135 research outputs found
Infrared Imaging of the Gravitational Lens PG 1115+080 with the Subaru Telescope
We present high spatial resolution images of the gravitational-lens system PG
1115+080 taken with the near-infrared camera (CISCO) on the Subaru telescope.
The FWHM of the combined image is in the -band, yielding spatial
resolution of after a deconvolution procedure. This is a first
detection of an extended emission adjacent to the A1/A2 components, indicating
the presence of a fairly bright emission region with a characteristic angular
radius of 5 mas (40 pc). The near-infrared image of the Einstein ring
was extracted in both the and bands. The color is found to be
significantly redder than that of a synthetic model galaxy with an age of 3
Gyr, the age of the universe at the quasar redshift.Comment: 11 pages, 6 figures. Accepted for publication in PASJ(2000
[OII]3727 Emission from the Companion to the Quasar BR 1202-0725 at z=4.7
Results of a narrow-band imaging for the redshifted [OII]3727 emission around
a quasar at z=4.7 obtained with the Subaru telescope and CISCO (a Cassegrain
near infrared camera) are presented. A significant emission line is detected in
the narrow-band H_2 (v=1-0 S(1)) filter at a location 2.4" northwest from the
quasar, where the presence of a companion has been reported in Lyman alpha
emission and the rest-frame UV continuum. We identify this line as [OII]3727
emission and confirm that the source really is a companion at z=4.7. The
[OII]3727 flux from the companion is estimated to be 2.5 x 10^{-17} erg s^{-1}
cm^{-2}. If the companion is a star forming object, the inferred star formation
rate is as high as 45-230 M_{solar} yr^{-1} even without assuming the
extinction correction. This value is higher than those derived from the Lyman
alpha emission or from the UV continuum. Thus, provided that the difference is
caused by dust extinction, the extinction corrected star formation rate is
calculated to be 45 to 2300 M_{solar} yr^{-1} depending on the assuming
extinction curves.Comment: 15 pages including 3 figures. Accepted for publication in PAS
Implications from the optical to UV flux ratio of FeII emission in quasars
We investigate FeII emission in Broad Line Region (BLR) of AGNs by analyzing
the FeII(UV), FeII(4570) and MgII emission lines in 884 quasars in the Sloan
Digital Sky Survey (SDSS) Quasar catalog in a redshift range of 0.727 < z <
0.804. FeII(4570)/FeII(UV) is used to infer the column density of FeII-emitting
clouds and explore the excitation mechanism of FeII emission lines. As
suggested before in various works, the classical photoionization models fail to
account for FeII(4570)/FeII(UV) by a factor of 10, which may suggest anisotropy
of UV FeII emission; otherwise, an alternative heating mechanism like shock is
working. The column density distribution derived from FeII(4570)/FeII(UV)
indicates that radiation pressure plays an important role in BLR gas dynamics.
We find a positive correlation between FeII(4570)/FeII(UV) and the Eddington
ratio. We also find that almost all FeII-emitting clouds are to be under
super-Eddington conditions unless ionizing photon fraction is much smaller than
that previously suggested. Finally we propose a physical interpretation of a
striking set of correlations between various emission-line properties, known as
``Eigenvector 1''.Comment: 10 pages, 10 figures, accepted for publication in MNRA
CISCO: Cooled Infrared Spectrograph and Camera for OHS on the Subaru Telescope
This paper describes a Cooled Infrared Spectrograph and Camera for OHS
(CISCO), mounted on the Nasmyth focus of the Subaru telescope. It is primarily
designed as a back-end camera of the OH-Airglow Suppressor (OHS), and is also
used as an independent, general-purpose near-infrared camera/spectrograph.
CISCO is based on a single 1024x1024 format HgCdTe HAWAII array detector, and
is capable of either wide-field imaging of 1.8'x1.8' field-of-view or
low-resolution spectroscopy from 0.9 to 2.4 um. The limiting magnitudes
measured during test observations were found to be J=23.5mag and K'=22.4mag
(imaging, 1" aperture, S/N=5, 1 hr exposure).Comment: 14 pages, 15 figures, accepted by PASJ. Figures with higher
resolution are available at
http://www.ioa.s.u-tokyo.ac.jp/~kmotohara/CISCO/ciscopap.tar.g
Signature of Electron Capture in Iron-Rich Ejecta of SN 2003du
Late-time near-infrared and optical spectra are presented for the
normal-bright SN2003du. At about 300 days after the explosion, the emission
profiles of well isolated [FeII] lines (in particular that of the strong
1.644mu feature) trace out the global kinematic distribution of radioactive
material in the expanding. In SN2003du, the 1.644 mu [FeII] line shows a
flat-topped, profile, indicative of a thick but hollow-centered expanding
shell, rather than a strongly-peaked profile that would be expected from a
``center-filled'' distribution.Based on detailed models for exploding
Chandrasekhar mass white dwarfs, we show that the feature is consistent with
spherical explosion models.Our model predicts central region of non-radioactive
electron-capture elements up to 2500--3000km/s as a consequence of burning
under high density, and an extended region of 56Ni up to 9,000--10,000km/s.
Furthermore our analysis indicates that the 1.644mu [FeII] profile is not
consistent with strong mixing between the regions of electron- capture isotopes
and the 56Ni layers as is predicted by detailed 3D models for nuclear
deflagration fronts. We discuss the possibility that the flat-topped profile
could be produced as a result of an infrared catastrophe and conclude that such
an explanation is unlikely. We put our results in context to other SNeIa and
briefly discuss the implications of our result for the use of SNe Ia as
cosmological standard candles.Comment: 12 pages + 8 figures, ApJ (in press, Dec. 20, 2004) For high
resolution figures send E-mail to [email protected]
Infrared Star Count Models and Their Application to the Subaru Deep Field
We construct infrared star count models of the Galaxy applicable at faint
magnitudes. In addition to dwarfs and subdwarfs, we also take into account L
dwarfs, T dwarfs, and white dwarfs of both disk and halo. As a test case of the
models, we analyze the infrared imaging data at J and K' obtained during the
Subaru Deep Field Survey to study stellar objects. Infrared star count models
we have obtained predict that the Next Generation Space Telescope will
primarily see T dwarfs, M subdwarfs, and old halo white dwarfs at faint
magnitudes.Comment: 20 pages, 3 figures. To be published in the November 2000 issue of
the Astronomical Journa
Herschel/PACS far-infrared photometry of two z>4 quasars
We present Herschel far-infrared (FIR) observations of two sub-mm bright
quasars at high redshift: SDSS J1148+5251 (z=6.42) and BR 1202-0725 (z=4.69)
obtained with the PACS instrument. Both objects are detected in the PACS
photometric bands. The Herschel measurements provide additional data points
that constrain the FIR spectral energy distributions (SEDs) of both sources,
and they emphasise a broad range of dust temperatures in these objects. For
lambda_rest ~< 20mu, the two SEDs are very similar to the average SEDs of
quasars at low redshift. In the FIR, however, both quasars show excess emission
compared to low-z QSO templates, most likely from cold dust powered by vigorous
star formation in the QSO host galaxies. For SDSS J1148+5251 we detect another
object at 160mu with a distance of ~10 arcseconds from the QSO. Although no
physical connection between the quasar and this object can be shown with the
available data, it could potentially confuse low-resolution measurements, thus
resulting in an overestimate of the FIR luminosity of the z=6.42 quasar.Comment: 4 pages, 3 figures, accepted for publication in the A&A special issue
on Hersche
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