116 research outputs found
ExHaLe-jet: Modeling blazar jets with an extended hadro-leptonic radiation code
Blazars emit across all electromagnetic wavelengths. While the so-called
one-zone model has described well both quiescent and flaring states, it cannot
explain the radio emission and fails in more complex data sets, such as AP
Librae. In order to self-consistently describe the entire electromagnetic
spectrum emitted by the jet, extended radiation models are necessary. Notably,
kinetic descriptions of extended jets can provide the temporal and spatial
evolution of the particle species and the full electromagnetic output. Here, we
present the initial results of a newly developed hadro-leptonic extended-jet
code: ExHaLe-jet. As protons take much longer than electrons to lose their
energy, they can transport energy over much larger distances than electrons and
are therefore essential for the energy transport in the jet. Furthermore,
protons induce injection of additional pairs through pion and Bethe-Heitler
pair production, which can explain a dominant leptonic radiation signal while
still producing neutrinos. In this talk, we discuss the differences between
leptonic and hadronic dominated SED solutions, the SED shapes, evolution along
the jet flow, and jet powers. We also highlight the important role of external
photon fields, such as the accretion disk and the BLR.Comment: Proceedings paper to the GAMMA2022 conference held in Barcelona,
Spain. To appear as PoS(Gamma2022)18
Spine-sheath jet model for low-luminosity AGNs
In several jetted AGNs, structured jets have been observed. In particular
spine-sheath configurations where the jet is radially divided into two or more
zones of different flow velocities. We present a model based on the particle
and radiation transport code CR-ENTREES. Here, interaction rates and secondary
particle and photon yields are pre-calculated by Monte Carlo event generators
or semi-analytical approximations. These are then used to create transition
matrices, that describe how each particle spectrum evolves with time. This code
allows for arbitrary injection of primary particles, and the possibility to
choose which interaction to include (photo-meson production, Bethe-Heitler
pair-production, inverse-Compton scattering, - pair production,
decay of all unstable particles, synchrotron radiation -- from electrons,
protons, and all relevant secondaries before their respective decays -- and
particle escape). In addition to the particle and radiation interactions taking
place in each homogeneous zone, we implement the feedback between the two zones
having different bulk velocities. The main mechanism at play when particles
cross the boundary between the two zones is shear acceleration. We follow a
microscopic description of this acceleration process to create a corresponding
transition matrix and include it in our numerical setup. Furthermore, each
zone's radiation field can be used as an external target photon field for the
other zone's particle interactions. We present here the first results of the
effect of a two-zone spine-sheath jet, by applying this model to typical
low-luminosity AGNs.Comment: PoS 444 (38th ICRC) 958 (accepted
Investigation of the recombination of the retarded shell of "born-again" CSPNe by time-dependent radiative transfer models
A standard planetary nebula stays more than 10 000 years in the state of a
photoionized nebula. As long as the timescales of the most important ionizing
processes are much smaller, the ionization state can be characterized by a
static photoionization model and simulated with codes like CLOUDY (Ferland et
al. 1998). When the star exhibits a late Helium flash, however, its ionizing
flux stops within a very short period. The star then re-appears from itsopaque
shell after a few years (or centuries) as a cold giant star without any hard
ionizing photons. Describing the physics of such behavior requires a fully
time-dependent radiative transfer model. Pollacco (1999), Kerber et al. (1999)
and Lechner & Kimeswenger (2004) used data of the old nebulae around V605 Aql
and V4334 Sgr to derive a model of the pre-outburst state of the CSPN in a
static model. Their argument was the long recombination time scale for such
thin media. With regard to these models Schoenberner (2008) critically raised
the question whether a significant change in the ionization state (and thus the
spectrum) has to be expected after a time of up to 80 years, and whether static
models are applicable at all.Comment: (3 pages, 1 figure, to appear in proceedings of the IAU Symposium
283: "Planetary Nebulae: An Eye to the Future", Eds.: A. Manchado, L.
Stanghellini and D. Schoenberner; presenting author: Stefan Kimeswenger
Characterizing the -ray Emission from FR0 Radio Galaxies
FR0 galaxies constitute the most abundant jet population in the local
Universe. With their compact jet structure, they are broadband photon emitters
and have been proposed as multi-messenger sources. Recently, these sources have
been detected for the first time in rays. Using a revised FR0 catalog,
we confirm that the FR0 population as a whole are -ray emitters, and we
also identify two significant sources. For the first time, we find a
correlation between the 5 GHz core radio luminosity and -ray luminosity
in the 1 - 800 GeV band, having a 4.5 statistical significance. This is
clear evidence that the jet emission mechanism is similar in nature for FR0s
and the well-studied canonical FR (FRI and FRII) radio galaxies. Furthermore,
we perform broadband SED modeling for the significantly detected sources as
well as the subthreshold source population using a one-zone SSC model. Within
the maximum jet power budget, our modeling shows that the detected gamma rays
from the jet can be explained as inverse Compton photons. To explain the
multi-wavelength observations for these galaxies, the modeling results
stipulate a low bulk Lorentz factor and a jet composition far from
equipartition, with the particle energy density dominating over the magnetic
field energy density.Comment: 24 pages, 9 figures, 2 tables. Submitted to the Astrophysical Journa
Multidimensional assessment of infant, parent and staff outcomes during a family centered care enhancement project in a tertiary neonatal intensive care unit:study protocol of a longitudinal cohort study
Background: The therapeutic advances and progress in the care for preterm infants have enabled the regular survival of very immature infants. However, the high burden of lifelong sequelae following premature delivery constitutes an ongoing challenge. Regardless of premature delivery, parental mental health and a healthy parent–child relationship were identified as essential prerogatives for normal infant development. Family centered care (FCC) supports preterm infants and their families by respecting the particular developmental, social and emotional needs in the Neonatal Intensive Care Unit. Due to the large variations in concepts and goals of different FCC initiatives, scientific data on the benefits of FCC for the infant and family outcome are sparse and its effects on the clinical team need to be elaborated. Methods: This prospective single centre longitudinal cohort study enrols preterm infants ≤ 32 + 0 weeks of gestation and/or birthweight ≤ 1500 g and their parents at the neonatal department of the Giessen University Hospital, Giessen, Germany. Following a baseline period, the rollout of additional FCC elements is executed following a stepwise 6-months approach that covers the NICU environment, staff training, parental education and psychosocial support for parents. Recruitment is scheduled over a 5.5. year period from October 2020 to March 2026. The primary outcome is corrected gestational age at discharge. Secondary infant outcomes include neonatal morbidities, growth, and psychomotor development up to 24 months. Parental outcome measures are directed towards parental skills and satisfaction, parent-infant-interaction and mental health. Staff issues are elaborated with particular focus on the item workplace satisfaction. Quality improvement steps are monitored using the Plan- Do- Study- Act cycle method and outcome measures cover the infant, the parents and the medical team. The parallel data collection enables to study the interrelation between these three important areas of research. Sample size calculation was based on the primary outcome. Discussion: It is scientifically impossible to allocate improvements in outcome measures to individual enhancement steps of FCC that constitutes a continuous change in NICU culture and attitudes covering diverse areas of change. Therefore, our trial is designed to allocate childhood, parental and staff outcome measures during the stepwise changes introduced by a FCC intervention program. Trial registration: Clinicaltrials.gov, trial registration number NCT05286983, date of registration 03/18/2022, retrospectively registered, http://clinicaltrials.gov .</p
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