Abstract
The fraction of galaxies supported by internal rotation compared to galaxies stabilized by internal pressure provides a strong constraint on galaxy formation models. In integral field ...spectroscopy surveys, this fraction is biased because survey instruments typically only trace the inner parts of the most massive galaxies. We present aperture corrections for the two most widely used stellar kinematic quantities V/σ and λR (spin parameter proxy). Our demonstration involves integral field data from the SAMI (Sydney-AAO Multi-object Integral-field spectrograph) Galaxy Survey and the ATLAS3D survey. We find a tight relation for both V/σ and λR when measured in different apertures that can be used as a linear transformation as a function of radius, i.e. a first-order aperture correction. In degraded seeing, however, the aperture corrections are more significant as the steeper inner profile is more strongly affected by the point spread function than the outskirts. We find that V/σ and λR radial growth curves are well approximated by second-order polynomials. By only fitting the inner profile (0.5Re), we successfully recover the profile out to one Re if a constraint between the linear and quadratic parameter in the fit is applied. However, the aperture corrections for V/σ and λR derived by extrapolating the profiles perform as well as applying a first-order correction. With our aperture-corrected λR measurements, we find that the fraction of slow rotating galaxies increases with stellar mass. For galaxies with log M*/M⊙ > 11, the fraction of slow rotators is 35.9 ± 4.3 per cent, but is underestimated if galaxies without coverage beyond one Re are not included in the sample (24.2 ± 5.3 per cent). With measurements out to the largest aperture radius, the slow rotator fraction is similar as compared to using aperture-corrected values (38.3 ± 4.4 per cent). Thus, aperture effects can significantly bias stellar kinematic integral field spectrograph studies, but this bias can now be removed with the method outlined here.
The coronavirus disease 2019 pandemic has made deployment of an effective vaccine a global health priority. We evaluated the protective activity of a chimpanzee adenovirus-vectored vaccine encoding a ...prefusion stabilized spike protein (ChAd-SARS-CoV-2-S) in challenge studies with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and mice expressing the human angiotensin-converting enzyme 2 receptor. Intramuscular dosing of ChAd-SARS-CoV-2-S induces robust systemic humoral and cell-mediated immune responses and protects against lung infection, inflammation, and pathology but does not confer sterilizing immunity, as evidenced by detection of viral RNA and induction of anti-nucleoprotein antibodies after SARS-CoV-2 challenge. In contrast, a single intranasal dose of ChAd-SARS-CoV-2-S induces high levels of neutralizing antibodies, promotes systemic and mucosal immunoglobulin A (IgA) and T cell responses, and almost entirely prevents SARS-CoV-2 infection in both the upper and lower respiratory tracts. Intranasal administration of ChAd-SARS-CoV-2-S is a candidate for preventing SARS-CoV-2 infection and transmission and curtailing pandemic spread.
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•Chimpanzee adenoviral vaccines encoding stabilized S induce neutralizing Abs•Chimpanzee adenoviral vaccines protect against SARS-CoV-2 infection and pneumonia•Intranasal vaccine delivery generates robust mucosal B and T cell responses•Intranasal ChAd-SARS-CoV-2 prevents upper and lower respiratory tract infection
Intranasal or intramuscular immunization of ChAd-SARS-CoV-2, a chimpanzee adenoviral vaccine encoding stabilized spike protein, prevents SARS-CoV-2 lung infection and pneumonia in mice. In particular, intranasally delivered ChAd-SARS-CoV-2 uniquely prevents both upper and lower respiratory tract infections, potentially protecting against SARS-CoV-2 infection and transmission.
