Correspondence to Sarah Rickard; Sarah.Rickard@nca.nhs.uk Introduction The National Health Service (NHS) England and Improvement (NHSE/I) blood pressure monitoring at home (BPM@Home) initiative was ...launched in 2020 in response to the COVID-19 pandemic to improve hypertension control while reducing GP appointments.1 Home blood pressure (BP) monitoring (HBPM), a better indicator of long-term morbidity and mortality than clinic readings,2 may reduce costs and complications of unnecessary antihypertension treatment in at least 10%–15% of the population with white coat hypertension,3 while facilitating appropriate treatment of elevated high home BP not detected in clinic. Mean systolic BP readings with 95% confidence intervals for periods within the study (including participant numbers) Discussion BPM@Home can be implemented rapidly in a community stroke setting where thoroughly trained CST nurses supervise and cascade training to other staff and patients and expedite timely HBPM control. Home blood pressure monitoring: methodology, clinical relevance and practical application: a 2021 position paper by the working group on blood pressure monitoring and cardiovascular variability of the European society of hypertension.
Radio galaxies are luminous structures created by the jets of supermassive black holes, and consist of atomic nuclei, relativistic electrons, and magnetic fields. In exceptional cases, radio galaxies ...attain cosmological, megaparsec extents - and thus turn into giants. Giants embody the most extreme known mechanism through which galaxies can impact the Cosmic Web around them. The triggers of giant growth remain a mystery. Excitingly, new sensitive low-frequency sky surveys hold promise to change this situation. In this work, we perform a precision measurement of the distribution of giant growth's central dynamical quantity: total length. We first construct a statistical geometric framework for radio galaxies that is both rigorous and practical. We then search the LOFAR Two-metre Sky Survey DR2 for giants, discovering 2050 previously unknown specimina: more than have been found in all preceding literature combined. Spectacular discoveries include the longest giant hosted by an elliptical galaxy, the longest giant hosted by a spiral galaxy, and 13 giants with an angular length larger than that of the full Moon. By combining theory and observations - and carefully forward modelling selection effects - we infer that giant radio galaxy lengths are well described by a Pareto distribution with tail index $-3.5 \pm 0.5$. This finding is a new observational constraint for models and simulations of radio galaxy growth. In addition, for the first time, we determine the comoving number density of giants, $5 \pm 2\ (100\ \mathrm{Mpc})^{-3}$, and the volume-filling fraction of giant radio galaxy lobes in clusters and filaments, $5\substack{+8\\-2}\cdot 10^{-6}$. We conclude that giants are truly rare - not only from an observational perspective, but also from a cosmological one. At any moment in time, most clusters and filaments - the building blocks of the modern Cosmic Web - do not harbour giants.
Faraday tomography of LoTSS-DR2 data Erceg, Ana; Jelić, Vibor; Haverkorn, Marijke ...
Astronomy and astrophysics (Berlin),
07/2022, Letnik:
663
Journal Article
Recenzirano
Odprti dostop
Context.
Observations of synchrotron emission at low radio frequencies reveal a labyrinth of polarised Galactic structures. However, the explanation for the wealth of structures remains uncertain due ...to the complex interactions between the interstellar medium and the magnetic field. A multi-tracer approach to the analysis of large sky areas is needed.
Aims.
This paper aims to use polarimetric images from the LOFAR Two metre Sky Survey to produce the biggest mosaic of polarised emission in the northern sky at low radio frequencies (150 MHz) to date. The large area this mosaic covers allows for detailed morphological and statistical studies of polarised structures in the high-latitude outer Galaxy, including the well-known Loop III region.
Methods.
We produced a 3100 square degree Faraday tomographic cube using a rotation measure synthesis tool. We calculated the statistical moments of Faraday spectra and compared them with data sets at higher frequencies (1.4 GHz) and with a map of a rotation measure derived from extragalactic sources.
Results.
