Galactic Winds

Johnson, H. E.; Axford, W. I.

doi:10.1086/150903

Cited by 69 publications

(41 citation statements)

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“…The pathlength through the magnetic disk should not be greater than about 4 kpc, so the Galaxy's disk should not deflect such a proton more than about 2 • . However, there is also the possibility of a galactic wind field (Johnson & Axford 1971;Jokipii & Morfill 1985) extending perhaps to a radius of 0.3 Mpc. Since the B-field of the wind falls as 1/r with radius, the differential form of equation 7¡ is needed: dφ = 5.3 × 10 4 (Z/E)B T (r)dr.…”

Section: Magnetic Bending and Nearby Radiogalaxiesmentioning

confidence: 99%

In search of a source for the 320 EeV Fly's Eye cosmic ray

Elbert¹,

Sommers²

1995

ApJ

184

193

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The 320 EeV air shower detected by the Fly's Eye poses an important problem. Careful analysis of pathlength limitations for the possible particle types due to cosmic background radiation verifies that the particle very likely traveled less than 50 Mpc from its source. The best candidates for accelerating particles to such high energies are the very powerful radiogalaxies, however they are all more than 100 Mpc distant. Our search finds no likely source within 50 Mpc in the direction from which the particle arrived. This prompts consideration of less likely astrophysical sources, like M82, as well as non-standard mechanisms like cosmic string annihilation. It is also conceivable that the air shower was produced by some non-standard particle whose pathlength is unlimited because it does not interact with the cosmic background radiation. A less radical alternative is that relatively strong magnetic fields deflected the particle's path through a large angle, so it could have originated at a nearby radiogalaxy at an earlier time of strong activity.

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Section: Magnetic Bending and Nearby Radiogalaxiesmentioning

confidence: 99%

In search of a source for the 320 EeV Fly's Eye cosmic ray

Elbert¹,

Sommers²

1995

ApJ

184

193

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“…rc ECn (12) where N(~) 1s given by (13) We choose the boundary conditions of Eqs. (10) and (11) so that at the surface of the central galaxy the temperature and density of the gas coincide with those of the intracl uster gas, for which we adopt the conventional isothermal sphere model with a temperature of T,.…”

Section: L~5lmentioning

confidence: 99%

Evaporation and Excess X-Ray Emission from the Central Giant Galaxy in a Cluster of Galaxies

Takahara

1979

Progress of Theoretical Physics

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Evaporation of gas from the central giant galaxy in a cluster of galaxies is investigated in connection with the point source in its extended X-ray source. We calculate the stationary outflow of the gas supplied by the stellar mass loss and heated by the conduction from the hot intracluster gas. The central point source identified with M87 in the Virgo cluster of galaxies can be well explained by the X-ray emission from the outflowing gas in the central massive galaxy. However, the point source identified with NGC 1275 in the Perseus cluster of galaxies can be explained only if the central galaxy is as massive as 10"M<;:> and its three-dimensional velocity dispersion exceeds 10 3 km/sec. of the extended source, while in the cooling model the softening of the energy spectrum is expected. These observations suggest that the heat conduction works very effectively.Secondly, according to the large accretion rate they have suggested, 30"'-'100 M 0 /y, the cool gas should accumulate in the central galaxy as much as 3 X 10 11 at East Tennessee State University on May 30, 2015

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“…The earliest works on galactic outflows were motivated by the observations of the starburst galaxy M82 (Lynds & Sandage 1963; Burbidge, Burbidge & Rubin 1964) and the detection of broad optical emission lines in some elliptical galaxies (Osterbrock 1960) that implied winds (Burke 1968). It was suggested that galactic winds cause ellipticals to shed their interstellar medium (ISM; Johnson & Axford 1971; Mathews & Baker 1971). Galactic outflows have since been frequently observed in both local and high‐redshift galaxies.…”

Section: Introductionmentioning

confidence: 99%

Galactic winds driven by cosmic ray streaming

Uhlig

Pfrommer

Sharma

et al. 2012

Monthly Notices of the Royal Astronomical Society

236

232

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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 10. Multiple driving processes of such winds have been proposed, including thermal pressure due to supernova heating, ultraviolet 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 by Coulomb and hadronic interactions, and advective CR transport. In addition, we introduce a novel implementation of CR streaming relative to the rest frame of the gas. Streaming CRs excite Alfv´en waves on which they scatter, thereby limiting the CRs’ effective bulk velocity.We find that CR streaming drives powerful and sustained winds in galaxies with virial massesM200 1011M . In dwarf galaxies (M200 ∼ 109M ) 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 biconical morphologies that are aligned with the disc’s angular momentum axis. We show that damping of Alfv´en waves excited by streaming CRs provides a means of heating the outflows to temperatures that scale with the square of the escape speed, kT ∝ υ2 esc. In larger haloes (M200 1011M ), CR streaming is able to drive fountain flows that excite turbulence, providing another means of heating the halo gas. For halo masses M200 1010M , we predict an observable level of Hα 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

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Galactic Winds

Cited by 69 publications

References 0 publications

In search of a source for the 320 EeV Fly's Eye cosmic ray

In search of a source for the 320 EeV Fly's Eye cosmic ray

Evaporation and Excess X-Ray Emission from the Central Giant Galaxy in a Cluster of Galaxies

Galactic winds driven by cosmic ray streaming

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