ABSTRACT
We estimate the intracluster light (ICL) component within a sample of 18 clusters detected in the XMM Cluster Survey (XCS) data using the deep (∼26.8 mag) Hyper Suprime-Cam Subaru Strategic ...Programme data release 1 i-band data. We apply a rest-frame μB = 25 mag arcsec−2 isophotal threshold to our clusters, below which we define light as the ICL within an aperture of RX,500 (X-ray estimate of R500) centred on the brightest cluster galaxy (BCG). After applying careful masking and corrections for flux losses from background subtraction, we recover ∼20 per cent of the ICL flux, approximately four times our estimate of the typical background at the same isophotal level (${\sim}5{{\ \rm per\ cent}}$). We find that the ICL makes up about ${\sim}24{{\ \rm per\ cent}}$ of the total cluster stellar mass on average (∼41 per cent including the flux contained in the BCG within 50 kpc); this value is well matched with other observational studies and semi-analytic/numerical simulations, but is significantly smaller than results from recent hydrodynamical simulations (even when measured in an observationally consistent way). We find no evidence for any links between the amount of ICL flux with cluster mass, but find a growth rate of 2–4 for the ICL between 0.1 < z < 0.5. We conclude that the ICL is the dominant evolutionary component of stellar mass in clusters from z ∼ 1. Our work highlights the need for a consistent approach when measuring ICL alongside the need for deeper imaging, in order to unambiguously measure the ICL across as broad a redshift range as possible (e.g. 10-yr stacked imaging from the Vera C. Rubin Observatory).
The size of the dust torus in active galactic nuclei (AGNs) and their high-luminosity counterparts, quasars, can be inferred from the time delay between UV/optical accretion disk continuum ...variability and the response in the mid-infrared (MIR) torus emission. This dust reverberation mapping (RM) technique has been successfully applied to ∼70 z 0.3 AGNs and quasars. Here we present first results of our dust RM program for distant quasars covered in the Sloan Digital Sky Survey Stripe 82 region combining ∼20 yr ground-based optical light curves with 10 yr MIR light curves from the WISE satellite. We measure a high-fidelity lag between W1 band (3.4 m) and g band for 587 quasars over 0.3 z 2 ( ) and two orders of magnitude in quasar luminosity. They tightly follow (intrinsic scatter ∼0.17 dex in lag) the IR lag-luminosity relation observed for z < 0.3 AGNs, revealing a remarkable size-luminosity relation for the dust torus over more than four decades in AGN luminosity, with little dependence on additional quasar properties such as Eddington ratio and variability amplitude. This study motivates further investigations in the utility of dust RM for cosmology and strongly endorses a compelling science case for the combined 10 yr Vera C. Rubin Observatory Legacy Survey of Space and Time (optical) and 5 yr Nancy Grace Roman Space Telescope 2 m light curves in a deep survey for low-redshift AGN dust RM with much lower luminosities and shorter, measurable IR lags. The compiled optical and MIR light curves for 7384 quasars in our parent sample are made public with this work.
Computationally expensive data processing in neuroimaging research places demands on energy consumption—and the resulting carbon emissions contribute to the climate crisis. We measured the carbon ...footprint of the functional magnetic resonance imaging (fMRI) preprocessing tool fMRIPrep, testing the effect of varying parameters on estimated carbon emissions and preprocessing performance. Performance was quantified using (a) statistical individual‐level task activation in regions of interest and (b) mean smoothness of preprocessed data. Eight variants of fMRIPrep were run with 257 participants who had completed an fMRI stop signal task (the same data also used in the original validation of fMRIPrep). Some variants led to substantial reductions in carbon emissions without sacrificing data quality: for instance, disabling FreeSurfer surface reconstruction reduced carbon emissions by 48%. We provide six recommendations for minimising emissions without compromising performance. By varying parameters and computational resources, neuroimagers can substantially reduce the carbon footprint of their preprocessing. This is one aspect of our research carbon footprint over which neuroimagers have control and agency to act upon.
Computing needed for data processing has a carbon footprint. We estimated the carbon emissions arising from eight variants of functional magnetic resonance imaging (fMRI) preprocessing pipeline fMRIPrep. Emissions can be reduced substantially without comprising preprocessing performance, measured using statistical activation and data smoothness. For instance, disabling FreeSurfer surface reconstruction reduced average emissions by 48%.
