scholarly journals Quantifying the effects of spatial resolution and noise on galaxy metallicity gradients

2020 ◽  
Vol 495 (4) ◽  
pp. 3819-3838
Author(s):  
Ayan Acharyya ◽  
Mark R Krumholz ◽  
Christoph Federrath ◽  
Lisa J Kewley ◽  
Nathan J Goldbaum ◽  
...  
Keyword(s):  
High Resolution ◽  
Galaxy Evolution ◽  
Spatial Resolution ◽  
Signal To Noise Ratio ◽  
Low Snr ◽  
Integral Field Spectroscopy ◽  
History Of ◽  
Gradient Measurements ◽  
Integral Field ◽  
Scale Length

ABSTRACT Metallicity gradients are important diagnostics of galaxy evolution, because they record the history of events such as mergers, gas inflow, and star formation. However, the accuracy with which gradients can be measured is limited by spatial resolution and noise, and hence, measurements need to be corrected for such effects. We use high-resolution (∼20 pc) simulation of a face-on Milky Way mass galaxy, coupled with photoionization models, to produce a suite of synthetic high-resolution integral field spectroscopy (IFS) datacubes. We then degrade the datacubes, with a range of realistic models for spatial resolution (2−16 beams per galaxy scale length) and noise, to investigate and quantify how well the input metallicity gradient can be recovered as a function of resolution and signal-to-noise ratio (SNR) with the intention to compare with modern IFS surveys like MaNGA and SAMI. Given appropriate propagation of uncertainties and pruning of low SNR pixels, we show that a resolution of 3–4 telescope beams per galaxy scale length is sufficient to recover the gradient to ∼10–20 per cent uncertainty. The uncertainty escalates to ∼60 per cent for lower resolution. Inclusion of the low SNR pixels causes the uncertainty in the inferred gradient to deteriorate. Our results can potentially inform future IFS surveys regarding the resolution and SNR required to achieve a desired accuracy in metallicity gradient measurements.

scholarly journals Kinematical signatures of disc instabilities and secular evolution in the MUSE TIMER Survey

2019 ◽  
Vol 14 (S353) ◽  
pp. 135-139
Author(s):  
Dimitri A. Gadotti ◽  
Adrian Bittner ◽  
Jesus Falcón-Barroso ◽  
Jairo Méndez-Abreu ◽  
Keyword(s):  
Spatial Resolution ◽  
High Signal ◽  
Stellar Kinematics ◽  
Secular Evolution ◽  
Integral Field Spectroscopy ◽  
Central Regions ◽  
Hydrodynamical Simulations ◽  
Cosmic History ◽  
Disc Galaxies ◽  
Integral Field

AbstractThe MUSE TIMER Survey has obtained high signal and high spatial resolution integral-field spectroscopy data of the inner ~ 6×6 kpc of 21 nearby massive disc galaxies. This allows studies of the stellar kinematics of the central regions of massive disc galaxies that are unprecedented in spatial resolution. We confirm previous predictions from numerical and hydrodynamical simulations of the effects of bars and inner bars on stellar and gaseous kinematics, and also identify box/peanuts via kinematical signatures in mildly and moderately inclined galaxies, including a box/peanut in a face-on inner bar. In 20/21 galaxies we find inner discs and show that their properties are fully consistent with the bar-driven secular evolution picture for their formation. In addition, we show that these inner discs have, in the region where they dominate, larger rotational support than the main galaxy disc, and discuss how their stellar population properties can be used to estimate when in cosmic history the main bar formed. Our results are compared with photometric studies in the context of the nature of galaxy bulges and we show that inner discs are identified in image decompositions as photometric bulges with exponential profiles (i.e., Sérsic indices near unity).

scholarly journals Integral field spectroscopy with optical fibres

1995 ◽  
Vol 149 ◽  
pp. 209-218 ◽  
Author(s):  
C. Vanderriest
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Optical Fibres ◽  
Future Developments ◽  
Integral Field Spectroscopy ◽  
Field Spectroscopy ◽  
Large Telescopes ◽  
New Generation ◽  
Integral Field ◽  
Large Wavelength

AbstractAn efficient technique for obtaining complete spectral informations over moderately extended objects is to transform the geometry of their telescopic images to match a classical long ”slit” aperture. This anamorphosis is conveniently made with bundles of optical fibres. Such devices are especially useful when high spatial resolution and large wavelength coverage are required at the same time. We review the existing instruments based on this technique and present some typical results. We discuss also the future developments of integral field spectroscopy with optical fibres (visible or IR domains) for the new generation of very large telescopes.

