1505.00010
Cosmic star formation history and AGN evolution near and far: AKARI reveals both
Goto, AKARI NEP team, AKARI all sky survey team
Understanding IR luminosity is fundamental to understanding the comics star formation history and AGN evolution, since their most intense stages are often obscured by dust. Japanese IR satellite, AKARI, provided unique data sets to probe this both at low and high z. The AKARI performed an all-sky survey in 6 IR bands (9,18,65,90,140, ad 160 um) with 3-10 times better sensitivity than IRAS, covering the crucial far-IR wavelengths across the peak of the dust emission. Combined with a better spatial resolution, AKARI can much more precisely measure the total IR luminosity (L_TIR) of individual galaxies, and this, the total IR luminosity density of the local Universe. In the AKARI NEP deep field, construct the rest-frame 8um, 12um and total IR (TIR) LFs at 0.15<z<2.2 using 4128 IR sources. A continuous filter coverage in the mid-IR wavelength (2.4,3.2,4.1, 7,9,11,15,18 and 24um) by the AKARI satellite allows an estimate rest frame 8um and 12um luminosities without using a large extrapolation based on a SED fit, which was the largest uncertainty in previous work. By combining these two results, reveal dust-hidden cosmic SFH and AGN evolution from z=0 to 2.2, all probed by the AKARI satellite.
1505.00012
Hyper suprime-camera survey of the AKARI NEP wide field
Goto, AKARI NEP team
The extragalactic background suggests half the energy generated by stars reprocessed into the IR by dust. At z~1.3, 90% of SF is obscured by dust. To fully understand the cosmic SFH, it is critical to investigate IR emission. AKARI has made deep mid-IR observation using its continuous 9-band filters the NEP field (5.4 deg2), using ~10% of the entire pointed observations available through its lifetime. However, there remain 11k AKARI's IR sources undetected with the previous CFHT/Megacam imaging (r~25.9AB mag). Redshift and IR luminosity of these sources are unknown. These sources may contribute significantly to the cosmic SFR density (CSFRD). For example, if they all lie at 1<z<2, the CSFRD will be twice as high at the epoch. Carrying out deep imaging of the NEP field in 5 broad bands (griz and y) using HSC, which has 1.5 deg field of view in diameter on Subaru 8m telescope. This will provide photometric z information, and thereby IR luminosity for the previously-undetected 11k faint AKARI IR sources. Combined with AKARI's mid-IR AGN/SF diagnosis, and accurate mid-IR luminosity measurement, this will allow a complete census of cosmic SF/AGN accretion history obscured by dust.
1505.00016
Binary frequencies in globular clusters
Ji, Bregman
Binary stars are predicted to have Dani important role in the evolution of globular clusters, obtained binary fractions for 35 globular clusters that were imaged in F606W and F814W with the ACS on the HST. When compared to the values of prior efforts, find significant discrepancies, despite each group correcting for contamination effects and having performed the appropriate reliability tests. The most reliable binary fractions are obtained when restricting the binary fraction to q>0.5. Analysis indicates that the range of the binary fractions is nearly an order of magnitude for the lowest dynamical ages, suggesting that there is a broad distribution in the binary fraction at globular cluster formation. Dynamical effects also appears to decrease the core binary fractions by a factor of two over a Hubble time, but this is a weak relationship. Confirm a correlation from previous work that the binary fraction within the core radius decreases with cluster age, indicating that younger clusters formed with higher binary fractions. The stronger radial gradient in the binary fraction with cluster radius appears to be a consequence of dynamical interactions. It is often not present in dynamically young clusters but nearly always present in dynamically old clusters.
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