92 research outputs found
Superwind-Driven Intense H_2 Emission in NGC 6240
We have performed a long-slit K band spectroscopic observation of the
luminous infrared galaxy NGC 6240. The peak position of the H_2 v=1-0 S(1)
emission in the slit is located ~0.3" - 0.4" north of the southern nucleus. It
is almost the midpoint between the southern nucleus and the peak position of
the ^12CO J=1-0 emission. Based on the line-ratio analyses, we suggest the
excitation mechanism of H_2 is pure thermal at most positions. In the southern
region we find the following three velocity components in the H_2 emission: the
blueshifted shell component (~-250 km s^-1 with respect to V_sys) which is
recognized as a distinct C-shape distortion in the velocity field around the
southern nucleus, the high-velocity blueshifted ``wing'' component (~-1000 km
s^-1 with respect to V_sys), and the component indicating possible line
splitting of ~500 km s^-1. The latter two components are extended to the south
from the southern nucleus. We show that the kinematic properties of these three
components can be reproduced by expanding motion of a shell-like structure
around the southern nucleus. The offset peak position of the H_2 emission can
be understood if we assume that the shell expanding to the north interacts with
the extragalactic molecular gas. At the interface between the shell and the
molecular gas concentration the cloud-crushing mechanism proposed by Cowie et
al. (1981) may work efficiently, and the intense H_2 emission is thus expected
there. All these findings lead us to propose a model that the most H_2 emission
is attributed to the shock excitation driven by the superwind activity of the
southern nucleus.Comment: 33 pages, 9 figures, accepted for publication in PAS
Dusty ERO Search behind Two Massive Clusters
We performed deep K'-band imaging observations of 2 massive clusters, MS
0451.6-0305 at z = 0.55 and MS 0440.5+0204 at z = 0.19, for searching
counterparts of the faint sub-mm sources behind these clusters, which would
provide one of the deepest extremely red object(ERO) samples. Comparing our
near-infrared images with optical images taken by the Hubble Space Telescope
and by the Subaru Telescope, we identified 13 EROs in these fields. The sky
distributions of EROs are consistent with the previous results, that there is a
sign of strong clustering among detected EROs. Also, the surface density with
corrected lensing amplification factors in both clusters are in good agreement
with that derived from previous surveys. We found 7 EROs and 3 additional very
red objects in a small area (\sim 0.6 arcmin^2) of the MS 0451.6-0305 field
around an extended SCUBA source. Many of their optical and near-infrared colors
are consistent with dusty star-forming galaxies at high redshifts(z \sim
1.0-4.0), and they may be constituting a cluster of dusty starburst galaxies
and/or lensed star-forming galaxies at high redshift. Their red J-K' colors and
faint optical magnitudes suggest they are relatively old massive stellar
systems with ages(>300 Mega years) suffering from dust obscuration. We also
found a surface-density enhancement of EROs around the SCUBA source in the MS
0440.5+0204 field.Comment: 19 pages, 11 figures, Latex(using pasj00.cls). To be published in
PASJ vol 55, No. 4(Aug 2003
A Shock-Induced Pair of Superbubbles in the High-Redshift Powerful Radio Galaxy MRC 0406-244
We present new optical spectroscopy of the high-redshift powerful radio
galaxy MRC 0406244 at redshift of 2.429. We find that the two extensions
toward NW and SE probed in the rest-frame ultraviolet image are heated mainly
by the nonthermal continuum of the active galactic nucleus. However, each
extension shows a shell-like morphology, suggesting that they are a pair of
superbubbles induced by the superwind activity rather than by the interaction
between the radio jet and the ambient gas clouds. If this is the case, the
intense starburst responsible for the formation of superbubbles could occur
yr ago. On the other hand, the age of the radio jets may
be of the order of yr, being much shorter than the starburst age.
Therefore, the two events, i.e., the starburst and the radio-jet activities,
are independent phenomena. However, their directions of the expanding motions
could be governed by the rotational motion of the gaseous component in the host
galaxy. This idea appears to explain the alignment effect of MRC 0406244.Comment: 4 pages (emulateapj.sty), Fig. 1 (jpeg) + Fig.2 (eps). Accepted for
publications in ApJ (Letters
Decomposition of the Superwind in M82
We present new optical images (, , and H) of the archetypical
starburst/superwind galaxy M82 obtained with the 8.2 m Subaru Telescope to
reveal new detailed structures of the superwind-driven nebula and the
high-latitude dark lanes. The emission-line nebula is decomposed into (1) a
ridge-dominated component comprising numerous filament/loop sub-structures
whose overall morphology appears as a pair of narrow cylinders, and (2) a
diffuse component extended over much wider opening angle from the nucleus. We
suggest that these two components have different origins. The ridge-dominated
component appears as a pair of cylinders rather than a pair of cones. Since
this morphological property is similar to that of hot plasma probed by soft
X-ray, this component seems to surround the hot plasma. On the other hand, the
diffuse component may arise from dust grains which scatter stellar light from
the galaxy. Since inner region of this component is seen over the prominent ^^
^^ X"-shaped dark lanes streaming out from the nuclear region and they can be
reproduced as a conical distribution of dust grains, there seems to be a dusty
cold outflow as well as the hot one probed by soft X-ray and shock-excited
optical emission lines. If this is the case, the presence of such high-latitude
dust grains implies that neutral gaseous matter is also blown out during the
course of the superwind activity.Comment: 12 pages, 6 figures. Accepted for publication in PAS
Electronic structure and correlation in β−Ti3O5 and λ−Ti3O5 studied by hard x-ray photoelectron spectroscopy
We have conducted hard x-ray photoelectron spectroscopy investigations of the electronic structure changes and electron correlation phenomena which take place upon the photoinduced reversible phase transition between β- and λ−Ti3O. From valence band spectra of β- and λ−Ti3O5, we have identified the bipolaron caused by the σ-type bonding of dxy orbitals in β−Ti3O5 and the π stacking between the dxy orbitals between different Ti sites in λ−Ti3O5, previously predicted by ab initio calculations. This indicates that the single electron band picture is valid for the description of photoinduced phase transitions. On the other hand, the Ti 2p and Ti 1s core level spectra exhibit nonlocal screening satellite features, which are typical spectroscopic signs of strong electron correlation in the coherent Tit2g states. The most striking result we obtain is that correlation in the valence band also manifests to reduce the plasmon energy, which results in an enhancement of the valence electron mass by a factor of 2.7
Radiological study on Garré osteomyelitis of the mandible in a child
We report a case of Garré osteomyelitis of the mandible involving a child. The patient was a 12–year–old girl with symptoms of swelling and pain of the left face. She presented to our hospital with asymmetrical swelling and tenderness and redness from the left cheek to the lower jaw, and tenderness of the left submandibular lymph nodes. Panoramic radiography revealed a well–demarcated radiolucent lesion that continued to the periodontal space of the second molar of the left mandible and was surrounded by a diffuse osteosclerotic area. In addition, cone beam CT images showed an onion peel–like periosteal reaction on the buccal side of the left mandible near this radiolucent lesion. A diagnosis of cellulitis of the left cheek and Garré osteomyelitis of the mandible was determined based on clinical and imaging findings. A cephem antibiotic (D.I.V.) and oral antibacterial drugs were started to improve inflammation. The symptoms promptly improved on the 4th day after the starr of treatment. It was reported that conservative therapy is appropriate treatment to repair tissues from the viewpoint of jaw development as well as the process of tooth formation in children. An early diagnosis based on specific findings like an onion peel appearance on imaging is required for effective treatment of osteomyelitis of the mandible in childhood
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