Hydrodynamics of high-redshift galaxy collisions: From gas-rich disks to dispersion-dominated mergers and compact spheroids - Astrophysics > Cosmology and Nongalactic AstrophysicsReportar como inadecuado




Hydrodynamics of high-redshift galaxy collisions: From gas-rich disks to dispersion-dominated mergers and compact spheroids - Astrophysics > Cosmology and Nongalactic Astrophysics - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: Disk galaxies at high redshift z~2 are characterized by high fractions ofcold gas, strong turbulence, and giant star-forming clumps. Major mergers ofdisk galaxies at high redshift should then generally involve such turbulentclumpy disks. Merger simulations, however, model the ISM as a stable,homogeneous, and thermally pressurized medium. We present the first mergersimulations with high fractions of cold, turbulent, and clumpy gas. We discussthe major new features of these models compared to models where the gas isartificially stabilized and warmed. Gas turbulence, which is already strong inhigh-redshift disks, is further enhanced in mergers. Some phases aredispersion-dominated, with most of the gas kinetic energy in the form ofvelocity dispersion and very chaotic velocity fields, unlike merger modelsusing a thermally stabilized gas. These mergers can reach very high starformation rates, and have multi-component gas spectra consistent withSubMillimeter Galaxies. Major mergers with high fractions of cold turbulent gasare also characterized by highly dissipative gas collapse to the center ofmass, with the stellar component following in a global contraction. The finalgalaxies are early-type with relatively small radii and high Sersic indices,like high-redshift compact spheroids. The mass fraction in a disk componentthat survives or re-forms after a merger is severely reduced compared to modelswith stabilized gas, and the formation of a massive disk component wouldrequire significant accretion of external baryons afterwards. Mergers thusappear to destroy extended disks even when the gas fraction is high, and thislends further support to smooth infall as the main formation mechanism formassive disk galaxies.



Autor: Frederic Bournaud 1, Damien Chapon 1, Romain Teyssier 1,4, Leila C. Powell 1, Bruce G. Elmegreen 2, Debra Meloy Elmegreen 3, Pier

Fuente: https://arxiv.org/







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