5,087 research outputs found

    The globular cluster system of the nearest Seyfert II galaxy Circinus

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    Context. The globular cluster (GC) system of Circinus galaxy has not been probed previously partly because of the location of the galaxy at - 3.8^\circ Galactic latitude which suffers severely from interstellar extinction, stellar crowding, and Galactic foreground contamination. However, the deep near-infrared (NIR) photometry by the VISTA Variables in the Via L\'actea Extended Survey (VVVX) in combination with the precise astrometry of Gaia EDR3 allow us to map GCs in this region. Aims. Our long-term goal is to study and characterise the distributions of GCs and Ultra-compact dwarfs of Circinus galaxy which is the nearest Seyfert II galaxy. Here we conduct the first pilot search for GCs in this galaxy. Methods. We use NIR VVVX photometry in combination with Gaia EDR3 astrometric features such as astrometric excess noise and BP/RP excess factor to build the first homogeneous catalogue of GCs in Circinus galaxy. A robust combination of selection criteria allows us to effectively clean interlopers from our sample. Results. We report the detection of\sim 70 GC candidates in this galaxy at a 3 σ\sigma confidence level. They show a bimodal colour distribution with the blue peak at (G-Ks)0_0 = 0.985±\pm0.127 mag with a dispersion of 0.211±\pm0.091 mag and the red peak at (G-Ks)0_0 = 1.625±\pm0.177 mag with a dispersion of 0.482±\pm0.114 mag. A GC specific frequency (SN_N) of 1.3±\pm0.2 was derived for the galaxy, and we estimated a total population of 120±\pm40 GCs. Based on the projected radial distribution it appears that Circinus has a different distribution of GC candidates than MW and M31. Conclusions. We demonstrate that Circinus galaxy hosts a sizeable number of cluster candidates. This result is the first leap towards understanding the evolution of old stellar clusters in this galaxy.Comment: 15 pages, 12 figure

    LimberJack.jl: auto-differentiable methods for angular power spectra analyses

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    We present LimberJack.jl, a fully auto-differentiable code for cosmological analyses of 2 point auto- and cross-correlation measurements from galaxy clustering, CMB lensing and weak lensing data written in Julia. Using Julia's auto-differentiation ecosystem, LimberJack.jl can obtain gradients for its outputs up to an order of magnitude faster than traditional finite difference methods. This makes LimberJack.jl greatly synergistic with gradient-based sampling methods, such as Hamiltonian Monte Carlo, capable of efficiently exploring parameter spaces with hundreds of dimensions. We first prove LimberJack.jl's reliability by reanalysing the DES Y1 3×\times2-point data. We then showcase its capabilities by using a O(100) parameters Gaussian Process to reconstruct the cosmic growth from a combination of DES Y1 galaxy clustering and weak lensing data, eBOSS QSO's, CMB lensing and redshift-space distortions. Our Gaussian process reconstruction of the growth factor is statistically consistent with the Λ\LambdaCDM Planck 2018 prediction at all redshifts. Moreover, we show that the addition of RSD data is extremely beneficial to this type of analysis, reducing the uncertainty in the reconstructed growth factor by 20%20\% on average across redshift. LimberJack.jl is a fully open-source project available on Julia's general repository of packages and GitHub.Comment: Prepared for OJA. Fixed minor typos. Comments welcomed

    Phase diagram for a Cubic Consistent-Q Interacting Boson Model Hamiltonian: signs of triaxiality

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    An extension of the Consistent-Q formalism for the Interacting Boson Model that includes the cubic QxQxQ term is proposed. The potential energy surface for the cubic quadrupole interaction is explicitly calculated within the coherent state formalism using the complete chi-dependent expression for the quadrupole operator. The Q-cubic term is found to depend on the asymmetry deformation parameter gamma as a linear combination of cos(3gamma) and cos^2(3\gamma) terms, thereby allowing for triaxiality. The phase diagram of the model in the large N limit is explored, it is described the order of the phase transition surfaces that define the phase diagram, and moreover, the possible nuclear equilibrium shapes are established. It is found that, contrary to expectations, there is only a very tiny region of triaxiality in the model, and that the transition from prolate to oblate shapes is so fast that, in most cases, the onset of triaxiality might go unnoticed.Comment: 18 pages, 19 figure

    Characterization of Mycobacterium tuberculosis Beijing isolates from the Mediterranean area