More often than not a lunch time conversation will veer off into bizarre and uncharted territories. In rare instances these frontiers of conversation can lead to deep insights about the Universe we ...inhabit. This paper details the fruits of one such conversation. In this paper we will answer the question: How many cows do you need to form a planetoid entirely comprised of cows, which will support a methane atmoosphere produced by the planetary herd? We will not only present the necessary assumptions and theory underpinning the cow-culations, but also present a thorough (and rather robust) discussion of the viability of, and implications for accomplishing, such a feat.
We study a phenomenological class of models where dark matter converts to dark radiation in the low redshift epoch. This class of models, dubbed DMDR, characterizes the evolution of comoving dark ...matter density with two extra parameters, and may be able to help alleviate the observed discrepancies between early- and late-time probes of the universe. We investigate how the conversion affects key cosmological observables such as the CMB temperature and matter power spectra. Combining 3x2pt data from Year 1 of the Dark Energy Survey, {\it Planck}-2018 CMB temperature and polarization data, supernovae (SN) Type Ia data from Pantheon, and baryon acoustic oscillation (BAO) data from BOSS DR12, MGS and 6dFGS, we place new constraints on the amount of dark matter that has converted to dark radiation and the rate of this conversion. The fraction of the dark matter that has converted since the beginning of the universe in units of the current amount of dark matter, \(\zeta\), is constrained at 68\% confidence level to be \(<0.32\) for DES-Y1 3x2pt data, \(<0.030\) for CMB+SN+BAO data, and \(<0.037\) for the combined dataset. The probability that the DES and CMB+SN+BAO datasets are concordant increases from 4\% for the \(\Lambda\)CDM model to 8\% (less tension) for DMDR. The tension in \(S_8 = \sigma_8 \sqrt{\Omega_{\rm m}/0.3}\) between DES-Y1 3x2pt and CMB+SN+BAO is slightly reduced from \(2.3\sigma\) to \(1.9\sigma\). We find no reduction in the Hubble tension when the combined data is compared to distance-ladder measurements in the DMDR model. The maximum-posterior goodness-of-fit statistics of DMDR and \(\Lambda\)CDM model are comparable, indicating no preference for the DMDR cosmology over \(\Lambda\)CDM.
We estimate the Intracluster Light (ICL) component within a sample of 18
clusters detected in XMM Cluster Survey (XCS) data using deep ($\sim$ 26.8 mag)
Hyper Suprime Cam Subaru Strategic Program DR1 ...(HSC-SSP DR1) $i$-band data. We
apply a rest-frame ${\mu}_{B} = 25 \ \mathrm{mag/arcsec^{2}}$ isophotal
threshold to our clusters, below which we define light as the ICL within an
aperture of $R_{X,500}$ (X-ray estimate of $R_{500}$) centered on the Brightest
Cluster Galaxy (BCG). After applying careful masking and corrections for flux
losses from background subtraction, we recover $\sim$20% of the ICL flux,
approximately four times our estimate of the typical background at the same
isophotal level ($\sim$ 5%). We find that the ICL makes up about $\sim$ 24% of
the total cluster stellar mass on average ($\sim$ 41% including the flux
contained in the BCG within 50 kpc); this value is well-matched with other
observational studies and semi-analytic/numerical simulations, but is
significantly smaller than results from recent hydrodynamical simulations (even
when measured in an observationally consistent way). We find no evidence for
any links between the amount of ICL flux with cluster mass, but find a growth
rate of $2-4$ for the ICL between $0.1 < z < 0.5$. We conclude that the ICL is
the dominant evolutionary component of stellar mass in clusters from $z \sim
1$. Our work highlights the need for a consistent approach when measuring ICL
alongside the need for deeper imaging, in order to unambiguously measure the
ICL across as broad a redshift range as possible (e.g. 10-year stacked imaging
from the Vera C. Rubin Observatory).
We present the statistical methods that have been developed to analyse the OzDES reverberation mapping sample. To perform this statistical analysis we have created a suite of customisable simulations ...that mimic the characteristics of each source in the OzDES sample. These characteristics include: the variability in the photometric and spectroscopic lightcurves, the measurement uncertainties, and the observational cadence. By simulating the sources in the OzDES sample that contain the CIV emission line, we developed a set of criteria that rank the reliability of a recovered time lag depending on the agreement between different recovery methods, the magnitude of the uncertainties, and the rate at which false positives were found in the simulations. These criteria were applied to simulated light curves and these results used to estimate the quality of the resulting Radius-Luminosity relation.We grade the results using three quality levels (gold, silver and bronze). The input slope of the R-L relation was recovered within \(1\sigma\) for each of the three quality samples, with the gold standard having the lowest dispersion with a recovered a R-L relation slope of \(0.454\pm 0.016\) with an input slope of 0.47. Future work will apply these methods to the entire OzDES sample of 771 AGN.
