78 research outputs found

    H-ATLAS/GAMA: The nature and characteristics of optically red galaxies detected at submillimetre wavelengths

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    We combine Herschel/SPIRE sub-millimeter (submm) observations with existing multi-wavelength data to investigate the characteristics of low redshift, optically red galaxies detected in submm bands. We select a sample of galaxies in the redshift range 0.01\leqz\leq0.2, having >5σ\sigma detections in the SPIRE 250 micron submm waveband. Sources are then divided into two sub-samples of redred and blueblue galaxies, based on their UV-optical colours. Galaxies in the redred sample account for \approx4.2 per cent of the total number of sources with stellar masses M_{*}\gtrsim1010^{10} Solar-mass. Following visual classification of the redred galaxies, we find that \gtrsim30 per cent of them are early-type galaxies and \gtrsim40 per cent are spirals. The colour of the redred-spiral galaxies could be the result of their highly inclined orientation and/or a strong contribution of the old stellar population. It is found that irrespective of their morphological types, redred and blueblue sources occupy environments with more or less similar densities (i.e., the Σ5\Sigma_5 parameter). From the analysis of the spectral energy distributions (SEDs) of galaxies in our samples based on MAGPHYS, we find that galaxies in the redred sample (of any morphological type) have dust masses similar to those in the blueblue sample (i.e. normal spiral/star-forming systems). However, in comparison to the redred-spirals and in particular blueblue systems, redred-ellipticals have lower mean dust-to-stellar mass ratios. Besides galaxies in the redred-elliptical sample have much lower mean star-formation/specific-star-formation rates in contrast to their counterparts in the blueblue sample. Our results support a scenario where dust in early-type systems is likely to be of an external origin

    Herschel-ATLAS/GAMA : what determines the far-infrared properties of radio galaxies?

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    We perform a stacking analysis of Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) data in order to obtain isothermal dust temperatures and rest-frame luminosities at 250 mu m (L-250), for a well-defined sample of 1599 radio sources over the H-ATLAS Phase 1/Galaxy and Mass Assembly (GAMA) area. The radio sample is generated using a combination of NRAO VLA Sky Survey data and K-band United Kingdom Infrared Telescope Deep Sky Survey-Large Area Survey data, over the redshift range 0.01 < z < 0.8. The far-infrared (FIR) properties of the sample are investigated as a function of 1.4-GHz luminosity, redshift, projected radio-source size and radio spectral index. In order to search for stellar-mass-dependent relations, we split the parent sample into those sources which are below and above 1.5 L-K*. After correcting for stellar mass and redshift, we find no relation between the 250-mu m luminosity and the 1.4-GHz radio luminosity of radio active galactic nuclei. This implies that a galaxy's nominal radio luminosity has little or no bearing on the star formation rate (SFR) and/or dust mass content of the host system, although this does not mean that other variables (e. g. radio source size) related to the jets do not have an effect. The L-250 of both the radio detected and non-radio-detected galaxies (defined as those sources not detected at 1.4 GHz but detected in the Sloan Digital Sky Survey with r' 30 kpc) counterparts. The higher dust temperature suggests that this may be attributed to enhanced SFRs in compact radio galaxies, but whether this is directly or indirectly due to radio activity (e. g. jet-induced or merger-driven star formation) is as yet unknown. For matched samples in L-K and g'-r', sub-1.5 L-K* and super-1.5 L-K* radio-detected galaxies have 0.89 +/- 0.18 and 0.49 +/- 0.12 times the 250 mu m luminosity of their non-radio-detected counterparts. Thus, while no difference in L-250 is observed in sub-1.5 L-K* radio-detected galaxies, a strong deficit is observed in super-1.5 L-K* radio-detected galaxies. We explain these results in terms of the hotter, denser and richer halo environments massive radio galaxies maintain and are embedded in. These environments are expected to quench the cold gas and dust supply needed for further star formation and therefore dust production. Our results indicate that all massive radio galaxies (>1.5 L-K*) may have systematically lower FIR luminosities (similar to 25 per cent) than their colour-matched non-radio-detected counterparts. Finally, no relation between radio spectral index and L-250 is found for the subset of 1.4-GHz radio sources with detections at 330 MHz

    A review of zoonotic infection risks associated with the wild meat trade in Malaysia.