Abstract Close binary systems present challenges to planet formation. As binary separations decrease, so do the occurrence rates of protoplanetary disks in young systems and planets in mature ...systems. For systems that do retain disks, their disk masses and sizes are altered by the presence of the binary companion. Through the study of protoplanetary disks in binary systems with known orbital parameters, we seek to determine the properties that promote disk retention and therefore planet formation. In this work, we characterize the young binary−disk system FO Tau. We determine the first full orbital solution for the system, finding masses of 0.35 − 0.05 + 0.06 M ⊙ and 0.34 ± 0.05 M ⊙ for the stellar components, a semimajor axis of 22 ( − 1 + 2 ) au, and an eccentricity of 0.21 ( − 0.03 + 0.04 ) . With long-baseline Atacama Large Millimeter/submillimeter Array interferometry, we detect 1.3 mm continuum and 12 CO ( J = 2–1) line emission toward each of the binary components; no circumbinary emission is detected. The protoplanetary disks are compact, consistent with being truncated by the binary orbit. The dust disks are unresolved in the image plane, and the more extended gas disks are only marginally resolved. Fitting the continuum and CO visibilities, we determine the inclination of each disk, finding evidence for alignment of the disk and binary orbital planes. This study is the first of its kind linking the properties of circumstellar protoplanetary disks to a precisely known binary orbit. In the case of FO Tau, we find a dynamically placid environment (coplanar, low eccentricity), which may foster its potential for planet formation.
We investigate the environmental dependence of the local gas-phase metallicity in a sample of star-forming galaxies from the MaNGA survey. Satellite galaxies with stellar masses in the range are ...found to be ∼0.05 dex higher in metallicity than centrals of similar stellar mass. Within the low-mass satellite population, we find that the interstellar medium (ISM) metallicity depends most strongly on the stellar mass of the galaxy that is central to the halo, though there is no obvious difference in the metallicity gradients. At fixed total stellar mass, the satellites of high-mass (M* > 1010.5 M ) centrals are ∼0.1 dex more metal-rich than the satellites of low-mass (M* < 1010 M ) centrals, controlling for local stellar mass surface density and gas fraction. Fitting a gas regulator model to the spaxel data, we are able to account for variations in the local gas fraction, stellar mass surface density, and local escape velocity-dependent outflows. We find that the best explanation for the metallicity differences is the variation in the average metallicity of accreted gas between different environments that depends on the stellar mass of the dominant galaxies in each halo. This is interpreted as evidence for the exchange of enriched gas between galaxies in dense environments that is predicted by recent simulations.
We present
lzifu
(LaZy-IFU), an
idl
toolkit for fitting multiple emission lines simultaneously in integral field spectroscopy (IFS) data.
lzifu
is useful for the investigation of the dynamical, ...physical and chemical properties of gas in galaxies.
lzifu
has already been applied to many world-class IFS instruments and large IFS surveys, including the Wide Field Spectrograph, the new Multi Unit Spectroscopic Explorer (MUSE), the Calar Alto Legacy Integral Field Area (CALIFA) survey, the Sydney-Australian-astronomical-observatory Multi-object Integral-field spectrograph (SAMI) Galaxy Survey. Here we describe in detail the structure of the toolkit, and how the line fluxes and flux uncertainties are determined, including the possibility of having multiple distinct kinematic components. We quantify the performance of
lzifu
, demonstrating its accuracy and robustness. We also show examples of applying
lzifu
to CALIFA and SAMI data to construct emission line and kinematic maps, and investigate complex, skewed line profiles presented in IFS data. The code is made available to the astronomy community through github.
lzifu
will be further developed over time to other IFS instruments, and to provide even more accurate line and uncertainty estimates.
Abstract
We present an updated prescription for the equilibrium tides suitable for population synthesis codes. A grid of 1D evolutionary models was created and the viscous timescale was calculated ...for each detailed model. A metallicity-dependent power-law relation was fitted to both the convective cores and convective envelopes of the models. The prescription was implemented into the population synthesis code Binary Star Evolution and predicts a 16.5% reduction in the overall number of merges, with those involving main-sequence stars most affected. The new prescription also reduces the overall supernova rate by 3.6% with individual channels being differently affected. The single degenerate Ia supernova occurrence is reduced by 12.8%. The merging of two carbon oxygen white dwarfs to cause a Ia supernova occurs 16% less frequently. The number of subsynchronously rotating stars in close binaries is substantially increased with our prescription, as is the number of noncircularized systems at the start of common-envelope evolution.
