0.9 for one to the Northeast. The FeK{alpha} is present in both
nuclei. Satyapal et al. (2004) class it as an object that reveals a hard nuclear
point source embedded in soft diffuse emission. Ptak et al. (2003) point out the
complexity of the nuclear spectrum of this galaxy and construct a more complex
model that, in addition to the standard MEKAL and power law components, also
includes a Gaussian fit for the FeK{alpha} and a Compton reflection component
with different column densities. To give an idea of the complexity of the source
let us point out that Boller et al. (2003) best-modeled the FeK{alpha} line as
resolved into 3 narrow lines: neutral FeK{alpha} at 6.4 keV, an ionized line at
6.7 keV, and a blend of higher ionized lines (FeXXVI and the Fe K{beta} line) at
7.0 keV. For consistency with the statistical analysis, we modeled the continuum
spectrum with a combination of thermal plus a power law component without taking
the complex FeK{alpha} line into account. High absorption is derived for this
source from both the spectral fitting and the estimation from color-color
diagrams (Table 6).

7. 2004A&A...419..501F
Re:NGC 6240
NGC 6240- The MIR emission of NGC 6240 is unresolved in the ISOCAM
data. We adopt a size of 3" based on the Br{gamma} map of Tecza et
al. (2000). As a comparison, we derive from brightness profile fitting a
HPBW of the order of 2.7", which is ill-constrained since it is smaller
than the cleaned PSF HPBW of 3". We adopted the Br{gamma} flux of Rieke
et al. (1985) measured in a 8.7" aperture, and the Pa{beta} flux of
Simpson et al. (1996) measured in a slit of width 1.5" oriented along
the major axis of the source. In view of the Br{gamma} map of Tecza et
al. (2000), these apertures should include the total fluxes. The Pa{alpha}
flux of de Poy et al. (1986), measured in a 5.5" aperture, yields a
negative extinction when combined with the Pa{beta} flux; it may thus be
strongly underestimated. MIR diagnostics indicate that starburst
activity dominates the dust emission and the low-excitation
fine-structure line emission at these wavelengths (Genzel et al. 1998;
Rigopoulou et al. 1999; Laurent et al. 2000; but see also Lutz et
al. 2003).

8. 2004A&A...418..465L
Re:NGC 6240
NGC 6240 is one of the sources deviating most from the correlation, in
the sense of high X-ray and low mid-IR. This could include a
contribution of adopting a high estimate for the intrinsic X-ray
emission (cf. also the lower estimate of Ikebe et al. 2000), and the
likely noticeable obscuration of the 6 micron continuum in this
object. See Lutz et al. (2003) for a full discussion of the mid-infrared
properties.

9. 2003ApJS..146..249B
Re:NGC 6240
5.16. NGC 6240
Although observed many times and tentatively detected by Henkel et al.
(1984), H_2_O maser emission was not conclusively detected in NGC 6240
until 2001. Both Hagiwara et al. (2002a) and Nakai et al. (2002)
reported the detection in late spring of 2001. Figure 1 shows a
tentative detection of this feature in 2000 March and clear detections
in 2001 January and December and 2002 April. We did not detect the
feature at a 3 {sigma} level of 30 mJy (channel spacing:
1.11 km s^-1^) in 2002 November. Velocities, determined by Gaussian
fit, were 7565.0 +/- 0.8 km s^-1^ in 2000 March, 7565.6 +/- 0.5
km s^-1^ in 2001 January, 7568.6 +/- 0.7 km s^-1^ in 2001 December,
and (two lines) 7567.6 +/- 0.1 km s^-1^ and 7612.1 +/- 0.1 km s^-1^ in
2002 April. The feature seen at 7567.6 km s^-1^ in 2002 April drifted
by 1.4 +/- 0.3 km s^-1^ yr^-1^ between 2000 March and 2002 April. In
Figure 2 we reproduce the sensitive GBT spectrum from 2002 April
showing a 1600 km s^-1^ velocity range.

