Abstract
We present the circumnuclear multiphase gas properties of the brightest cluster galaxy (BCG) in the center of Abell 1644-South (A1644-S). A1644-S is the main cluster in a merging system, ...which is well known for X-ray hot gas sloshing in its core. The sharply peaked X-ray profile of A1644-S implies the presence of a strongly cooling gas core. In this study, we analyze ALMA
12
CO (1–0) data, JVLA H
i
data, and KaVA 22 GHz data for the central region of A1644-S to probe the potential origin of the cool gas and its role in (re)powering the central active galactic nucleus (AGN). We find CO clumps distributed in an arc shape along the X-ray gas sloshing, which is suggestive of a connection between the cold gas and the hot intracluster medium (ICM). H
i
and CN are detected in absorption against the AGN continuum emission. The absorption dip is observed at the systemic velocity of the BCG with an extended, redshifted tail. Based on the spatial and spectral configurations of the H
i
, CN, and CO gases, it is inferred that cool gas spirals into the core of the BCG, which is then fed to the central AGN. Indeed, our KaVA observation reveals a parsec-scale bipolar jet, implying that this AGN could have been (re)powered quite recently. Combining this, we suggest that some cold gas in A1644-S could have been formed from the cooling of the ICM, triggering the activity of the central AGN in the early development of a cool-core cluster.
Abstract
To advance our understanding of the fuelling and feedback processes which power the Universe’s most massive black holes, we require a significant increase in our knowledge of the molecular ...gas which exists in their immediate surroundings. However, the behaviour of this gas is poorly understood due to the difficulties associated with observing it directly. We report on a survey of 18 brightest cluster galaxies lying in cool cores, from which we detect molecular gas in the core regions of eight via carbon monoxide (CO), cyanide (CN) and silicon monoxide (SiO) absorption lines. These absorption lines are produced by cold molecular gas clouds which lie along the line of sight to the bright continuum sources at the galaxy centres. As such, they can be used to determine many properties of the molecular gas which may go on to fuel supermassive black hole accretion and AGN feedback mechanisms. The absorption regions detected have velocities ranging from −45 to 283 km s−1 relative to the systemic velocity of the galaxy, and have a bias for motion towards the host supermassive black hole. We find that the CN N = 0 − 1 absorption lines are typically 10 times stronger than those of CO J = 0 − 1. This is due to the higher electric dipole moment of the CN molecule, which enhances its absorption strength. In terms of molecular number density CO remains the more prevalent molecule with a ratio of CO/CN ∼10, similar to that of nearby galaxies. Comparison of CO, CN, and H i observations for these systems shows many different combinations of these absorption lines being detected.
Abstract
Hypercalcemia can manifest with various symptoms and poses diagnostic challenges due to its multifactorial etiology. This case highlights a 74-year-old patient with hypercalcemia of complex ...origin. The patient had a history of chronic liver disease, chronic kidney disease, and a previous episode of hypercalcemia associated with excessive oral Vitamin D intake. On admission, the patient presented with disorientation and increased drowsiness. Further evaluation revealed persistently high serum calcium levels, low parathyroid hormone levels, and elevated levels of Vitamin D. Investigations identified a duodenal nodule with multiple lymph node enlargement, suggesting a malignancy as the underlying cause. Other potential factors contributing to hypercalcemia, such as a granulomatous disease, prolonged immobilization, and a deactivating mutation of the 24-hydroxylase gene (CYP24A1), were also considered. Despite interventions, including hemodialysis and denosumab administration, the patient’s condition deteriorated due to sepsis and hypotensive shock, ultimately resulting in death. This case emphasizes the importance of considering multiple etiologies in cases of hypercalcemia in the elderly and the challenges involved in managing severe symptomatic hypercalcemia. Medical professionals must employ sound clinical reasoning and comprehensive diagnostic approaches to accurately identify and address the underlying cause. Hemodialysis may be necessary in refractory cases to achieve serum calcium normalization.
ABSTRACT
We present Atacama Large Millimetre/submillimetre Array observations of the brightest cluster galaxy Hydra-A, a nearby (z = 0.054) giant elliptical galaxy with powerful and extended radio ...jets. The observations reveal CO(1−0), CO(2–1), 13CO(2–1), CN(2–1), SiO(5–4), HCO+(1–0), HCO+(2–1), HCN(1–0), HCN(2–1), HNC(1–0), and H2CO(3–2) absorption lines against the galaxy’s bright and compact active galactic nucleus. These absorption features are due to at least 12 individual molecular clouds that lie close to the centre of the galaxy and have velocities of approximately −50 to +10 km s−1 relative to its recession velocity, where positive values correspond to inward motion. The absorption profiles are evidence of a clumpy interstellar medium within brightest cluster galaxies composed of clouds with similar column densities, velocity dispersions, and excitation temperatures to those found at radii of several kpc in the Milky Way. We also show potential variation in a ∼10 km s−1 wide section of the absorption profile over a 2 yr time-scale, most likely caused by relativistic motions in the hot spots of the continuum source that change the background illumination of the absorbing clouds.
