bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accretion and star formation in ‘radio-quiet’ quasars
Authors: White Sarah V. , Jarvis Matt J. , Kalfountzou Eleni , Hardcastle Martin J. , Verma Aprajita , Cao Orjales José M. , Stevens Jason 
Published: January 2021

AbstractRadio observations allow us to identify a wide range of active galactic nuclei (AGN), which play a significant role in the evolution of galaxies. Amongst AGN at low radio-luminosities is the ‘radio-quiet’ quasar (RQQ) population, but how they contribute to the total radio emission is under debate, with previous studies arguing that it is predominantly through star formation. In this talk, SVW summarised the results of recent papers on RQQs, including the use of far-infrared data to disentangle the radio emission from the AGN and that from star formation. This provides evidence that black-hole accretion, instead, dominates the radio emission in RQQs. In addition, we find that this accretion-related emission is correlated with the optical luminosity of the quasar, whilst a weaker luminosity-dependence is evident for the radio emission connected with star formation. What remains unclear is the process by which this accretion-related emission is produced. Understanding this for RQQs will then allow us to investigate how this type of AGN influences its surroundings. Such studies have important implications for modelling AGN feedback, and for determining the accretion and star-formation histories of the Universe.
Clustering dependence of Chandra COSMOS Legacy AGN on host galaxy properties
Authors: Allevato Viola 
Published: January 2021

AbstractThe presence of a super massive BH in almost all galaxies in the Universe is an accepted paradigm in astronomy. How these BHs form and how they co-evolve with the host galaxy is one of the most intriguing unanswered problems in modern Cosmology and of extreme relevance to understand the issue of galaxy formation. Clustering measurements can powerfully test theoretical model predictions of BH triggering scenarios and put constraints on the typical environment where AGN live in, through the connection with their host dark matter halos. In this talk, I will present some recent results on the AGN clustering dependence on host galaxy properties, such as galaxy stellar mass, star formation rate and specific BH accretion rate, based on X-ray selected Chandra COSMOS Legacy Type 2 AGN. We found no significant AGN clustering dependence on galaxy stellar mass and specif BHAR for Type 2 COSMOS AGN at mean z ∼ 1.1, with a stellar - halo mass relation flatter than predicted for non active galaxies in the Mstar range probed by our sample. We also observed a negative clustering dependence on SFR, with AGN hosting halo mass increasing with decreasing SFR. Mock catalogs of active galaxies in hosting dark matter halos with logMh[Msun] > 12.5, matched to have the same X-ray luminosity, stellar mass and BHAR of COSMOS AGN predict the observed Mstar - Mh, BHAR - Mh and SFR-Mh relations, at z ∼ 1.
Radio jets: Properties, life and impact
Authors: Morganti Raffaella 
Published: January 2021

AbstractOur view of the properties of extragalactic radio jets and the impact they have on the host galaxy has expanded in the recent years. This has been possible thanks to the data from new or upgraded radio telescopes. This review briefly summarises the current status of the field and describes some of the exciting recent results and the surprises they have brought. In particular, the physical properties of radio jets as function of their radio power will be discussed together with the advance made in understanding the life-cycle of radio sources. The evolutionary stage (e.g. newly born, dying, restarted) of the radio AGN can be derived from their morphology and properties of the radio spectra. The possibilities offered by the new generation of low-frequency radio telescopes make it possible to derive (at least to first order) the time-scale spent in each phase. The presence of a cycle of activity ensures a recurrent impact of the radio jets on their surrounding inter-stellar and inter-galactic medium and, therefore, their relevance for AGN feedback. The last part is dedicated to the recent results showing the effect of jets on the surrounding galactic medium. The predictions made by numerical simulations on the impact of a radio jet (and in particular a newly born jet) on a clumpy medium describe well what is seen by the observations. The high resolution studies of jet-driven outflows of cold gas (and molecular) has provided new important addition both in term of quantifying the impact of the outflows and their relevance for feedback as well as for providing an unexpected view of the physical conditions of the gas under these extreme conditions.
Understanding the origin of radio outflows in Seyfert galaxies using radio polarimetry
Authors: Sebastian Biny , Kharb Preeti , O’ Dea Christopher P. , Gallimore Jack F. , Baum Stefi A. , Colbert Edward J. M. 
Published: January 2021

