227 research outputs found
The Politics of Wishful Thinking? Disentangling the Role of the Scholar-Scientist from that of the Public Intellectual in the Modern Academic Study of Religion
Although religion may well have relevance for various social, political, economic, cultural, and other related issues in society, I will argue here that this does not oblige the academic student of religion to become engaged with those matters. Indeed, to do so - not as a citizen but as a member of the academic guild which has responsibility to the field/discipline of Religious Studies and the modern research university at large - is to fuse and therefore confuse advocacy and scholarship. The task of the student of religion, qua scientist, is to seek to understand and to explain religion and religions, not to create the good society. I attempt to show here that with the infiltration of the ideal of the student of religion as public intellectual - whether as religious critic, critic of religion, or member of a new secular clerisy - the scientific agenda of seeking disinterested knowledge about religion and religions has been, and continues to be, eroded if not displaced
A bibliography of physical, chemical, and biological studies of rings in the world's oceans
This bibliography marks the end of several years of sporadic attempts
to put together a set of references on rings. The scope of the effort
encompasses the chemistry, biology, and physics of the long-lived,
coherent features which are commonly referred to as rings after Fuglister
(1972). There is a vast literature on the mesoscale eddy field in
different parts of the world. The present set of references includes a
subset of this body of work. The basic criterion used in the compilation of this bibliography is
fairly narrow compared to the range of eddies found in the world's
oceans. The emphasis here is on the highly nonlinear features formed due
to the instability processes in boundary currents and in the planetary
scale jet which surrounds the Antarctic. The nomenclature "ring", refers
to the strong encircling current which forms a kinematic trap in which
the core of the ring is embedded
BLAST Autonomous Daytime Star Cameras
We have developed two redundant daytime star cameras to provide the fine
pointing solution for the balloon-borne submillimeter telescope, BLAST. The
cameras are capable of providing a reconstructed pointing solution with an
absolute accuracy < 5 arcseconds. They are sensitive to stars down to
magnitudes ~ 9 in daytime float conditions. Each camera combines a 1 megapixel
CCD with a 200 mm f/2 lens to image a 2 degree x 2.5 degree field of the sky.
The instruments are autonomous. An internal computer controls the temperature,
adjusts the focus, and determines a real-time pointing solution at 1 Hz. The
mechanical details and flight performance of these instruments are presented.Comment: 8 pages, 6 figures, 1 table. To be published in conference
proceedings for the "Ground-based and Airborne Instrumentation for Astronomy"
part of the SPIE Astronomical Telescopes and Instrumentation Symposium that
will be held 24-31 May 2006 in Orlando, F
A panchromatic study of BLAST counterparts: total star-formation rate, morphology, AGN fraction and stellar mass
We carry out a multi-wavelength study of individual galaxies detected by the
Balloon-borne Large Aperture Submillimeter Telescope (BLAST) and identified at
other wavelengths, using data spanning the radio to the ultraviolet (UV). We
develop a Monte Carlo method to account for flux boosting, source blending, and
correlations among bands, which we use to derive deboosted far-infrared (FIR)
luminosities for our sample. We estimate total star-formation rates for BLAST
counterparts with z < 0.9 by combining their FIR and UV luminosities. Star
formation is heavily obscured at L_FIR > 10^11 L_sun, z > 0.5, but the
contribution from unobscured starlight cannot be neglected at L_FIR < 10^11
L_sun, z < 0.25. We assess that about 20% of the galaxies in our sample show
indication of a type-1 active galactic nucleus (AGN), but their submillimeter
emission is mainly due to star formation in the host galaxy. We compute stellar
masses for a subset of 92 BLAST counterparts; these are relatively massive
objects, with a median mass of ~10^11 M_sun, which seem to link the 24um and
SCUBA populations, in terms of both stellar mass and star-formation activity.
The bulk of the BLAST counterparts at z<1 appear to be run-of-the-mill
star-forming galaxies, typically spiral in shape, with intermediate stellar
masses and practically constant specific star-formation rates. On the other
hand, the high-z tail of the BLAST counterparts significantly overlaps with the
SCUBA population, in terms of both star-formation rates and stellar masses,
with observed trends of specific star-formation rate that support strong
evolution and downsizing.Comment: Accepted for publication in the Astrophysical Journal. 44 pages, 11
figures. The SED template for the derivation of L_FIR has changed (added new
figure) and the discussion on the stellar masses has been improved. The
complete set of full-color postage-stamps can be found at
http://blastexperiment.info/results_images/moncelsi
BLAST: The Mass Function, Lifetimes, and Properties of Intermediate Mass Cores from a 50 Square Degree Submillimeter Galactic Survey in Vela (l = ~265)
We present first results from an unbiased 50 deg^2 submillimeter Galactic
survey at 250, 350, and 500 micron from the 2006 flight of the Balloon-borne
Large Aperture Submillimeter Telescope (BLAST). The map has resolution ranging
from 36 arcsec to 60 arcsec in the three submillimeter bands spanning the
thermal emission peak of cold starless cores. We determine the temperature,
luminosity, and mass of more than one thousand compact sources in a range of
evolutionary stages and an unbiased statistical characterization of the
population. From comparison with C^(18)O data, we find the dust opacity per gas
mass, kappa r = 0.16 cm^2 g^(-1) at 250 micron, for cold clumps. We find that
2% of the mass of the molecular gas over this diverse region is in cores colder
than 14 K, and that the mass function for these cold cores is consistent with a
power law with index alpha = -3.22 +/- 0.14 over the mass range 14 M_sun < M <
80 M_sun. Additionally, we infer a mass-dependent cold core lifetime of t_c(M)
