1,957 research outputs found
A Biographical Sketch of John Greenleaf Whittier from The Early Poems of John Greenleaf Whittier
Biographical sketch from The Early Poems of John Greenleaf Whittier. Spine title Whittier\u27s Poetical Works. Biographical sketch written by N. H. Dole. Pages ix-xxxii. Portrait of Whittier included.https://digitalcommons.georgefox.edu/quakerbooks/1040/thumbnail.jp
Correlated Anisotropies in the Cosmic Far-Infrared Background Detected by MIPS/Spitzer: Constraint on the Bias
We report the detection of correlated anisotropies in the Cosmic Far-Infrared
Background at 160 microns. We measure the power spectrum in the Spitzer/SWIRE
Lockman Hole field. It reveals unambiguously a strong excess above cirrus and
Poisson contributions, at spatial scales between 5 and 30 arcminutes,
interpreted as the signature of infrared galaxy clustering. Using our model of
infrared galaxy evolution we derive a linear bias b=1.74 \pm 0.16. It is a
factor 2 higher than the bias measured for the local IRAS galaxies. Our model
indicates that galaxies dominating the 160 microns correlated anisotropies are
at z~1. This implies that infrared galaxies at high redshifts are biased
tracers of mass, unlike in the local Universe.Comment: ApJ Letters, in pres
DEVELOPEMENT AND VALIDATION OF ANALYTICAL METHOD FOR SIMULTANEOUS ESTIMATION OF CILNIDIPINE AND OLMESARTAN MEDOXOMIL IN BULK AND TABLET DOSAGE FORM BY RP-HPLC
An economical, precise, rapid and accurate RP HPLC method has been developed for the simultaneous estimation of Olmesartan Medoxomil and Cilnidipine in bulk and tablet dosage form. Separation was carried out on Jasco HPLC system equipped with HiQ sil C18 column (250 × 4.6 mm i.d.) and PDA detector using Methanol: 40 mM Potassium dihydrogen ortho phosphate buffer (90:10 v/v) as the mobile phase.Ortho-phosphoric acid was used to adjust pH to 3.0, and detection was carried out at 254 nm. Results were linear in the range of 5-30 μg/ml for Cilnidipine and 10-50 μg/ml for Olmesartan Medoxomil respectively. The method was successfully applied for the analysis of drugs in pharmaceutical formulation. Results of the analysis were validated statistically and by recovery studies
Multi-wavelength characterisation of z~2 clustered, dusty star forming galaxies discovered by Planck
(abridged) We report the discovery of PHz G95.5-61.6, a complex structure
detected in emission in the Planck all-sky survey that corresponds to two
over-densities of high-redshift galaxies. This is the first source from the
Planck catalogue of high-z candidates that has been completely characterised
with follow-up observations from the optical to the sub-millimetre domain.
Herschel/SPIRE observations at 250, 350 and 500 microns reveal the existence of
five sources producing a 500 microns emission excess that spatially corresponds
to the candidate proto-clusters discovered by Planck. Further observations at
CFHT in the optical bands (g and i) and in the near infrared (J, H and K_s),
plus mid infrared observations with IRAC/Spitzer (at 3.6 and 4.5 microns)
confirm that the sub-mm red excess is associated with an over-density of
colour-selected galaxies. Follow-up spectroscopy of 13 galaxies with
VLT/X-Shooter establishes the existence of two high-z structures: one at z~1.7
(three confirmed member galaxies), the other at z~2.0 (six confirmed members).
