%0 Generic %1 Uhlig2012 %A Uhlig, M. %A Pfrommer, C. %A Sharma, M. %A Nath, B. B. %A Ensslin, T. A. %A Springel, V. %D 2012 %K cosmic galaxy rays winds %T Galactic winds driven by cosmic-ray streaming %U http://arxiv.org/abs/1203.1038 %X Galactic winds are observed in many spiral galaxies with sizes from dwarfs up to the Milky Way, and they sometimes carry a mass in excess of that of newly formed stars by up to a factor of ten. Multiple driving processes of such winds have been proposed, including thermal pressure due to supernova-heating, UV radiation pressure on dust grains, or cosmic ray (CR) pressure. We here study wind formation due to CR physics using a numerical model that accounts for CR acceleration by supernovae, CR thermalization, and advective CR transport. In addition, we introduce a novel implementation of CR streaming relative to the rest frame of the gas. We find that CR streaming drives powerful and sustained winds in galaxies with virial masses M_200 < 10^11 Msun. In dwarf galaxies (M_200 ~ 10^9 Msun) the winds reach a mass loading factor of ~5, expel ~60 per cent of the initial baryonic mass contained inside the halo's virial radius and suppress the star formation rate by a factor of ~5. In dwarfs, the winds are spherically symmetric while in larger galaxies the outflows transition to bi-conical morphologies that are aligned with the disc's angular momentum axis. We show that damping of Alfven waves excited by streaming CRs provides a means of heating the outflows to temperatures that scale with the square of the escape speed. In larger haloes (M_200 > 10^11 Msun), CR streaming is able to drive fountain flows that excite turbulence. For halo masses M_200 > 10^10 Msun, we predict an observable level of H-alpha and X-ray emission from the heated halo gas. We conclude that CR-driven winds should be crucial in suppressing and regulating the first epoch of galaxy formation, expelling a large fraction of baryons, and - by extension - aid in shaping the faint end of the galaxy luminosity function. They should then also be responsible for much of the metal enrichment of the intergalactic medium.

@misc{Uhlig2012, abstract = { Galactic winds are observed in many spiral galaxies with sizes from dwarfs up to the Milky Way, and they sometimes carry a mass in excess of that of newly formed stars by up to a factor of ten. Multiple driving processes of such winds have been proposed, including thermal pressure due to supernova-heating, UV radiation pressure on dust grains, or cosmic ray (CR) pressure. We here study wind formation due to CR physics using a numerical model that accounts for CR acceleration by supernovae, CR thermalization, and advective CR transport. In addition, we introduce a novel implementation of CR streaming relative to the rest frame of the gas. We find that CR streaming drives powerful and sustained winds in galaxies with virial masses M_200 < 10^{11} Msun. In dwarf galaxies (M_200 ~ 10^9 Msun) the winds reach a mass loading factor of ~5, expel ~60 per cent of the initial baryonic mass contained inside the halo's virial radius and suppress the star formation rate by a factor of ~5. In dwarfs, the winds are spherically symmetric while in larger galaxies the outflows transition to bi-conical morphologies that are aligned with the disc's angular momentum axis. We show that damping of Alfven waves excited by streaming CRs provides a means of heating the outflows to temperatures that scale with the square of the escape speed. In larger haloes (M_200 > 10^{11} Msun), CR streaming is able to drive fountain flows that excite turbulence. For halo masses M_200 > 10^{10} Msun, we predict an observable level of H-alpha and X-ray emission from the heated halo gas. We conclude that CR-driven winds should be crucial in suppressing and regulating the first epoch of galaxy formation, expelling a large fraction of baryons, and - by extension - aid in shaping the faint end of the galaxy luminosity function. They should then also be responsible for much of the metal enrichment of the intergalactic medium. }, added-at = {2012-03-07T05:37:35.000+0100}, author = {Uhlig, M. and Pfrommer, C. and Sharma, M. and Nath, B. B. and Ensslin, T. A. and Springel, V.}, biburl = {https://www.bibsonomy.org/bibtex/222bc86c58ad5eb247c72916b77eb18d2/miki}, description = {[1203.1038] Galactic winds driven by cosmic-ray streaming}, interhash = {2840b3ad889d0bfef0f7cd0b0387baf3}, intrahash = {22bc86c58ad5eb247c72916b77eb18d2}, keywords = {cosmic galaxy rays winds}, note = {cite arxiv:1203.1038Comment: 24 pages, 14 figures, submitted to MNRAS}, timestamp = {2012-03-07T05:37:35.000+0100}, title = {Galactic winds driven by cosmic-ray streaming}, url = {http://arxiv.org/abs/1203.1038}, year = 2012 }