We investigate Box/Peanut and bar structures in image data of edge-on and faceon nearby galaxies taken from SDSS (Sloan Digital Sky Survey) to present catalogues containing the surface brightness parameters and the morphology classification. About 1700 edge-on galaxies and 2600 face-on galaxies are selected from SDSS DR7 in g, r and i-band. The images of each galaxy are fitted with the model of 2-dimensional surface brightness of Sérsic bulge and exponential disk. After removing some irregular data, Box/Peanut, bar and other structures are easily distinguished by eye using residual (observed minus model) images. We find 292 Box/Peanut structures in the 1329 edgeon samples and 630 bar structures in 1890 face-on samples in i-band, after removing some irregular data. Then the fraction of Box/Peanut galaxies is about 22 percent against the edge-on samples, and that of bar is about 33 percent (about 50 percent if 629 elliptical galaxies are removed) against the face-on samples. Furthermore the strengths of the Box/Peanut and bar are evaluated as "Strong", "Standard" and "Weak". We find that the strength increases slightly with increasing B/T (Bulgeto-Total flux ratio), and that the fraction of Box/Peanut is generally about a half of that of bar irrespective of the strength and the B/T . Our result supports the idea that the Box/Peanut is bar seen edge-on.
The origin of huge infrared luminosities of ultraluminous infrared galaxies (ULIGs) is still in question. Recently, Genzel et al. made mid-infrared (MIR) spectroscopy of a large number of ULIGs and found that the major energy source in them is massive stars formed in the recent starburst activity; i.e., ∼ 70%-80% of the sample are predominantly powered by the starburst. However, it is known that previous optical spectroscopic observations showed that the majority of ULIGs are classified as Seyferts or LINERs (low-ionization nuclear emission-line regions). In order to reconcile this difference, we compare types of emission-line activity for a sample of ULIGs which have been observed in both optical and MIR. We confirm the results of previous studies that the majority of ULIGs classified as LINERs based on the optical emission-line diagnostics turn to be starburst-dominated galaxies based on the MIR ones. Since the MIR spectroscopy can probe more heavily-reddened, inner parts of the ULIGs, it is quite unlikely that the inner parts are powered by the starburst while the outer parts are powered by non-stellar ionization sources. The most probable resolution of this dilemma is that the optical emission-line nebulae with the LINER properties are powered predominantly by shock heating driven by the superwind activity; i.e., a blast wave driven by a collective effect of a large number of supernovae in the central region of galaxy mergers.
The current status of the AKARI-FIS Point Source Catalogue is reported. The first version of the Bright Source Catalogue has been in public since March 2010 and used extensively in the various fields in astronomy. The second version of the Bright Source Catalogue and the first version of the Faint Source Catalogue are currently under development. The revised Bright Source Catalogue is expected to have improved completeness, reliability, and accuracy compared to the current version. The Faint Source Catalogue will have a scan-density dependent detection limit and will enable much deeper exploration of the sky especially in the high-ecliptic latitude regions. Both catalogues will be available in a year time scale.
We investigate colors and mass-to-light ratios (M/Ls) of the bulges and disks for 28 nearby spiral galaxies with various morphological types of Sab to Scd, using images in optical and near-infrared (V , I, and J) bands and published rotation curves. It is shown that the observed colors and M/Ls generally agree with the galaxy formation model with an exponentially declining star formation rate and shallow slope (ex. Scalo) initial mass function (IMF) for both the bulges and the disks. We find that the bulge M/L is generally higher than the disk M/L and that the galaxies with larger bulge-to-total luminosity ratio tend to have a smaller bulge M/L. The fact indicates that the luminosity-weighted average age of bulges for early-type spirals is younger than that of later-type spirals. These results support a formation scenario that produces young stars for the bulges of middle-type and early-type spirals.
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