52 research outputs found
BeppoSAX observations of the Seyfert 1 Galaxy NGC 3516
We present the results of two observations of the bright Seyfert 1 galaxy NGC
3516, obtained with BeppoSAX in 1996 November and 1997 March. Useful signal is
detected between 0.2 and 60 keV, allowing for the first time the simultaneous
observation of all main spectral features. The source was brighter by a factor
2 at the second epoch of observation. Both spectra present a strong Fe Kalpha
line, and a reflection hump at high energy. An absorption edge at 0.8 keV is
visible in the later spectrum, but not in the earlier one, indicating that this
feature is strongly variable.Comment: to appear in : The Active X-ray Sky: Results from BeppoSAX and
Rossi-XTE, Nuclear Physics B Proceedings Supplements, L. Scarsi, H. Bradt, P.
Giommi and F. Fiore (eds.), Elsevier Science B.V. 4 pages LateX and 6 ps
figures, using espcrc2 and epsfi
The UV spectra of NLS1s - Implications for their broad line regions
We study the UV spectra of NLS1 galaxies and compare them with typical
Seyfert 1 galaxies and quasars. The NLS1 spectra show narrower UV lines as well
as weaker CIV lambda 1549 and CIII] lambda 1909 emission. We show that these
line properties are due to a lower ionization parameter and somewhat higher BLR
cloud densities. These modified conditions can be explained by the hotter big
blue bumps observed in NLS1s, which are in turn due to higher L/L_Edd ratios,
as shown by our accretion disk and corona modeling of the NLS1 continua. We
also present evidence that the Boroson & Green eigenvector 1, which is
correlated with the optical and UV emission-line properties, is not driven by
orientation and hence NLS1s, which have extreme eigenvector 1 values, are not
viewed from an extreme viewing angle.Comment: Contributed talk presented at the Joint MPE,AIP,ESO workshop on
NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also
available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho
Tracking Performance of the Scintillating Fiber Detector in the K2K Experiment
The K2K long-baseline neutrino oscillation experiment uses a Scintillating
Fiber Detector (SciFi) to reconstruct charged particles produced in neutrino
interactions in the near detector. We describe the track reconstruction
algorithm and the performance of the SciFi after three years of operation.Comment: 24pages,18 figures, and 1 table. Preprint submitted to NI
Measurement of single pi0 production in neutral current neutrino interactions with water by a 1.3 GeV wide band muon neutrino beam
Neutral current single pi0 production induced by neutrinos with a mean energy
of 1.3 GeV is measured at a 1000 ton water Cherenkov detector as a near
detector of the K2K long baseline neutrino experiment. The cross section for
this process relative to the total charged current cross section is measured to
be 0.064 +- 0.001 (stat.) +- 0.007 (sys.). The momentum distribution of
produced pi0s is measured and is found to be in good agreement with an
expectation from the present knowledge of the neutrino cross sections.Comment: 6 pages, 4 figures, Submitted to Phys. Lett.
A Galaxy-scale Fountain of Cold Molecular Gas Pumped by a Black Hole
We present Atacama Large Millimeter/submillimeter Array and Multi-Unit Spectroscopic Explorer observations of the brightest cluster galaxy in Abell 2597, a nearby (z = 0.0821) cool core cluster of galaxies. The data map the kinematics of a three billion solar mass filamentary nebula that spans the innermost 30 kpc of the galaxy's core. Its warm ionized and cold molecular components are both cospatial and comoving, consistent with the hypothesis that the optical nebula traces the warm envelopes of many cold molecular clouds that drift in the velocity field of the hot X-ray atmosphere. The clouds are not in dynamical equilibrium, and instead show evidence for inflow toward the central supermassive black hole, outflow along the jets it launches, and uplift by the buoyant hot bubbles those jets inflate. The entire scenario is therefore consistent with a galaxy-spanning "fountain," wherein cold gas clouds drain into the black hole accretion reservoir, powering jets and bubbles that uplift a cooling plume of low-entropy multiphase gas, which may stimulate additional cooling and accretion as part of a self-regulating feedback loop. All velocities are below the escape speed from the galaxy, and so these clouds should rain back toward the galaxy center from which they came, keeping the fountain long lived. The data are consistent with major predictions of chaotic cold accretion, precipitation, and stimulated feedback models, and may trace processes fundamental to galaxy evolution at effectively all mass scales
Raining in MKW 3 s: a Chandra-MUSE analysis of X-Ray cold filaments around 3CR 318.1
High Energy Astrophysic
Оптимизация конструкции захвата для детали «Барабан»
