3,312 research outputs found
Deep WFPC2 and Ground-based Imaging of a Complete Sample of 3C Quasars and Galaxies
We present the results of an HST and ground-based imaging study of a complete
3C sample of z ~ 1 sources, including 5 quasars and 5 radio galaxies. We have
resolved continuum structure around all of our quasars in the WFPC2 images and
in four of the five ground-based K' images. All of the quasars have some
optical continuum structure that is aligned with the radio axis. In 3 of these
cases, some of this optical structure is most likely due to optical synchrotron
radiation, including optical counterparts to two radio jets and one radio lobe.
Two quasars have aligned continuum and emission-line structures that are
probably not due to beamed optical synchrotron emission. In another quasar, we
see a red aligned object that lies 3 arcsec beyond the radio lobe, and may be
an unassociated foreground galaxy, but has a remarkable morphological
resemblance to the radio lobe itself. The radio galaxies and the quasars in
this small sample have similar incidence of alignment, and the optical and K'
flux densities are consistent within the high dispersion. The average quasar
host galaxy luminosity is equivalent to, or a little fainter than, L*. All
components around the quasars have optical-infrared colors that are redder than
or similar to the colors of their respective nuclei; this is generally more
consistent with a stellar rather than scattered origin for the emission. This
study provides qualitative support for the unification of FRII quasars and
galaxies.Comment: 69 pages, LaTeX (aaspp4.sty); 10 tables (aj_pt4.sty); 22 figures;
accepted to A.J., August 199
The story of a small trout fishery
This article relates the experience of creating and developing a fishery in southern England. The fishery was made from a small stream which dries up from time to time, and marks the boundary between a Sussex farm and a large coniferous forest. The preparation of the site and creation of the impoundment are described, and early experiences outlined. The fishery was expanded in later years, as a result of its popularity, and records of its use by anglers are illustrated. The performance of the fishery is measured in terms of "good fish" (more than 675 g) taken, and their number has increased from 81 in 1984 to 226 in 1991. The aquatic plants, invertebrates, and birds of the fishery are discussed, as are the natural predators of the fish
Deep Spectroscopy in the Field of 3C 212
We present the results of longslit and multiaperture spectroscopy of faint
galaxies in the field of the z=1.049 quasar 3C212. We show that an apparently
aligned optical feature beyond the NW radio lobe has a redshift z=0.928, and a
similarly aligned feature just beyond the SE radio lobe has a redshift z=1.053,
quite close to that of the quasar. While the NW optical component is extremely
well aligned with the radio jet and has a morphology that is very similar to
that of the radio lobe lying 3" interior to it, the fact that we find three
other field galaxies with closely similar redshifts indicates that it is most
likely a member of an intervening group rather than an unusual example of true
alignment with the radio structure. In addition, we have found two galaxies
(besides the one near the SE radio lobe) having redshifts close to that of
3C212. We have firm or probable redshifts for 66 out of 82 galaxies we have
observed in this field. Comparison with the redshift distribution of faint
field galaxies indicates that a large fraction of the remaining 16 galaxies are
likely to be at redshifts >1.4. There are at least two low-redshift dwarf
starburst galaxies showing low metal abundance and high ionization in our
sample; such galaxies are likely to be relatively common in very faint samples,
and, under certain conditions, they could be confused with high-redshift
objects.Comment: 15 pages, 4 figures, one of which is a separate JPEG plate. To be
published in the April 1998 issue of The Astronomical Journa
A Comparative Study of Giving and Volunteering Patterns Among Adults with Seventh-day Adventist and Other Christian Religious Identities
Problem. In an environment that challenges the non-profit sector, including church-based organizations, to do more with less, it is important to understand the mechanisms that build and sustain two key resources-individual giving and volunteering. Research indicates that there is a great deal of variation in the extent to which individuals provide help. An integrative theoretical model is utilized to examine and compare the giving and volunteering behaviors, socialization, attitudes, reasons, and motivations of adults with Seventh-day Adventist and other Christian religious identities, with secondary consideration given to the effect of potential ethnic variations.
Method. The sample (N = 1359) for this study was selected for the purpose of comparing Seventh-day Adventist adults with those of other Christian religious identities (controlled for church membership and attendance). The survey instrument utilized was the Study of Giving and Volunteering obtained from the Independent Sector. Chi-square, t tests, and analysis of variance were performed to investigate the relationships between a wide range of attitudinal, motivational, behavioral, and diversity variables and giving and volunteering behaviors.
