2,913 research outputs found
Linking radio and gamma ray emission in Ap Librae
Ap Lib is one of the rare Low Synchrotron Peaked blazars detected so far at
TeV energies. This type of source is not properly modelled by standard one-zone
leptonic Synchrotron-self-Compton (SSC) emission scenarios. The aim of this
paper is to study the relevance of additional components which should naturally
occur in a SSC scenario for a better understanding of the emission mechanisms,
especially at very high energies (VHE). Methods. We use simultaneous data from
a multi-wavelength campaign of Planck, Swift-UVOT and Swift-XRT telescopes
carried out in February 2010, as well as quasi-simultaneous data of WISE, Fermi
and H.E.S.S. taken in 2010. The multi-lambda emission of Ap Lib is modelled by
a blob-in-jet SSC scenario including the contribution of the base of the VLBI
extended jet, the radiative blob-jet interaction, the accretion disk and its
associated external photon field. We show that signatures of a strong
parsec-scale jet and of an accretion disk emission are present in the SED. We
can link the observationnal VLBI jet features from MOJAVE to parameters
expected for a VHE emitting blob accelerated near the jet base. The VHE
emission appears to be dominated by the inverse-Compton effect of the blob
relativistic electrons interacting with the jet synchrotron radiation. In such
scenario Ap Lib appears as an intermediate source between BL Lac objects and
Flat Spectrum Radio Quasars. Ap Lib could be a bright representative of a
specific class of blazars, in which the parsec-scale jet luminosity is no more
negligible compared to the blob and contributes to the high energy emission via
inverse Compton processes.Comment: 12 pages, 7 figures, Accepted for publication in A&
Shocks in relativistic transverse stratified jets, a new paradigm for radio-loud AGN
The transverse stratification of active galactic nuclei (AGN) jets is
suggested by observations and theoretical arguments, as a consequence of
intrinsic properties of the central engine (accretion disc + black hole) and
external medium. On the other hand, the one-component jet approaches are
heavily challenged by the various observed properties of plasmoids in radio
jets (knots), often associated with internal shocks. Given that such a
transverse stratification plays an important role on the jets acceleration,
stability, and interaction with the external medium, it should also induce
internal shocks with various strengths and configurations, able to describe the
observed knots behaviours. By establishing a relation between the transverse
stratification of the jets, the internal shock properties, and the multiple
observed AGN jet morphologies and behaviours, our aim is to provide a
consistent global scheme of the various AGN jet structures. Working on a large
sample of AGN radio jets monitored in very long baseline interferometry (VLBI)
by the MOJAVE collaboration, we determined the consistency of a systematic
association of the multiple knots with successive re-collimation shocks. We
then investigated the re-collimation shock formation and the influence of
different transverse stratified structures by parametrically exploring the two
relativistic outflow components with the specific relativistic hydrodynamic
(SRHD) code AMRVAC. We were able to link the different spectral classes of AGN
with specific stratified jet characteristics, in good accordance with their
VLBI radio properties and their accretion regimes.Comment: 16 pages, 12 figures, accepted for publication in A&
Connection between type B (or C) and F factorizations and construction of algebras
In a recent paper (Del Sol Mesa A and Quesne C 2000 J. Phys. A: Math. Gen. 33
4059), we started a systematic study of the connections among different
factorization types, suggested by Infeld and Hull, and of their consequences
for the construction of algebras. We devised a general procedure for
constructing satellite algebras for all the Hamiltonians admitting a type E
factorization by using the relationship between type A and E factorizations.
Here we complete our analysis by showing that for Hamiltonians admitting a type
F factorization, a similar method, starting from either type B or type C ones,
leads to other types of algebras. We therefore conclude that the existence of
satellite algebras is a characteristic property of type E factorizable
Hamiltonians. Our results are illustrated with the detailed discussion of the
Coulomb problem.Comment: minor changes, 1 additional reference, final form to be published in
JP
Optical-NIR spectroscopy of the puzzling gamma-ray source 3FGL 1603.9-4903/PMN J1603-4904 with X-shooter
The Fermi/LAT instrument has detected about two thousands Extragalactic High
Energy (E > 100 MeV) gamma-ray sources. One of the brightest is 3FGL
1603.9-4903, associated to the radio source PMN J1603-4904. Its nature is not
yet clear, it could be either a very peculiar BL Lac or a CSO (Compact
Symmetric Object) radio source, considered as the early stage of a radio
galaxy. The latter, if confirmed, would be the first detection in gamma-rays
for this class of objects. Recently a redshift z=0.18 +/- 0.01 has been claimed
on the basis of the detection of a single X-ray line at 5.44 +/- 0.05 keV
interpreted as a 6.4 keV (rest frame) fluorescent line. We aim to investigate
the nature of 3FGL 1603.9-4903/PMN J1603-4904 using optical to NIR
spectroscopy. We observed PMN J1603-4904 with the UV-NIR VLT/X-shooter
spectrograph for two hours. We extracted spectra in the VIS and NIR range that
we calibrated in flux and corrected for telluric absorption and we
systematically searched for absorption and emission features. The source was
detected starting from ~6300 Ang down to 24000 Ang with an intensity comparable
to the one of its 2MASS counterpart and a mostly featureless spectrum. The
continuum lacks absorption features and thus is non-stellar in origin and
likely non-thermal. On top of this spectrum we detected three emission lines
that we interpret as the Halpha-[NII] complex, the [SII] 6716,6731 doublet and
the [SIII] 9530 line, obtaining a redshift estimate of z= 0.2321 +/- 0.0004.
