![\begin{figure}
\par\includegraphics[angle=-90,width=8.7cm]{7301fig1.eps}\end{figure}](/articles/aa/full/2007/24/aa7301-07/img15.gif) |
Figure 1:
The central 3'' of Arp 220 in CO(2-1) integrated over 770 km s-1,
with the 1.3 mm continuum subtracted. The beam ( lower left) is
0.30'' with
 K/Jy. Contours are 2 to 10 by 2, then 14
to 54 by 4 (in Jy km s-1). The CO-West peak is 56.5 Jy km s-1; CO-NE
is 33.4 Jy km s-1.
|
| Open with DEXTER | |
In the text
![\begin{figure}
\par\includegraphics[angle=-90,width=8.7cm]{7301fig2.eps}\end{figure}](/articles/aa/full/2007/24/aa7301-07/img16.gif) |
Figure 2: Continuum map at 1.3mm (229.4 GHz). Contour steps are 6 mJy beam-1. The Arp 220-West peak is 79 mJy beam-1, and the East peak is 23 mJy beam-1. Note that the continuum peaks do not coincide with the CO(2-1) peaks, which are marked with crosses. The beam is 0.30'' (lower right). |
| Open with DEXTER | |
In the text
![\begin{figure}
\par\includegraphics[angle=-90,width=8.7cm]{7301fig3.eps}\end{figure}](/articles/aa/full/2007/24/aa7301-07/img19.gif) |
Figure 3:
East-west CO(2-1) position-velocity cut, through the West nucleus.
CO(2-1) contours are in steps of 10 mJy beam-1, with the
1.3 mm continuum subtracted. The CO ring around the West nucleus
covers velocities from -370 to +300 km s-1, and is cut by absorption
at -60 to +40 km s-1. Velocity offsets are relative to 226.422 GHz
(
 = 5450 km s-1). RA offsets are relative to the
West continuum peak, indicated by the horizontal line (position in
Table 1).
|
| Open with DEXTER | |
In the text
![\begin{figure}
\par\includegraphics[angle=-90,width=8.7cm]{7301fig4.eps}\end{figure}](/articles/aa/full/2007/24/aa7301-07/img41.gif) |
Figure 4:
Evidence for foreground obscuration: CO(2-1) spectra across
Arp 220-West, with the 1.3 mm continuum subtracted. Each box is a
step of 0.1'', north is up, east is left, and (RA, Dec) offsets
are in the upper left of each box. The grid center at (0,0) is the
1.3 mm West continuum peak (Table 1). Velocities run from -400 to
+400 km s-1, the spectral resolution is 5 km s-1, and zero velocity
(the center of the spectra) is at 226.422 GHz (
 5450 km s-1). Intensities run from 0 to 200 mJy beam-1. The
beam is 0.30'' with
K/Jy, which means the
directly-observed, beam-smoothed, peak CO brightness temperatures are
40 K. Note the deep absorption near the line center in some of the
spectra, which indicates foreground, cooler gas.
|
| Open with DEXTER | |
In the text
![\begin{figure}
\par\includegraphics[angle=-90,width=8.7cm]{7301fig5.eps}\end{figure}](/articles/aa/full/2007/24/aa7301-07/img57.gif) |
Figure 5:
Our model of the radio-to-mid-IR continuum spectrum of
Arp 220-West. The spectrum is dominated by an opaque, 170 K blackbody
dust component, with a luminosity of 9
  ,
that
only becomes optically thin below 1.1 mm. The dust blackbody is
absorbed by a foreground screen (the West-CO ring and possibly part
of the Eastern disk)
that has a foreground opacity of 1.7 at 25  m. The
effect of the foreground screen is to attenuate the intrinsic mid-IR
fluxes, thus shifting the apparent peak of the dust blackbody to
longer wavelengths, giving the illusion of a lower temperature (dashed
curve). Besides the millimeter-to-mid-IR dust component, there is a
free-free component that becomes optically thick below 20 cm, and
extended synchrotron emission mixed with the ionized gas, that turns
over below 20 cm due to free-free absorption. The data points at 113
and 229 GHz are from this paper. The other radio fluxes are from the
references cited in the text, and the mid-IR points are the 10 to
25 m fluxes measured by Soifer et al. (1999).
|
| Open with DEXTER | |
In the text