CONSTRAINING THE PHYSICAL CONDITIONS IN THE JETS OF γ-RAY FLARING BLAZARS USING CENTIMETER-BAND POLARIMETRY AND RADIATIVE TRANSFER SIMULATIONS. II. EXPLORING PARAMETER SPACE AND IMPLICATIONS

Context. OMC-2/3 is one of the nearest embedded cluster-forming regions that includes intermediate-mass protostars at early stages of evolution. A previous CO (3–2) mapping survey towards this region revealed outflow activity related to sources at different evolutionary phases. Aims. The present work presents a study of the warm gas in the high-velocity emission from several outflows found in CO (3–2) emission by previous observations, determines their physical conditions, and makes a comparison with previous results in low-mass star-forming regions. Methods. We used the CHAMP+ heterodyne array on the APEX telescope to map the CO (6–5) and CO (7–6) emission in the OMC-2 FIR 6 and OMC-3 MMS 1-6 regions, and to observe 13CO (6–5) at selected positions. We analyzed these data together with previous CO (3–2) observations. In addition, we mapped the SiO (5–4) emission in OMC-2 FIR 6. Results. The CO (6–5) emission was detected in most of the outflow lobes in the mapped regions, while the CO (7–6) was found mostly in the OMC-3 outflows. In the OMC-3 MMS 5 outflow, a previously undetected extremely high-velocity gas was found in CO (6–5). This extremely high-velocity emission arises from the regions close to the central object MMS 5. Radiative transfer models revealed that the high-velocity gas from MMS 5 outflow consists of gas with nH2 = 104–105 cm−3 and T > 200 K, similar to what is observed in young Class 0 low-mass protostars. For the other outflows, values of nH2 > 104 cm−3 were found. Conclusions. The physical conditions and kinematic properties of the young intermediate-mass outflows presented here are similar to those found in outflows from Class 0 low-mass objects. Due to their excitation requirements, mid − J CO lines are good tracers of extremely high-velocity gas in young outflows likely related to jets.

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SOC program for dust continuum radiative transfer

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834354 ◽

2019 ◽

Vol 622 ◽

pp. A79 ◽

Cited By ~ 6

Author(s):

Mika Juvela

Keyword(s):

Monte Carlo ◽

Radiative Transfer ◽

Convergence Rates ◽

Dust Emission ◽

Interstellar Clouds ◽

Physical Conditions ◽

Cloud Models ◽

Order Of Magnitude ◽

Speed Up ◽

Run Time

Context. Thermal dust emission carries information on physical conditions and dust properties in many astronomical sources. Because observations represent a sum of emission along the line of sight, their interpretation often requires radiative transfer (RT) modelling. Aims. We describe a new RT program, SOC, for computations of dust emission, and examine its performance in simulations of interstellar clouds with external and internal heating. Methods. SOC implements the Monte Carlo RT method as a parallel program for shared-memory computers. It can be used to study dust extinction, scattering, and emission. We tested SOC with realistic cloud models and examined the convergence and noise of the dust-temperature estimates and of the resulting surface-brightness maps. Results. SOC has been demonstrated to produce accurate estimates for dust scattering and for thermal dust emission. It performs well with both CPUs and GPUs, the latter providing a speed-up of processing time by up to an order of magnitude. In the test cases, accelerated lambda iterations (ALIs) improved the convergence rates but was also sensitive to Monte Carlo noise. Run-time refinement of the hierarchical-grid models did not help in reducing the run times required for a given accuracy of solution. The use of a reference field, without ALI, works more robustly, and also allows the run time to be optimised if the number of photon packages is increased only as the iterations progress. Conclusions. The use of GPUs in RT computations should be investigated further.

