808 research outputs found
Compact to extended Lyman- emitters in MAGPI: strong blue peak emission at
We report the discovery of three double-peaked Lyman- emitters (LAEs)
exhibiting strong blue peak emission at 2.9 4.8, in the
VLT/MUSE data obtained as part of the Middle Ages Galaxy Properties with
Integral Field Spectroscopy (MAGPI) survey. These strong blue peak systems
provide a unique window into the scattering of Lyman- photons by
neutral hydrogen (HI), suggesting gas inflows along the line-of-sight and low
HI column density. Two of them at and are spatially extended
halos with their core regions clearly exhibiting stronger blue peak emissions
than the red peak. However, spatial variations in the peak ratio and peak
separation are evident over kpc () and kpc
() regions in these extended halos. Notably, these systems do not fall
in the regime of Lyman- blobs or nebulae. To the best of our knowledge,
such a Lyman- halo with a dominant blue core has not been observed
previously. In contrast, the LAE at is a compact system spanning a
kpc region and stands as the highest-redshift strong blue peak
emitter ever detected. The peak separation of the bright cores in these three
systems ranges from to km/s. The observed
overall trend of decreasing peak separation with increasing radius is supposed
to be controlled by HI column density and gas covering fraction. Based on
various estimations, in contrast to the compact LAE, our halos are found to be
good candidates for LyC leakers. These findings shed light on the complex
interplay between Lyman- emission, gas kinematics, and ionising
radiation properties, offering valuable insights into the evolution and nature
of high-redshift galaxies.Comment: 2 Figures, 1 Table, accepted for A&A Letter
SimSpin v2.6.0 -- Constructing synthetic spectral IFU cubes for comparison with observational surveys
In this work, we present a methodology and a corresponding code-base for
constructing mock integral field spectrograph (IFS) observations of simulated
galaxies in a consistent and reproducible way. Such methods are necessary to
improve the collaboration and comparison of observation and theory results, and
accelerate our understanding of how the kinematics of galaxies evolve over
time. This code, SimSpin, is an open-source package written in R, but also with
an API interface such that the code can be interacted with in any coding
language. Documentation and individual examples can be found at the open-source
website connected to the online repository. SimSpin is already being utilised
by international IFS collaborations, including SAMI and MAGPI, for generating
comparable data sets from a diverse suite of cosmological hydrodynamical
simulations.Comment: 20 pages, 15 figures, 2 tables. Accepted for publication in PASA.
30/08/2
Light absorption by anthocyanins in juvenile, stressed, and senescing leaves
The optical properties of leaves from five species, Norway maple (Acer platanoides L.), cotoneaster (Cotoneaster alaunica Golite), hazel (Corylus avellana L.), Siberian dogwood (Cornus alba L.), and Virginia creeper (Parthenocissus quinquefolia (L.) Planch.), differing in pigment composition and at different stages of ontogenesis, were studied. Anthocyanin absorption maxima in vivo, as estimated with spectrophotometry of intact anthocyanic versus acyanic leaves and microspectrophotometry of vacuoles in the leaf cross-sections, were found between 537 nm and 542 nm, showing a red shift of 5–20 nm compared with the corresponding maxima in acidic water–methanol extracts. In non-senescent leaves, strong anthocyanin absorption was found between 500 nm and 600 nm (with a 70–80 nm apparent bandwidth). By and large, absorption by anthocyanin in leaves followed a modified form of the Lambert–Beer law, showing a linear trend up to a content of nearly 50 nmol cm−2, and permitting thereby a non-invasive determination of anthocyanin content. The apparent specific absorption coefficients of anthocyanins at 550 nm showed no substantial dependence on the species. Anthocyanin contribution to total light absorption at 550 nm was followed in maple leaves in the course of autumn senescence. Photoprotection by vacuolar anthocyanins is discussed with special regard to their distribution within a leaf; radiation screening by anthocyanins predominantly localized in the epidermal cells in A. platanoides and C. avellana leaves was also evaluated
A systems approach to identifying correlated gene targets for the loss of colour pigmentation in plants
<p>Abstract</p> <p>Background</p> <p>The numerous diverse metabolic pathways by which plant compounds can be produced make it difficult to predict how colour pigmentation is lost for different tissues and plants. This study employs mathematical and <it>in silico </it>methods to identify correlated gene targets for the loss of colour pigmentation in plants from a whole cell perspective based on the full metabolic network of <it>Arabidopsis</it>. This involves extracting a self-contained flavonoid subnetwork from the AraCyc database and calculating feasible metabolic routes or elementary modes (EMs) for it. Those EMs leading to anthocyanin compounds are taken to constitute the anthocyanin biosynthetic pathway (ABP) and their interplay with the rest of the EMs is used to study the minimal cut sets (MCSs), which are different combinations of reactions to block for eliminating colour pigmentation. By relating the reactions to their corresponding genes, the MCSs are used to explore the phenotypic roles of the ABP genes, their relevance to the ABP and the impact their eliminations would have on other processes in the cell.