A galaxy's stellar mass is one of its most fundamental properties, but it remains challenging to measure reliably. With the advent of very large optical spectroscopic surveys, efficient methods that ...can make use of low signal-to-noise spectra are needed. With this in mind, we created a new software package for estimating effective stellar mass-to-light ratios that uses a principal component analysis (PCA) basis set to optimize the comparison between observed spectra and a large library of stellar population synthesis models. In Paper I, we showed that with a set of six PCA basis vectors we could faithfully represent most optical spectra from the Mapping Nearby Galaxies at APO (MaNGA) survey, and we tested the accuracy of our M/L estimates using synthetic spectra. Here, we explore sources of systematic error in our mass measurements by comparing our new measurements to data from the literature. We compare our stellar mass surface density estimates to kinematics-derived dynamical mass surface density measurements from the DiskMass Survey and find some tension between the two that could be resolved if the disk scale heights used in the kinematic analysis were overestimated by a factor of ∼1.5. We formulate an aperture-corrected stellar mass catalog for the MaNGA survey, and compare to previous stellar mass estimates based on multiband optical photometry, finding typical discrepancies of 0.1 dex. Using the spatially resolved MaNGA data, we evaluate the impact of estimating total stellar masses from spatially unresolved spectra, and we explore how the biases that result from unresolved spectra depend upon the galaxy's dust extinction and star formation rate. Finally, we describe an SDSS Value-Added Catalog that will include both spatially resolved and total (aperture-corrected) stellar masses for MaNGA galaxies.
Gaseous inflows are necessary suppliers of galaxies' star-forming fuel, but are difficult to characterize at the survey scale. We use integral-field spectroscopic measurements of gas-phase ...metallicity and single-dish radio measurements of total atomic gas mass to estimate the magnitude and frequency of gaseous inflows incident on star-forming galaxies. We reveal a mutual correlation between steep oxygen abundance profiles between 0.25 and 1.5 Re, increased variability of metallicity between 1.25 and 1.75 Re, and elevated H i content at fixed total galaxy stellar mass. Employing a simple but intuitive inflow model, we find that galaxies with total stellar mass less than 1010.1 M have local oxygen abundance profiles consistent with reinvigoration by inflows. Approximately 10%-25% of low-mass galaxies possess signatures of recent accretion, with estimated typical enhancements of approximately 10%-90% in local gas mass surface density. Higher-mass galaxies have limited evidence for such inflows. The large diversity of H i mass implies that inflow-associated gas ought to reside far from the star-forming disk. We therefore propose that a combination of high H i mass, steep metallicity profile between 0.25 and 1.5 Re, and wide metallicity distribution function between 1.25 and 1.75 Re be employed to target possible hosts of inflowing gas for high-resolution radio follow-up.
Abstract
We present, for the first time, the relationship between local stellar mass surface density, Σ
*
, and N/O derived from SDSS-IV MaNGA data, using a sample of 792,765 high signal-to-noise ...ratio star-forming spaxels. Using a combination of phenomenological modeling and partial correlation analysis, we find that Σ
*
alone is insufficient to predict the N/O in MaNGA spaxels and that there is an additional dependence on the local star formation rate surface density, Σ
SFR
. This effect is a factor of 3 stronger than the dependence of 12+log(O/H) on Σ
SFR
. Surprisingly, we find that the local N/O scaling relations also depend on the total galaxy stellar mass at fixed Σ
*
and the galaxy size at fixed stellar mass. We find that more compact galaxies are more nitrogen rich, even when Σ
*
and Σ
SFR
are controlled for. We show that ∼50% of the variance of N/O is explained by the total stellar mass and size. Thus, the evolution of nitrogen in galaxies is set by more than just local effects and does not simply track the buildup of oxygen in galaxies. The precise form of the N/O–O/H relation is therefore sensitive to the sample of galaxies from which it is derived. This result casts doubt on the universal applicability of nitrogen-based strong-line metallicity indicators derived in the local universe.
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