AbstractThe role of starburst winds versus active galactic nuclei (AGN) jets/winds in the formation of the kiloparsec scale radio emission seen in Seyferts is not yet well understood. In order to be able to disentangle the role of various components, we have observed a sample of Seyfert galaxies exhibiting kpc-scale radio emission suggesting outflows, along with a comparison sample of starburst galaxies, with the EVLA B-array in polarimetric mode at 1.4 GHz and 5 GHz. The Seyfert galaxy NGC 2639, shows highly polarized secondary radio lobes, not observed before, which are aligned perpendicular to the known pair of radio lobes. The additional pair of lobes represent an older epoch of emission. A multi-epoch multi-frequency study of the starburst-Seyfert composite galaxy NGC 3079, reveals that the jet together with the starburst superwind and the galactic magnetic fields might be responsible for the well-known 8-shaped radio lobes observed in this galaxy. We find that many of the Seyfert galaxies in our sample show bubble-shaped lobes, which are absent in the starburst galaxies that do not host an AGN.
The space VLBI mission RadioAstron: AGN results
Authors: Kovalev Yuri 
Published: January 2021

AbstractThe RadioAstron Space VLBI mission utilized the 10-m radio telescope on board the dedicated Spektr-R spacecraft to observe cosmic radio sources with an unprecedented angular resolution at centimeter wave lengths in total and polarized light. The longest baseline of the space-ground interferometer is about 350000 km. It operated in 2011–2019 together with 58 largest ground radio telescopes. Resolution as high as 10 microarcsec has been achieved. An overview of its AGN science results will be presented in the talk. It includes a probe of jet emission mechanism through brightness temperature measurements, reconstruction of magnetic field structure close to the jet origin using polarization data, jet formation and collimation study for well resolved nearby AGN, as well as observations and analysis of jet precession and plasma instabilities. We will also discuss a new scattering effect which was discovered by RadioAstron to affect high resolution radio measurements of AGN and SgrA*.
Optical variations in changing-look AGNs selected at X-rays
Authors: Cazzoli Sara , Masegosa Josefa , Márquez Isabel , Hernández-García Lorena , Álvarez-Hernández A. , Hermosa-Muñoz Laura 
Published: January 2021

AbstractRecent observations of local AGNs have revealed that many of them show a ‘changing look’ behavior at optical and X-rays wavelengths in the sense of transiting between different AGNs families (e.g. from type-1 to type-2 or vice-versa). In order to pinpoint the possible relation of the changes, we performed optical spectroscopic observations (with CAFOS/CAHA) of 15 changing look AGNs selected at X-rays. Highlights from our spectroscopic study are presented.
NGC7469 as seen by MEGARA at the GTC
Authors: Cazzoli Sara , Gil de Paz Armando , Márquez Isabel , Masegosa Josefa , Iglesias Jorge , Gallego Jesus , Carrasco Esperanza , Cedazo Raquel , Luisa García-Vargas María , Castillo-Morales África , Pascual Sergio , Cardiel Nicolás , Pérez-Calpena Ana , Gómez-Alvarez Pedro , Martínez-Delgado Ismael , Hermosa-Muñoz Laura 
Published: January 2021

AbstractWe present the main results from the analysis of the Hα-[NII] emission lines with integral field spectroscopy observations gathered with MEGARA at the GTC of the nearby Seyfert 1.5 galaxy NGC7469. We obtained maps of the ionised gas in the inner 12.5 arcsec × 11.3 arcsec, at spatial scales of 0.62 arcsec, with an unprecedented spectral resolution (R ˜ 20 000). We characterized the kinematics and ionisation mechanism of the distinct kinematic components (Cazzoli et al.2019).
Optical spectral properties of radio loud quasars along the main sequence
Authors: del Olmo Ascensión , Marziani Paola , Ganci Valerio , D’Onofrio Mauro , Bon Edi , Bon Natasa , Negrete Alenka C. 
Published: January 2021

AbstractWe analyze the optical properties of Radio-Loud quasars along the Main Sequence (MS) of quasars. A sample of 355 quasars selected on the basis of radio detection was obtained by cross-matching the FIRST survey at 20cm and the SDSS DR12 spectroscopic survey. We consider the nature of powerful emission at the high-Fe ii end of the MS. At variance with the classical radio-loud sources which are located in the Population B domain of the MS optical plane, we found evidence indicating a thermal origin of the radio emission of the highly accreting quasars of Population A.
Accretion rate in AGN and X-ray-to-optical flux ratio at z ≤ 0.2
Authors: Gaulle Asrate , Pović Mirjana , Zewdie Dejene 
Published: January 2021

