749 research outputs found
Chandra Observations of Arp 220: The Nuclear Source
We present the first results from 60ks of observations of Arp 220 using the
ACIS-S instrument on Chandra. We report the detection of several sources near
the galaxy's nucleus, including a point source with a hard spectrum that is
coincident with the western radio nucleus B. This point source is mildly
absorbed (N_H ~ 3 x 10^22 cm^-2) and has an estimated luminosity of 4 x 10^40
erg/s. In addition, a fainter source may coincide with the eastern nucleus A.
Extended hard X-ray emission in the vicinity raises the total estimated nuclear
2-10 keV X-ray luminosity to 1.2 x 10^41 erg/s, but we cannot rule out a hidden
AGN behind columns exceeding 5 x 10^24 cm^-2. We also detect a peak of soft
X-ray emission to the west of the nucleus, and a hard point source 2.5 kpc from
the nucleus with a luminosity of 6 x 10^39 erg/s.Comment: Accepted for publication in Ap
Chandra Observations of Arp 220: The Nuclear Source
We present the first results from 60ks of observations of Arp 220 using the
ACIS-S instrument on Chandra. We report the detection of several sources near
the galaxy's nucleus, including a point source with a hard spectrum that is
coincident with the western radio nucleus B. This point source is mildly
absorbed (N_H ~ 3 x 10^22 cm^-2) and has an estimated luminosity of 4 x 10^40
erg/s. In addition, a fainter source may coincide with the eastern nucleus A.
Extended hard X-ray emission in the vicinity raises the total estimated nuclear
2-10 keV X-ray luminosity to 1.2 x 10^41 erg/s, but we cannot rule out a hidden
AGN behind columns exceeding 5 x 10^24 cm^-2. We also detect a peak of soft
X-ray emission to the west of the nucleus, and a hard point source 2.5 kpc from
the nucleus with a luminosity of 6 x 10^39 erg/s.Comment: Accepted for publication in Ap
Note: "Lock-in accelerometry" to follow sink dynamics in shaken granular matter
Understanding the penetration dynamics of intruders in granular beds is
relevant not only for fundamental Physics, but also for geophysical processes
and construction on sediments or granular soils in areas potentially affected
by earthquakes. While the penetration of intruders in two dimensional (2D)
laboratory granular beds can be followed using video recording, it is useless
in three dimensional (3D) beds of non-transparent materials such as common
sand. Here we propose a method to quantify the sink dynamics of an intruder
into laterally shaken granular beds based on the temporal correlations between
the signals from a reference accelerometer fixed to the shaken granular bed,
and a probe accelerometer deployed inside the intruder. Due to its analogy with
the working principle of a lock in amplifier, we call this technique Lock in
accelerometry (LIA). During Earthquakes, some soils can lose their ability to
sustain shear and deform, causing subsidence and sometimes substantial building
damage due to deformation or tumblin
Chandra Observations of Extended X-ray Emission in Arp 220
We resolve the extended X-ray emission from the prototypical ultraluminous
infrared galaxy Arp 220. Extended, faint edge-brightened, soft X-ray lobes
outside the optical galaxy are observed to a distance of 10 to 15 kpc on each
side of the nuclear region. Bright plumes inside the optical isophotes coincide
with the optical line emission and extend 11 kpc from end to end across the
nucleus. The data for the plumes cannot be fit by a single temperature plasma,
and display a range of temperatures from 0.2 to 1 keV. The plumes emerge from
bright, diffuse circumnuclear emission in the inner 3 kpc centered on the
Halpha peak, which is displaced from the radio nuclei. There is a close
morphological correspondence between the Halpha and soft X-ray emission on all
spatial scales. We interpret the plumes as a starburst-driven superwind, and
discuss two interpretations of the emission from the lobes in the context of
simulations of the merger dynamics of Arp 220.Comment: Accepted for publication in ApJ; see also astro-ph/0208477 (Paper 1
UV/Vis spectroelectrochemistry of o-vanillin: Study of the antioxidant properties
UV/Vis absorption spectroelectrochemistry is a very useful technique to study complex electrochemical mechanisms. In this work, we have studied the electrochemistry of o-vanillin in presence and absence of oxygen. This compound exhibits good antioxidant properties. The products of the reaction of o-vanillin with the superoxide anion, electrogenerated when oxygen is reduced in an aprotic medium, have been detected using UV/Vis absorption spectroelectrochemistry. This technique allows us to shed more light on the antioxidant properties of o-vanillin, providing valuable information not only on the antioxidant properties of this compound but also about other compounds that follow a similar mechanism. In this work we have deconvolved the electrochemical signal in the different components that are related to the processes taking place at the electrode and in the solution adjacent to it.Ministerio de Economía y Competitividad (CTQ2017-83935-R-AEI/FEDERUE), Junta de Castilla y León (BU297P18), Ministerio de Ciencia, Innovación y Universidades (RED2018- 102412-T)
Obstructive Jaundice Due to Hepatocarcinoma With Intraductal Growth. Report of a Successful Resection
We present a patient with hepatocellular carcinoma causing obstructive jaundice due to intraductal
growth, diagnosed intraoperatively by cholangiography and histological examination, and radically
treated by left lobectomy, extrahepatic biliary tract resection and Roux-en-Y hepaticojejunostomy.
Survival after operation was 13 months. Other similar cases reported in the literature are reviewed
Mid-Infrared T-ReCS Spectroscopy of Local LIRGs
We present T-ReCS high spatial resolution N-band (8-13 micron) spectroscopy of the central regions (a few kpc) of 3 local LIRGs. The nuclear spectra show deep 9.7 micron silicate absorption feature and the high ionization [SIV]10.5 micron emission line, consistent with their optical classification as AGN. The two LIRGs with unresolved mid-IR emission do not show PAH emission at 11.3 micron in their nuclear spectra. The spatially resolved mid-IR spectroscopy of NGC 5135 allows us to separate out the spectra of the Seyfert nucleus, an HII region, and the diffuse region between them on scales of less than 2.5 arcsec ~ 600 pc. The diffuse region spectrum is characterized by strong PAH emission with almost no continuum, whereas the HII region shows PAH emission with a smaller equivalent width as well as [NeII]12.8 micron line
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