10. 2002ApJS..143...47D
Re:IRAS 16504+0228
IRAS 16504+0228 (NGC 6240).---This is a very well-known ultraluminous
infrared merger remnant with a strong nonthermal radio excess. Our red
continuum image shows the strong tidal tails which have resulted from
the merger, while the H{alpha} emission is much more strongly
concentrated in the nucleus and has an asymmetric shape with
spider-like morphology. This is surrounded by a series of faint
filamentary arcs with very complex morphology. NGC 6240 is known to
have a double nucleus (e.g., Condon et al. 1982; Schulz et al. 1993).
The extended H{alpha} emission is strongest northwest of the galaxy,
in contrast to the red continuum extended emission, which is
predominantly in the north and western tails. NGC 6240 has a LINER or
Sy2 optical spectrum (Kewley et al. 2001b; Goldader et al. 1997a,
1997b; Kim et al. 1995; Veilleux et al. 1995) and shows evidence for
an obscured AGN in X-rays and radio (e.g., Ikebe et al. 2000; Risaliti
et al. 2000; Kewley et al. 2000).

11. 2001ApJ...563..527G
Re:NGC 6240
NGC 6240. - Our new H-band stellar data are in excellent agreement with
the earlier K-band imaging spectroscopy obtained with the MPE
three-dimensional spectrometer by Tecza et al. (2000). Both nuclei
counterrotate in a retrograde-prograde overall geometry. The rotation
velocities of the two nuclei are of similar size and are very large
(~300 +/- 70 km s^-1^; Fig. 8 of Tecza et al. 2000). The velocity
dispersion is large throughout the region encompassing both nuclei but has
a maximum between the nuclei, on/near the millimeter CO emission peak found
with 1.3 mm interferometry by Tacconi et al. (1999). The large velocity
dispersion at the CO peak cannot be explained by the rotation properties
of the two disks that may overlap in that direction. The line connecting
the two galaxies (and passing through the CO peak) is at large angles
relative to the line of nodes of both galaxy bulges. Hence, velocity
gradients along this line are fairly small and the velocity dispersion
peak must be due to a local effect. Our LOSVDs in Figure 5 suggest that
the large velocity dispersion at the CO peak is caused by a blueshifted
component (300-600 km s^-1^) that is not present in the other directions,
again in excellent agreement with the Tecza et al. (2000) K-band data.
We thus concur with Tacconi et al. (1999) and Tecza et al. (2000) that
there probably is a major self-gravitating mass concentration of
interstellar gas between the two nuclei, although the possibility of
nonequilibrium dynamics has to be taken into account (Mihos 1999).

12. 2000MNRAS.318..173M
Re:NGC 6240
2.3 NGC 6240
The direct nuclear emission of NGC 6240 is revealed by the PDS
(Vignati et al. 1999; see also Netzer, Turner & George 1998 for ASCA
results). The column density is 2 x 10^24^ cm^-2^. An ionized reflector
is also clearly present: a power-law continuum is required by the data,
and there is clear evidence for ionized iron lines (see also
Iwasawa & Comastri 1998). Evidence for cold reflection is instead
ambiguous. The intrinsic 2-10 keV luminosity deduced from the best fit
is ~1.2 x 10^44^ erg s^-1^.

13. 2000AJ....119..991S
Re:NGC 6240
The double nuclei in NGC 6240 are separated by 1.6" (0.8 kpc)
north-south and the southern nucleus is relatively brighter at long
wavelengths. The reddening peaks to the north and slightly east of the
southern nucleus. In the radio continuum, there are also two nuclei, but
their separation is only 1.4" (Carral, Turner, & Ho 1990). The
millimeter wave CO (2-1) emission peak is located between these nuclei
(Tacconi et al. 1999; Bryant & Scoville 1999). In addition, the
near-infrared CO bandhead velocity dispersion of giant stars exhibits an
increase between the nuclei (Tacconi et al. 1997), all of which indicate
a significant mass concentration (perhaps largely interstellar gas)
between the nuclei.