AbstractWe explored a sample of 545 local galaxies using data from the 3XMM-DR7 and SDSS-DR8 surveys. We carried out all analyses up to z ˜ 0.2, and we studied the relation between X/O flux ratio and accretion rate for different classes of active galaxies such as LINERs and Seyfert 2. We obtained a slight correlation between the two parameters if the whole sample of AGN is used. However, LINERs and Sy2 galaxies show different properties, slight correlation and slight anti-correlation, respectively. This could confirm that LINERs and Sy2 galaxies have different accretion efficiencies and maybe different accretion disc properties, as has been suggested previously.
A search for new γ-ray blazars from infrared selected candidates
Authors: Musiimenta Blessing , Sversut Arsioli Bruno , Jurua Edward , Mutabazi Tom 
Published: January 2021

AbstractWe present a systematic study of gamma-ray blazar candidates based on a sample of 40 objects taken from the WIBR catalogue. By using a likelihood analysis, 26 of the 40 sources showed significant gamma-ray signatures ⩾ 3σ. Using high-energy test statistics (TS) maps, we confirm 8 sources, which are completely new, and show another 15 promising γ-ray candidates. The results from this analysis show that a multi-frequency approach can help to improve the current description of the gamma-ray sky.
Feii strength in NLS1s – dependence on the viewing angle and FWHM(Hβ)
Authors: Panda Swayamtrupta , Marziani Paola , Czerny Bożena 
Published: January 2021

AbstractWe address the effect of orientation of the accretion disk plane and the geometry of the broad line region (BLR) in the context of understanding the distribution of quasars along their Main Sequence. We utilize the photoionization code CLOUDY to model the BLR, incorporating the ‘un-constant’ virial factor. We show the preliminary results of the analysis to highlight the co-dependence of the Eigenvector 1 parameter, RFeII on the broad HβFWHM (i.e. the line dispersion) and the inclination angle (θ), assuming fixed values for the Eddington ratio (Lbol/ LEdd), black hole mass (MBH), spectral energy distribution (SED) shape, cloud density (nH) and composition.†
Understanding galaxy mergers and AGN feedback with UVIT
Authors: Rubinur Khatun , Das Mousumi , Kharb Preeti , Rahne P. T. 
Published: January 2021

AbstractSimulations expect an enhanced star-formation and active galactic nuclei (AGN) activity during galaxy mergers, which can lead to formation of binary/dual AGN. AGN feedback can enhance or suppress star-formation. We have carried out a pilot study of a sample of ˜10 dual nuclei galaxies with AstroSat’s Ultraviolet Imaging Telescope (UVIT). Here, we present the initial results for two sample galaxies (Mrk 739, ESO 509) and deep multi-wavelength data of another galaxy (Mrk 212). UVIT observations have revealed signatures of positive AGN feedback in Mrk 739 and Mrk 212, and negative feedback in ESO 509. Deeper UVIT observations have recently been approved; these will provide better constraints on star-formation as well as AGN feedback in these systems.
Extragalactic background light inhomogeneities and Lorentz-Invariance Violation in gamma-gamma absorption and Compton scattering
Authors: Abdalla Hassan 
Published: January 2021

AbstractAt energies approaching the Planck energy scale 1019GeV, several quantum-gravity theories predict that familiar concepts such as Lorentz (LIV) symmetry can be broken. Such extreme energies are currently unreachable by experiments on Earth, but for photons traveling over cosmological distances the accumulated deviations from the Lorentz symmetry may be measurable using the Cherenkov Telescope Array (CTA). To study the spectral hardening feature observed in some VHE gamma-ray blazars, we calculate the reduction of the EBL gamma-gamma opacity due to the existence of underdense regions along the line of sight to VHE -gamma ray sources and we compared with the possibility of a LIV signature. Considering the LIV effect, we found that the cosmic opacity for VHE-gamma rays with energy more than 10 TeV can be strongly reduced. I will further discuss the impact of LIV on the Compton scattering process, and how future CTA observations may open an exciting window on studies of the fundamental physics.
Mass-radius relation of compact objects
Authors: Abaraya Seman , Biressa Tolu 
Published: January 2021