The size of the dust torus in Active Galactic Nuclei (AGN) and their high-luminosity counterparts, quasars, can be inferred from the time delay between UV/optical accretion disk continuum variability ...and the response in the mid-infrared (MIR) torus emission. This dust reverberation mapping (RM) technique has been successfully applied to \(\sim 70\) \(z\lesssim 0.3\) AGN and quasars. Here we present first results of our dust RM program for distant quasars covered in the SDSS Stripe 82 region combining \(\sim 20\)-yr ground-based optical light curves with 10-yr MIR light curves from the WISE satellite. We measure a high-fidelity lag between W1-band (3.4 \(\mu\)m) and \(g\) band for 587 quasars over \(0.3\lesssim z\lesssim 2\) (\(\left<z\right>\sim 0.8\)) and two orders of magnitude in quasar luminosity. They tightly follow (intrinsic scatter \(\sim 0.17\) dex in lag) the IR lag-luminosity relation observed for \(z<0.3\) AGN, revealing a remarkable size-luminosity relation for the dust torus over more than four decades in AGN luminosity, with little dependence on additional quasar properties such as Eddington ratio and variability amplitude. This study motivates further investigations in the utility of dust RM for cosmology, and strongly endorses a compelling science case for the combined 10-yr Vera C. Rubin Observatory Legacy Survey of Space and Time (optical) and 5-yr Nancy Grace Roman Space Telescope 2\(\mu\)m light curves in a deep survey for low-redshift AGN dust RM with much lower luminosities and shorter, measurable IR lags. The compiled optical and MIR light curves for 7,384 quasars in our parent sample are made public with this work.
We estimate the Intracluster Light (ICL) component within a sample of 18 clusters detected in XMM Cluster Survey (XCS) data using deep (\(\sim\) 26.8 mag) Hyper Suprime Cam Subaru Strategic Program ...DR1 (HSC-SSP DR1) \(i\)-band data. We apply a rest-frame \({\mu}_{B} = 25 \ \mathrm{mag/arcsec^{2}}\) isophotal threshold to our clusters, below which we define light as the ICL within an aperture of \(R_{X,500}\) (X-ray estimate of \(R_{500}\)) centered on the Brightest Cluster Galaxy (BCG). After applying careful masking and corrections for flux losses from background subtraction, we recover \(\sim\)20% of the ICL flux, approximately four times our estimate of the typical background at the same isophotal level (\(\sim\) 5%). We find that the ICL makes up about \(\sim\) 24% of the total cluster stellar mass on average (\(\sim\) 41% including the flux contained in the BCG within 50 kpc); this value is well-matched with other observational studies and semi-analytic/numerical simulations, but is significantly smaller than results from recent hydrodynamical simulations (even when measured in an observationally consistent way). We find no evidence for any links between the amount of ICL flux with cluster mass, but find a growth rate of \(2-4\) for the ICL between \(0.1 < z < 0.5\). We conclude that the ICL is the dominant evolutionary component of stellar mass in clusters from \(z \sim 1\). Our work highlights the need for a consistent approach when measuring ICL alongside the need for deeper imaging, in order to unambiguously measure the ICL across as broad a redshift range as possible (e.g. 10-year stacked imaging from the Vera C. Rubin Observatory).
The relationship between aphids and their host plants is thought to be functionally analogous to plant-pathogen interactions. Although virulence effector proteins that mediate plant defenses are ...well-characterized for pathogens such as bacteria, oomycetes, and nematodes, equivalent molecules in aphids and other phloem-feeders are poorly understood. A dual transcriptomic-proteomic approach was adopted to generate a catalog of candidate effector proteins from the salivary glands of the pea aphid, Acyrthosiphon pisum. Of the 1557 transcript supported and 925 mass spectrometry identified proteins, over 300 proteins were identified with secretion signals, including proteins that had previously been identified directly from the secreted saliva. Almost half of the identified proteins have no homologue outside aphids and are of unknown function. Many of the genes encoding the putative effector proteins appear to be evolving at a faster rate than homologues in other insects, and there is strong evidence that genes with multiple copies in the genome are under positive selection. Many of the candidate aphid effector proteins were previously characterized in typical phytopathogenic organisms (e.g., nematodes and fungi) and our results highlight remarkable similarities in the saliva from plant-feeding nematodes and aphids that may indicate the evolution of common solutions to the plant-parasitic lifestyle.
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