726 research outputs found
Mapping the Epoch of Reionization with C+ Line Tomography
Our KISS program has laid the theoretical foundations for probing the epoch of reionization with C+
tomography measurements, developed unique lithographed millimeter-wave spectrometer technology,
and initiated a first-light C+ experiment named TIME-Pilot. With KISS support we have carried out the
following investigations:
1) Developed the case for line intensity mapping methods to study the epoch of reionization
using singly ionized carbon (C+), typically the most luminous emission line in galaxies. The
theoretical studies not only explored the amplitude of the signal, and the usefulness in
determining physical properties of the partially ionized intergalactic medium, but also the
effects of foreground confusion from low-redshift galaxies. Our team made the first
calculations of C+ clustering fluctuations from the reionization epoch, and estimated the
effect of foreground galaxy confusion, largely from CO line emission at z ~ 1. We also
authored the first papers on tomographic measurements with the Ly emission line, which
shows great promise for near-infrared intensity mapping measurements with the SPHEREx
SMEX mission concept.
2) Developed a complete design for a first-detection instrument of [CII] large-scale clustering
emission named TIME-Pilot, based on an array of 32 novel waveguide spectrometers. The
spectrometers are mounted in a linear array in two polarizations, and observations are
carried out by scanning the detectors in a 1-deg linear strip, which maximizes depth (small
survey area) while preserving sensitivity on large scales (long scan length).
3) Demonstrated the key waveguide spectrometer technology, which confines radiation in 2
dimensions and the power propagates between parallel plates and is dispersed and
collimated by a curved grating. The waveguide spectrometers greatly reduce the mass and
volume that would otherwise be required with a conventional 3-d grating spectrometer.
4) Demonstrated a prototype superconducting detector array. These high-sensitivity
superconducting bolometers are mounted on the focal surface across multiple
spectrometers, and read out by superconducting current amplifiers. The devices present
unique micro-machining challenges to produce edge-butted sub-arrays that do not leave
spectral gaps between channels.
5) Completed the full cryogenic system for the instrument. We commandeered an existing 4
K cryostat from another project, and added cooling stages to an ultimate temperature of
220 mK to meet the TIME-Pilot cooling requirements. The system is fully tested and
operational.
6) Formed a partnership with ASIAA in Taiwan, led by Tzu-Ching Chang who attended the
original KISS study. ASIAA is providing major hardware components for the TIME-Pilot
instrument, and in the past year have developed a prototype of the spectrometer, and
procured cables and cryogenic coolers. ASIAA has also become the managing institution
for the James Clerk Maxwell Telescope (JCMT) in Hawaii, and ideal facility for carrying out
observations with the instrument
Large array of low-frequency readout quantum capacitance detectors
Quantum capacitance detectors (QCDs) are photon shot noise-limited terahertz detectors based on a single Cooper-pair box superconducting qubit. The QCD has demonstrated photon shot noise-limited performance for 1.5 THz radiation under loading conditions between 10⁻²⁰ and 10⁻¹⁸ W and single-photon detection and counting at that frequency. We report here fabrication and preliminary characterization of a 441 pixel array of QCDs with readout frequencies between 700 and 850 MHz
Mapping the Epoch of Reionization with C+ Line Tomography
Our KISS program has laid the theoretical foundations for probing the epoch of reionization with C+
tomography measurements, developed unique lithographed millimeter-wave spectrometer technology,
and initiated a first-light C+ experiment named TIME-Pilot. With KISS support we have carried out the
following investigations:
1) Developed the case for line intensity mapping methods to study the epoch of reionization
using singly ionized carbon (C+), typically the most luminous emission line in galaxies. The
theoretical studies not only explored the amplitude of the signal, and the usefulness in
determining physical properties of the partially ionized intergalactic medium, but also the
effects of foreground confusion from low-redshift galaxies. Our team made the first
calculations of C+ clustering fluctuations from the reionization epoch, and estimated the
effect of foreground galaxy confusion, largely from CO line emission at z ~ 1. We also
authored the first papers on tomographic measurements with the Ly emission line, which
shows great promise for near-infrared intensity mapping measurements with the SPHEREx
SMEX mission concept.
2) Developed a complete design for a first-detection instrument of [CII] large-scale clustering
emission named TIME-Pilot, based on an array of 32 novel waveguide spectrometers. The
spectrometers are mounted in a linear array in two polarizations, and observations are
carried out by scanning the detectors in a 1-deg linear strip, which maximizes depth (small
survey area) while preserving sensitivity on large scales (long scan length).
3) Demonstrated the key waveguide spectrometer technology, which confines radiation in 2
dimensions and the power propagates between parallel plates and is dispersed and
collimated by a curved grating. The waveguide spectrometers greatly reduce the mass and
volume that would otherwise be required with a conventional 3-d grating spectrometer.