The mosaic is dominated by polarised emission connected to Loop III. Additionally, the mosaic reveals an abundance of other morphological structures, mainly narrow and extended depolarisation canals, which are found to be ubiquitous.
Conclusions.
We find a correlation between the map of an extragalactic rotation measure and the LoTSS first Faraday moment image. The ratio of the two deviates from a simple model of a Burn slab (Burn, B. J. 1966, MNRAS, 133, 67) along the line of sight, which highlights the high level of complexity in the magnetoionic medium that can be studied at these frequencies.
Context.
The Low Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS) is a low-frequency radio continuum survey of the Northern sky at an unparalleled resolution and sensitivity.
Aims.
In order to ...fully exploit this huge dataset and those produced by the Square Kilometre Array in the next decade, automated methods in machine learning and data-mining will be increasingly essential both for morphological classifications and for identifying optical counterparts to the radio sources.
Methods.
Using self-organising maps (SOMs), a form of unsupervised machine learning, we created a dimensionality reduction of the radio morphologies for the ∼25k extended radio continuum sources in the LoTSS first data release, which is only ∼2 percent of the final LoTSS survey. We made use of
PINK
, a code which extends the SOM algorithm with rotation and flipping invariance, increasing its suitability and effectiveness for training on astronomical sources.
Results.
After training, the SOMs can be used for a wide range of science exploitation and we present an illustration of their potential by finding an arbitrary number of morphologically rare sources in our training data (424 square degrees) and subsequently in an area of the sky (∼5300 square degrees) outside the training data. Objects found in this way span a wide range of morphological and physical categories: extended jets of radio active galactic nuclei, diffuse cluster haloes and relics, and nearby spiral galaxies. Finally, to enable accessible, interactive, and intuitive data exploration, we showcase the LOFAR-PyBDSF Visualisation Tool, which allows users to explore the LoTSS dataset through the trained SOMs.
Abstract
Ram pressure stripping is a crucial evolutionary driver for cluster galaxies. It is thought to be able to accelerate the evolution of their star formation, trigger the activity of their ...central active galactic nucleus (AGN) and the interplay between galactic and environmental gas, and eventually dissipate their gas reservoirs. We explored the outcomes of ram pressure stripping by studying the nonthermal radio emission of the jellyfish galaxy JW100 in the cluster A2626 (
z
= 0.055), by combining LOw Frequency Array, MeerKAT, and Very Large Array observations from 0.144 to 5.5 GHz. We studied the integrated spectra of the stellar disk, the stripped tail, and the AGN; mapped the spectral index over the galaxy; and constrained the magnetic field intensity to between 11 and 18
μ
G in the disk and <10
μ
G in the tail. The stellar disk radio emission is dominated by a radiatively old plasma, likely related to an older phase of a high star formation rate. This suggests that the star formation was quickly quenched by a factor of 4 in a few 10
7
yr. The radio emission in the tail is consistent with the stripping scenario, where the radio plasma that originally accelerated in the disk is subsequently displaced in the tail. The morphology of the radio and X-ray emissions supports the scenario of the accretion of magnetized environmental plasma onto the galaxy. The AGN nonthermal spectrum indicates that relativistic electron acceleration may have occurred simultaneously with a central ionized gas outflow, thus suggesting a physical connection between the two processes.
Luminous giants populate the dense Cosmic Web Martijn S. S. L. Oei; van Weeren, Reinout J; Hardcastle, Martin J ...
