Ly�� blobs as an observational signature of cold accretion streams into galaxies

Lyα Blobs as an Observational Signature of Cold Accretion Streams into Galaxies

Recent hydrodynamic simulations of galaxy formation reveal streams of cold (T ∼ 10 K) gas flowing into the centers of dark matter halos as massive as 10M⊙ at redshifts z ∼ 1–3. In this paper we show that if > ∼ 10% of the gravitational binding energy of the gas is radiated away, then the simulated cold flows are spatially extended Lyα sources with luminosities, Lyα line widths, and number densi...

Gravity-driven Lyα blobs from cold streams into galaxies

We use high-resolution cosmological hydrodynamical adaptive mesh refinement (AMR) simulations to predict the characteristics of Lyα emission from the cold gas streams that fed galaxies in massive haloes at high redshift. The Lyα luminosity in our simulations is powered by the release of gravitational energy as gas flows from the intergalactic medium into the halo potential wells. The ultraviole...

Explaining the Observed Lyα ‘Blobs’ as Cold Streams of Gas in the Halos of Galaxies

Over the past decade, mysterious blobs of Lyα emission by hydrogen have been discovered in the vicinity of galaxies at early cosmic times . Although a number of possible models were proposed to explain these blobs , none appeared to be consistent with all available data. In a seemingly unrelated frontier, the latest computer simulations of galaxy formation reveal streams of cold (∼ 10 K) gas fe...

Local Galaxies as Damped Ly-α Analogs

We calculate in detail the expected properties of low redshift DLAs under the assumption that they arise in the gaseous disks of galaxies like those in the z ≈ 0 population. A sample of 355 nearby galaxies is analysed, for which high quality H i 21-cm emission line maps are available as part of an extensive survey with the Westerbork telescope (WHISP). We find that expected luminosities, impact...

Kelvin-Helmholtz Evolution in Subsonic Cold Streams Feeding Galaxies