Astronomy Department

AzTEC/ASTE 2007 Science Projects

Star Formation

Complete survey of massive young stellar objects in the eta Carinae giant molecular cloud (Y. Yonekura) We will obtain a 1.1 mm image of the entire eta Carinae giant molecular cloud, within which massive stars are forming by various modes. From these observations, we will obtain an unbiased sample of massive clumps >10 solar masses. Comparing the 1.1 mm emission with information on the molecular gas from existing line observations, we will investigate the correlation between the mass of the forming stars and the physical properties of the associated molecular clouds, and the difference in star formation efficiency and the mass of the forming stars between induced and stimulated star formation.

ASTE/AzTEC 1.1 mm continuum observations toward the rho Ophiuchi Dark Cloud (K. Kamegai)

The rho Oph dark cloud complex is home to a sample of dense cores which have different properites in mode of star formation and evolutionary stage. We will map the "head-tail" structure formed by the main body of the cloud - a young, cluster forming region - and by an older, less active star forming filamentary cloud with AzTEC. This data will provide us a mass function of cores, clustering degree, and distributions of the density and size of cores over a significantly wide mass range. Combining these results with those from molecular line observations, we can gain a better understanding of dense core evolution and star formation.

Evolution of molecular clouds from a study of dust and gas in the Magellanic Clouds (N. Mizuno)

This study involves observations of the thermal dust emission of molecular clouds in the Magellanic Clouds in order to search for cold cores in an environment different from that of the Milky Way. In particular, the LMC is known to contain many populous clusters. Combined with recent results from Akari and Spitzer, we can derive dust temperatures and masses accurately, which will bring us deeper knowledge of the dust and molecular components of molecular clouds in the Magellanic Clouds and provide a better understanding of massive cluster formation.

Embedded very young protostars in southern star forming regions (K. Tachihara)

We will map the star forming regions Lupus 1, 4, and the Ophiuchus north region in a survey for very young protostars (class 0 objects) embedded in compact dense cores with AzTEC on ASTE. Combining this mm data with existing NIR-FIR photometric data, we can derive stellar bolometric luminosities and temperatures from the SEDs of these objects and determine their evolutionary stages. The addition of exisiting molecular line observations will allow the determination of the physical properties of these cloud cores (eg. mass, density, infalling/outflowing motions) and a comparison of these properties to the evolutionary stages of the associated protostars. Extragalactic

AzTEC/ASTE imaging of the GOODS-S field (M.S. Yun)

During the 2007 season we are surveying the GOODS-S field at 1.1 mm with AzTEC on the ASTE telescope. Our survey covers the entire 16'x10' region of the Spitzer Space Telescope IRAC and MIPS survey with uniform coverage.

Submillimeter galaxies in cluster environments (G.W. Wilson)

We are carrying out deep, wide-field (12'x12') surveys for submillimeter galaxies (SMGs) towards known overdensities in order to study the evolution of SMG number counts in cluster or proto-cluster environments with redshift. Our target fields include clusters and proto-clusters that are either X-ray selected (low-z sample) or centered on radio galaxies (high-z sample). Over the course of two observing seasons in 2007 and 2008, we will image 30-40 different fields, which will give us a statistically significant sample of SMGs in biased enviroments in four redshift bins of z < 0.5, 0.5 < z < 1.5, 1.5 < z < 2.0, and z > 2.5.

AzTEC/ASTE survey of submillimeter galaxies (K. Kohno)

We will conduct deep, wide field surveys of some selected regions, such as the SEP low cirrus region, with AzTEC on ASTE in a search for previously unknown submillimeter galaxies (SMGs). The SEP is a region with very low cirrus emission and extremely deep IR/FIR multi-band AKARI data will be available. The emphasis will be placed on the comparison of our new deep and wide images with the optical/infrared deep images taken with the SUBARU telescope, AKARI satellite, and other optical/infrared missions. It allows us to compare the distributions of SMGs with those of optically selected and other optical/infrared missions. It allows us to compare the distributions of SMGs with those of optically selected high-z populations (such as LAEs/LABs, EROs, DRGs, etc.) and to understand their relationship in terms of galaxy formation/evolution. Other

Surface profile diagnosis with AzTEC (N. Ukita)

AzTEC on ASTE is a unique chance to better understand the characteristics of the ASTE main-reflector. We will make phase retrieval holography diagnoses of the main-reflector surface profile under various environmental conditions with AzTEC. The holography maps obtained from these data sets will uncover surface profile degradation due to gravity and thermal loadings, which are necessary in order to consider daytime operations for astronomical observations with ASTE.