= 4E6 (M/20 M_sun)^(-0.9) years - longer than what has been found in previous
surveys of either low or high mass cores, and significantly longer than free
fall or likely turbulent decay times. This implies some form of non-thermal
support for cold cores during this early stage of star formation.Comment: Accepted for publication in the Astrophysical Journal. Maps available
at http://blastexperiment.info
A Bright Submillimeter Source in the Bullet Cluster (1E0657--56) Field Detected with BLAST
We present the 250, 350, and 500 micron detection of bright submillimeter
emission in the direction of the Bullet Cluster measured by the Balloon-borne
Large Aperture Submillimeter Telescope (BLAST). The 500 micron centroid is
coincident with an AzTEC 1.1 mm point-source detection at a position close to
the peak lensing magnification produced by the cluster. However, the 250 micron
and 350 micron centroids are elongated and shifted toward the south with a
differential shift between bands that cannot be explained by pointing
uncertainties. We therefore conclude that the BLAST detection is likely
contaminated by emission from foreground galaxies associated with the Bullet
Cluster. The submillimeter redshift estimate based on 250-1100 micron
photometry at the position of the AzTEC source is z_phot = 2.9 (+0.6 -0.3),
consistent with the infrared color redshift estimation of the most likely IRAC
counterpart. These flux densities indicate an apparent far-infrared luminosity
of L_FIR = 2E13 Lsun. When the amplification due to the gravitational lensing
of the cluster is removed, the intrinsic far-infrared luminosity of the source
is found to be L_FIR <= 10^12 Lsun, consistent with typical luminous infrared
galaxies.Comment: Accepted for publication in the Astrophysical Journal. Maps are
available at http://blastexperiment.info
Over half of the far-infrared background light comes from galaxies at z >= 1.2
Submillimetre surveys during the past decade have discovered a population of
luminous, high-redshift, dusty starburst galaxies. In the redshift range 1 <= z
<= 4, these massive submillimetre galaxies go through a phase characterized by
optically obscured star formation at rates several hundred times that in the
local Universe. Half of the starlight from this highly energetic process is
absorbed and thermally re-radiated by clouds of dust at temperatures near 30 K
with spectral energy distributions peaking at 100 microns in the rest frame. At
1 <= z <= 4, the peak is redshifted to wavelengths between 200 and 500 microns.
The cumulative effect of these galaxies is to yield extragalactic optical and
far-infrared backgrounds with approximately equal energy densities. Since the
initial detection of the far-infrared background (FIRB), higher-resolution
experiments have sought to decompose this integrated radiation into the
contributions from individual galaxies. Here we report the results of an
extragalactic survey at 250, 350 and 500 microns. Combining our results at 500
microns with those at 24 microns, we determine that all of the FIRB comes from
individual galaxies, with galaxies at z >= 1.2 accounting for 70 per cent of
it. As expected, at the longest wavelengths the signal is dominated by
ultraluminous galaxies at z > 1.Comment: Accepted to Nature. Maps available at http://blastexperiment.info
The balloon-borne large-aperture submillimeter telescope for polarimetry: BLAST-Pol
The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry
(BLAST-Pol) is a suborbital mapping experiment designed to study the role
played by magnetic fields in the star formation process. BLAST-Pol is the
reconstructed BLAST telescope, with the addition of linear polarization
capability. Using a 1.8 m Cassegrain telescope, BLAST-Pol images the sky onto a
focal plane that consists of 280 bolometric detectors in three arrays,
observing simultaneously at 250, 350, and 500 um. The diffraction-limited
optical system provides a resolution of 30'' at 250 um. The polarimeter
consists of photolithographic polarizing grids mounted in front of each
bolometer/detector array. A rotating 4 K achromatic half-wave plate provides
additional polarization modulation. With its unprecedented mapping speed and
resolution, BLAST-Pol will produce three-color polarization maps for a large
number of molecular clouds. The instrument provides a much needed bridge in
spatial coverage between larger-scale, coarse resolution surveys and narrow
field of view, and high resolution observations of substructure within
molecular cloud cores. The first science flight will be from McMurdo Station,
Antarctica in December 2010.Comment: 14 pages, 9 figures Submitted to SPIE Astronomical Telescopes and
Instrumentation Conference 201
The BLAST Survey of the Vela Molecular Cloud: Physical Properties of the Dense Cores in Vela-D
The Balloon-borne Large-Aperture Submillimeter Telescope (BLAST) carried out
a 250, 350 and 500 micron survey of the galactic plane encompassing the Vela
Molecular Ridge, with the primary goal of identifying the coldest dense cores
possibly associated with the earliest stages of star formation. Here we present
the results from observations of the Vela-D region, covering about 4 square
degrees, in which we find 141 BLAST cores. We exploit existing data taken with
the Spitzer MIPS, IRAC and SEST-SIMBA instruments to constrain their
(single-temperature) spectral energy distributions, assuming a dust emissivity
index beta = 2.0. This combination of data allows us to determine the
temperature, luminosity and mass of each BLAST core, and also enables us to
separate starless from proto-stellar sources. We also analyze the effects that
the uncertainties on the derived physical parameters of the individual sources
have on the overall physical properties of starless and proto-stellar cores,
and we find that there appear to be a smooth transition from the pre- to the
proto-stellar phase. In particular, for proto-stellar cores we find a
correlation between the MIPS24 flux, associated with the central protostar, and
the temperature of the dust envelope. We also find that the core mass function
of the Vela-D cores has a slope consistent with other similar (sub)millimeter
surveys.Comment: Accepted for publication in the Astrophysical Journal. Data and maps
are available at http://blastexperiment.info
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