scholarly journals The KMOS Galaxy Clusters Project

2014 ◽  
Vol 10 (S311) ◽  
pp. 110-115
Author(s):  
Roger L. Davies ◽  
A. Beifiori ◽  
R. Bender ◽  
M. Cappellari ◽  
J. Chan ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Galaxy Evolution ◽  
Star Formation History ◽  
Cluster Galaxies ◽  
V Band ◽  
Spectral Bands ◽  
Formation History ◽  
The Status ◽  
History Of ◽  
Integral Field

AbstractKMOS is a cryogenic infrared spectrograph fed by twentyfour deployable integral field units that patrol a 7.2 arcminute diameter field of view at the Nasmyth focus of the ESO VLT. It is well suited to the study of galaxy clusters at 1 < z < 2 where the well understood features in the restframe V-band are shifted into the KMOS spectral bands. Coupled with HST imagining, KMOS offers a window on the critical epoch for galaxy evolution, 7-10 Gyrs ago, when the key properties of cluster galaxies were established. We aim to investigate the size, mass, morphology and star formation history of galaxies in the clusters. Here we describe the instrument, discuss the status of the observations and report some preliminary results.

scholarly journals A New Method for Measuring the Detailed Chemical Composition of Globular Clusters from High-Resolution, Integrated-Light Spectra

2002 ◽  
Vol 207 ◽  
pp. 739-742 ◽  
Author(s):  
Rebecca A. Bernstein ◽  
Andrew McWilliam
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Globular Clusters ◽  
Signal To Noise Ratio ◽  
High Signal ◽  
Analysis Method ◽  
Individual Stars ◽  
Light Spectra ◽  
History Of ◽  
Detailed Chemical

We are developing a method for measuring the detailed chemical composition and evolutionary history of extragalactic star clusters from high resolution spectra of their integrated light as one would from spectra of individual stars. In this paper, we show high signal-to-noise ratio echelle spectra of the integrated light of two Galactic globular clusters and equivalent-quality spectra of individual stars in those clusters in order to briefly illustrate some subtleties of the analysis method.

scholarly journals High Spatial Resolution Integral Field Spectroscopy of extended Ionized Gas around three Quasars

1995 ◽  
Vol 149 ◽  
pp. 254-256
Author(s):  
F. Durret ◽  
E. Pécontal ◽  
P. Petitjean ◽  
J. Bergeron
Keyword(s):  
Spatial Resolution ◽  
Spectral Resolution ◽  
Rest Frame ◽  
High Spatial Resolution ◽  
Wavelength Region ◽  
Ionized Gas ◽  
Integral Field Spectroscopy ◽  
Field Spectroscopy ◽  
Integral Field Spectrograph ◽  
Integral Field

Three quasars, Ton 616, 4C 37.43 and PKS 2251+113 (Stockton and MacKenty 1987) were observed in 1992 at the 3.6 m CFH telescope with the Integral Field Spectrograph TIGER (Courtès et al. 1987, Pécontal 1991) under subarcsecond seeing (0.5 - 0.7”). The spatial sampling was 0.39” in a field 7 by 7 ”, and the spectral resolution 8 ÅFWHM in the Hβ - [OIII]λ 5007 wavelength region (in the rest frame of the objects). The scaling is 4.5, 5.9 and 5.3 kpc.arcsec−1 for Ton 616, 4C 37.43 and PKS 2251+113 respectively (H0 = 75 km.s−1.Mpc−1). The data were reduced with the software developed at Observatoire de Lyon by Rousset, Bacon and Pécontal (Rousset 1992). A detailed account of our results is reported in Durret et al. 1994.

scholarly journals FROM GLOBAL TO SPATIALLY RESOLVED IN LOW-REDSHIFT GALAXIES

2021 ◽  
Vol 57 (1) ◽  
Author(s):  
S. F. Sánchez ◽  
C. J. Walcher ◽  
C. Lopez-Cobá ◽  
J. K. Barrera-Ballesteros ◽  
A. Mejía-Narváez ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Galaxy Evolution ◽  
Ionized Gas ◽  
Evolution Of Galaxies ◽  
Spatially Resolved ◽  
Integral Field Spectroscopy ◽  
Field Spectroscopy ◽  
Stellar Properties ◽  
Integral Field ◽  
Redshift Galaxies