This double structure is also seen in the photometric redshift analysis of a
sample of 127 galaxies located inside a circular region of 1'-radius containing
the five Herschel/SPIRE sources, where we found a double-peaked excess of
galaxies at z~1.7 and z~2.0 with respect to the surrounding region. These
results suggest that PHz G95.5-61.6 corresponds to two accreting nodes, not
physically linked to one another, embedded in the large scale structure of the
Universe at z~2 and along the same line-of-sight. In conclusion, the data,
methods and results illustrated in this pilot project confirm that Planck data
can be used to detect the emission from clustered, dusty star forming galaxies
at high-z, and, thus, to pierce through the early growth of cluster-scale
structures.Comment: 15 pages, 13 figures. Accepted for publication in Astronomy and
Astrophysic
The infrared luminosity function of galaxies at redshifts z=1 and z~2 in the GOODS fields
We present the rest-frame 8 micron luminosity function (LF) at redshifts z=1
and ~2, computed from Spitzer 24 micron-selected galaxies in the GOODS fields
over an area of 291 sq. arcmin. Using classification criteria based on X-ray
data and IRAC colours, we identify the AGN in our sample. The rest-frame 8
micron LF for star-forming galaxies at redshifts z=1 and ~2 have the same shape
as at z~0, but with a strong positive luminosity evolution. The number density
of star-forming galaxies with log_{10}(nu L_nu(8 micron))>11 increases by a
factor >250 from redshift z~0 to 1, and is basically the same at z=1 and ~2.
The resulting rest-frame 8 micron luminosity densities associated with star
formation at z=1 and ~2 are more than four and two times larger than at z~0,
respectively. We also compute the total rest-frame 8 micron LF for star-forming
galaxies and AGN at z~2 and show that AGN dominate its bright end, which is
well-described by a power-law. Using a new calibration based on Spitzer
star-forming galaxies at 0<z<0.6 and validated at higher redshifts through
stacking analysis, we compute the bolometric infrared (IR) LF for star-forming
galaxies at z=1 and ~2. We find that the respective bolometric IR luminosity
densities are (1.2+/-0.2) x 10^9 and (6.6^{+1.2}_{-1.0}) x 10^8 L_sun Mpc^{-3},
in agreement with previous studies within the error bars. At z~2, around 90% of
the IR luminosity density associated with star formation is produced by
luminous and ultraluminous IR galaxies (LIRG and ULIRG), with the two
populations contributing in roughly similar amounts. Finally, we discuss the
consistency of our findings with other existing observational results on galaxy
evolution.Comment: Accepted for publication in the ApJ. 33 pages, 15 figures. Uses
emulateap
A lensed protocluster candidate at identified in JWST observations of the galaxy cluster SMACS0723-7327
According to the current paradigm of galaxy formation, the first galaxies
have been likely formed within large dark matter haloes. The fragmentation of
these massive haloes led to the formation of galaxy protoclusters, which are
usually composed of one to a few bright objects, surrounded by numerous fainter
(and less massive) galaxies. These early structures could have played a major
role in reionising the neutral hydrogen within the first billion years of the
Universe; especially, if their number density is significant.Taking advantage
of the unprecedented sensitivity reached by the \textit{James Webb Space
Telescope (JWST)}, galaxy protoclusters can now be identified and studied in
increasing numbers beyond 6. Characterising their contribution to the
UV photon budget could supply new insights into the reionisation process. We
analyse the first JWST dataset behind SMACS0723-7327 to search for
protoclusters at , combining the available spectroscopic and
photometric data. We then compare our findings with semi-analytical models and
simulations. In addition to two bright galaxies (26.5 AB in F277W),
separated by 11\arcsec and spectroscopically confirmed at
, we identify 6 additional galaxies with similar colors in a
\arcsec radius around these (corresponding to R kpc in
the source plane). Using several methods, we estimate the mass of the dark
matter halo of this protocluster, 3.310M
accounting for magnification, consistent with various predictions. The physical
properties of all protocluster members are also in excellent agreement with
what has been previously found at lower redshifts: star-formation main sequence
and protocluster size. This detection adds to just a few protoclusters
currently known in the first billion years of the universe.Comment: 7 pages, 6 Figures. Accepted for publication in A&A Lette
Simulations of the cosmic infrared and submillimeter background for future large surveys: I. Presentation and first application to Herschel/SPIRE and Planck/HFI
The coming Planck and Herschel missions will survey the sky at unprecedented
angular scales and sensitivities. Simulations are needed for better
interpretating the results of the surveys and for testing new methods of, e.g.,
source extraction and component separation. We present new simulations of the
infrared and submillimeter cosmic background, including the correlation between
infrared galaxies. The simulations were used to quantify the source-detection
thresholds for Herschel/SPIRE and Planck/HFI, as well as to study the
detectability of the cosmic infrared background correlated fluctuations.
