116 research outputs found
AKARI Far-Infrared Source Counts in the Lockman Hole
We report initial results of far-infrared observations of the Lockman hole
with Far-Infrared Surveyor (FIS) onboard the AKARI infrared satellite. On the
basis of slow scan observations of a 0.6 deg x 1.2 deg contiguous area, we
obtained source number counts at 65, 90 and 140 um down to 77, 26 and 194 mJy
(3 sigma), respectively. The counts at 65 and 140 um show good agreement with
the Spitzer results. However, our 90 um counts are clearly lower than the
predicted counts by recent evolutionary models that fit the Spitzer counts in
all the MIPS bands. Our 90 um counts above 26 mJy account for about 7% of the
cosmic background. These results provide strong constraints on the evolutionary
scenario and suggest that the current models may require modifications.Comment: 25 pages, 8 figures, Publications of the Astronomical Society of
Japan, in pres
Detection of CFIRB with AKARI/FIS Deep Observations
The Cosmic Far-Infrared Background (CFIRB) contains information about the
number and distribution of contributing sources and thus gives us an important
key to understand the evolution of galaxies. Using a confusion study to set a
fundamental limit to the observations, we investigate the potential to explore
the CFIRB with AKARI/FIS deep observations. The Far-Infrared Surveyor (FIS) is
one of the focal-plane instruments on the AKARI (formerly known as ASTRO-F)
satellite, which was launched in early 2006. Based upon source distribution
models assuming three different cosmological evolutionary scenarios (no
evolution, weak evolution, and strong evolution), an extensive model for
diffuse emission from infrared cirrus, and instrumental noise estimates, we
present a comprehensive analysis for the determination of the confusion levels
for deep far-infrared observations. We use our derived sensitivities to suggest
the best observational strategy for the AKARI/FIS mission to detect the CFIRB
fluctuations. If the source distribution follows the evolutionary models,
observations will be mostly limited by source confusion. We find that we will
be able to detect the CFIRB fluctuations and that these will in turn provide
information to discriminate between the evolutionary scenarios of galaxies in
most low-to-medium cirrus regions.Comment: 12 pages, 5 figures, uses elsart.cls, Accepted for publication in
Advances in Space Research, 36th COSPAR Scientific Assembly Beijing, China,
16 ~ 23 July 200
ASTRO-F/FIS Observing Simulation: Detection Limits for Point Sources
We describe the observing simulation software FISVI (FIS Virtual Instrument),
which was developed for the Far-Infrared Surveyor (FIS) that will be on the
Japanese infrared astronomy mission ASTRO-F. The FISVI has two purposes: one is
to check the specifications and performances of the ASTRO-F/FIS as a whole; the
other is to prepare input data sets for the data analysis softwares prior to
launch. In the FISVI, special care was taken by introducing the "Compiled PSF
(Point Spread Function)" to optimise inevitable, but time-consuming,
convolution processes. With the Compiled PSF, we reduce the computation time by
an order of magnitude. The photon and readout noises are included in the
simulations. We estimate the detection limits for point sources from the
simulation of virtual patches of the sky mostly consisting of distant galaxies.
We studied the importance of source confusion for simple power-law models for
N(>S), the number of sources brighter than S. We found that source confusion
plays a dominant role in the detection limits only for models with rapid
luminosity evolution for the galaxy counts, the evolution of which is suggested
by recent observations.Comment: 27 pages, 35 postscript figures, LaTex, gzipped tar file, accepted
for publication in PASJ (High resolution version is available from
http://astro.snu.ac.kr/~jeongws/preprints/fisvi_pasj.pdf), some changes;
added figures, revised tex
Myotonic Dystrophy Type 1 Presenting as Male Infertility
Myotonic dystrophy 1 (DM1) is a multi-system disorder characterized by endocrine defects that include testicular and tubular atrophy, oligospermia and azoospermia, and increased follicle-stimulating hormone levels. We describe a rare case of DM1 presenting as infertility in a 29-year-old man
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