scholarly journals Extragalactic optical and near-infrared foregrounds to 21-cm epoch of reionisation experiments

2017 ◽  
Vol 12 (S333) ◽  
pp. 183-190
Author(s):  
Matt J. Jarvis ◽  
Rebecca A.A. Bowler ◽  
Peter W. Hatfield

AbstractForeground contamination is one of the most important limiting factors in detecting the neutral hydrogen in the epoch of reionisation. These foregrounds can be roughly split into galactic and extragalactic foregrounds. In these proceedings we highlight information that can be gleaned from multi-wavelength extragalactic surveys in order to overcome this issue. We discuss how clustering information from the lower-redshift, foreground galaxies, can be used as additional information in accounting for the noise associated with the foregrounds. We then go on to highlight the expected contribution of future optical and near-infrared surveys for detecting the galaxies responsible for ionising the Universe. We suggest that these galaxies can also be used to reduce the systematics in the 21-cm epoch of reionisation signal through cross-correlations if enough common area is surveyed.

2015 ◽  
Vol 11 (S319) ◽  
pp. 92-95 ◽  
Author(s):  
K. Kohno ◽  
Y. Yamaguchi ◽  
Y. Tamura ◽  
K. Tadaki ◽  
B. Hatsukade ◽  
...  

AbstractWe have conducted 1.1 mm ALMA observations of a contiguous 105” × 50” or 1.5 arcmin2 window in the SXDF-UDS-CANDELS. We achieved a 5σ sensitivity of 0.28 mJy, giving a flat sensus of dusty star-forming galaxies with LIR ~6×1011L⊙ (if Tdust=40K) up to z ~ 10 thanks to the negative K-correction at this wavelength. We detected 5 brightest sources (S/N>6) and 18 low-significant sources (5>S/N>4; they may contain spurious detections, though). One of the 5 brightest ALMA sources (S1.1mm = 0.84 ± 0.09 mJy) is extremely faint in the WFC3 and VLT/HAWK-I images, demonstrating that a contiguous ALMA imaging survey uncovers a faint dust-obscured population invisible in the deep optical/near-infrared surveys. We find a possible [CII]-line emitter at z=5.955 or a low-z CO emitting galaxy within the field, allowing us to constrain the [CII] and/or CO luminosity functions across the history of the universe.


2015 ◽  
Vol 8 (1) ◽  
pp. 451-461 ◽  
Author(s):  
L.-W. A. Chen ◽  
J. C. Chow ◽  
X. L. Wang ◽  
J. A. Robles ◽  
B. J. Sumlin ◽  
...  

Abstract. A thermal/optical carbon analyzer equipped with seven-wavelength light source/detector (405–980 nm) for monitoring spectral reflectance (R) and transmittance (T) of filter samples allowed "thermal spectral analysis (TSA)" and wavelength (λ)-dependent organic-carbon (OC)–elemental-carbon (EC) measurements. Optical sensing was calibrated with transfer standards traceable to absolute R and T measurements, adjusted for loading effects to report spectral light absorption (as absorption optical depth (τa, λ)), and verified using diesel exhaust samples. Tests on ambient and source samples show OC and EC concentrations equivalent to those from conventional carbon analysis when based on the same wavelength (~ 635 nm) for pyrolysis adjustment. TSA provides additional information that evaluates black-carbon (BC) and brown-carbon (BrC) contributions and their optical properties in the near infrared to the near ultraviolet parts of the solar spectrum. The enhanced carbon analyzer can add value to current aerosol monitoring programs and provide insight into more accurate OC and EC measurements for climate, visibility, or health studies.


Author(s):  
Xiaowei Luan ◽  
Yongchun Pan ◽  
Yanfeng Gao ◽  
Yujun Song

Light has witnessed the history of mankind and even the universe. It is of great significances to the life of human society, contributing to energy, agriculture, communication, and much more....


