403,180 research outputs found

    Extended X-ray emission in radio galaxies: the peculiar case of 3C 305

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    Extended X-ray structures are common in Active Galactic Nuclei (AGNs). Here we present the first case of a Compact Steep Spectrum (CSS) radio galaxy, 3C 305, in which the X-ray radiation appears to be associated with the optical emission line region, dominated by the [O III]5007. On the basis of a morphological study, performed using the comparison between the X-rays, the optical and the radio band, we argue that the high energy emission has a thermal nature and it is not directly linked to the radio jet and hotspots of this source. Finally, we discuss the origin of the extended X-ray structure connected with the optical emission line region following two different interpretations: as due to the interaction between matter outflows and shock-heated environment gas, or as due to gas photoionized by nuclear emission.Comment: 5 pages, 2 figures, Accepted for publication in The ApJL Comments: references and affilitations correcte

    Jet-cloud interations and the brightening of the narrow line region in Seyfert galaxies

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    We study the kinematical and brightness evolution of emission line clouds in the narrow line region (NLR) of Seyfert galaxies during the passage of a jet. We derive a critical density above which a cloud remains radiative after compression by the jet cocoon. The critical density depends mainly on the cocoon pressure. Super-critical clouds increase in emission line brightness, while sub-critical clouds generally are highly overheated reducing their luminosity below that of the inter-cloud medium. Due to the pressure stratification in the bow-shock of the jet, a cylindrical structure of nested shells develops around the jet. The most compact and brightest compressed clouds surround the cloud-free channel of the radio jet. To support our analytical model we present a numerical simulation of a supersonic jet propagating into a clumpy NLR. The position-velocity diagram of the simulated H_alpha emission shows total line widths of the order of 500 km/s with large-scale variations in the radial velocities of the clouds due to the stratified pressure in the bow-shock region of the jet. Most of the luminosity is concentrated in a few dense clouds surrounding the jet. These morphological and kinematic signatures are all found in the well observed NLR of NGC1068 and other Seyfert galaxies.Comment: 11 pages, 3 figures, accepted for publication in The Astrophysical Journal Letter

    Morphological Analysis of Frontier Villages in Cyprus

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    [EN] Borders may be built for security reasons however; they also demarcate administrative, economic, socio-cultural, ethnic or religious divergence. Borders change the destinies of the societies at both sides because they affect the process of urban development and delimit the economic and socio-cultural interactions. Cyprus has been experiencing an interrupted continuity along the border, i.e. green line, under the rule of UN that divides north from the south. In this regard the aim of the study is to figure out how the de facto borders affect the configuration of villages upon their existing position. As a part of an ongoing research which investigates all eleven frontier villages and towns located along the border line, this paper only focuses on the morphological and syntactic comparison of four frontier villages. Within this context, initial exploration is about the village morphologies by means of Morphological Regions based on the evolutionary insights of Conzen (2004) and Whitehand (2009). Additionally, considering shifted centrality and transformed social gathering spaces, research discusses the applicability of the comparative analyses of syntactic and morphological methods in order to reveal the characteristics of the frontier villages. The preliminary findings of the research indicates that edge villages located along the green line have a controlled spatial development with dead ends and loop layouts, where the spatial configuration presents an introverted structure. On the other hand, villages divided by the green line, presents a relatively integrated spatial structure developed on both sides of the border, maintaining traditional centrality along with emphasizing forced territoriality.Edgu, E.; Zafer Comert, N.; Ozgece, N. (2018). Morphological Analysis of Frontier Villages in Cyprus. En 24th ISUF International Conference. Book of Papers. Editorial Universitat Politècnica de València. 1255-1264. https://doi.org/10.4995/ISUF2017.2017.5128OCS1255126

    U-Pb isotopic results for single shocked and polycrystalline zircons record 550-65.5-Ma ages for a K-T target site and 2700-1850-Ma ages for the Sudbury impact event

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    The refractory mineral zircon develops distinct morphological features during shock metamorphism and retains these features under conditions that would anneal them in other minerals. In addition, weakly shocked zircon grains give primary ages for the impact site, while highly reconstituted (polycrystalline) single grains give ages that approach the age of the impact event. Data for a series of originally coeval grains will define a mixing line that gives both of these ages providing that no subsequent geological disturbances have overprinted the isotopic systematics. In this study, we have shown that the three zircon grain types described by Bohor, from both K-T distal ejecta (Fireball layer, Raton Basin, Colorado) and the Onaping Formation, represent a progressive increase in impact-related morphological change that coincides with a progressive increase in isotopic resetting in zircons from the ejecta and basement rocks. Unshocked grains are least affected by isotopic resetting while polycrystalline grains are most affected. U-Pb isotopic results for 12 of 14 single zircon grains from the Fireball layer plot on or close to a line recording a primary age of 550 +/- 10 Ma and a secondary age of 65.5 +/- 3 Ma. Data for the least and most shocked grains plot closest to the primary and secondary ages respectively. The two other grains each give ages between 300 and 350 Ma. This implies that the target ejecta was dominated by 550-Ma rocks and that the recrystallization features of the zircon were superimposed during the impact event at 65.5 Ma. A predominant age of 550 Ma for zircons from the Fireball layer provides an excellent opportunity to identify the impact site and to test the hypothesis that multiple impacts occurred at this time. A volcanic origin for the Fireball layer is ruled out by shock-related morphological changes in zircon and the fact that the least shocked grains are old. Basement Levack gneisses north of the Sudbury structure have a primary age of 2711 Ma. Data for three single zircons from this rock, which record a progressive increase in shock features, are displaced 24, 36, and 45 percent along a Pb-loss line toward the 1850 +/- 1 Ma minimum age for the impact as defined by the age of the norite. Southeast of the structure three shocked grains from the Murray granite record a primary age of 2468 Ma and are displaced 24, 41, and 56 percent toward the 1853 +/- 4 Ma even as defined by coexisting titanite

    Raman Studies of Structural Changes in Diamond-like Carbon Films on Si Induced by Ultrafast Laser Ablation

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    In this study, the diamond-like carbon (DLC), a tetrahedral amorphous carbon sample deposited on Si, was irradiated using a picosecond laser. We evaluated the picosecond-laser-induced structural and morphological changes in DLC using micro-Raman spectroscopy via line measurements. We obtained the spatial distribution of the structure and morphology of DLC on Si by regression analysis of the Raman spectra. The photo-induced crater could be categorized into four regions: peripheral, morphological-change, structural-changes, and ablated regions. The structure and morphology of the peripheral region were similar to those of the as-received DLC. In the morphological-change region, which is inside the periphery region, the thickness of the DLC decreased without any structural changes. At the center of the crater, which is shown in black in the optical image, two regions were identified by Raman spectroscopy. On the outer side, there is a structural-change region where the graphitization of DLC materialized with a reduction in the film thickness. Inside the structural-change region, there is an ablated region where the DLC was degraded by laser ablation
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