Astronomy and astrophysics (Berlin),
06/2024, Letnik:
686
Journal Article
Recenzirano
Context. Giant radio galaxies (GRGs, giant RGs, or giants) are megaparsec-scale, jet-driven outflows from accretion disks of supermassive black holes, and represent the most extreme pathway by which ...galaxies can impact the Cosmic Web around them. A long-standing but unresolved question is why giants are so much larger than other radio galaxies. Aims. It has been proposed that, in addition to having higher jet powers than most RGs, giants might live in especially low-density Cosmic Web environments. In this work, we aim to test this hypothesis by pinpointing Local Universe giants and other RGs in physically principled, Bayesian large-scale structure reconstructions. Methods. More specifically, we localised a LOFAR Two-metre Sky Survey (LoTSS) DR2–dominated sample of luminous (lν(ν = 150 MHz)≥1024 W Hz−1) giants and a control sample of LoTSS DR1 RGs, both with spectroscopic redshifts up to zmax = 0.16, in the BORG SDSS Cosmic Web reconstructions. We measured the Cosmic Web density on a smoothing scale of ∼2.9 Mpc h−1 for each RG; for the control sample, we then quantified the relation between RG radio luminosity and Cosmic Web density. With the BORG SDSS tidal tensor, we also measured for each RG whether the gravitational dynamics of its Cosmic Web environment resemble those of clusters, filaments, sheets, or voids. Results. For both luminous giants and general RGs, the Cosmic Web density distribution is gamma distribution–like. Luminous giants populate large-scale environments that tend to be denser than those of general RGs. This result is corroborated by gravitational dynamics classification and a cluster catalogue crossmatching analysis. We find that the Cosmic Web density around RGs with 150 MHz radio luminosity lν is distributed as 1 + ΔRG | Lν = lν ∼ Γ(k, θ), where k = 4.8 + 0.2 · √, θ = 1.4 + 0.02 · √, and √:= log10(lν (1023 W Hz−1)−1). Conclusions. This work presents more than a thousand inferred megaparsec-scale densities around radio galaxies, which may be correct up to a factor of order unity – except in clusters of galaxies, where the densities can be more than an order of magnitude too low. We pave the way to a future in which megaparsec-scale densities around RGs are common inferred quantities, which help to better understand their dynamics, morphology, and interaction with the enveloping Cosmic Web. Our data demonstrate that luminous giants inhabit denser environments than general RGs. This shows that – at least at high jet powers – low-density environments are no prerequisite for giant growth. Using general RGs, we quantified the relation between radio luminosity at 150 MHz and Cosmic Web density on a smoothing scale of ∼2.9 Mpc h−1. This positive relation, combined with the discrepancy in radio luminosity between known giants and general RGs, reproduces the discrepancy in Cosmic Web density between known giants and general RGs. Our findings are consistent with the view that giants are regular, rather than mechanistically special, members of the radio galaxy population.
Abstract
Jellyfish galaxies, characterized by long filaments of stripped interstellar medium extending from their disks, are the prime laboratories to study the outcomes of ram pressure stripping. At ...radio wavelengths, they often show unilateral emission extending beyond the stellar disk, and an excess of radio luminosity with respect to that expected from their current star formation rate. We present new 144 MHz images provided by the LOFAR Two-metre Sky Survey for a sample of six galaxies from the GASP survey. These galaxies are characterized by a high global luminosity at 144 MHz (6−27 × 10
22
W Hz
−1
), in excess compared to their ongoing star formation rate. The comparison of radio and H
α
images smoothed with a Gaussian beam corresponding to ∼10 kpc reveals a sublinear spatial correlation between the two emissions with an average slope of
k
= 0.50. In their stellar disk we measure
k
= 0.77, which is close to the radio-to-star formation linear relation. We speculate that, as a consequence of the ram pressure, in these jellyfish galaxies cosmic ray transport is more efficient than in normal galaxies. Radio tails typically have higher radio-to-H
α
ratios than the disks, thus we suggest that the radio emission is boosted by electrons stripped from the disks. In all galaxies, the star formation rate has decreased by a factor ≤10 within the last ∼10
8
yr. The observed radio emission is consistent with the past star formation, so we propose that this recent decline may be the cause of their radio luminosity-to-star formation rate excess.
Faraday tomography of LoTSS-DR2 data Erceg, Ana; Jelić, Vibor; Haverkorn, Marijke ...