The simulations are based on an empirical model of IR galaxy evolution. For
the correlations, we only included the linear clustering, assuming that
infrared galaxies are biased tracers of the dark-matter fluctuation density
field. We used the simulations with different bias parameters to predict the
confusion noise for Herschel/SPIRE and Planck/HFI and the completeness levels.
We also discuss the detectability of the linear clustering in Planck/HFI power
spectra, including the foreground and backgrounds components.
Simulated maps and catalogs are publicly available online at
http://www.ias.u-psud.fr/irgalaxies/simulations.phpComment: A&A, 2008, in pres
Habitable Climates: The Influence of Eccentricity
In the outer regions of the habitable zone, the risk of transitioning into a
globally frozen "snowball" state poses a threat to the habitability of planets
with the capacity to host water-based life. We use a one-dimensional energy
balance climate model (EBM) to examine how obliquity, spin rate, orbital
eccentricity, and ocean coverage might influence the onset of such a snowball
state. For an exoplanet, these parameters may be strikingly different from the
values observed for Earth. Since, for constant semimajor axis, the annual mean
stellar irradiation scales with (1-e^2)^(-1/2), one might expect the greatest
habitable semimajor axis (for fixed atmospheric composition) to scale as
(1-e^2)^(-1/4). We find that this standard ansatz provides a reasonable lower
bound on the outer boundary of the habitable zone, but the influence of
obliquity and ocean fraction can be profound in the context of planets on
eccentric orbits. For planets with eccentricity 0.5, our EBM suggests that the
greatest habitable semimajor axis can vary by more than 0.8 AU (78%!) depending
on obliquity, with higher obliquity worlds generally more stable against
snowball transitions. One might also expect that the long winter at an
eccentric planet's apoastron would render it more susceptible to global
freezing. Our models suggest that this is not a significant risk for Earth-like
planets around Sun-like stars since such planets are buffered by the thermal
inertia provided by oceans covering at least 10% of their surface. Since
planets on eccentric orbits spend much of their year particularly far from the
star, such worlds might turn out to be especially good targets for direct
observations with missions such as TPF-Darwin. Nevertheless, the extreme
temperature variations achieved on highly eccentric exo-Earths raise questions
about the adaptability of life to marginally or transiently habitable
conditions.Comment: References added, text and figures updated, accepted by Ap
Spitzer 70 and 160-micron Observations of the COSMOS Field
We present Spitzer 70 and 160 micron observations of the COSMOS Spitzer
survey (S-COSMOS). The data processing techniques are discussed for the
publicly released products consisting of images and source catalogs. We present
accurate 70 and 160 micron source counts of the COSMOS field and find
reasonable agreement with measurements in other fields and with model
predictions. The previously reported counts for GOODS-North and the
extragalactic First Look Survey are updated with the latest calibration, and
counts are measured based on the large area SWIRE survey to constrain the
bright source counts. We measure an extragalactic confusion noise level of
sigma_c = 9.4+/-3.3 mJy (q=5) for the MIPS 160-micron band based on the deep
S-COSMOS data and report an updated confusion noise level of sigma_c =
0.35+/-0.15 mJy (q=5) for the MIPS 70-micron band.Comment: Accepted AJ, 15 Aug. 2009. Data available at
http://spider.ipac.caltech.edu/staff/frayer/mycosmos/ until released by IRS
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