High-energy radiation from collisions of high-velocity clouds and the Galactic disc

High-velocity clouds (HVCs) are interstellar clouds of atomic hydrogen that do not follow normal Galactic rotation and have velocities of a several hundred kilometres per second. A considerable number of these clouds are falling down towards the Galactic disc. HVCs form large and massive complexes,...

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Autores principales: Valle, María Victoria del, Müller, A. L., Romero, Gustavo Esteban
Formato: Articulo
Lenguaje:Inglés
Publicado: 2018
Materias:
Ciencias Astronómicas
(ISM:) cosmic rays
ISM: clouds
Radiation mechanisms: non-thermal
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/96867
https://ri.conicet.gov.ar/11336/82423
https://academic.oup.com/mnras/article-abstract/475/4/4298/4876037
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-96867
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Astronómicas
(ISM:) cosmic rays
ISM: clouds
Radiation mechanisms: non-thermal
spellingShingle Ciencias Astronómicas
(ISM:) cosmic rays
ISM: clouds
Radiation mechanisms: non-thermal
Valle, María Victoria del
Müller, A. L.
Romero, Gustavo Esteban
High-energy radiation from collisions of high-velocity clouds and the Galactic disc
topic_facet Ciencias Astronómicas
(ISM:) cosmic rays
ISM: clouds
Radiation mechanisms: non-thermal
description High-velocity clouds (HVCs) are interstellar clouds of atomic hydrogen that do not follow normal Galactic rotation and have velocities of a several hundred kilometres per second. A considerable number of these clouds are falling down towards the Galactic disc. HVCs form large and massive complexes, so if they collide with the disc a great amount of energy would be released into the interstellar medium. The cloud-disc interaction produces two shocks: one propagates through the cloud and the other through the disc. The properties of these shocks depend mainly on the cloud velocity and the disc-cloud density ratio. In this work, we study the conditions necessary for these shocks to accelerate particles by diffusive shock acceleration and we study the non-thermal radiation that is produced. We analyse particle acceleration in both the cloud and disc shocks. Solving a time-dependent two-dimensional transport equation for both relativistic electrons and protons, we obtain particle distributions and non-thermal spectral energy distributions. In a shocked cloud, significant synchrotron radio emission is produced along with soft gamma rays. In the case of acceleration in the shocked disc, the non-thermal radiation is stronger; the gamma rays, of leptonic origin, might be detectable with current instruments. A large number of protons are injected into the Galactic interstellar medium, and locally exceed the cosmic ray background. We conclude that under adequate conditions the contribution from HVC-disc collisions to the galactic population of relativistic particles and the associated extended non-thermal radiation might be important.
format Articulo
Articulo
author Valle, María Victoria del
Müller, A. L.
Romero, Gustavo Esteban
author_facet Valle, María Victoria del
Müller, A. L.
Romero, Gustavo Esteban
author_sort Valle, María Victoria del
title High-energy radiation from collisions of high-velocity clouds and the Galactic disc
title_short High-energy radiation from collisions of high-velocity clouds and the Galactic disc
title_full High-energy radiation from collisions of high-velocity clouds and the Galactic disc
title_fullStr High-energy radiation from collisions of high-velocity clouds and the Galactic disc
title_full_unstemmed High-energy radiation from collisions of high-velocity clouds and the Galactic disc
title_sort high-energy radiation from collisions of high-velocity clouds and the galactic disc
publishDate 2018
url http://sedici.unlp.edu.ar/handle/10915/96867
https://ri.conicet.gov.ar/11336/82423
https://academic.oup.com/mnras/article-abstract/475/4/4298/4876037
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AT mulleral highenergyradiationfromcollisionsofhighvelocitycloudsandthegalacticdisc
AT romerogustavoesteban highenergyradiationfromcollisionsofhighvelocitycloudsandthegalacticdisc
bdutipo_str Repositorios
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