2,438 research outputs found
The Las Campanas Infra-red Survey. V. Keck Spectroscopy of a large sample of Extremely Red Objects
(Abridged) We present deep Keck spectroscopy, using the DEIMOS and LRIS
spectrographs, of a large and representative sample of 67 ``Extremely Red
Objects'' (EROs) to H=20.5, with I-H>3.0, in three of the Las Campanas Infrared
Survey fields. Spectroscopic redshifts are determined for 44 sources, of which
only two are contaminating low mass stars. When allowance is made for
incompleteness, the spectroscopic redshift distribution closely matches that
predicted earlier on the basis of photometric data. Our spectra are of
sufficient quality that we can address the important question of the nature and
homogeneity of the z>0.8 ERO population. A dominant old stellar population is
inferred for 75% of our spectroscopic sample; a higher fraction than that seen
in smaller, less-complete samples with broader photometric selection criteria
(e.g. R-K). However, only 28% have spectra with no evidence of recent star
formation activity, such as would be expected for a strictly passively-evolving
population. More than ~30% of our absorption line spectra are of the `E+A' type
with prominent Balmer absorption consistent, on average, with mass growth of
5-15% in the past Gyr. We use our spectroscopic redshifts to improve earlier
estimates of the spatial clustering of this population as well as to understand
the significant field-to-field variation. Our spectroscopy enables us to
pinpoint a filamentary structure at z=1.22 in the Chandra Deep Field South.
Overall, our study suggests that the bulk of the ERO population is an
established population of clustered massive galaxies undergoing intermittent
activity consistent with continued growth over the redshift interval 0.8<z<1.6.Comment: 27 pages, including 14 figures and appendix of spectra (at low
resolution). Full resolution paper can be found at
http://www.ast.cam.ac.uk/~md . To appear in MNRA
Exploring socio-demographic and urban form indices in demand forecasting models to reflect spatial variations: Case study of childcare centres in hobart, Australia
This study investigated whether indices for socioeconomic, demographic and urban form characteristics can reflect the overall effect of each category in a demand forecasting model. Regression equations were developed for trip generation of the land use of long day care centres (LDCC) in the metropolitan region of Hobart, Australia, to estimate the morning peak hourly private car trip generation of the centres. The independent variables for the model were functions of socioeconomic, demographic and urban form related indices, while the dependent variable was private car trip generation per number of staff or children. Findings show that using indices for socioeconomic, demographic and urban form characteristics enhances overall model performance, while the models based on the commonly used method for estimating trip generation present acceptable results in just some specific sites. The use of socioeconomic, demographic and urban form indices can reflect differences in these characteristics across suburbs when estimating trip generation
Serendipitously Detected Galaxies in the Hubble Deep Field
We present a catalog of 74 galaxies detected serendipitously during a
campaign of spectroscopic observations of the Hubble Deep Field North (HDF) and
its environs. Among the identified objects are five candidate Ly-alpha emitters
at z > 5, a galaxy cluster at z = 0.85, and a Chandra source with a heretofore
undetermined redshift of z = 2.011. We report redshifts for 25 galaxies in the
central HDF, 13 of which had no prior published spectroscopic redshift. Of the
remaining 49 galaxies, 30 are located in the single-orbit HDF Flanking Fields.
We discuss the redshift distribution of the serendipitous sample, which
contains galaxies in the range 0.10 < z < 5.77 with a median redshift of z =
0.85, and we present strong evidence for redshift clustering. By comparing our
spectroscopic redshifts to optical/IR photometric studies of the HDF, we find
that photometric redshifts are in most cases capable of producing reasonable
predictions of galaxy redshifts. Finally, we estimate the line-of-sight
velocity dispersion and the corresponding mass and expected X-ray luminosity of
the galaxy cluster, we present strong arguments for interpreting the Chandra
source as an obscured AGN, and we discuss in detail the spectrum of one of the
candidate z > 5 Ly-alpha emitters.Comment: 18 pages, 9 figures, accepted for publication in the Astronomical
Journa
Mexican Cartel Tactical Note No. 12: Forensics of Recovered Weapons from Piedras Negras Tactical Engagement Between Los Zetas and GATE (Grupo de Armas y Tácticas Especiales)
Mexican Cartel Tactical Note No. 4: Cartel Military Weapons Cache Discovered Near Fronton, Texas.
Mexican Cartel Tactical Note No. 15: IED Recovered from Trunk of Car by Police Station in Ciudad Victoria, Tamaulipas
Mexican Cartel Tactical Note No. 10: Claymore Anti-Personnel Mine (and Other Military Hardware) Recovered in Zacatecas
Hydrogeology and stratigraphy of the Dakota formation in Northwest Iowa
https://ir.uiowa.edu/igs_wsb/1012/thumbnail.jp
Potential energy and dipole moment surfaces of H3- molecule
A new potential energy surface for the electronic ground state of the
simplest triatomic anion H3- is determined for a large number of geometries.
Its accuracy is improved at short and large distances compared to previous
studies. The permanent dipole moment surface of the state is also computed for
the first time. Nine vibrational levels of H3- and fourteen levels of D3- are
obtained, bound by at most ~70 cm^{-1} and ~ 126 cm^{-1} respectively. These
results should guide the spectroscopic search of the H3- ion in cold gases
(below 100K) of molecular hydrogen in the presence of H3- ions
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