447 research outputs found
Identifications and SEDs of the detected sources from the AKARI Deep Field South
In order to find counterparts of the detected objects in the AKARI Deep Field
South (ADFS) in all available wavelengths, we searched public databases (NED,
SIMBAD and others). Checking 500 sources brighter than 0.0482 Jy in the AKARI
Wide-S band, we found 114 sources with possible counterparts, among which 78
were known galaxies. We present these sources as well as our first attempt to
construct spectral energy distributions (SEDs) for the most secure and most
interesting sources among them, taking into account all the known data together
with the AKARI measurements in four bands.Comment: 4 pages, 10 figures, To appear in: the proceedings of the conference
"AKARI, a light to illuminate the misty Universe", February 16-19 2009, Toky
Infrared Spectroscopy of CO Ro-vibrational Absorption Lines toward the Obscured AGN IRAS 08572+3915
We present high-resolution spectroscopy of gaseous CO absorption in the
fundamental ro-vibrational band toward the heavily obscured active galactic
nucleus (AGN) IRAS 08572+3915. We have detected absorption lines up to highly
excited rotational levels (J<=17). The velocity profiles reveal three distinct
components, the strongest and broadest (delta_v > 200 km s-1) of which is due
to blueshifted (-160 km s-1) gas at a temperature of ~ 270 K absorbing at
velocities as high as -400 km s-1. A much weaker but even warmer (~ 700 K)
component, which is highly redshifted (+100 km s-1), is also detected, in
addition to a cold (~ 20 K) component centered at the systemic velocity of the
galaxy. On the assumption of local thermodynamic equilibrium, the column
density of CO in the 270 K component is NCO ~ 4.5 x 10^18 cm-2, which in fully
molecular gas corresponds to a H2 column density of NH2 ~ 2.5 x 10^22 cm-2. The
thermal excitation of CO up to the observed high rotational levels requires a
density greater than nc(H2) > 2 x 10^7 cm-3, implying that the thickness of the
warm absorbing layer is extremely small (delta_d < 4 x 10-2 pc) even if it is
highly clumped. The large column densities and high radial velocities
associated with these warm components, as well as their temperatures, indicate
that they originate in molecular clouds near the central engine of the AGN.Comment: 13 pages, 7 figures, accepted for publication in PASJ (Vol.65 No.1
2013/02/25
Monolithic Ge:Ga Detector Development for SAFARI
We describe the current status and the prospect for the development of
monolithic Ge:Ga array detector for SAFARI. Our goal is to develop a 64x64
array for the 45 -- 110 um band, on the basis of existing technologies to make
3x20 monolithic arrays for the AKARI satellite. For the AKARI detector we have
achieved a responsivity of 10 A/W and a read-out noise limited NEP (noise
equivalent power) of 10^-17 W/rHz. We plan to develop the detector for SAFARI
with technical improvements; significantly reduced read-out noise with newly
developed cold read-out electronics, mitigated spectral fringes as well as
optical cross-talks with a multi-layer antireflection coat. Since most of the
elemental technologies to fabricate the detector are flight-proven, high
technical readiness levels (TRLs) should be achieved for fabricating the
detector with the above mentioned technical demonstrations. We demonstrate some
of these elemental technologies showing results of measurements for test
coatings and prototype arrays.Comment: To appear in Proc. Workshop "The Space Infrared Telescope for
Cosmology & Astrophysics: Revealing the Origins of Planets and Galaxies".
Eds. A.M. Heras, B. Swinyard, K. Isaak, and J.R. Goicoeche
Finite spin-glass transition of the XY model in three dimensions
A three-dimensional XY spin-glass model is investigated by a
nonequilibrium relaxation method. We have introduced a new criterion for the
finite-time scaling analysis. A transition temperature is obtained by a
crossing point of obtained data. The scaling analysis on the relaxation
functions of the spin-glass susceptibility and the chiral-glass susceptibility
shows that both transitions occur simultaneously. The result is checked by
relaxation functions of the Binder parameters and the glass correlation lengths
of the spin and the chirality. Every result is consistent if we consider that
the transition is driven by the spin degrees of freedom.Comment: 11 pages, 8 figures, incorrect arguments are delete
Density Matrix Renormalization Group Study of the Disorder Line in the Quantum ANNNI Model
We apply Density Matrix Renormalization Group methods to study the phase
diagram of the quantum ANNNI model in the region of low frustration where the
ferromagnetic coupling is larger than the next-nearest-neighbor
antiferromagnetic one. By Finite Size Scaling on lattices with up to 80 sites
we locate precisely the transition line from the ferromagnetic phase to a
paramagnetic phase without spatial modulation. We then measure and analyze the
spin-spin correlation function in order to determine the disorder transition
line where a modulation appears. We give strong numerical support to the
conjecture that the Peschel-Emery one-dimensional line actually coincides with
the disorder line. We also show that the critical exponent governing the
vanishing of the modulation parameter at the disorder transition is .Comment: 4 pages, 5 eps figure
AKARI Detections of Hot Dust in Luminous Infrared Galaxies
We present a new sample of active galactic nuclei (AGNs) identified using the
catalog of the AKARI Mid-infrared(MIR) All-Sky Survey. Our MIR search has an
advantage in detecting AGNs that are obscured at optical wavelengths due to
extinction. We first selected AKARI 9micron excess sources with
F(9micron)/F(K_S)>2 where K_S magnitudes were taken from the Two Micron All Sky
Survey. We then obtained follow-up near-infrared spectroscopy with the
AKARI/IRC, to confirm that the excess is caused by hot dust. We also obtained
optical spectroscopy with the Kast Double Spectrograph on the Shane 3-m
telescope at Lick Observatory. On the basis of on these observations, we
detected hot dust with a characteristic temperature of ~500K in two luminous
infrared galaxies. The hot dust is suspected to be associated with AGNs that
exhibit their nonstellar activity not in the optical, but in the near- and
mid-infrared bands, i.e., they harbor buried AGNs. The host galaxy stellar
masses of 4-6 x 10^9 M_sun are small compared with the hosts in
optically-selected AGN populations. These objects were missed by previous
surveys, demonstrating the power of the AKARI MIR All-Sky Survey to widen AGN
searches to include more heavily obscured objects. The existence of multiple
dusty star clusters with massive stars cannot be completely ruled out with our
current data.Comment: 15 pages, 4 figures, to be published in Astronomy & Astrophysic
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