Active galactic nuclei play a crucial role in the accretion and ejection of gas in galaxies. Although their outflows are well studied, finding direct evidence of accretion has proved very difficult ...and has so far been done for very few sources. A promising way to study the significance of cold accretion is by observing the absorption of an active galactic nucleus's extremely bright radio emission by the cold gas lying along the line of sight. As such, we present ALMA CO(1-0) and CO(2-1) observations of the Hydra-A brightest cluster galaxy (z = 0.054) which reveal the existence of cold, molecular gas clouds along the line of sight to the galaxy's extremely bright and compact mm-continuum source. They have apparent motions relative to the central supermassive black hole of between -43 and -4 km s-1 and are most likely moving along stable, low ellipticity orbits. The identified clouds form part of a ˜109 M⊙, approximately edge-on disc of cold molecular gas. With peak CO(2-1) optical depths of τ = 0.88 ^{+0.06}_{-0.06}, they include the narrowest and by far the deepest absorption of this type which has been observed to date in a brightest cluster galaxy. By comparing the relative strengths of the lines for the most strongly absorbing region, we are able to estimate a gas temperature of 42^{+25}_{-11} K and line of sight column densities of N_{CO}=2^{+3}_{-1}× 10 ^{17} {cm}^{-2} and N_{H2 }=7^{+10}_{-4}× 10 ^{20} {cm}^{-2}.
Purpose
The growing force of disruptive change is creating whitewater work environments across the profit and not-for-profit world. To help leaders overcome the challenge of achieving improvements in ...leadership performance, this study aims to outline research and case examples that illustrate a four-point roadmap for improving this performance at scale.
Design/methodology/approach
The study summarizes new research on leadership and organizational high performance and practices that drive high performance today. It relates these finding to trends evidenced in the work being done by HR organizations and the consulting firms that serve them. It then outlines an evidence-based roadmap for achieving improvements in leadership performance that HR organizations can adopt to achieve improvements in leadership performance.
Findings
Successful organizations intervene at four leverage points to meet the challenge achieving the shifts in leadership behavior needed for success in today’s permanent whitewater environments. These organizations are focusing on two types of leadership, leveraging two approaches to its development and are leveraging critical enablers that benefit from strong alignments within HR and between HR and their business leader colleagues.
Originality/value
The study highlights new research finding and research-based models of leadership performance that meet the demands of today’s workplace. It synthesizes a new four-point roadmap to success from trends discovered in recent research on leadership, technology-assisted behavior change and organizational effectiveness, as well as in the example of in high-performing organizations.
Dementia is a condition that affects the psychological and emotional wellbeing of not only the person with the diagnosis but also those around them. Therefore, providing holistic support and care to ...the entire family is essential. Psychosocial interventions have a significant impact on families living with dementia. They are a broad category of strategies and approaches that support the whole person by recognising their inherent strengths, and acknowledging and addressing the challenges they face. These interventions can range from a simple conversation over a cup of tea to more structured forms of psychotherapy.
ABSTRACT
We present new ALMA CO(2-1) observations tracing $2.2 \times 10^{10}\, \textnormal {M}_{\odot }$ of molecular gas in Abell 2390’s brightest cluster galaxy, where half the gas is located in a ...one-sided plume extending 15 kpc out from the galaxy centre. This molecular gas has a smooth and positive velocity gradient, and is receding 250 km s−1 faster at its farthest point than at the galaxy centre. To constrain the plume’s origin, we analyse our new observations alongside existing X-ray, optical, and radio data. We consider the possibility that the plume is a jet-driven outflow with lifting aided by jet-inflated X-ray bubbles, is a trail of gas stripped from the main galaxy by ram pressure, or is formed of more recently cooled and infalling gas. The galaxy’s star formation and gas cooling rate suggest the lifespan of its molecular gas may be low compared with the plume’s age – which would favour a recently cooled plume. Molecular gas in close proximity to the active galactic nucleus is also indicated by 250 km s−1 wide CO(2-1) absorption against the radio core, as well as previously detected CO(1-0) and H i absorption. This absorption is optically thick and has a line-of-sight velocity towards the galaxy centre of 200 km s−1. We discuss simple models to explain its origin.
ABSTRACT
Variability of a galaxy’s core radio source can be a significant consequence of active galactic nucleus accretion. However, this variability has not been well studied, particularly at high ...radio frequencies. As such, we report on a campaign monitoring the high radio frequency variability of 20 nearby, cool-core brightest cluster galaxies. From our representative sample, we show that most vary significantly on time-scales of approximately 1 yr and longer. Our highest cadence observations are at 15 GHz and are from the Owens Valley Radio Observatory. They have a median time interval of 7 d and mostly span between 8 and 13 yr. We apply a range of variability detection techniques to the sources’ light curves to analyse changes on week to decade long time-scales. Most notably, at least half of the sources show 20 per cent peak to trough variability on 3 yr time-scales, while at least a third vary by 60 per cent on 6 yr time-scales. Significant variability, which is important to studies of the Sunyaev–Zel’dovich Effect in the radio/sub-mm, is therefore a common feature of these sources. We also show how the variability relates to spectral properties at frequencies of up to 353 GHz using data from the Korean VLBI network, the NIKA2 instrument of the IRAM 30-m telescope, and the SCUBA-2 instrument of the James Clerk Maxwell Telescope.
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