Our understanding of the structure, composition and evolution of galaxies hasstrongly improved in the last decades, mostly due to new results based on large spectro-scopic and imaging surveys. In particular, the nature of ionized gas, its ionization mech-anisms, its relation with the stellar properties and chemical composition, the existence ofscaling relations that describe the cycle between stars and gas, and the corresponding evo-lution patterns have been widely explored and described. More recently, the introduction ofadditional techniques, in particular integral field spectroscopy, and their use in large galaxysurveys, have forced us to re-interpret most of those recent results from a spatially resolvedperspective. This review is aimed to complement recent efforts to compile and summarizethis change of paradigm in the interpretation of galaxy evolution. To this end we replicatepublished results, and present novel ones, based on the largest compilation of IFS data ofgalaxies in the nearby universe to date.

scholarly journals Novel Configurations of Ultrahigh Frequency (≤600 MHz) Analog Frontend for High Resolution Ultrasound Measurement

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2598
Author(s):  
Min Kim ◽  
Jinhyoung Park ◽  
Qifa Zhou ◽  
Koping Shung
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
Signal To Noise Ratio ◽  
Ultrahigh Frequency ◽  
Ultrasound Measurement ◽  
Functional Responses ◽  
Signal To Noise ◽  
Coded Excitation ◽  
Noise Ratio ◽  
The Difference

In this article, an approach to designing and developing an ultrahigh frequency (≤600 MHz) ultrasound analog frontend with Golay coded excitation sequence for high resolution imaging applications is presented. For the purpose of visualizing specific structures or measuring functional responses of micron-sized biological samples, a higher frequency ultrasound is needed to obtain a decent spatial resolution while it lowers the signal-to-noise ratio, the difference in decibels between the signal level and the background noise level, due to the higher attenuation coefficient. In order to enhance the signal-to-noise ratio, conventional approach was to increase the transmit voltage level. However, it may cause damaging the extremely thin piezoelectric material in the ultrahigh frequency range. In this paper, we present a novel design of ultrahigh frequency (≤600 MHz) frontend system capable of performing pseudo Golay coded excitation by configuring four independently operating pulse generators in parallel and the consecutive delayed transmission from each channel. Compared with the conventional monocycle pulse approach, the signal-to-noise ratio of the proposed approach was improved by 7–9 dB without compromising the spatial resolution. The measured axial and lateral resolutions of wire targets were 16.4 µm and 10.6 µm by using 156 MHz 4 bit pseudo Golay coded excitation, respectively and 4.5 µm and 7.7 µm by using 312 MHz 4 bit pseudo Golay coded excitation, respectively.

scholarly journals From Rings to Bulges: Evidence for Rapid Secular Galaxy Evolution atz∼ 2 from Integral Field Spectroscopy in the SINS Survey

2008 ◽  
Vol 687 (1) ◽  
pp. 59-77 ◽  
Author(s):  
R. Genzel ◽  
A. Burkert ◽  
N. Bouché ◽  
G. Cresci ◽  
N. M. Förster Schreiber ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Integral Field Spectroscopy ◽  
Field Spectroscopy ◽  
Integral Field

scholarly journals Fast and High-Resolution Neonatal Brain MRI Through Super-Resolution Reconstruction From Acquisitions With Variable Slice Selection Direction

2021 ◽  
Vol 15 ◽  
Author(s):  
Yao Sui ◽  
Onur Afacan ◽  
Ali Gholipour ◽  
Simon K. Warfield
Keyword(s):  
High Resolution ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Signal To Noise Ratio ◽  
Brain Mri ◽  
Super Resolution ◽  
Neonatal Brain ◽  
Signal To Noise ◽  
High Quality ◽  
Noise Ratio

The brain of neonates is small in comparison to adults. Imaging at typical resolutions such as one cubic mm incurs more partial voluming artifacts in a neonate than in an adult. The interpretation and analysis of MRI of the neonatal brain benefit from a reduction in partial volume averaging that can be achieved with high spatial resolution. Unfortunately, direct acquisition of high spatial resolution MRI is slow, which increases the potential for motion artifact, and suffers from reduced signal-to-noise ratio. The purpose of this study is thus that using super-resolution reconstruction in conjunction with fast imaging protocols to construct neonatal brain MRI images at a suitable signal-to-noise ratio and with higher spatial resolution than can be practically obtained by direct Fourier encoding. We achieved high quality brain MRI at a spatial resolution of isotropic 0.4 mm with 6 min of imaging time, using super-resolution reconstruction from three short duration scans with variable directions of slice selection. Motion compensation was achieved by aligning the three short duration scans together. We applied this technique to 20 newborns and assessed the quality of the images we reconstructed. Experiments show that our approach to super-resolution reconstruction achieved considerable improvement in spatial resolution and signal-to-noise ratio, while, in parallel, substantially reduced scan times, as compared to direct high-resolution acquisitions. The experimental results demonstrate that our approach allowed for fast and high-quality neonatal brain MRI for both scientific research and clinical studies.

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