14. 2000A&AS..141..385V
Re:NGC 6240
D-28 = NGC 6240. (A,E,G,N) This galaxy is a merger product with a
luminosity profile similar to that of an elliptical and it is a
superliminous IRAS galaxy. In its inner parts many crossed optical loops
can be seen, while the outer regions show an extensive set of shells.
The H I emission line spectrum may be influenced by absorption against
the strong continuum, since it is a strong radio source. CCD images: see
PRC. It has a LINER optical spectrum (Goldader et al. 1997; Kim et al.
1995; Rieke et al. 1985; Veilleux et al. 1995); stellar kinematics: see
Lester (1994) The object contains a strong continuum source
(650 mJy at 21 cm), and thus care has to be taken in accurately
determining the radio telescope's passband in both polarisations used;
we did this at Nancay using a strong quasar. An absorption profile was
detected at Nancay as well as in several Arecibo and VLA studies (see
Table 3): only the Arecibo profile of Garwood et al. (1987) has a FWHM
(173 km s^-1^) comparable to our Nancay measurement, the others are
considerably broader (average 405 km s^-1^). The OH lines also show an
absorption profile (Baan et al. 1985, 1992). No H2_O_ megamaser activity
was detected (Braatz et al. 1997). Near-infrared imaging and spectrum:
see Doyon et al. (1994), Rieke et al. (1985), Zhou et al. (1993). No
other galaxies were found within the Nancay search area.

15. 1999A&A...350....9O
Re:NGC 6240
3.4.3. NGC6240
This peculiar object is an interacting system with a bolometric
luminosity close to the limit of IRAS ultraluminous galaxies. A deeply
hidden AGN is revealed by X-ray spectra showing a prominent Fe K 6.4keV
line and powerful continuum emission at 100 keV (Iwasawa & Comastri
1998, Iwasawa 1999, Matt 1999). The active nucleus is much less evident
at longer wavelengths but its contribution to the bolometric luminosity
is likely to be important because the L(100 keV)/{alpha} ratio is
similar to that measured in the Circinus galaxy.
Several IR spectroscopic studies exist in the literature (Doyon
et al. 1994, Lester & Gaffney 1994, Shier et al. 1996) reaching
contradictory conclusions on the nature of the red stellar population,
i.e. young supergiants/AGB stars vs. old, low mass giants. In
particular, the very large velocity dispersion and relatively high mass
to light ratio have been used to argue for an old elliptical-like system
(e.g. Doyon et al. 1994). However, these conclusions were drawn without
correcting the stellar flux for extinction which is indeed very high,
about 1 magnitude at 1.65 microns (see Table 2).
The mass to light ratio derived here is unequivocally in the
starburst domain and demonstrates that the near IR emission from this
massive object is still dominated by a young stellar population. It
should be noted that this conclusion is still valid if the larger
velocity dispersion quoted in the above papers, i.e.
{sigma} = 350 km s^-1^, is adopted.
Another peculiarity of this object is the combination of very
strong CO(2,0), the deepest in our sample, and relatively shallow
CO(6,3). The ratio W_{lambda}(2.29)_/W_{lambda}(1.62)_=4.1 is 30% larger
than in starburst galaxies and young LMC clusters (see Table 1 and
Fig. 5 of Oliva & Origlia 1998). The only other object with a comparably
large ratio is NGC330, a well known young and metal poor cluster in the
SMC. Since W_{lambda}(1.62)_ is much more sensitive to metallicity than
W_{lambda}(2.29)_, this indicates that NGC6240 is a relatively metal
poor system as well. Detailed modeling confirms this idea and yields a
metallicity ~1/10 solar, the lowest among the galaxies in our sample
(see Oliva & Origlia 1998).

16. 1998A&A...333...38B
Re:NGC 6240
2.3. NGC 6240
NGC 6240 is very luminous with two central sources separated by ~2" (Condon et
al. 1982; Schulz et al. 1993). They are assumed to be the remnants of the nuclei
of the pre-merger galaxies. The IRAS fluxes are very "warm" -
-S_60{mu}_/S_100{mu}_~0.9. Radio data at 1.49, 4.6, and 8.1 GHz are from Colbert
et al. (1994); a synchrotron spectral index of -0.8 and a thermal fraction of
10% at 10 GHz provide a good fit to the data.

