7 research outputs found
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
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
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