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    <p>Abstract</p> <p>Background</p> <p>The Beijing lineage of <it>Mycobacterium tuberculosis </it>is causing concern due to its global distribution and its involvement in severe outbreaks. Studies focused on this lineage are mainly restricted to geographical settings where its prevalence is high, whereas those in other areas are scarce. In this study, we analyze Beijing isolates in the Mediterranean area, where this lineage is not prevalent and is mainly associated with immigrant cases.</p> <p>Results</p> <p>Only 1% (N = 26) of the isolates from two population-based studies in Spain corresponded to Beijing strains, most of which were pan-susceptible and from Peruvian and Ecuadorian patients. Restriction fragment length polymorphism typing with the insertion sequence IS<it>6110 </it>identified three small clusters (2-3 cases). Mycobacterial interspersed repetitive unit-variable number tandem repeat typing (MIRU-15) offered low discriminatory power, requiring the introduction of five additional loci. A selection of the Beijing isolates identified in the Spanish sample, together with a sample of Beijing strains from Italy, to broaden the analysis context in the Mediterranean area, were assayed in an infection model with THP-1 cells. A wide range of intracellular growth rates was observed with only two isolates showing an increased intracellular replication, in both cases associated with contained production of TNF-α. No correlation was observed between virulence and the Beijing phylogenetic group, clustered/orphan status, or resistance. The Beijing strain responsible for extensive spread on Gran Canaria Island was also identified in Madrid, but did not lead to secondary cases and did not show high infectivity in the infection model.</p> <p>Conclusions</p> <p>The Beijing lineage in our area is a non-homogeneous family, with only certain highly virulent representatives. The specific characterization of Beijing isolates in different settings could help us to accurately identify the virulent representatives before making general assumptions about this lineage.</p

    Pulsating stars in ω Centauri. Near-IR properties and period-luminosity relations

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    Indexación: Scopus.ω Centauri (NGC 5139) contains many variable stars of different types, including the pulsating type II Cepheids, RR Lyrae and SX Phoenicis stars. We carried out a deep, wide-field, near-infrared (IR) variability survey of ω Cen, using the VISTA telescope. We assembled an unprecedented homogeneous and complete J and KS near-IR catalog of variable stars in the field of ω Cen. In this paper we compare optical and near-IR light curves of RR Lyrae stars, emphasizing the main differences. Moreover, we discuss the ability of near-IR observations to detect SX Phoenicis stars given the fact that the amplitudes are much smaller in these bands compared to the optical. Finally, we consider the case in which all the pulsating stars in the three different variability types follow a single period-luminosity relation in the near-IR bands.https://www.epj-conferences.org/articles/epjconf/pdf/2017/21/epjconf_puls2017_07005.pd

    Phase diagram and influence of defects in the double perovskites

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    The phase diagram of the double perovskites of the type Sr_{2-x} La_x Fe Mo O_6 is analyzed, with and without disorder due to antisites. In addition to an homogeneous half metallic ferrimagnetic phase in the absence of doping and disorder, we find antiferromagnetic phases at large dopings, and other ferrimagnetic phases with lower saturation magnetization, in the presence of disorder.Comment: 4 pages, 3 postscript figures, some errata correcte

    A colour-excess extinction map of the southern Galactic disc from the VVV and GLIMPSE surveys

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    An improved high-resolution and deep A Ks foreground dust extinction map is presented for the Galactic disc area within 295◦ ≾ l ≾ 350◦, −1.0◦ ≾ b ≾ +1.0◦. At some longitudes the map reaches up to |b| ~ 2.25◦, for a total of ~148 deg 2. The map was constructed via the Rayleigh–Jeans colour excess (RJCE) technique based on deep near-infrared (NIR) and mid-infrared (MIR) photometry. The new extinction map features a maximum bin size of 1 arcmin, and relies on NIR observations from the Two Micron All-Sky Survey (2MASS) and new data from ESO’s Vista Variables in the Vía Láctea (VVV) survey, in concert with MIR observations from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire. The VVV photometry penetrates ~4 mag fainter than 2MASS, and provides enhanced sampling of the underlying stellar populations in this heavily obscured region. Consequently, the new results supersede existing RJCE maps tied solely to brighter photometry, revealing a systematic underestimation of extinction in prior work that was based on shallower data. The new high-resolution and large-scale extinction map presented here is readily available to the community through a web query interface.Peer reviewe
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