17. 1997ApJS..113...23T
Re:NGC 6240
A20. NGC 6240
NGC 6240 has a disturbed morphology thought to be due to a merger interaction
with another galaxy (Fosbury & Wall 1979). NGC 6240 is an ultraluminous
infrared source (Wright, Joseph, & Meikle 1984) in which 99% of the bolometric
luminosity emerges in the infrared (Soifer et al. 1984). We detect line
emission from species of Ne, Mg, Si, and S as well as Fe. The overall continuum
shape can be described by models featuring complex absorption or two continuum
components. The 8 ks PSPC observation of this source from 1992 September shows
marginal evidence for extended emission; unfortunately, the HRI observation is
not yet available in the public archive.

18. 1997ApJS..108..449G
Re:NGC 6240
This galaxy was observed through very uniform, but thick, cirrus
(~1 mag extinction) that arrived immediately prior to the observations.
The data themselves are free of the noise pattern characteristic of
rapidly varying atmospheric transmission, and the comparison and standard
stars were observed through the same cirrus. Given that our
spectrophotometry is quite comparable to that in previous works, we have
made no corrections to the photometry.

19. 1996ApJS..103...81C
Re:NGC 6240
NGC 6240.--Seyfert 2. VV 617. Merger. See Colbert, Wilson, & Bland-Hawthorn
(1994) for multifrequency VLA maps and references to earlier radio maps.

20. 1996A&AS..115..253L
Re:NGC 6240
The H + K spectrum of the central 5" of NGC 6240 stands out because of its
peculiar line ratios, molecular hydrogen and [Fe II] 1.64 microns emission
being particularly strong (see also Becklin et al. 1984; Rieke et al. 1985;
DePoy et al. 1986). The signal-to-noise ratio does not allow for a detailed
description of the continuum. However the weak curvature in the H band
suggests a dominant eontribution from supergiant stars, as in NGC 1614 or
Mrk 331. This is consistent with the exceptional power of the starburst (Rieke
et al. 1985) and with the correspondence between the sizes of the aperture and
of the double-peaked active regions (Eales et al. 1990; Van der Werf et al.
1993).

21. 1994AJ....107...99R
Re:NGC 6240
D-28 = NGC 6240= UGC 10592. This superluminous IRAS galaxy is a merger
product: short exposures reveal many crossed optical loops and deeper
exposures show an extensive set of shells. The GB 140' reports a gas mass
of 8.2 x 10^9^ M_sun_ within an irregular profile of large linewidth
(about 600 km s^-1^). Since this galaxy is a radio source, it is possible
that our emission spectrum is being influenced by absorption against the
continuum. NED lists no optical companions within 10', and only one
fairly faint galaxy within the GB 140' beam.

22. 1993ApJ...412..535W
Re:NGC 6240
NGC 6240.- A radio map of this galaxy is presented in Eales et al.
(1990). The optical peak lies within 1" of the southern radio source.
Multiaperture measurements at 10 and 20 microns (Fig. 1), when taken
together with the high value for the compactness, imply a characteristic
radius of not more than 1" (500pc).

23. 1976RC2...C...0000d
Re:NGC 6240
= 4C 02.44
= PKS 1650+024
Spectrum:
Australian J. Phys., 25, 233, 1972 (emission)

24. 1973UGC...C...0000N
Re:UGC 10592
Pec (de Vaucouleurs)
Irregular loop southwards, large diffuse plume northeast
Companions 2.9, 170, 0.3 x 0.1; and 4.3, 30, 0.55 x 0.10

25. 1964RC1...C...0000d
Re:NGC 6240
Complex core with strong dark lane. Distorted. Faint outer filament. No
nearby object of similar size. Another very peculiar object.


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