Astronomy and astrophysics (Berlin),
07/2022, Letnik:
663
Journal Article
Recenzirano
Odprti dostop
Context. Observations of synchrotron emission at low radio frequencies reveal a labyrinth of polarised Galactic structures. However, the explanation for the wealth of structures remains uncertain due ...to the complex interactions between the interstellar medium and the magnetic field. A multi-tracer approach to the analysis of large sky areas is needed. Aims. This paper aims to use polarimetric images from the LOFAR Two metre Sky Survey to produce the biggest mosaic of polarised emission in the northern sky at low radio frequencies (150 MHz) to date. The large area this mosaic covers allows for detailed morphological and statistical studies of polarised structures in the high-latitude outer Galaxy, including the well-known Loop III region. Methods. We produced a 3100 square degree Faraday tomographic cube using a rotation measure synthesis tool. We calculated the statistical moments of Faraday spectra and compared them with data sets at higher frequencies (1.4 GHz) and with a map of a rotation measure derived from extragalactic sources. Results. The mosaic is dominated by polarised emission connected to Loop III. Additionally, the mosaic reveals an abundance of other morphological structures, mainly narrow and extended depolarisation canals, which are found to be ubiquitous. Conclusions. We find a correlation between the map of an extragalactic rotation measure and the LoTSS first Faraday moment image. The ratio of the two deviates from a simple model of a Burn slab (Burn, B. J. 1966, MNRAS, 133, 67) along the line of sight, which highlights the high level of complexity in the magnetoionic medium that can be studied at these frequencies.
Low-frequency radio observations show an increasing number of radio galaxies located in galaxy clusters that display peculiar morphologies and spectral profiles. This is the result of the dynamical ...interaction of the galaxy with the surrounding medium. Studying this phenomenon is key to understanding the evolution of low-energy relativistic particles in the intracluster medium. We present a multi-frequency study of the three head-tail (HT) radio galaxies and the radio halo in the galaxy cluster ZwCl0634.1+4747. We make use of observations at four frequencies performed with LOFAR LBA (53 MHz), HBA (144 MHz), GMRT (323 MHz) and VLA (1518 MHz) data. The use of extremely low radio frequency observations, such as LOFAR at 53 and 144 MHz, allowed us to detect the extension of the tails up to a distance of ~ 1 Mpc. We extracted spectral profiles along the tails in order to identify possible departures from a pure ageing model, such as the Jaffe-Perola (JP) model, which only involves synchrotron and inverse-Compton losses. We found clear evidence of departures from this simple ageing model, such as surface brightness enhancement and spectral flattening along all of the tails. This can be interpreted as the consequence of particle re-acceleration along the tails. Possible explanations for this behaviour include the interaction between a shock and the radio tails or a turbulence-driven re-acceleration mechanism. We show that the latter scenario is able to reproduce the characteristic features that we observed in our profiles.
Previous research into children's perceptions of science shows that children like science but often hold stereotypical views of scientists and commonly do not see themselves with a career as a ...scientist.
The aim of this study is to examine if a carefully designed medium-term, teacher-led STEM intervention, 'Scientist of the Week' which showcased a diverse range of working scientists and the skills they need, can lead to a positive change in the perception of scientists among young people.
Using a case-control approach, this research used a tracked sample of 118 young people from aged 7 to 11 in a primary school in the North East of England. Words associated with scientists were collected before and after (directly, one month, one year) the intervention from the tracked sample and analysed to assess changes in stereotypical perceptions and any difference in responses between male and female participants.
Before the intervention, young children held many of the common stereotypes associated with scientists. Shortly afterwards, and one year following the intervention, the use of common stereotypes had fallen significantly across all children, with particular improvements in counter-stereotypical word usage for males. It also found that stereotypical images of scientists as highly intelligent were more difficult to counteract and that many of the positive changes in this view seen in the short term (weeks and months) diminished in the long term (one year later).
This research has shown that with minimal expense and effort from teachers, negative stereotypes of scientists can be reduced through an intervention that does not require bringing scientists into the classroom. Some of the observed changes persisted in the longer-term, suggesting a lasting alteration in children's perceptions of scientists following the intervention.
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