The equivalent width of the Halpha-[NII] complex implies that PMN J1603-4904
does not follow the observational definition of BL Lac, the line ratios suggest
that a LINER/Seyfert nucleus is powering the emission. This new redshift
measurement implies that the X-ray line previously detected should be
interpreted as a 6.7 keV line which is very peculiar.Comment: Published in Astronomy and Astrophysic
Impact of curvature on the optimal configuration of flexible luminescent solar concentrators
Flexible luminescent solar concentrators (LSCs) could deliver integrated photovoltaics in all aspects of our lives, from architecture to wearable electronics. We present and experimentally verify a model for the optimization of the external optical efficiency of LSCs under varying degrees of curvature. We demonstrate differences between the optimization of flat and bent LSCs, showing that optimal fluorophore concentrations can differ by a factor of two
Particle acceleration, magnetic field generation, and emission in relativistic pair jets
Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas.
Plasma waves and their associated instabilities (e.g., Buneman, Weibel and
other two-stream instabilities) created in collisionless shocks are responsible
for particle (electron, positron, and ion) acceleration. Using a 3-D
relativistic electromagnetic particle (REMP) code, we have investigated
particle acceleration associated with a relativistic jet front propagating into
an ambient plasma. We find that the growth times of Weibel instability are
proportional to the Lorentz factors of jets. Simulations show that the Weibel
instability created in the collisionless shock front accelerates jet and
ambient particles both perpendicular and parallel to the jet propagation
direction.Comment: 4 pages, 2 figures, submitted to Il nuovo cimento (4th Workshop
Gamma-Ray Bursts in the Afterglow Era, Rome, 18-22 October 2004
Recommended from our members
Evaporation Reduction Investigations Relating to Small Reservoirs In Arid Regions
This item is part of the Agricultural Experiment Station archive. It was digitized from a physical copy provided by the University Libraries at the University of Arizona. For more information, please email CALS Publications at [email protected]
Particle acceleration in electron-ion jets
Weibel instability created in collisionless shocks is responsible for
particle (electron, positron, and ion) acceleration. Using a 3-D relativistic
electromagnetic particle (REMP) code, we have investigated particle
acceleration associated with a relativistic electron-ion jet fronts propagating
into an ambient plasma without initial magnetic fields with a longer simulation
system in order to investigate nonlinear stage of the Weibel instability and
its acceleration mechanism. The current channels generated by the Weibel
instability induce the radial electric fields. The z component of the Poynting
vector (E x B) become positive in the large region along the jet propagation
direction. This leads to the acceleration of jet electrons along the jet. In
particular the E x B drift with the large scale current channel generated by
the ion Weibel instability accelerate electrons effectively in both parallel
and perpendicular directions.Comment: 2 pages, 1 figure, Proceedings for Astrophysical Sources of High
Energy Particles and Radiation, AIP proceeding Series, eds . T. Bulik, G.
Madejski and B. Ruda
Standardization of molecular monitoring for chronic myeloid leukemia in Latin America using locally produced secondary cellular calibrators
Residual disease in chronic myeloid leukemia (CML) patients undergoing therapy with tyrosine kinase inhibitors (TKIs) is measured by assessing the quantity of transcripts of the BCR-ABL1 fusion gene in peripheral white blood cells. This analysis is based on reverse-transcription quantitative PCR (RT–qPCR) technology; however, the wide array of methods used worldwide has led to large variation in quantitative BCR-ABL1 measurements, which hamper inter-laboratory comparative studiesFil: Ruiz, María Sol. Fundación Cáncer. Centro de Investigaciones Oncológicas; ArgentinaFil: Medina, M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Tapia, I.. Fundación Cáncer. Centro de Investigaciones Oncológicas; ArgentinaFil: Mordoh, Jose. Fundación Cáncer. Centro de Investigaciones Oncológicas; ArgentinaFil: Cross, N. C. P.. Universidad de Southampton Uk; Reino UnidoFil: Larripa, Irene Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Bianchini, Michele. Fundación Cáncer. Centro de Investigaciones Oncológicas; Argentin
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