AbstractCompact objects are of great interest in astrophysical research. There are active research interests in understanding better various aspects of formation and evolution of these objects. In this paper we addressed some problems related to the compact objects mass limit. We employed Einstein field equations (EFEs) to derive the equation of state (EoS). With the assumption of high densities and low temperature of compact sources, the derived equation of state is reduced to polytropic kind. Studying the polytropic equations we obtained similar physical implications, in agreement to previous works. Using the latest version of Mathematica-11 in our numerical analysis, we also obtained similar results except slight differences in accuracy.
Mass-loss varying luminosity and its implication to the solar evolution
Authors: Tilahun Shukure Negessa , Tessema Solomon Belay , Mengistu Endalkachew 
Published: January 2021

AbstractSeveral models of the solar luminosity, , in the evolutionary timescale, have been computed as a function of time. However, the solar mass-loss, , is one of the drivers of variation in this timescale. The purpose of this study is to model mass-loss varying solar luminosity, , and to predict the luminosity variation before it leaves the main sequence. We numerically computed the up to 4.9 Gyrs from now. We used the solution to compute the modeled . We then validated our model with the current solar standard model (SSM). The shows consistency up to 8 Gyrs. At about 8.85 Gyrs, the Sun loses 28% of its mass and its luminosity increased to 2.2. The model suggests that the total main sequence lifetime is nearly 9 Gyrs. The model explains well the stage at which the Sun exhausts its central supply of hydrogen and when it will be ready to leave the main sequence. It may also explain the fate of the Sun by making some improvements in comparison to previous models.
The Association Between Chronic Disease and Psychological Distress: An Australian Twin Study
Authors: Tyler Jessica , Lam Janine , Scurrah Katrina , Dite Gillian 
Published: January 2021

AbstractThere is a commonly observed association between chronic disease and psychological distress, but many potential factors could confound this association. This study investigated the association using a powerful twin study design that can control for unmeasured confounders that are shared between twins, including genetic and environmental factors. We used twin-paired cross-sectional data from the Adult Health and Lifestyle Questionnaire collected by Twins Research Australia from 2014 to 2017. Linear regression models fitted using maximum likelihood estimations (MLE) were used to test the association between self-reported chronic disease status and psychological distress, measured by the Kessler Psychological Distress Scale (K6). When comparing between twin pairs, having any chronic disease was associated with a 1.29 increase in K6 (95% CI: 0.91, 1.66; p < .001). When comparing twins within a pair, having any chronic disease was associated with a 0.36 increase in K6 (95% CI: 0.002, 0.71; p = .049). This within-pair estimate is of most interest as comparing twins within a pair naturally controls for shared factors such as genes, age and shared lived experiences. Whereas the between-pair estimate does not. The weaker effect found within pairs tells us that genetic and environmental factors shared between twins confounds the relationship between chronic disease and psychological distress. This suggests that associations found in unrelated samples may show exaggerated estimates.
Non‐Linear Response of Ammonia Volatilization to Periphyton in Paddy Soils
Authors: Huang Jing , Liu Xuemei , Liu Yuqing , Yan Xing , Yan Xiaoyuan , Wu Yonghong , Xia Yongqiu 
Published: January 2021

AbstractAmmonia (NH3) volatilization from paddy soils is one of the main contributors to agricultural NH3 emissions, however, little attention has been paid to the role of the ubiquitous periphyton in paddy soils on NH3 volatilization. Considering that the composition of periphyton is dominated by autotrophs that directly affect the redox and pH conditions, it is hypothesized that the presence of periphyton may be an important factor affecting NH3 emissions. In this study, NH3 volatilization was determined under six periphyton biomass treatments and under treatments with six different N application rates to evaluate the contribution of periphyton to NH3 volatilization in the laboratory representing the paddy soils system. Results showed that periphyton had trade‐off effects on NH3 volatilization through pH and the NH4+ concentration. Periphyton had net inhibition effects on NH3 volatilization when the periphyton biomass was higher than 110 g·m−2. In contrast, periphyton had net promotion effects on NH3 volatilization when the periphyton biomass was less than 110 g·m−2. The contribution of periphyton to NH3 volatilization increased exponentially with increasing N application rates (i.e., with the increasing nitrogen concentration of the overlying water). In the low‐nitrogen treatments (≤20 kg N·ha−1), periphyton had no significant effect on NH3 volatilization. In contrast, periphyton contributed as much as 47.4% of NH3 volatilization at high nitrogen concentrations (100 kg N·ha−1). This study provides valuable insight into the role of periphyton on NH3 volatilization, offers quantified relationship between periphyton and NH3 volatilization, and improves the accuracy of NH3 volatilization estimation in regional paddy soils.
PDX1LOW MAFALOW β-cells contribute to islet function and insulin release
Authors: Nasteska Daniela , Fine Nicholas H. F. , Ashford Fiona B. , Cuozzo Federica , Viloria Katrina , Smith Gabrielle , Dahir Aisha , Dawson Peter W. J. , Lai Yu-Chiang , Bastidas-Ponce Aimée , Bakhti Mostafa , Rutter Guy A. , Fiancette Remi , Nano Rita , Piemonti Lorenzo , Lickert Heiko , Zhou Qiao , Akerman Ildem , Hodson David J. 
Published: January 2021

