Figure 3.3 represents the far-IR observation of
M101 with Akari (Suzuki et al.2007).
Using 4 bands of Akari FIS and 3 bands of ISO, the SED of this
galaxy is fitted with two components of dust emissions with
Spiral galaxies (not classified with either AGN or starburst galaxy)
have a far-IR temperature with 20K-50K as a whole
from Revised Shapley-Ames
galaxy survey by IRAS De Jong et al 1984).
As shown in Fig.3.4 (a),
cold component well correlates with that of gas distribution,
while warm one has a relation to star formation regions.
Fig.3.4(b) plots the warm-to-cold ratio of
intensities, which seems to show the distribution of
star formation efficiency star formation rate/gas mass.
Some peaks in this plot correspond to famous HII regions.
Center of the galaxy and the end of the galactic bar indicate
peaks in this map.
Since barred galaxies have larger star formation rate than
spiral galaxies without bars, the central peaks are regarded
as a region where gas is accumulated by the effect of a bar potential.
Equations (eq:Kennicutt-correlation-1) and (3.7)
indicates that the star formation efficiency
Kohji Tomisaka 2012-10-03