Aims. Dust-obscured star-formation increases with increasing intensity and increasing redshift. We aim to reveal the cosmic starformation history obscured by dust using deep infrared observation with AKARI. Methods. We constructed restframe 8 μm, 12 μm, and total infrared (TIR) luminosity functions (LFs) at 0.15 < z < 2.2 using 4128 infrared sources in the AKARI NEP-deep field. A continuous filter coverage in the mid-IR wavelength (2.4, 3.2, 4.1, 7, 9, 11, 15, 18, and 24 μm) by the AKARI satellite allowed us to estimate restframe 8 μm and 12 μm luminosities without using a large extrapolation based on an SED fit, which was the largest uncertainty in previous work. Results. We find that all 8 μm (0.38 < z < 2.2), 12 μm (0.15 < z < 1.16), and TIR LFs (0.2 < z < 1.6) show continuous and strong evolution toward higher redshift. Our direct estimate of 8 μm LFs is useful since previous work often had to use a large extrapolation from the Spitzer 24 μm to 8 μm, where SED modeling is more difficult because of the PAH emissions. In terms of cosmic infrared luminosity density (Ω IR ), which was obtained by integrating analytic fits to the LFs, we find good agreement with previous work at z < 1.2. We find the Ω IR evolves as ∝ (1 + z) 4.4±1.0 . When we separate contributions to Ω IR by LIRGs and ULIRGs, we found more IR luminous sources are increasingly more important at higher redshift. We find that the ULIRG (LIRG) contribution increases by a factor of 10 (1.8) from z = 0.35 to z = 1.4. Key words. infrared: galaxies -galaxies: luminosity function, mass function -galaxies: evolution -galaxies: high-redshiftgalaxies: formation -galaxies: starburst This research is based on the observations with AKARI, a JAXA project with the participation of ESA.Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.JSPS SPD fellow.

We present a Giant Molecular Cloud (GMC) catalog toward M33, containing 71 GMCs in total, based on wide field and high sensitivity CO(J = 3−2) observations with a spatial resolution of 100 pc using the ASTE 10 m telescope. Employing archival optical data, we identify 75 young stellar groups (YSGs) from the excess of the surface stellar density, and estimate their ages by comparing with stellar evolution models. A spatial comparison among the GMCs, YSGs, and Hii regions enable us to classify GMCs into four categories: Type A showing no sign of massive star formation (SF), Type B being associated only with Hii regions, Type C with both Hii regions and < 10 Myr-old YSGs and Type-D with both Hii regions and 10-30 Myr YSGs. Out of 65 GMCs (discarding those at the edges of the observed fields), 1 (1%), 13 (20%), 29 (45%), and 22 (34%) are Types A, B, C, and D, respectively. We interpret these categories as stages in a GMC evolutionary sequence. Assuming that the timescale for each evolutionary stage is proportional to the number of GMCs, the lifetime of a GMC with a mass > 10 5 M is estimated to be 20-40 Myr. In addition, we find that the dense gas fraction as traced by the CO(J = 3 − 2)/CO(J = 1 − 0) ratio is enhanced around SF regions. This confirms a scenario where dense gas is preferentially formed around previously generated stars, and will be the fuel for the next stellar generation. In this way, massive SF gradually propagates in a GMC until gas is exhausted.

We present a catalog of star clusters with V F555W < 23 mag detected in the interacting spiral galaxy M51 system based on mosaic images taken with the Hubble Space Telescope Advanced Camera for Surveys by the Hubble Heritage Team. We have selected about 3600 clusters based on their morphological information through visual inspection. The final star cluster catalog includes 2224 clusters that are relatively well isolated and have a circular shape. The star clusters in M51 are mostly distributed around the spiral arms of NGC 5194. The color-magnitude diagrams show that most of the star clusters in M51 are bluer than (B F435W − V F555W ) = 0.5 and (V F555W − I F814W ) = 0.8. There are also some red star clusters with (B F435W − V F555W ) > 0.7, uniformly distributed over the M51 field. Some of these red clusters are suspected to be a part of the halo or old disk population based on their old ages (t 10 9 yrs) and their spatial distribution. The luminosity function of the star clusters is well fitted by a single power law with α = −2.59 ± 0.03 for the range −10.0 < M V < −8.0 mag. We find that the size distribution of the star clusters can be fitted with three Gaussian components with peaks at effective radii of 2.27, 4.80, and 7.51 pc. Some large star clusters with red color are faint fuzzy clusters, and they are distributed not only around NGC 5195 but also around NGC 5194. These faint fuzzies are found to display an elongated spatial distribution, while the normal compact red clusters show a relatively uniform distribution around NGC 5194.

Images of JHK and gi obtained with the Canada-France-Hawaii Telescope are used to investigate the stellar contents of the resolved asymptotic giant branch (AGB) population in the area of 3. 6×6. 3 on the central bar of the dwarf irregular galaxy NGC 6822. The upper envelope of near-infrared (J − K, K) and (H − K, K) color−magnitude diagrams (CMDs) shows four components of main-sequence stars, foreground stars, massive supergiants, and AGB stars. These components are also noticeable in the bright part of (g − i, g) CMD.We select AGB stars in NGC 6822 from the (g − K, g) CMD, which has a long spectral wavelength base line in the color index. There are 141 C stars with a mean absolute magnitude of M K = −7.60 ± 0.50, and with mean colors of (J − K) 0 = 1.77 ± 0.41, and (H − K) 0 = 0.75 ± 0.28. The number ratio of C stars to M-giants (C/M) is estimated as 0.27 ± 0.03, while the northern part of the bar has a somewhat lower C/M ratio than the southern part. The (J − K) and (H − K) color distributions of AGB stars contain a main peak of M-giant stars and a red tail of C stars. The broad color distributions for M-giants indicate that NGC 6822 has a wide range of intermediate ages with a peak at log(t yr ) ∼ 9.0. The M K luminosity function (LF) for C stars in the central bar of NGC 6822 is likely to be a Gaussian distribution, while the LF of C stars in the southern part is slightly skewed to the brighter side than in northern part. The mean bolometric magnitude of 141 C stars in NGC 6822 is M bol = −4.36 ± 0.54. The bolometric LF for M-giants extends up to M bol = −6.5, while the one for C stars spans −5.8 < M bol < −3.5.

We present a study of H II regions in M51 using the Hubble Space Telescope ACS images taken as part of the Hubble Heritage Program. We have catalogued about 19,600 H II regions in M51 with Hα luminosity in the range of L = 10 35.5 erg s −1 to 10 39.0 erg s −1 . The Hα luminosity function of H II regions (H II LF) in M51 is well represented by a double power law with its index α = −2.25±0.02 for the bright part and α = −1.42±0.01 for the faint part, separated at a break point L = 10 37.1 erg s −1 . This break was not found in previous studies of M51 H II regions. Comparison with simulated H II LFs suggests that this break is caused by the transition of H II region ionizing sources, from low mass clusters (with ∼ 10 3 M ⊙ , including several OB stars) to more massive clusters (including several tens of OB stars). The H II LFs with L < 10 37.1 erg s −1 are found to have different slopes for different parts in M51: the H II LF for the interarm region is steeper than those for the arm and the nuclear regions. This observed difference in H II LFs can be explained by evolutionary effects that H II regions in the interarm region are relatively older than those in the other parts of M51.