297 research outputs found
EVN Observations of HESS J1943+213: Evidence for an Extreme TeV BL Lac Object
We report on the 1.6 GHz (18 cm) VLBI observations of the unresolved, steady
TeV source HESS J1943+213 located in the Galactic plane, performed with the
European VLBI Network (EVN) in 2014. Our new observations with a nearly full
EVN array provide the deepest image of HESS J1943+213 at the highest resolution
ever achieved, enabling us to resolve the long-standing issues of the source
identification. The milliarcsecond-scale structure of HESS J1943+213 has a
clear asymmetric morphology, consisting of a compact core and a diffuse
jet-like tail. This is broadly consistent with the previous e-EVN observations
of the source performed in 2011, and re-analyzed in this work. The core
component is characterized by the brightness temperature of K, which is typical for low-luminosity blazars in general. Overall, radio
properties of HESS J1943+213 are consistent with the source classification as
an "extreme high-frequency-peaked BL Lac object". Remarkably, we note that
since HESS J1943+213 does not reveal any optical or infrared signatures of the
AGN activity, it would never be recognized and identified as a BL Lac object,
if not its location close to the Galactic plane where the High Energy
Stereoscopic System has surveyed, and the follow-up dedicated X-ray and radio
studies triggered by the source detection in the TeV range. Our results suggest
therefore a presence of an unrecognized, possibly very numerous population of
particularly extreme HBLs, and simultaneously demonstrate that the
low-frequency VLBI observations with high-angular resolution are indispensable
for a proper identification of such objects.Comment: 8 pages, 3 figures, accepted to ApJ
Enzyme Histochemical Studies on the Parathyroid Gland and Thyroid C-cells in the Common Dolphin (Delphinus Delphis)
A drawing learning support system based on the drawing process model
ArticleInteractive Technology and Smart Education. 11(2): 146-164 (2014)journal articl
A drawing learning support system based on the drawing process model
ArticleInteractive Technology and Smart Education. 11(2): 146-164 (2014)journal articl
High-Sensitivity 86GHz (3.5mm) VLBI Observations of M87: Deep Imaging of the Jet Base at a 10 Schwarzschild-Radius Resolution
We report on results from new high-sensitivity, high-resolution 86GHz (3.5
millimeter) observations of the jet base in the nearby radio galaxy M87,
obtained by the Very Long Baseline Array in conjunction with the Green Bank
Telescope. The resulting image has a dynamic range exceeding 1500 to 1, the
highest ever achieved for this jet at this frequency, resolving and imaging a
detailed jet formation/collimation structure down to ~10 Schwarzschild radii
(Rs). The obtained 86GHz image clearly confirms some important jet features
known at lower frequencies, i.e., a wide-opening angle jet base, a
limb-brightened intensity profile, a parabola-shape collimation profile and a
counter jet. The limb-brightened structure is already well developed at <
0.2mas (< 28Rs, projected) from the core, where the corresponding apparent
opening angle becomes as wide as ~100 degrees. The subsequent jet collimation
near the black hole evolves in a complicated manner; there is a "constricted"
structure at tens Rs from the core, where the jet cross section is locally
shrinking. We suggest that an external pressure support from the inner part of
radiatively-inefficient accretion flow may be dynamically important in
shaping/confining the footprint of the magnetized jet. We also present the
first VLBI 86GHz polarimetric experiment for this source, where a highly
polarized (~20%) feature is detected near the jet base, indicating the presence
of a well-ordered magnetic field. As a by-product, we additionally report a
43/86 GHz polarimetric result for our calibrator 3C 273 suggesting an extreme
rotation measure near the core.Comment: Accepted for publication in ApJ. 39 pages, 11 figures, 3 table
VERA monitoring of the radio jet 3C 84 during 2007--2013: detection of non-linear motion
We present a kinematic study of the subparsec-scale radio jet of the radio
galaxy 3C 84/NGC 1275 with the VLBI Exploration of Radio Astrometry (VERA)
array at 22 GHz for 80 epochs from 2007 October to 2013 December. The averaged
radial velocity of the bright component "C3" with reference to the radio core
is found to be between 2007 October and 2013 December. This
constant velocity of C3 is naturally explained by the advancing motion of the
head of the mini-radio lobe. We also find a non-linear component in the motion
of C3 with respect to the radio core. We briefly discuss possible origins of
this non-linear motion.Comment: 11 pages, 7 figures, 8 tables (table 1 - 5 are supplementaries),
accepted for publication on PAS
Parabolic Jets from the Spinning Black Hole in M87
The M87 jet is extensively examined by utilizing general relativistic
magnetohydrodynamic (GRMHD) simulations as well as the steady axisymmetric
force-free electrodynamic (FFE) solution. Quasi-steady funnel jets are obtained
in GRMHD simulations up to the scale of gravitational radius
() for various black hole (BH) spins. As is known, the funnel edge
is approximately determined by the following equipartitions; i) the magnetic
and rest-mass energy densities and ii) the gas and magnetic pressures. Our
numerical results give an additional factor that they follow the outermost
parabolic streamline of the FFE solution, which is anchored to the event
horizon on the equatorial plane. We also identify the matter dominated,
non-relativistic corona/wind play a dynamical role in shaping the funnel jet
into the parabolic geometry. We confirm a quantitative overlap between the
outermost parabolic streamline of the FFE jet and the edge of jet sheath in
VLBI observations at -, suggesting that the
M87 jet is likely powered by the spinning BH. Our GRMHD simulations also
indicate a lateral stratification of the bulk acceleration (i.e., the
spine-sheath structure) as well as an emergence of knotty superluminal
features. The spin characterizes the location of the jet stagnation surface
inside the funnel. We suggest that the limb-brightened feature could be
associated with the nature of the BH-driven jet, if the Doppler beaming is a
dominant factor. Our findings can be examined with (sub-)mm VLBI observations,
giving a clue for the origin of the M87 jet.Comment: 29 pages, 23 figures, accepted for publication in Ap
Histopathologically confirmed very late stent thrombosis associated with stent fracture after implantation of first-generation drug eluting stent
Parabolic Jets from the Spinning Black Hole in M87
The M87 jet is extensively examined by utilizing general relativistic magnetohydrodynamic (GRMHD) simulations, as well as the steady axisymmetric force-free electrodynamic (FFE) solution. Quasi-steady funnel jets are obtained in GRMHD simulations up to the scale of ~100 gravitational radii (r(sub g)) for various black hole (BH) spins. As is known, the funnel edge is approximately determined by the following equipartitions: (i) the magnetic and rest-mass energy densities and (ii) the gas and magnetic pressures. Our numerical results give an additional factor that they follow the outermost parabolic streamline of the FFE solution, which is anchored to the event horizon on the equatorial plane. We also show that the matter-dominated, nonrelativistic corona/wind plays a dynamical role in shaping the funnel jet into the parabolic geometry. We confirm a quantitative overlap between the outermost parabolic streamline of the FFE jet and the edge of the jet sheath in very long baseline interferometry (VLBI) observations at ~(10(exp 1)10(exp 5))r(sub g), suggesting that the M87 jet is likely powered by the spinning BH. Our GRMHD simulations also indicate a lateral stratification of the bulk acceleration (i.e., the spine-sheath structure), as well as an emergence of knotty superluminal features. The spin characterizes the location of the jet stagnation surface inside the funnel. We suggest that the limb-brightened feature could be associated with the nature of the BH-driven jet, if the Doppler beaming is a dominant factor. Our findings can be examined with (sub)millimeter VLBI observations, giving a clue for the origin of the M87 jet
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