237 research outputs found

    The Inner Galaxy resolved at IJK using DENIS data

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    We present the analysis of three colour optical/near-infrared images, in IJK, taken for the DENIS project. The region considered covers 17.4 square deg and lies within |l|<5 deg, |b|<1.5 deg. The adopted methods for deriving photometry and astrometry in these crowded images, together with an analysis of the deficiencies nevertheless remaining, are presented. The numbers of objects extracted in I,J and K are 748000, 851000 and 659000 respectively, to magnitude limits of 17,15 and 13. 80% completeness levels typically fall at magnitudes 16, 13 and 10 respectively, fainter by about 2 magnitudes than the usual DENIS limits due to the crowded nature of these fields. A simple model to describe the disk contribution to the number counts is constructed, and parameters for the dust layer derived. We find that a formal fit of parameters for the dust plane, from these data in limited directions, gives a scalelength and scaleheight of 3.4+-1.0 kpc and 40+-5 pc respectively, and a solar position 14.0+-2.5 pc below the plane. This latter value is likely to be affected by localised dust asymmetries. We convolve a detailed model of the systematic and random errors in the photometry with a simple model of the Galactic disk and dust distribution, to simulate expected colour-magnitude diagrams. These are in good agreement with the observed diagrams, allowing us to isolate those stars from the inner disk and bulge. After correcting for local dust-induced asymmetries, we find evidence for longitude-dependent asymmetries in the distant J and K sources, consistent with the general predictions of some Galactic bar models. We consider complementary L-band observations in a second paper.Comment: 14 pages, 33 figures, LaTeX, MNRAS accepte

    A benchmark of light field view interpolation methods

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    Light field view interpolation provides a solution that reduces the prohibitive size of a dense light field. This paper examines state-ofthe-art light field view interpolation methods with a comprehensive benchmark on challenging scenarios specific for interpolation tasks. Each method is analyzed in terms of their strengths and weaknesses in handling different challenges. We find that large disparities in a scene are the main source of challenge for the light field view interpolation methods. We also find that a basic backward warping based on the depth estimation from optical flow provides comparable performance against usually complex learning-based methods

    Dark Sector Glueballs at the LHC

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    We study confining dark sectors where the lightest hadrons are glueballs. Such models can provide viable dark matter candidates and appear in some neutral naturalness scenarios. In this work, we introduce a new phenomenological model of dark glueball hadronization inspired by the Lund string model. This enables us to make realistic predictions for dark glueball phenomenology at the LHC for the first time. Our model reproduces the expected thermal distribution of hadron species as an emergent consequence of hadronization dynamics. The ability to predict the production of glueball states heavier than the lightest species significantly expands the reach of long-lived glueball searches in MATHUSLA compared to previous simplified estimates. We also characterize regions of parameter space where emerging and/or semivisible jets could arise from pure-glue dark sectors, thereby providing new benchmark models that motivate searches for these signatures.Comment: 27 pages + appendices + references, 11 + 4 figure

    Stellar sources in the ISOGAL intermediate bulge fields

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    We present a study of ISOGAL sources in the "intermediate" galactic bulge (∣|ll∣| << 2∘^\circ, ∣|bb∣| ∼\sim 1∘^\circ--4∘^\circ), observed by ISOCAM at 7 and 15 μm\mu m. In combination with near-infrared (I, J, Ks_{\rm s}) data of DENIS survey, complemented by 2MASS data, we discuss the nature of the ISOGAL sources, their luminosities, the interstellar extinction and the mass-loss rates. A large fraction of the 1464 detected sources at 15 μm\mu m are AGB stars above the RGB tip, a number of them show an excess in ([7]-[15])0_{\rm 0} and (Ks_{\rm s}-[15])0_{\rm 0} colours, characteristic of mass-loss. The latter, especially (Ks_{\rm s}-[15])0_{\rm 0}, provide estimates of the mass-loss rates and show their distribution in the range 10−8^{-8} to 10−5^{-5} M⊙_{\rm \odot}/yr.Comment: 16 pages, accepted for publication in Astronomy and Astrophysic