4) Demonstrated a prototype superconducting detector array. These high-sensitivity
superconducting bolometers are mounted on the focal surface across multiple
spectrometers, and read out by superconducting current amplifiers. The devices present
unique micro-machining challenges to produce edge-butted sub-arrays that do not leave
spectral gaps between channels.
5) Completed the full cryogenic system for the instrument. We commandeered an existing 4
K cryostat from another project, and added cooling stages to an ultimate temperature of
220 mK to meet the TIME-Pilot cooling requirements. The system is fully tested and
operational.
6) Formed a partnership with ASIAA in Taiwan, led by Tzu-Ching Chang who attended the
original KISS study. ASIAA is providing major hardware components for the TIME-Pilot
instrument, and in the past year have developed a prototype of the spectrometer, and
procured cables and cryogenic coolers. ASIAA has also become the managing institution
for the James Clerk Maxwell Telescope (JCMT) in Hawaii, and ideal facility for carrying out
observations with the instrument
Review: far-infrared instrumentation and technological development for the next decade
Far-infrared astronomy has advanced rapidly since its inception in the late 1950s, driven by a maturing technology base and an expanding community of researchers. This advancement has shown that observations at far-infrared wavelengths are important in nearly all areas of astrophysics, from the search for habitable planets and the origin of life to the earliest stages of galaxy assembly in the first few hundred million years of cosmic history. The combination of a still-developing portfolio of technologies, particularly in the field of detectors, and a widening ensemble of platforms within which these technologies can be deployed, means that far-infrared astronomy holds the potential for paradigm-shifting advances over the next decade. We examine the current and future far-infrared observing platforms, including ground-based, suborbital, and space-based facilities, and discuss the technology development pathways that will enable and enhance these platforms to best address the challenges facing far-infrared astronomy in the 21st century
Origins Space Telescope: predictions for far-IR spectroscopic surveys
We illustrate the extraordinary potential of the (far-IR) Origins Survey
Spectrometer (OSS) on board the Origins Space Telescope (OST) to address a
variety of open issues on the co-evolution of galaxies and AGNs. We present
predictions for blind surveys, each of 1000 h, with different mapped areas (a
shallow survey covering an area of 10 deg and a deep survey of 1
deg) and two different concepts of the OST/OSS: with a 5.9 m telescope
(Concept 2, our reference configuration) and with a 9.1 m telescope (Concept 1,
previous configuration). In 1000 h, surveys with the reference concept will
detect from to lines from
- star-forming galaxies and from
to lines from - AGNs. The shallow survey will detect
substantially more sources than the deep one; the advantage of the latter in
pushing detections to lower luminosities/higher redshifts turns out to be quite
limited. The OST/OSS will reach, in the same observing time, line fluxes more
than one order of magnitude fainter than the SPICA/SMI and will cover a much
broader redshift range. In particular it will detect tens of thousands of
galaxies at , beyond the reach of that instrument. The polycyclic
aromatic hydrocarbons lines are potentially bright enough to allow the
detection of hundreds of thousands of star-forming galaxies up to ,
i.e. all the way through the re-ionization epoch. The proposed surveys will
allow us to explore the galaxy-AGN co-evolution up to with very
good statistics. OST Concept 1 does not offer significant advantages for the
scientific goals presented here.Comment: 24 pages, 20 figures, 2 tables, accepted for publication in PAS
Formation of the oxygen torus in the inner magnetosphere: Van Allen Probes observations
We study the formation process of an oxygen torus during the 12–15 November 2012 magnetic storm, using the magnetic field and plasma wave data obtained by Van Allen Probes. We estimate the local plasma mass density (ρL) and the local electron number density (neL) from the resonant frequencies of standing Alfvén waves and the upper hybrid resonance band. The average ion mass (M) can be calculated by M ∼ ρL/neL under the assumption of quasi-neutrality of plasma. During the storm recovery phase, both Probe A and Probe B observe the oxygen torus at L = 3.0–4.0 and L = 3.7–4.5, respectively, on the morning side. The oxygen torus has M = 4.5–8 amu and extends around the plasmapause that is identified at L∼3.2–3.9. We find that during the initial phase, M is 4–7 amu throughout the plasma trough and remains at ∼1 amu in the plasmasphere, implying that ionospheric O+ ions are supplied into the inner magnetosphere already in the initial phase of the magnetic storm. Numerical calculation under a decrease of the convection electric field reveals that some of thermal O+ ions distributed throughout the plasma trough are trapped within the expanded plasmasphere, whereas some of them drift around the plasmapause on the dawnside. This creates the oxygen torus spreading near the plasmapause, which is consistent with the Van Allen Probes observations. We conclude that the oxygen torus identified in this study favors the formation scenario of supplying O+ in the inner magnetosphere during the initial phase and subsequent drift during the recovery phase
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