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    The overhunting of wildlife for food and commercial gain presents a major threat to biodiversity in tropical forests and poses health risks to humans from contact with wild animals. Using a recent survey of wildlife offered at wild meat markets in Malaysia as a basis, we review the literature to determine the potential zoonotic infection risks from hunting, butchering and consuming the species offered. We also determine which taxa potentially host the highest number of pathogens and discuss the significant disease risks from traded wildlife, considering how cultural practices influence zoonotic transmission. We identify 51 zoonotic pathogens (16 viruses, 19 bacteria and 16 parasites) potentially hosted by wildlife and describe the human health risks. The Suidae and the Cervidae families potentially host the highest number of pathogens. We conclude that there are substantial gaps in our knowledge of zoonotic pathogens and recommend performing microbial food safety risk assessments to assess the hazards of wild meat consumption. Overall, there may be considerable zoonotic risks to people involved in the hunting, butchering or consumption of wild meat in Southeast Asia, and these should be considered in public health strategies

    Publisher Correction: Discovery of rare variants associated with blood pressure regulation through meta-analysis of 1.3 million individuals

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    SARS-CoV-2 lineage dynamics in England from September to November 2021: high diversity of Delta sub-lineages and increased transmissibility of AY.4.2

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    Background: Since the emergence of SARS-CoV-2, evolutionary pressure has driven large increases in the transmissibility of the virus. However, with increasing levels of immunity through vaccination and natural infection the evolutionary pressure will switch towards immune escape. Genomic surveillance in regions of high immunity is crucial in detecting emerging variants that can more successfully navigate the immune landscape. Methods: We present phylogenetic relationships and lineage dynamics within England (a country with high levels of immunity), as inferred from a random community sample of individuals who provided a self-administered throat and nose swab for rt-PCR testing as part of the REal-time Assessment of Community Transmission-1 (REACT-1) study. During round 14 (9 September–27 September 2021) and 15 (19 October–5 November 2021) lineages were determined for 1322 positive individuals, with 27.1% of those which reported their symptom status reporting no symptoms in the previous month. Results: We identified 44 unique lineages, all of which were Delta or Delta sub-lineages, and found a reduction in their mutation rate over the study period. The proportion of the Delta sub-lineage AY.4.2 was increasing, with a reproduction number 15% (95% CI 8–23%) greater than the most prevalent lineage, AY.4. Further, AY.4.2 was less associated with the most predictive COVID-19 symptoms (p = 0.029) and had a reduced mutation rate (p = 0.050). Both AY.4.2 and AY.4 were found to be geographically clustered in September but this was no longer the case by late October/early November, with only the lineage AY.6 exhibiting clustering towards the South of England. Conclusions: As SARS-CoV-2 moves towards endemicity and new variants emerge, genomic data obtained from random community samples can augment routine surveillance data without the potential biases introduced due to higher sampling rates of symptomatic individuals. © 2022, The Author(s)

    A submillimetre survey of the star-formation history of radio galaxies

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    We present the results of the first major systematic submillimetre survey of radio galaxies spanning the redshift range 1 2.5, and the average submillimetre luminosity rises as (1+z)^3 out to z~4. Moreover our extensive sample allows us to argue that this behaviour is not driven by underlying correlations with other radio galaxy properties such as radio power, radio spectral index, or radio source size/age. Although radio selection may introduce other more subtle biases, the redshift distribution of our detected objects is in fact consistent with the most recent estimates of the redshift distribution of comparably bright submillimetre sources discovered in blank field surveys. The evolution of submillimetre luminosity found here for radio galaxies may thus be representative of massive ellipticals in general

    DETECTION OF A LARGE MASS OF DUST IN A RADIO GALAXY AT REDSHIFT Z=3.8

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    ELLIPTICAL galaxies are thought to have formed most of their stars in a rapid burst in the early Universe1, but an unambiguous example of a 'primaeval' elliptical galaxy (one undergoing its first major burst of star formation) has yet to be discovered. High-redshift radio galaxies are among the most promising candidates2'3, because their low-redshift counterparts are identified exclusively with ellipticals, but the presence of an active nucleus complicates the analysis of their evolutionary state from optical-infrared observations3"5. The failure of optical searches to detect primaeval ellipticals6"9 suggests that they may be very dusty, prompting us to search for thermal emission from the dust, which will be red-shifted to submillimetre wavelengths in our reference frame. Our detection of submillimetre emission from the radio galaxy 4C41.17, reported here, suggests that it contains a large mass of dust, probably located in a dust lane obscuring the centre of the galaxy10"14. The observations are consistent with the recent occurrence of a massive burst of star formation, but probably not the first such episode. We conclude that this galaxy was already in the final stages of its formation at a look-back time of 12-15 billion years
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