Astrophysical Jets

et al. 2004

ApJ

Several physical mechanisms have been studied in order to explain why composite supernova remnants (SNRs) have shell-like morphologies in the radio continuum while their X-ray emission is centrally peaked. One of the proposed mechanisms has been the presence of thermal conduction, which can raise the density at the center of SNRs, increasing the X-ray emission from these regions. In this work, we have carried out axisymmetric numerical simulations with the adaptive grid Yguazú-a code, which includes advection of the magnetic field and thermal conduction. We have considered cases with anisotropic and isotropic thermal conduction, as well as with no conduction. We have simulated X-ray (as well as radio synchrotron) emission maps from our numerical simulations, which can be directly compared with observations.

Section: The Yguazú-a Codementioning

confidence: 96%

Section: The Yguazú-a Codementioning

confidence: 99%

Effects of Thermal Conduction on the X‐Ray and Synchrotron Emission from Supernova Remnants

Velázquez

Martinell

et al. 2004

ApJ

“…They are the main contributors to the cooling function. The YGUAZÚ -A code employs the flux-vector splitting algorithm of Van Leer (1982), and it was described in detail by Raga, Navarro-González, & Villagrán-Muniz (2000). The reaction rates and the nonequilibrium cooling function that we have used are given by Raga et al (2002).…”

Section: The Numerical Computationsmentioning

confidence: 99%

The Precession of the Giant HH 34 Outflow: A Possible Jet Deceleration Mechanism

Masciadri

Pino

et al. 2002

ApJ

Self Cite

The giant jets represent a fundamental trace of the historical evolution of the outflow activity over timescales of $10 4 yr, i.e., a timescale comparable to the accretion time of the outflow sources in their main protostellar phase. The study of such huge jets provides the possibility of retrieving important elements related to the life of the outflow sources. In this paper, we study the role of precession (combined with jet velocity variability and the resulting enhanced interaction with the surrounding environment) as a deceleration mechanism for giant jets, using a numerical approach. This thesis was proposed for the first time by Devine et al., but it could not be numerically explored until now, because it is intrinsically difficult to reproduce, at the same time, the large range of scales from $100 AU up to a few parsecs. In the present paper, we obtain predictions of H intensity maps and position-velocity diagrams from three-dimensional simulations of the giant HH 34 jet (including an appropriate ejection velocity time variability and a precession of the outflow axis), and we compare them with previously published observations of this object. Our simulations represent a step forward from previous numerical studies of HH objects, in that the use of a seven-level, binary adaptive grid has allowed us to compute models that appropriately cover all relevant scales of a giant jet, from the $100 AU jet radius close to the source to the $1 pc length of the outflow. A good qualitative and quantitative agreement is found between the model predictions and the observations, indicating that a precession of the jet axis can indeed be the probable cause of the deceleration of the giant jets. Moreover, we show that a critical parameter for obtaining a better or worse agreement with the observations is the ratio j = a between the jet and the environmental densities. The implications of this result in the context of the current star formation models are discussed.

“…This code integrates the gasdynamic equations with a second order (in space and time) implementation of the "fluxvector splitting" method of van Leer (1982) and is described in detail by Raga, Navarro-González, & Villagrán-Muniz (2000). As the radiative losses are not important for the dynamics of the flow (see Cantó et al 2000), they were not included in the energy equation.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Simulated X-Ray Images and Spectra of the Arches Cluster

The Astrophysical Journal

Velázquez

Cantó

et al. 2001

Self Cite

We present three-dimensional numerical simulations of the wind from the Arches cluster. In order to make the model as realistic as possible, we have placed stellar wind sources at the positions on the plane of the sky of the 60 brightest stars of the cluster and have calculated three different possible distributions of the stars along the line of sight. From the resulting flows, we have computed the X-ray emission, obtaining emission maps and (spatially integrated) spectra. These results are compared with the recent Chandra observations of the Arches cluster of Yusef-Zadeh and coworkers, and a good qualitative agreement is found.