3,135 research outputs found
The principle of symmetric bracket invariance as the origin of first and second quantization
The principle of invariance of the c-number symmetric bracket is used to
derive both the quantum operator commutator relation
and the time-dependent Schr\"odinger equation. A c-number dynamical equation is
found which leads to the second quantized field theory of bosons and fermions.Comment: 14 pages. Contributed Paper: XIX International Symposium on Lepton
and Photon Interactions at High Energies, Stanford University, August 9-14,
199
Infalling Faint [OII] Emitters in Abell 851. I. Spectroscopic Confirmation of Narrowband-Selected Objects
We report on a spectroscopic confirmation of narrowband-selected [OII]
emitters in Abell 851 catalogued by Martin et al. (2000). The optical spectra
obtained from the Keck I Low Resolution Imaging Spectrometer (LRIS) and Keck II
Deep Imaging Multi-Object Spectrograph (DEIMOS) have confirmed [OII]3727
emission in narrowband-selected cluster [OII] candidates at a 85% success rate
for faint (i <~ 25) blue (g-i < 1) galaxies. The rate for the successful
detection of [OII] emission is a strong function of galaxy color, generally
proving the efficacy of narrowband [OII] search supplemented with broadband
colors in selecting faint cluster galaxies with recent star formation. Balmer
decrement-derived reddening measurements show a high degree of reddening
[E(B-V) >~ 0.5] in a significant fraction of this population. Even after
correcting for dust extinction, the [OII]/Ha line flux ratio for the
high-E(B-V) galaxies remains generally lower by a factor of ~2 than the mean
[OII]/Ha ratios reported by the studies of nearby galaxies. The strength of
[OII] equivalent width shows a negative trend with galaxy luminosity while the
Ha equivalent width does not appear to depend as strongly on luminosity. This
in part is due to the high amount of reddening observed in luminous galaxies.
Furthermore, emission line ratio diagnostics show that AGN-like galaxies are
abundant in the high luminosity end of the cluster [OII]-emitting sample, with
only moderately strong [OII] equivalent widths, consistent with a scenario of
galaxy evolution connecting AGNs and suppression of star-forming activity in
massive galaxies.Comment: 11 pages (LaTeX emulateapj), 8 figures, to appear in ApJ. A version
with high resolution figures available from the lead autho
Limits on the evolution of galaxies from the statistics of gravitational lenses
We use gravitational lenses from the Cosmic Lens All-Sky Survey (CLASS) to
constrain the evolution of galaxies since redshift in the current
\LCDM cosmology. This constraint is unique as it is based on a mass-selected
lens sample of galaxies. Our method of statistical analysis is the same as in
Chae (2003). We parametrise the early-type number density evolution in the form
of and the velocity dispersion as . We find that
() if we assume , implying
that the number density of early-type galaxies is within 50% to 164% of the
present-day value at redshift . Allowing the velocity dispersion to
evolve, we find that (), indicating that
the velocity dispersion must be within 57% and 107% of the present-day value at
. These results are consistent with the early formation and passive
evolution of early-type galaxies. More stringent limits from lensing can be
obtained from future large lens surveys and by using very high-redshift quasars
(z \ga 5) such as those found from the Sloan Digital Sky Survey.Comment: 10 pages (preprint format), 2 figures, ApJL in press (December 20th
issue
The Massive End of the Stellar Mass Function
We derive average flux corrections to the \texttt{Model} magnitudes of the
Sloan Digital Sky Survey (SDSS) galaxies by stacking together mosaics of
similar galaxies in bins of stellar mass and concentration. Extra flux is
detected in the outer low surface brightness part of the galaxies, leading to
corrections ranging from 0.05 to 0.32 mag for the highest stellar mass
galaxies. We apply these corrections to the MPA-JHU (Max-Planck Institute for
Astrophysics - John Hopkins University) stellar masses for a complete sample of
half a million galaxies from the SDSS survey to derive a corrected galaxy
stellar mass function at in the stellar mass range
. We find that the flux corrections and the use
of the MPA-JHU stellar masses have a significant impact on the massive end of
the stellar mass function, making the slope significantly shallower than that
estimated by Li \& White (2009), but steeper than derived by Bernardi et al.
(2013). This corresponds to a mean comoving stellar mass density of galaxies
with stellar masses that is a factor of 3.36
larger than the estimate by Li \& White (2009), but is 43\% smaller than
reported by Bernardi et al. (2013).Comment: 11 pages, 8 figures, Accepted to MNRA
Defining And Measuring Green FDI: An Exploratory Review Of Existing Work And Evidence
This paper was developed at the request of the OECD Working Party of the Investment Committee to document efforts to date to define and measure green FDI and to investigate the practicability of various possible definitions, as well as to identify investment policy restrictions to green FDI. It does so by reviewing the literature and existing work on the contributions of FDI to the environment; by providing a two-part definition of green FDI; and by discussing various assumptions necessary to estimate the magnitude of \u27green\u27 FDI
The scale-dependence of relative galaxy bias: encouragement for the halo model description
We investigate the relationship between the colors, luminosities, and
environments of galaxies in the Sloan Digital Sky Survey spectroscopic sample,
using environmental measurements on scales ranging from 0.2 to 6 Mpc/h. We
find: (1) that the relationship between color and environment persists even to
the lowest luminosities we probe (absolute magnitude in the r band of about -14
for h=1); (2) at luminosities and colors for which the galaxy correlation
function has a large amplitude, it also has a steep slope; and (3) in regions
of a given overdensity on small scales (1 Mpc/h), the overdensity on large
scales (6 Mpc/h) does not appear to relate to the recent star formation history
of the galaxies. Of these results, the last has the most immediate application
to galaxy formation theory. In particular, it lends support to the notion that
a galaxy's properties are related only to the mass of its host dark matter
halo, and not to the larger scale environment.Comment: submitted to ApJ; full resolution figures and slide material
available at http://cosmo.nyu.edu/blanton/scale_density.htm
Parametrizing the Stellar Haloes of Galaxies
We study the stellar haloes of galaxies out to 70-100 kpc as a function of
stellar mass and galaxy type by stacking aligned and band images from a
sample of 45508 galaxies from SDSS DR9 in the redshift range
and in the mass range r. We derive surface brightness profiles to a depth of
almost . We find that the
ellipticity of the stellar halo is a function of galaxy stellar mass and that
the haloes of high concentration () galaxies are more elliptical than
those of low concentration () galaxies. The - colour profile of
high concentration galaxies reveals that the - colour of the stellar
population in the stellar halo is bluer than in the main galaxy, and the colour
of the stellar halo is redder for higher mass galaxies. We further demonstrate
that the full two-dimensional surface intensity distribution of our galaxy
stacks can only be fit through multi-component S\'{e}rsic models. Using the
fraction of light in the outer component of the models as a proxy for the
fraction of accreted stellar light, we show that this fraction is a function of
stellar mass and galaxy type. For high concentration galaxies, the fraction of
accreted stellar light rises from to for galaxies in the stellar
mass range from to . The fraction of
accreted light is much smaller in low concentration systems, increasing from
to over the same mass range. This work provides important
constraints for the theoretical understanding of the formation of stellar
haloes of galaxies.Comment: Submitted to MNRAS, 18 pages, 19 figure
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