2018 ◽  
Vol 14 (S343) ◽  
pp. 456-457
Author(s):  
Foteini Lykou ◽  
Josef Hron ◽  
Daniela Klotz

AbstractRecent advances in high-angular resolution instruments (VLT and VLTI, ALMA) have enabled us to delve deep into the circumstellar envelopes of AGB stars from the optical to the sub-mm wavelengths, thus allowing us to study in detail the gas and dust formation zones (e.g., their geometry, chemistry and kinematics). This work focuses on four (4) C-rich AGB stars observed with a high-angular resolution technique in the near-infrared: a multi-wavelength tomographic study of the dusty layers of the circumstellar envelopes of these C-rich stars, i.e. the variations in the morphology and temperature distribution.


2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Luca Fasolato ◽  
Nadia Andrea Andreani ◽  
Roberta De Nardi ◽  
Giulia Nalotto ◽  
Lorenzo Serva ◽  
...  

Near infrared spectroscopy (NIRs) and ultraviolet visible spectroscopy (UV-vis) have been investigated as rapid techniques to characterize foodborne bacteria through the analysis of the spectra of whole cells or microbial suspensions. The use of spectra collected from broth cultures could be used as a fingerprint for strain classification using a combined polyphasic approach. The aim of this study was to evaluate the feasibility of NIRs and UV-vis for the characterization of blue strains belonging to the Pseudomonas fluorescens group. The bacteria were isolated from different food matrices, including some spoiled samples (blue discoloration). Eightyone strains previously identified at the species level were grown in Minimal Bacterial Medium broth under standard conditions at 22°C. Two biological replicates were centrifuged in order to separate the bacterial cells from the extracellular products. Six aliquots per strain were analyzed on a small ring cup in transflectance mode (680-2500 nm, gap 2 nm). A subset of 39 strains was evaluated by UV-vis to determine changes in the spectral characteristics at 48 and 72 hours. Several chemometric approaches were tested to assess the performance of NIRs and UVvis. According to the variable importance in projection (VIP), the 1892-2020 nm spectral region showed the highest level of discrimination between blue strains and others. Additional information was provided in the 680-886 and 1454-1768 nm regions (aromatic C-H bonds) and in the 2036-2134 nm region (fatty acids). Changes in UV-vis spectral data (at 48 and 72 hours) appear to indicate the presence of phenazine and catecholic compounds in extracellular products.


Geosciences ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 289 ◽  
Author(s):  
Serena Benatti

Exoplanet research has shown an incessant growth since the first claim of a hot giant planet around a solar-like star in the mid-1990s. Today, the new facilities are working to spot the first habitable rocky planets around low-mass stars as a forerunner for the detection of the long-awaited Sun-Earth analog system. All the achievements in this field would not have been possible without the constant development of the technology and of new methods to detect more and more challenging planets. After the consolidation of a top-level instrumentation for high-resolution spectroscopy in the visible wavelength range, a huge effort is now dedicated to reaching the same precision and accuracy in the near-infrared. Actually, observations in this range present several advantages in the search for exoplanets around M dwarfs, known to be the most favorable targets to detect possible habitable planets. They are also characterized by intense stellar activity, which hampers planet detection, but its impact on the radial velocity modulation is mitigated in the infrared. Simultaneous observations in the visible and near-infrared ranges appear to be an even more powerful technique since they provide combined and complementary information, also useful for many other exoplanetary science cases.


2017 ◽  
Vol 1 ◽  
pp. maapoc.0000013 ◽  
Author(s):  
Klara Dégardin ◽  
Yves Roggo

Currently, counterfeit medicine is a significant issue for the pharmaceutical world, and it targets all types of therapeutic areas. The health consequences are appalling, since counterfeit medicines can contain impurities and the wrong chemical composition, and can be manufactured and/or stored in dreadful conditions. The provision of fast and reliable analytical tools can contribute to an efficient fight against this phenomenon. In this paper, an analytical strategy based on mobile and forensic laboratories is presented. The mobile equipment, composed of handheld x-ray fluorescence, Raman, infrared, and near-infrared spectrometers, and a handheld microscope, can be used as a first screening tool to detect counterfeits. The counterfeits can then be confirmed in a forensic-dedicated lab in which the chemical composition of the counterfeits is determined to evaluate the danger encountered by the patients. Relevant links with former counterfeit cases then can be revealed based on the analytical data, and can be interpreted from a forensic intelligence perspective in order to provide additional information for law enforcement.


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