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Outflow from a central black hole in dwarf spheroidal galaxies

Grant number: 18/22021-3
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): February 01, 2019
Effective date (End): January 31, 2020
Field of knowledge:Physical Sciences and Mathematics - Astronomy
Principal Investigator:Gustavo Amaral Lanfranchi
Grantee:Larissa Santos de Oliveira
Home Institution: Pró-Reitoria de Pós-Graduação e Pesquisa. Universidade Cruzeiro do Sul (UNICSUL). São Paulo , SP, Brazil

Abstract

Dwarf Spheroidal Galaxies are simple systems, but with a complex evolution not yet fully understood. A striking feature of these objects is the complete absence of neutral gas in their central regions. Several physical mechanisms have already been proposed as being responsible for the removal of the gaseous content of dwarf spheroids, both internal (stellar feedback, for example) and external (ram pressure, tidal stripping, etc.). A physical process, however, not fully analysed in the Dwarf Spheroidal Galaxies is the outflow of an intermediate mass black hole in the center of these galaxies. Nowadays, it is assumed that spiral and elliptical galaxies contain a central massive black hole (10^6 Msun), which, while active, gives rise to intense jets that can remove large amounts of material from the interstellar medium of the galaxy. In dwarf galaxies, recent observational evidence indicates the presence of intermediate mass black holes (10 ^ 4 Msun) at its center. The effects of the outflow of such black holes in the interstellar medium of these galaxies, however, have not yet been explored in the literature. In the first stage of this work, the physical conditions (density and speed) of the outflow of the black hole were analysed, by means of a 3D hydrodynamic simulation code adjusted for a typical Dwarf Spheroidal Galaxy, in order to verify when it can develop in the central region of the galaxy and propagate through the ISM. An outflow with density larger than 3 x 10^-3 particles per cm^3 and with an initial velocity in the order of 1000 km/s propagates both in a homogeneous medium and in a medium disturbed by supernovae explosions. In this case, however, its propagation is much more difficult. This project will continue the work begun in 2017 by analyzing other scenarios for the outflow propagation, its contribution to the loss of mass of the galaxy and the interaction of its feedback with those of supernovae. In addition, the code will continue to be improved.