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Solving the γ-ray radiative transfer equation for supernovae

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1367 ◽

2019 ◽

Vol 487 (1) ◽

pp. 1218-1226 ◽

Cited By ~ 3

Author(s):

Kevin D Wilk ◽

D John Hillier ◽

Luc Dessart

Keyword(s):

Radiative Transfer ◽

Energy Deposition ◽

Radiative Transfer Equation ◽

Moving Frame ◽

Synthetic Spectrum ◽

Monte Carlo Code ◽

Line Profiles ◽

Large Expansion ◽

Γ Rays ◽

Γ Ray

ABSTRACT We present a new relativistic radiative transfer code for γ-rays of energy less than 5 MeV in supernova (SN) ejecta. This code computes the opacities, the prompt emissivity (i.e. decay), and the scattering emissivity, and solves for the intensity in the co-moving frame. Because of the large expansion velocities of SN ejecta, we ignore redistribution effects associated with thermal motions. The energy deposition is calculated from the energy removed from the radiation field by scattering or photoelectric absorption. This new code yields comparable results to an independent Monte Carlo code. However, both yield non-trivial differences with the results from a pure absorption treatment of γ-ray transport. A synthetic observer’s frame spectrum is also produced from the co-moving frame intensity. At early times when the optical depth to γ-rays is large, the synthetic spectrum shows asymmetric line profiles with redshifted absorption as seen in SN 2014J. This new code is integrated within cmfgen and allows for an accurate and fast computation of the decay energy deposition in SN ejecta.

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BAYESIAN IMPLICATIONS OF COLLIDER AND SUSY DARK MATTER DIRECT AND INDIRECT SEARCHES

Modern Physics Letters A ◽

10.1142/s0217732313400087 ◽

2013 ◽

Vol 28 (02) ◽

pp. 1340008

Author(s):

LESZEK ROSZKOWSKI ◽

ENRICO MARIA SESSOLO ◽

YUE-LIN SMING TSAI

Keyword(s):

Dark Matter ◽

Parameter Space ◽

Direct Detection ◽

The Sun ◽

Bayesian Analyses ◽

Dwarf Spheroidal Galaxies ◽

Γ Ray ◽

One Year ◽

Spheroidal Galaxies

In this talk we present our recent Bayesian analyses of the Constrained MSSM in which the model's parameter space is constrained by the CMS αT 1.1/fb data at the LHC, the XENON100 dark matter direct detection data, and Fermi-LAT γ-ray data from dwarf spheroidal galaxies (dSphs). We also show that the projected one-year sensitivities for annihilation-induced neutrinos from the Sun in the 86-string configuration of IceCube/DeepCore have the potential to yield additional constraining power on the parameter space of the CMSSM.

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Modeling of the Be Stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311027517 ◽

2011 ◽

Vol 7 (S282) ◽

pp. 261-262 ◽

Cited By ~ 1

Author(s):

K. Šejnová ◽

V. Votruba ◽

P. Koubský

Keyword(s):

Radiative Transfer ◽

Parameter Space ◽

Three Dimensional ◽

Line Of Sight ◽

Circumstellar Disk ◽

Physical Parameters ◽

Be Stars ◽

Star Program ◽

Be Star ◽

Moving Media

AbstractThe Be stars are still a big unknown in respect to the origin and geometry of the circumstellar disk around the star. Program shellspec is designed to solve the simple radiative transfer along the line of sight in three-dimensional moving media. Our goal was to develop an effective method to search in parameter space, which can allow us to find a good estimate of the physical parameters of the disk. We also present here our results for Be star 60 Cyg using the modified code.

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Astrochemistry in external galaxies: how to use molecules as probes of their physical conditions

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316007195 ◽

2015 ◽

Vol 11 (S315) ◽

pp. 17-25 ◽

Cited By ~ 2

Author(s):

Serena Viti

Keyword(s):

Radiative Transfer ◽

Spatial Resolution ◽

High Spatial Resolution ◽

Molecular Gas ◽

Molecular Emission ◽

Physical Conditions ◽

External Galaxies ◽

Molecular Ratios ◽

Multiple Chemical ◽

Resolution Data

AbstractIt is now well established that chemistry in external galaxies is rich and complex. In this review I will explore whether one can use molecular emissions to determine their physical conditions. There are several considerations to bear in mind when using molecular emission, and in particular molecular ratios, to determine the densities, temperatures and energetics of a galaxy, which I will briefly summarise here. I will then present an example of a study that uses multiple chemical and radiative transfer analyses in order to tackle the too often neglected ‘degeneracies’ implicit in the interpretation of molecular ratios and show that only via such analyses combined with multi-species and multi-lines high spatial resolution data one can truly make molecules into powerful diagnostics of the evolution and distribution of molecular gas.

