130 research outputs found
Nonlinear optical signals and spectroscopy with quantum light
Conventional nonlinear spectroscopy uses classical light to detect matter
properties through the variation of its response with frequencies or time
delays. Quantum light opens up new avenues for spectroscopy by utilizing
parameters of the quantum state of light as novel control knobs and through the
variation of photon statistics by coupling to matter. We present an intuitive
diagrammatic approach for calculating ultrafast spectroscopy signals induced by
quantum light, focusing on applications involving entangled photons with
nonclassical bandwidth properties - known as "time-energy entanglement".
Nonlinear optical signals induced by quantized light fields are expressed using
time ordered multipoint correlation functions of superoperators. These are
different from Glauber's g- functions for photon counting which use normally
ordered products of ordinary operators. Entangled photon pairs are not
subjected to the classical Fourier limitations on the joint temporal and
spectral resolution. After a brief survey of properties of entangled photon
pairs relevant to their spectroscopic applications, different optical signals,
and photon counting setups are discussed and illustrated for simple multi-level
model systems
JWST NIRCam Time Series Observations
We explain how to make time-series observations with the Near-Infrared camera (NIRCam) science instrument of the James Webb Space Telescope. Both photometric and spectroscopic observations are described. We present the basic capabilities and performance of NIRCam and show examples of how to set its observing parameters using the Space Telescope Science Institute's Astronomer's Proposal Tool (APT)
Manipulation of two-photon fluorescence spectra of chromophore aggregates with entangled photons: A simulation study
The non-classical spectral and temporal features of entangled photons offer
new possibilities to investigate the interactions of excitons in photosynthetic
complexes, and to target the excitation of specific states. Simulations of
fluorescence in the bacterial reaction center induced by entangled light
demonstrate a selectivity of double-exciton states which is not possible using
classical stochastic light with the same power spectrum.Comment: 11 pages, 13 figures, published versio
Nonlinear spectroscopy of chromophore aggregates with entangled photon pulses
Abstract. The response of the bacterial reaction center to entangled photons is com pared with stochastic and chirped pulses. Nonlinear optical signals reveal how distribu tions of exciton states may be controlled by quantum light. Nonlinear spectroscopy with quantum light Quantum light provides novel possibilities for nonlinear spectroscopy by tuning parameters of the pho ton wavefunction. Frequency-entangled photons possess various attractive features for spectroscopic applications. The coherent interaction of pairs of photons scales linearly in the pump intensity, thus allowing for much lower light intensities for nonlinear signal
A strong H<sup>-</sup>opacity signal in the near-infrared emission spectrum of the ultra-hot Jupiter KELT-9b
Transiting Exoplanet Studies and Community Targets for JWST's Early Release Science Program
The James Webb Space Telescope will revolutionize transiting exoplanet
atmospheric science due to its capability for continuous, long-duration
observations and its larger collecting area, spectral coverage, and spectral
resolution compared to existing space-based facilities. However, it is unclear
precisely how well JWST will perform and which of its myriad instruments and
observing modes will be best suited for transiting exoplanet studies. In this
article, we describe a prefatory JWST Early Release Science (ERS) program that
focuses on testing specific observing modes to quickly give the community the
data and experience it needs to plan more efficient and successful future
transiting exoplanet characterization programs. We propose a multi-pronged
approach wherein one aspect of the program focuses on observing transits of a
single target with all of the recommended observing modes to identify and
understand potential systematics, compare transmission spectra at overlapping
and neighboring wavelength regions, confirm throughputs, and determine overall
performances. In our search for transiting exoplanets that are well suited to
achieving these goals, we identify 12 objects (dubbed "community targets") that
meet our defined criteria. Currently, the most favorable target is WASP-62b
because of its large predicted signal size, relatively bright host star, and
location in JWST's continuous viewing zone. Since most of the community targets
do not have well-characterized atmospheres, we recommend initiating preparatory
observing programs to determine the presence of obscuring clouds/hazes within
their atmospheres. Measurable spectroscopic features are needed to establish
the optimal resolution and wavelength regions for exoplanet characterization.
Other initiatives from our proposed ERS program include testing the instrument
brightness limits and performing phase-curve observations.(Abridged)Comment: This is a white paper that originated from an open discussion at the
Enabling Transiting Exoplanet Science with JWST workshop held November 16 -
18, 2015 at STScI (http://www.stsci.edu/jwst/science/exoplanets). Accepted
for publication in PAS
The Spitzer Infrared Nearby Galaxies Survey: A High-Resolution Spectroscopy Anthology
High resolution mid-infrared spectra are presented for 155 nuclear and
extranuclear regions from the Spitzer Infrared Nearby Galaxies Survey (SINGS).