    First HARPSpol discoveries of magnetic fields in massive stars

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    In the framework of the Magnetism in Massive Stars (MiMeS) project, a HARPSpol Large Program at the 3.6m-ESO telescope has recently started to collect high-resolution spectropolarimetric data of a large number of Southern massive OB stars in the field of the Galaxy and in many young clusters and associations. In this Letter, we report on the first discoveries of magnetic fields in two massive stars with HARPSpol - HD 130807 and HD 122451, and confirm the presence of a magnetic field at the surface of HD 105382 that was previously observed with a low spectral resolution device. The longitudinal magnetic field measurements are strongly varying for HD 130807 from ∼\sim-100 G to ∼\sim700 G. Those of HD 122451 and HD 105382 are less variable with values ranging from ∼\sim-40 to -80 G, and from ∼\sim-300 to -600 G, respectively. The discovery and confirmation of three new magnetic massive stars, including at least two He-weak stars, is an important contribution to one of the MiMeS objectives: the understanding of origin of magnetic fields in massive stars and their impacts on stellar structure and evolution.Comment: 4 pages, 2 figures, accepted for publication in A&A Lette

    IFN regulatory factor 4 controls post-ischemic inflammation and prevents chronic kidney disease

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    Ischemia reperfusion injury (IRI) of the kidney results in interferon regulatory factor 4 (IRF4)–mediated counter-regulation of the acute inflammatory response. Beyond that, IRF4 exerts important functions in controlling the cytokine milieu, T-cell differentiation, and macrophage polarization. The latter has been implicated in tissue remodeling. It therefore remains elusive what the role of IRF4 is in terms of long-term outcome following IRI. We hypothesized that an inability to resolve chronic inflammation in Irf4−/− mice would promote chronic kidney disease (CKD) progression. To evaluate the effects of IRF4 in chronic upon acute injury in vivo, a mouse model of chronic injury following acute IRI was employed. The expression of Irf4 increased within 10 days after IRI in renal tissue. Both mRNA and protein levels remained high up to 5 weeks upon IRI, suggesting a regulatory function in the chronic phase. Mice deficient in IRF4 display increased tubular cell loss and defective clearance of infiltrating macrophages. These phenomena were associated with increased expression of pro-inflammatory macrophage markers together with reduced expression of alternatively activated macrophage markers. In addition, IRF4-deficient mice showed defective development of alternatively activated macrophages. Hints of a residual M1 macrophage signature were further observed in human biopsy specimens of patients with hypertensive nephropathy vs. living donor specimens. Thus, IRF4 restricts CKD progression and kidney fibrosis following IRI, potentially by enabling M2 macrophage polarization and restricting a Th1 cytokine response. Deteriorated alternative macrophage subpopulations in Irf4−/− mice provoke chronic intrarenal inflammation, tubular epithelial cell loss, and renal fibrosis in the long course after IRI in mice. The clinical significance of these finding for human CKD remains uncertain at present and warrants further studies

    First ISOCAM images of the Milky Way

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    ISOGAL is a 15 &#956;m ISOCAM survey of &#8764; 12 deg2 in the Galactic Plane interior to |&#x2113;| = 45&#176;. In combination with IJK data from the near-infrared southern sky survey DENIS, the ISO images allow the first detailed study of stellar populations throughout the inner Galaxy. We present preliminary results from a test observation at &#x2113; = 45&#176; with 6" pixels and completeness limit 8 mJy. Of the &#8764; 3000 sources deg2 detected, about half are KM giants, seen through extinction of up to Av, ∼, 30,while most of the remainder are probably dusty young stars. Although away from bright IRAS regions, the field displays spectacular emission features, and, unexpectedly, a number of regions which are optically thick at 15 &#956;m. The dark regions are presumably dense filaments with Av, >, 25
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