Results. Seventh-day Adventist adults (SDA) were found to be more likely to give and volunteer, and to give more extensively than those of other Christian religious identities (CRI). SDA giving rates were less labile in response to most variables than the CRI rates. While there were many small, significant differences between the SDA and CRI groups, most were small enough to be relatively unimportant. There is a strong relationship between asking people to help and their helping across all groups. The SDA group appeared to be exposed slightly more to various socialization experiences. Findings for this study, consistent with those from other studies, indicate that the most important differences between racial and ethnic identity and giving and volunteering are related to education and income.
Conclusions. Findings from this explorative and comparative study support the theoretical assertions of selected portions of the integrative model of helping utilized (kinship, socialization, and cultural ethnic factors). Based on the support of the theory, best practices are suggested related to bonding, empathizing, value development and transmission, practice of caring and personal responsibility, diversifying, conflict resolution, networking, and globalization
Avondale
A copy of a brochure detailing Avondale history and real estate options. Likely from the 1920\u27
High-Resolution K' Imaging of the z = 1.786 Radio Galaxy 3C 294
We have obtained imaging in the K' band (~I-band rest frame) of the z=1.786
radio galaxy 3C 294 with the 36-element curvature-sensing adaptive optics
system Hokupa`a and the Canada-France-Hawaii Telescope. At a resolution of <
\~0."15, the galaxy is seen as a group of small but resolved knots distributed
over a roughly triangular region ~1."4 across. The interpretation of the
structure depends on the location of the nucleus, as indicated by the compact
radio core. Its position is uncertain by > ~0."5 (2-sigma) because of
uncertainties in the optical astrometry, but our best estimate places it at or
near the southern apex of the distribution. If this location is correct, the
most likely interpretation is that of a hidden quasar nucleus illuminating
dusty infalling dwarf-galaxy-like clumps having characteristic sizes of ~1.5
kpc.Comment: 8 pages. One figure in gif format. Postscript version including fig.
(240 kb) available at http://www.ifa.hawaii.edu/~canaguby/preprints.html To
appear in ApJ. Letter
The Nature of Optical Features in the Inner Region of the 3C48 Host Galaxy
The well-known quasar 3C48 is the most powerful compact steep-spectrum
radio-loud QSO at low redshifts. It also has two unusual optical features
within the radius of the radio jet (~1"): (1) an anomalous, high-velocity
narrow-line component, having several times as much flux as does the
narrow-line component coinciding with the broad-line redshift; and (2) a bright
continuum peak (3C48A) ~1" northeast of the quasar. Both of these optical
features have been conjectured to be related to the radio jet. Here we explore
these suggestions. We have obtained Gemini North GMOS integral-field-unit (IFU)
spectroscopy of the central region around 3C48. We use the unique features of
the IFU data to remove unresolved emission at the position of the quasar. The
resolved emission at the wavelength of the high-velocity component is peaked
<~0.25" north of the quasar, at virtually the same position angle as the base
of the radio jet. These observations appear to confirm that this high-velocity
gas is connected with the radio jet. However, most of the emission comes from a
region where the jet is still well collimated, rather than from the regions
where the radio maps indicate strong interaction with an external medium. We
also present the results of HST STIS spectroscopy of 3C48A. We show that 3C48A
is dominated by stars with a luminosity-weighted age of ~1.4 X 10^8 years,
substantially older than any reasonable estimate for the age of the radio
source. Our IFU data indicate a similar age. Thus, 3C48A almost certainly
cannot be attributed to jet-induced star formation. The host galaxy of 3C48 is
clearly the result of a merger, and 3C48A seems much more likely to be the
distorted nucleus of the merging partner, in which star formation was induced
during the previous close passage.Comment: 10 pages, accepted by The Astrophysical Journa
Extremely Red Objects in Two Quasar Fields at z ~ 1.5
We present an investigation of the properties and environments of bright
extremely red objects (EROs) found in the fields of the quasars TXS 0145+386
and 4C 15.55, both at z ~ 1.4. There is marginal evidence from Chandra ACIS
imaging for hot cluster gas with a luminosity of a few 10^44 ergs/s in the
field of 4C 15.55. The TXS 0145+386 field has an upper limit at a similar
value, but it also clearly shows an overdensity of faint galaxies. None of the
EROs are detected as X-ray sources. For two of the EROs that have
spectral-energy distributions and rest-frame near-UV spectra that show that
they are strongly dominated by old stellar populations, we determine
radial-surface-brightness profiles from adaptive-optics images. Both of these
galaxies are best fit by profiles close to exponentials, plus a compact nucleus
comprising ~30% of the total light in one case and 8% in the other. Neither is
well fit by an r^1/4-law profile. This apparent evidence for the formation of
massive ~2 X 10^11 disks of old stars in the early universe indicates that at
least some galaxies formed essentially monolithically, with high star-formation
rates sustained over a few 10^8 years, and without the aid of major mergers.Comment: 25 pages, 13 figures, accepted to Ap
- …