AbstractTranscriptionally mature and immature β-cells co-exist within the adult islet. How such diversity contributes to insulin release remains poorly understood. Here we show that subtle differences in β-cell maturity, defined using PDX1 and MAFA expression, contribute to islet operation. Functional mapping of rodent and human islets containing proportionally more PDX1HIGH and MAFAHIGH β-cells reveals defects in metabolism, ionic fluxes and insulin secretion. At the transcriptomic level, the presence of increased numbers of PDX1HIGH and MAFAHIGH β-cells leads to dysregulation of gene pathways involved in metabolic processes. Using a chemogenetic disruption strategy, differences in PDX1 and MAFA expression are shown to depend on islet Ca2+ signaling patterns. During metabolic stress, islet function can be restored by redressing the balance between PDX1 and MAFA levels across the β-cell population. Thus, preserving heterogeneity in PDX1 and MAFA expression, and more widely in β-cell maturity, might be important for the maintenance of islet function.
Universally bistable shells with nonzero Gaussian curvature for two-way transition waves
Authors: Vasios Nikolaos , Deng Bolei , Gorissen Benjamin , Bertoldi Katia 
Published: January 2021

AbstractMulti-welled energy landscapes arising in shells with nonzero Gaussian curvature typically fade away as their thickness becomes larger because of the increased bending energy required for inversion. Motivated by this limitation, we propose a strategy to realize doubly curved shells that are bistable for any thickness. We then study the nonlinear dynamic response of one-dimensional (1D) arrays of our universally bistable shells when coupled by compressible fluid cavities. We find that the system supports the propagation of bidirectional transition waves whose characteristics can be tuned by varying both geometric parameters as well as the amount of energy supplied to initiate the waves. However, since our bistable shells have equal energy minima, the distance traveled by such waves is limited by dissipation. To overcome this limitation, we identify a strategy to realize thick bistable shells with tunable energy landscape and show that their strategic placement within the 1D array can extend the propagation distance of the supported bidirectional transition waves.
De novo DNA methyltransferase activity in colorectal cancer is directed towards H3K36me3 marked CpG islands
Authors: Masalmeh Roza H. Ali , Taglini Francesca , Rubio-Ramon Cristina , Musialik Kamila I. , Higham Jonathan , Davidson-Smith Hazel , Kafetzopoulos Ioannis , Pawlicka Kamila P. , Finan Hannah M. , Clark Richard , Wills Jimi , Finch Andrew J. , Murphy Lee , Sproul Duncan 
Published: January 2021

AbstractThe aberrant gain of DNA methylation at CpG islands is frequently observed in colorectal tumours and may silence the expression of tumour suppressors such asMLH1. Current models propose that these CpG islands are targeted by de novo DNA methyltransferases in a sequence-specific manner, but this has not been tested. Using ectopically integrated CpG islands, here we find that aberrantly methylated CpG islands are subject to low levels of de novo DNA methylation activity in colorectal cancer cells. By delineating DNA methyltransferase targets, we find that instead de novo DNA methylation activity is targeted primarily to CpG islands marked by the histone modification H3K36me3, a mark associated with transcriptional elongation. These H3K36me3 marked CpG islands are heavily methylated in colorectal tumours and the normal colon suggesting that de novo DNA methyltransferase activity at CpG islands in colorectal cancer is focused on similar targets to normal tissues and not greatly remodelled by tumourigenesis.