The fluxes for nine atomic forbidden and three molecular hydrogen mid-infrared
emission lines are also provided, along with upper limits in key lines for
infrared-faint targets. The SINGS sample shows a wide range in the ratio of
[SIII]18.71um/[SIII]33.48um, but the average ratio of the ensemble indicates a
typical interstellar electron density of 300-400 cm^{-3} on ~23"x15" scales and
500-600 cm^{-3} using ~11"x9" apertures, independent of whether the region
probed is a star-forming nuclear, a star-forming extranuclear, or an AGN
environment. Evidence is provided that variations in gas-phase metallicity play
an important role in driving variations in radiation field hardness, as
indicated by [NeIII]15.56um/[NeII]12.81um, for regions powered by star
formation. Conversely, the radiation hardness for galaxy nuclei powered by
accretion around a massive black hole is independent of metal abundance.
Furthermore, for metal-rich environments AGN are distinguishable from
star-forming regions by significantly larger [NeIII]15.56um/[NeII]12.81um
ratios. Finally, [FeII]25.99um/[NeII]12.81um versus [SiII]34.82um/[SIII]33.48um
also provides an empirical method for discerning AGN from normal star-forming
sources. However, similar to [NeIII]15.56um/[NeII]12.81um, these mid-infrared
line ratios lose their AGN/star-formation diagnostic powers for very low
metallicity star-forming systems with hard radiation fields.Comment: Accepted for publication in Ap
Infrared Variability of Two Dusty White Dwarfs
The most heavily polluted white dwarfs often show excess infrared radiation from circumstellar dust disks, which are modeled as a result of tidal disruption of extrasolar minor planets. Interaction of dust, gas, and disintegrating objects can all contribute to the dynamical evolution of these dust disks. Here, we report two infrared variable dusty white dwarfs, SDSS J1228+1040 and G29-38. For SDSS J1228+1040, compared to the first measurements in 2007, the IRAC [3.6] and [4.5] fluxes decreased by 20% before 2014 to a level also seen in the recent 2018 observations. For G29-38, the infrared flux of the 10 μm silicate emission feature became 10% stronger between 2004 and 2007, We explore several scenarios that could account for these changes, including tidal disruption events, perturbation from a companion, and runaway accretion. No satisfactory causes are found for the flux drop in SDSS J1228+1040 due to the limited time coverage. Continuous tidal disruption of small planetesimals could increase the mass of small grains and concurrently change the strength of the 10 μm feature of G29-38. Dust disks around white dwarfs are actively evolving and we speculate that there could be different mechanisms responsible for the temporal changes of these disks
First Sample of H+[O III] 5007 Line Emitters at through JWST/NIRCam Slitless Spectroscopy: Physical Properties and Line Luminosity Functions
We present a sample of four emission-line galaxies at that were
serendipitously discovered using the commissioning data for the JWST/NIRCam
wide-field slitless spectroscopy (WFSS) mode. One of them (at ) has
been reported previously while the others are new discoveries. These sources
are selected by the secure detections of both [O III] 5007 and
H lines with other fainter lines tentatively detected in some cases
(e.g., [O II] 3727, [O III] 4959 and [N II] 6583).
In the [O III]/H - [N II]/H Baldwin-Phillips-Terlevich diagram,
these galaxies occupy the same parameter space as that of star-forming
galaxies, indicating that they have been enriched rapidly to sub-solar
metallicities (0.6 ), similar to galaxies with comparable
stellar masses at much lower redshifts. The detection of strong H lines
suggests a higher ionizing photon production efficiency within galaxies in the
early Universe. We find brightening of the [O III] 5007 line
luminosity function (LF) from to 6, and no or weak redshift evolution of
the H line LF from to 6. Both LFs are under-predicted at
by a factor of 10 in certain cosmological simulations. This further
indicates a global Ly photon escape fraction of 5-7% at , much
lower than previous estimates through the comparison of the UV-derived
star-formation rate density and Ly luminosity density. Our sample
recovers % of galaxies in the survey volume with
stellar masses greater than , suggesting the ubiquity
of strong H and [O III] line emitters in the Epoch of Reionization,
which will be further uncovered in the era of JWST.Comment: 25 pages, 11 figures, submitted to Ap
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