VLBI Imagings of Kilo-parsec Knot in 3C 380

We investigate observational properties of a kilo-parsec scale knot in radio-loud quasar 3C 380 by using two epoch archival data obtained by Very Long Baseline Interferometry (VLBI) at 5 GHz on 1998 July and 2001 April. We succeed in obtaining the highest spatial resolution image of the bright knot K1 located at 732 milliarcseconds, or more than 20 kpc de-projected, downstream from the nucleus three times better than previously obtained highest resolution image by Papageorgiou et al. (2006). Our images reveal, with new clarity, "inverted bow-shock" structure in K1 facing the nucleus and its morphology resembles a conical shock wave. By comparing the two epoch images directly, we explore the kinematics of K1 and obtain the upper limit of apparent velocity, 0.25 mas/yr or 9.8 c of K1 for the first time. The upper limit of apparent velocity is marginally smaller than superluminal motions seen in the core region. Further new epoch VLBI observations are necessary to measure the proper motion at K1.Comment: 15 pages, 4 figures, accepted for publication in PAS

Kiloparsec-scale Radio Structures in Narrow-line Seyfert 1 Galaxies

We report the finding of kiloparsec (kpc)-scale radio structures in three radio-loud narrow-line Seyfert 1 (NLS1) galaxies from the Faint Images of the Radio Sky at Twenty-centimeters (FIRST) of the Very Large Array (VLA), which increases the number of known radio-loud NLS1s with kpc-scale structures to six, including two gamma-ray emitting NLS1s (PMN J0948+0022 and 1H 0323+342) detected by the Fermi Gamma-ray Space Telescope. The detection rate of extended radio emissions in NLS1s is lower than that in broad-line active galactic nuclei (AGNs) with a statistical significance. We found both core-dominated (blazar-like) and lobe-dominated (radio-galaxy-like) radio structures in these six NLS1s, which can be understood in the framework of the unified scheme of radio-loud AGNs that considers radio galaxies as non-beamed parent populations of blazars. Five of the six NLS1s have (i) extended radio luminosities suggesting jet kinetic powers of >~10^44 erg/s, which is sufficient to make jets escape from hosts' dense environments, (ii) black holes of >~10^7 solar mass, which can generate the necessary jet powers from near-Eddington mass accretion, and (iii) two-sided radio structures at kpc scales, requiring expansion rates of ~0.01c--0.3c and kinematic ages of >~10^7 years. On the other hand, most typical NLS1s would be driven by black holes of <~10^7 solar mass in a limited lifetime of ~10^7 years. Hence the kpc-scale radio structures may originate in a small window of opportunity during the final stage of the NLS1 phase just before growing into broad-line AGNs.Comment: 12 pages, 3 figures, 3 tables, accepted for publication in the Astrophysical Journa

Benign Pigmented Schwannoma of the Great Omentum: Report of a Rare Case and Review of the Literature

Schwannoma in the abdomen is an uncommon neoplasm that occurs most frequently in the cranial and peripheral nerves; it is extremely rare in the great omentum and only 6 cases of schwannoma of the great omentum have been observed previously. We report the case of a schwannoma found in the great omentum of a 55-year-old man who was treated with laparoscopic surgery. Though it was difficult to diagnose preoperatively, the tumor showed malignant potential by rapidly increasing in size. Histologically it was configured by a well-encapsulated round mass measuring 30 × 18 × 15 mm in diameter. Immunohistochemically most of the neoplastic cells reacted moderately to NSE, NCAM and S-100 protein. We document the clinicopathological study of a schwannoma of the great omentum, followed by a review of the literature

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

ALMA ACA detection of submillimeter emission associated with the west hot spot of the radio galaxy Pictor A

In order to investigate the far-infrared excess detected from the west hot spot of the radio galaxy Pictor A with the Herschel observatory, a submillimeter photometry is performed with the Atacama Compact Array (ACA) of the Atacama Large Millimeter/submillimeter Array at Band 8 with the reference frequency of 405 GHz. A submillimeter source is discovered at the radio peak of the hot spot. Because the 405 GHz flux density of the source, $80.7\pm3.1$ mJy, agrees with the extrapolation of the synchrotron radio spectrum, the far-infrared excess is suggested to exhibit no major contribution at the ACA band. In contrast, by subtracting the power-law spectrum tightly constrained by the radio and ACA data, the significance of the excess in the Herschel band is well confirmed. No diffuse submillimeter emission is detected within the ACA field of view, and thus, the excess is ascribed to the west hot spot itself. In comparison to the previous estimate based on the Herschel data, the relative contribution of the far-infrared excess is reduced by a factor of $\sim 1.5$. The spectrum of the excess below the far-infrared band is determined to be harder than that of the diffusive shock acceleration. This strengthens the previous interpretation that the excess originates via the magnetic turbulence in the substructures within the hot spot. The ACA data are utilized to evaluate the magnetic field strength of the excess and of diffuse radio structure associated to the hot spot.Comment: 10 pages,4 figures, 3 tables, accepted for Ap

VLBI Monitoring of 3C 84 (NGC 1275) in Early Phase of the 2005 Outburst

Multi-epoch Very Long Baseline Interferometry (VLBI) study of the sub-pc scale jet of 3C 84 is presented. We carried out 14-epoch VLBI observations during 2006-2009 with the Japanese VLBI Network (JVN) and the VLBI Exploration of Radio Astrometry (VERA), immediately following the radio outburst that began in 2005. We confirmed that the outburst was associated with the central ~1 pc core, accompanying the emergence of a new component. This is striking evidence of the recurrence of jet activity. The new component became brighter during 2008, in contrast to the constant gamma-ray emission that was observed with the Fermi Gamma-ray Space Telescope during the same time. We found that the projected speed of the new component is 0.23c from 2007/297 (2007 October 24) to 2009/114 (2009 April 24). The direction of movement of this component differs from that of the pre-existing component by ~40 degree. This is the first measurement of kinematics of a sub-pc jet in a gamma-ray active phase. Possible detection of jet deceleration and the jet kinematics in connection with the gamma-ray emission is discussed.Comment: 5 pages, 3 figures. Accepted for publication in PAS