</p> <p>Results</p> <p>Simulation and prediction results of the effect of different MCSs for eliminating colour pigmentation correspond with existing experimental observations. Two examples are: i) two MCSs which require the simultaneous suppression of genes DFR and ANS to eliminate colour pigmentation, correspond to observational results of the same genes being co-regulated for eliminating floral pigmentation in <it>Aquilegia </it>and; ii) the impact of another MCS requiring CHS suppression, corresponds to findings where the suppression of the early gene CHS eliminated nearly all flavonoids but did not affect the production of volatile benzenoids responsible for floral scent.</p> <p>Conclusions</p> <p>From the various MCSs identified for eliminating colour pigmentation, several correlate to existing experimental observations, indicating that different MCSs are suitable for different plants, different cells, and different conditions and could also be related to regulatory genes. Being able to correlate the predictions with experimental results gives credence to the use of these mathematical and <it>in silico </it>analyses methods in the design of experiments. The methods could be used to prioritize target enzymes for different objectives to achieve desired outcomes, especially for less understood pathways.</p
The MAGPI Survey: impact of environment on the total internal mass distribution of galaxies in the last 5 Gyr
We investigate the impact of environment on the internal mass distribution of galaxies using the Middle Ages Galaxy Properties with Integral field spectroscopy (MAGPI) survey. We use 2D resolved stellar kinematics to construct Jeans dynamical models for galaxies at mean redshift z ∼ 0.3, corresponding to a lookback time of 3–4 Gyr. The internal mass distribution for each galaxy is parametrized by the combined mass density slope γ (baryons + dark matter), which is the logarithmic change of density with radius. We use a MAGPI sample of 28 galaxies from low-to-mid density environments and compare to density slopes derived from galaxies in the high density Frontier Fields clusters in the redshift range 0.29 < z < 0.55, corresponding to a lookback time of ∼5 Gyr. We find a median density slope of γ = −2.22 ± 0.05 for the MAGPI sample, which is significantly steeper than the Frontier Fields median slope (γ = −2.00 ± 0.04), implying the cluster galaxies are less centrally concentrated in their mass distribution than MAGPI galaxies. We also compare to the distribution of density slopes from galaxies in ATLAS3D at z ∼ 0, because the sample probes a similar environmental range as MAGPI. The ATLAS3D median total slope is γ = −2.25 ± 0.02, consistent with the MAGPI median. Our results indicate environment plays a role in the internal mass distribution of galaxies, with no evolution of the slope in the last 3–4 Gyr. These results are in agreement with the predictions of cosmological simulations
The MAGPI Survey: Drivers of kinematic asymmetries in the ionised gas of star-forming galaxies
Galaxy gas kinematics are sensitive to the physical processes that contribute
to a galaxy's evolution. It is expected that external processes will cause more
significant kinematic disturbances in the outer regions, while internal
processes will cause more disturbances for the inner regions. Using a subsample
of 47 galaxies () from the Middle Ages Galaxy Properties with
Integral Field Spectroscopy (MAGPI) survey, we conduct a study into the source
of kinematic disturbances by measuring the asymmetry present in the ionised gas
line-of-sight velocity maps at the (inner regions) and (outer
regions) elliptical annuli. By comparing the inner and outer kinematic
asymmetries, we aim to better understand what physical processes are driving
the asymmetries in galaxies. We find the local environment plays a role in
kinematic disturbance, in agreement with other integral field spectroscopy
studies of the local universe, with most asymmetric systems being in close
proximity to a more massive neighbour. We do not find evidence suggesting that
hosting an Active Galactic Nucleus (AGN) contributes to asymmetry within the
inner regions, with some caveats due to emission line modelling. In contrast to
previous studies, we do not find evidence that processes leading to asymmetry
also enhance star formation in MAGPI galaxies. Finally, we find a weak
anti-correlation between stellar mass and asymmetry (ie. high stellar mass
galaxies are less asymmetric). We conclude by discussing possible sources
driving the asymmetry in the ionised gas, such as disturbances being present in
the colder gas phase (either molecular or atomic) prior to the gas being
ionised, and non-axisymmetric features (e.g., a bar) being present in the
galactic disk. Our results highlight the complex interplay between ionised gas
kinematic disturbances and physical processes involved in galaxy evolution.Comment: e.g., 20 pages, 19 figure
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