The halo shape and evolution of polar disc galaxies

We examine the properties and evolution of a simulated polar disc galaxy. This galaxy is composed of two orthogonal discs, one of which contains old stars (old stellar disc) and the other both younger stars and cold gas (polar disc). By exploring the shape of the inner region of the dark matter halo...

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Detalles Bibliográficos
Publicado:	2012
Materias:	Galaxies: evolution Galaxies: formation Galaxies: haloes Galaxies: interactions Galaxies: structure
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00358711_v425_n3_p1967_Snaith http://hdl.handle.net/20.500.12110/paper_00358711_v425_n3_p1967_Snaith
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_00358711_v425_n3_p1967_Snaith
record_format	dspace
spelling	paper:paper_00358711_v425_n3_p1967_Snaith2023-06-08T15:01:34Z The halo shape and evolution of polar disc galaxies Galaxies: evolution Galaxies: formation Galaxies: haloes Galaxies: interactions Galaxies: structure We examine the properties and evolution of a simulated polar disc galaxy. This galaxy is composed of two orthogonal discs, one of which contains old stars (old stellar disc) and the other both younger stars and cold gas (polar disc). By exploring the shape of the inner region of the dark matter halo, we are able to confirm that the halo shape is an oblate ellipsoid flattened in the direction of the polar disc. We also note that there is a twist in the shape profile, where the innermost 3kpc of the halo flattens in the direction perpendicular to the old disc and then aligns with the polar disc out until the virial radius. This result is then compared to the halo shape inferred from the circular velocities of the two discs. We also use the temporal information of the simulation to track the system's evolution and identify the processes which give rise to this unusual galaxy type. We confirm the proposal that the polar disc galaxy is the result of the last major merger, where the angular moment of the interaction is orthogonal to the angle of the infalling gas. This merger is followed by the resumption of coherent gas infall. We emphasize that the disc is rapidly restored after the major merger and that after this event the galaxy begins to tilt. A significant proportion of the infalling gas comes from filaments. This infalling gas from the filament gives the gas its angular momentum, and, in the case of the polar disc galaxy, the direction of the gas filament does not change before or after the last major merger. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. 2012 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00358711_v425_n3_p1967_Snaith http://hdl.handle.net/20.500.12110/paper_00358711_v425_n3_p1967_Snaith
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Galaxies: evolution Galaxies: formation Galaxies: haloes Galaxies: interactions Galaxies: structure
spellingShingle	Galaxies: evolution Galaxies: formation Galaxies: haloes Galaxies: interactions Galaxies: structure The halo shape and evolution of polar disc galaxies
topic_facet	Galaxies: evolution Galaxies: formation Galaxies: haloes Galaxies: interactions Galaxies: structure
description	We examine the properties and evolution of a simulated polar disc galaxy. This galaxy is composed of two orthogonal discs, one of which contains old stars (old stellar disc) and the other both younger stars and cold gas (polar disc). By exploring the shape of the inner region of the dark matter halo, we are able to confirm that the halo shape is an oblate ellipsoid flattened in the direction of the polar disc. We also note that there is a twist in the shape profile, where the innermost 3kpc of the halo flattens in the direction perpendicular to the old disc and then aligns with the polar disc out until the virial radius. This result is then compared to the halo shape inferred from the circular velocities of the two discs. We also use the temporal information of the simulation to track the system's evolution and identify the processes which give rise to this unusual galaxy type. We confirm the proposal that the polar disc galaxy is the result of the last major merger, where the angular moment of the interaction is orthogonal to the angle of the infalling gas. This merger is followed by the resumption of coherent gas infall. We emphasize that the disc is rapidly restored after the major merger and that after this event the galaxy begins to tilt. A significant proportion of the infalling gas comes from filaments. This infalling gas from the filament gives the gas its angular momentum, and, in the case of the polar disc galaxy, the direction of the gas filament does not change before or after the last major merger. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.
title	The halo shape and evolution of polar disc galaxies
title_short	The halo shape and evolution of polar disc galaxies
title_full	The halo shape and evolution of polar disc galaxies
title_fullStr	The halo shape and evolution of polar disc galaxies
title_full_unstemmed	The halo shape and evolution of polar disc galaxies
title_sort	halo shape and evolution of polar disc galaxies
publishDate	2012
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00358711_v425_n3_p1967_Snaith http://hdl.handle.net/20.500.12110/paper_00358711_v425_n3_p1967_Snaith
_version_	1768544677271699456

The halo shape and evolution of polar disc galaxies

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