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Formation of the Musca filament: evidence for asymmetries in the accretion flow due to a cloud–cloud collision

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038281 ◽

2020 ◽

Vol 644 ◽

pp. A27

Author(s):

L. Bonne ◽

S. Bontemps ◽

N. Schneider ◽

S. D. Clarke ◽

D. Arzoumanian ◽

...

Keyword(s):

Magnetic Field ◽

Radiative Transfer ◽

Velocity Gradient ◽

Large Scale ◽

Transverse Velocity ◽

Local Magnetic Field ◽

Filament Formation ◽

Field Orientation ◽

Physical Conditions ◽

The Magnetic Field

Context. Dense molecular filaments are ubiquituous in the interstellar medium, yet their internal physical conditions and the role of gravity, turbulence, the magnetic field, radiation, and the ambient cloud during their evolution remain debated. Aims. We study the kinematics and physical conditions in the Musca filament, the ambient cloud, and the Chamaeleon-Musca complex to constrain the physics of filament formation. Methods. We produced CO(2–1) isotopologue maps with the APEX telescope that cut through the Musca filament. We further study a NANTEN2 12CO(1–0) map of the full Musca cloud, H I emission of the Chamaeleon-Musca complex, a Planck polarisation map, line radiative transfer models, Gaia data, and synthetic observations from filament formation simulations. Results. The Musca cloud, with a size of ~3–6 pc, contains multiple velocity components. Radiative transfer modelling of the CO emission indicates that the Musca filament consists of a cold (~10 K), dense (nH2 ∼ 104 cm−3) crest, which is best described with a cylindrical geometry. Connected to the crest, a separate gas component at T ~ 15 K and nH2 ∼ 103 cm−3 is found, the so-called strands. The velocity-coherent filament crest has an organised transverse velocity gradient that is linked to the kinematics of the nearby ambient cloud. This velocity gradient has an angle ≥30° with respect to the local magnetic field orientation derived from Planck, and the magnitude of the velocity gradient is similar to the transonic linewidth of the filament crest. Studying the large scale kinematics, we find coherence of the asymmetric kinematics from the 50 pc H I cloud down to the Musca filament. We also report a strong [C18O]/[13CO] abundance drop by an order of magnitude from the filament crest to the strands over a distance <0.2 pc in a weak ambient far-ultraviolet (FUV) field. Conclusions. The dense Musca filament crest is a long-lived (several crossing times), dynamic structure that can form stars in the near future because of continuous mass accretion replenishing the filament. This mass accretion on the filament appears to be triggered by a H I cloud–cloud collision, which bends the magnetic field around dense filaments. This bending of the magnetic field is then responsible for the observed asymmetric accretion scenario of the Musca filament, which is, for instance, seen as a V-shape in the position–velocity (PV) diagram.

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The Origin of AGN-IR Emission

Symposium - International Astronomical Union ◽

10.1017/s0074180900175400 ◽

1994 ◽

Vol 159 ◽

pp. 336-336

Author(s):

L. G. Stenholm

Keyword(s):

Radiative Transfer ◽

Thick Disk ◽

Physical Conditions ◽

Wide Range ◽

Dust Disk ◽

Silicate Feature ◽

Ir Emission

Advanced multi dimension radiative transfer calculations for an AGN source with a dust disk shows that the AGN-IR emission can be due to reradiation from heated dust in a thick disk. The models produces a weak silicate feature for a wide range of physical conditions, in agreement with the observations.

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