Грузозахватные приспособления обычно применяются при производстве работ по подъему и перемещению грузов с применением грузоподъемных машин. Использование приспособлений позволяет реализовать максимальное удобство и безопасность производственного процесса. Грузозахватные приспособления конструируются для определенного этапа технологического процесса, для конкретного изделия. При проектировании таких приспособлений необходимо учитывать основные показатели оптимальности конструкции: прочность, надежность, простота, удобство и безопасность при эксплуатации, эргономичность. Кроме того, нужно стремиться к наименьшей массе и, соответственно, металлоемкости захвата. Конструкция грузозахватного приспособления, в основном, будет зависеть от назначенных технологом поверхностей, за которые можно крепиться и от максимальной высоты подъема крюка крана. В статье описана задача по конструированию захвата для детали «Барабан¬ в новом технологическом процессе. Рассмотрена конструкция существующего захвата, взятого за прототип. Приведен анализ различных вариантов конструктивных решений, созданных в процессе проектирования. Выбран вариант конструкции захвата, который в наибольшей степени соответствует требованиям технического задания. Конструкция этого модернизированного приспособления представляет собой захват с тремя лапами, удерживающими деталь, и подвес в виде траверсы. Разработанная конструкторская документация утверждена производством и отделом промышленной безопасности
Load partitioning in honeycomb-like silicon carbide aluminum alloy composites
A 50/50 vol.% Al/SiC composite was made via melt infiltration of an aluminum alloy into a porous beech wood-derived SiC preform. The honeycomb-like composite microstructure consisted of an interconnected SiC phase surrounding discrete Al “fibers” aligned in the growth direction of the beech wood. High energy synchrotron X-ray diffraction was used to measure the volume averaged lattice strains in both the SiC and Al phases during in situ compressive loading up to an applied stress of −530 MPa. Load transfer from the Al to the SiC was observed, and the Al yielded at an applied stress of above −213 MPa. The elastic behavior of the composite was modeled with both an isostrain rule of mixtures calculation and variational bounds for the effective elastic modulus. Furthermore, calculations of the von Mises effective stress of the SiC and Al phases showed that the wood-derived SiC was a more effective reinforcement than either SiC particle- or whisker-reinforced composites
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The Cambridge–Cambridge ROSAT Serendipity Survey – II. Classification of X-ray-luminous Galaxies
We present the results of an intermediate-resolution (1.5\AA) spectroscopic study of 17 X-ray luminous narrow emission-line galaxies previously identified in the Cambridge-Cambridge {\it ROSAT} Serendipity Survey and the {\it Einstein} Extended Medium Sensitivity Survey. Emission-line ratios reveal that the sample is composed of ten Seyfert and seven starburst galaxies. Measured linewidths for the narrow Hα emission lines lie in the range 170−460kms−1. Five of the objects show clear evidence for asymmetry in the [OIII]λ5007 emission-line profile. Broad Hα emission is detected in six of the Seyfert galaxies, which range in type from Seyfert 1.5 to 2. Broad Hβ emission is only detected in one Seyfert galaxy. The mean full width at half maximum for the broad lines in the Seyfert galaxies is FWHM=3900±1750kms−1. Broad (FWHM=2200±600kms−1) Hα emission is also detected in three of the starburst galaxies, which could originate from stellar winds or supernovae remnants. The mean Balmer decrement for the sample is Hα/Hβ=3, consistent with little or no reddening for the bulk of the sample. There is no evidence for any trend with X-ray luminosity in the ratio of starburst galaxies to Seyfert galaxies. Based on our previous observations, it is therefore likely that both classes of object comprise ∼10per cent of the 2keV X-ray background.Astronom
X-ray absorption and re-emission from an ionized outflow in the Type I quasi-stellar object 2MASS 234449+1221 observed by XMM-Newton
We report on the analysis of a short XMM–Newton observation of the reddened Type 1 quasistellar object (QSO) 2MASS 234449+1221 first identified in the Two-Micron All-Sky Survey (2MASS). The underlying X-ray continuum is found to be typical of a broad-line active galaxy, with photon index Γ ∼ 1.9. Low-energy absorption can be modelled by a column NH ∼ 10²² cm−² of moderately ionized gas or a smaller column of cold gas. Addition of a soft X-ray emission component significantly improves the fit in both cases. With the assumption that the
soft X-ray flux represents emission from gas photoionized by the incident X-ray continuum, a comparison of the absorbed and emitted luminosities indicates a covering factor of ∼8–17 per cent. The unusual opportunity simultaneously to observe and quantify ionized absorption and emission in 2MASS 234449+1221 is due to the relatively large opacity – for a Type 1 active galactic nucleus (AGN) – of the absorbing gas, which depresses the normally strong
continuum below ∼1 keV. A comparison of the soft X-ray emission of 2MASS 234449+1221
with that of other Type 1 and Type 2AGNs suggests the existence of an inner turbulent extension to ionized outflows, not detected in current high-resolution X-ray spectra
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