226 research outputs found
Distribution of Faraday Rotation Measure in Jets from Active Galactic Nuclei II. Prediction from our Sweeping Magnetic Twist Model for the Wiggled Parts of AGN Jets and Tails
Distributions of Faraday rotation measure (FRM) and the projected magnetic
field derived by a 3-dimensional simulation of MHD jets are investigated based
on our "sweeping magnetic twist model". FRM and Stokes parameters were
calculated to be compared with radio observations of large scale wiggled AGN
jets on kpc scales. We propose that the FRM distribution can be used to discuss
the 3-dimensional structure of magnetic field around jets and the validity of
existing theoretical models, together with the projected magnetic field derived
from Stokes parameters. In the previous paper, we investigated the basic
straight part of AGN jets by using the result of a 2-dimensional axisymmetric
simulation. The derived FRM distribution has a general tendency to have a
gradient across the jet axis, which is due to the toroidal component of the
magnetic field generated by the rotation of the accretion disk. In this paper,
we consider the wiggled structure of the AGN jets by using the result of a
3-dimensional simulation. Our numerical results show that the distributions of
FRM and the projected magnetic field have a clear correlation with the large
scale structure of the jet itself, namely, 3-dimensional helix. Distributions,
seeing the jet from a certain direction, show a good matching with those in a
part of 3C449 jet. This suggests that the jet has a helical structure and that
the magnetic field (especially the toroidal component) plays an important role
in the dynamics of the wiggle formation because it is due to a current-driven
helical kink instability in our model.Comment: Accepted for publication in Ap
Distribution of Faraday Rotation Measure in Jets from Active Galactic Nuclei I. Prediction from our Sweeping Magnetic Twist Model
Using the numerical data of MHD simulation for AGN jets based on our
``sweeping magnetic twist model'', we calculated the Faraday rotation measure
(FRM) and the Stokes parameters to compare with observations. We propose that
the FRM distribution can be used to discuss the 3-dimensional structure of
magnetic field around jets, together with the projected magnetic field derived
from the Stokes parameters. In the present paper, we supposed the basic
straight part of AGN jet, and used the data of axisymmetric simulation. The FRM
distribution we derived has a general tendency to have gradient across the jet
axis, which is due to the toroidal component of the helical magnetic field
generated by the rotation of the accretion disk. This kind of gradient in the
FRM distribution is actually observed in some AGN jets (e.g. Asada et al.
2002), which suggests helical magnetic field around the jets and thus supports
our MHD model. Following this success, we are now extending our numerical
observation to the wiggled part of the jets using the data of 3-dimensional
simulation based on our model in the following paper.Comment: Accepted for publication in Ap
Radiocesium Contamination Histories of Japanese Flounder (Paralichthys olivaceus) After the 2011 Fukushima Nuclear Power Plant Accident
Host-symbiont co-speciation and reductive genome evolution in gut symbiotic bacteria of acanthosomatid stinkbugs
Vasa-Like DEAD-Box RNA Helicases of Schistosoma mansoni
Genome sequences are available for the human blood flukes, Schistosoma japonicum, S. mansoni and S. haematobium. Functional genomic approaches could aid in identifying the role and importance of these newly described schistosome genes. Transgenesis is established for functional genomics in model species, which can lead to gain- or loss-of-functions, facilitate vector-based RNA interference, and represents an effective forward genetics tool for insertional mutagenesis screens. Progress toward routine transgenesis in schistosomes might be expedited if germ cells could be reliably localized in cultured schistosomes. Vasa, a member of the ATP-dependent DEAD-box RNA helicase family, is a prototypic marker of primordial germ cells and the germ line in the Metazoa. Using bioinformatics, 33 putative DEAD-box RNA helicases exhibiting conserved motifs that characterize helicases of this family were identified in the S. mansoni genome. Moreover, three of the helicases exhibited vasa-like sequences; phylogenetic analysis confirmed the three vasa-like genes—termed Smvlg1, Smvlg2, and Smvlg3—were members of the Vasa/PL10 DEAD-box subfamily. Transcripts encoding Smvlg1, Smvlg2, and Smvlg3 were cloned from cDNAs from mixed sex adult worms, and quantitative real time PCR revealed their presence in developmental stages of S. mansoni with elevated expression in sporocysts, adult females, eggs, and miracidia, with strikingly high expression in the undeveloped egg. Whole mount in situ hybridization (WISH) analysis revealed that Smvlg1, Smvlg2 and Smvlg3 were transcribed in the posterior ovary where the oocytes mature. Germ cell specific expression of schistosome vasa-like genes should provide an informative landmark for germ line transgenesis of schistosomes, etiologic agents of major neglected tropical diseases
Plant manipulation through gall formation constrains amino acid transporter evolution in sap-feeding insects
RNA-seq analysis of the gonadal transcriptome during Alligator mississippiensis temperature-dependent sex determination and differentiation
Can postoperative mean transprosthetic pressure gradient predict survival after aortic valve replacement?
Genomic insights into an obligate epibiotic bacterial predator: Micavibrio aeruginosavorus ARL-13
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