957 research outputs found
Self-assembly and charge transport properties of a benzobisthiazole end-capped with dihexylthienothiophene units
The synthesis of a new conjugated material is reported; BDHTT–BBT features a central electron-deficient benzobisthiazole capped with two 3,6-dihexyl-thieno[3,2-b]thiophenes. Cyclic voltammetry was used to determine the HOMO (−5.7 eV) and LUMO (−2.9 eV) levels. The solid-state properties of the compound were investigated by X-ray diffraction on single-crystal and thin-film samples. OFETs were constructed with vacuum deposited films of BDHTT–BBT. The films displayed phase transitions over a range of temperatures and the morphology of the films affected the charge transport properties of the films. The maximum hole mobility observed from bottom-contact, top-gate devices was 3 × 10−3 cm2 V−1 s−1, with an on/off ratio of 104–105 and a threshold voltage of −42 V. The morphological and self-assembly characteristics versus electronic properties are discussed for future improvement of OFET devices
A Catalogue of Morphologically Classified Galaxies from the Sloan Digital Sky Survey: North Equatorial Region
We present a catalogue of morphologically classified bright galaxies in the
north equatorial stripe (230 deg) derived from the Third Data Release of
the Sloan Digital Sky Survey (SDSS). Morphological classification is performed
by visual inspection of images in the band. The catalogue contains 2253
galaxies complete to a magnitude limit of after Galactic extinction
correction, selected from 2658 objects that are judged as extended in the
photometric catalogue in the same magnitude limit. 1866 galaxies in our
catalogue have spectroscopic information. A brief statistical analysis is
presented for the frequency of morphological types and mean colours in the
catalogue. A visual inspection of the images reveals that the rate of
interacting galaxies in the local Universe is approximately 1.5% in the
sample. A verification is made for the photometric catalogue generated
by the SDSS, especially as to its bright end completeness.Comment: Accepted for publication in Astronomical Journal. Table 2 available
at http://www.icrr.u-tokyo.ac.jp/~fukugita/MCGpaper/table2.tx
A new quadruple gravitational lens from the Hyper Suprime-Cam Survey: the puzzle of HSC~J115252+004733
We report the serendipitous discovery of a quadruply lensed source at , HSC~J115252+004733, from the Hyper Suprime-Cam (HSC) Survey. The
source is lensed by an early-type galaxy at and a satellite
galaxy. Here, we investigate the properties of the source by studying its size
and luminosity from the imaging and the luminosity and velocity width of the
Ly- line from the spectrum. Our analyses suggest that the source is
most probably a low-luminosity active galactic nucleus (LLAGN) but the
possibility of it being a compact bright galaxy (e.g., a Lyman- emitter
or Lyman Break Galaxy) cannot be excluded. The brighter pair of lensed images
appears point-like except in the HSC -band (with a seeing ). The
extended emission in the -band image could be due to the host galaxy
underneath the AGN, or alternatively, due to a highly compact lensed galaxy
(without AGN) which appears point-like in all bands except in -band. We also
find that the flux ratio of the brighter pair of images is different in the
Ks-band compared to optical wavelengths. Phenomena such as differential
extinction and intrinsic variability cannot explain this chromatic variation.
While microlensing from stars in the foreground galaxy is less likely to be the
cause, it cannot be ruled out completely. If the galaxy hosts an AGN, then this
represents the highest redshift quadruply imaged AGN known to date, enabling
study of a distant LLAGN. Discovery of this unusually compact and faint source
demonstrates the potential of the HSC survey.Comment: 9 pages, 7 figures, 3 Tables, MNRAS accepted, text reduce
Southern Cosmology Survey I: Optical Cluster Detections and Predictions for the Southern Common-Area Millimeter-Wave Experiments
We present first results from the Southern Cosmology Survey, a new
multiwavelength survey of the southern sky coordinated with the Atacama
Cosmology Telescope (ACT), a recently commissioned ground-based mm-band Cosmic
Microwave Background experiment. This article presents a full analysis of
archival optical multi-band imaging data covering an 8 square degree region
near right ascension 23 hours and declination -55 degrees, obtained by the
Blanco 4-m telescope and Mosaic-II camera in late 2005. We describe the
pipeline we have developed to process this large data volume, obtain accurate
photometric redshifts, and detect optical clusters. Our cluster finding process
uses the combination of a matched spatial filter, photometric redshift
probability distributions and richness estimation. We present photometric
redshifts, richness estimates, luminosities, and masses for 8 new
optically-selected clusters with mass greater than 3\times10^{14}M_{\sun} at
redshifts out to 0.7. We also present estimates for the expected
Sunyaev-Zel'dovich effect (SZE) signal from these clusters as specific
predictions for upcoming observations by ACT, the South Pole Telescope and
Atacama Pathfinder Experiment.Comment: 12 pages, 8 figures, accepted in ApJ. Reflects changes from referee
as well as a new Table providing mass estimates and positions for all
clusters in the surve
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