ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength O O O O O O O O O O O O O O O O O O O O O O B-Tag O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Citation I-Citation I-Citation I-Citation O B-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O B-Model O O O B-Citation I-Citation I-Citation I-Citation I-Citation O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Model O O O B-Formula I-Formula I-Formula O O O O O O O O O O O
tokens: ⊙ and 0.2 × 10 6 M ⊙ , respectively; the Plummer equivalent co-moving gravitational softening is 2.66 and 1.33 kpc, limited to a maximum physical softening of 0.7 and 0.35 kpc, respectively. The simulations assume the cosmological parameters of Planck Collaboration ( 2014 ), and the minor differences with the Planck Collaboration ( 2016 ) parameters adopted in that paper are unlikely to be important. To compare to the data presented earlier, we need to identify both DLAs and LAEs in eagle . Since neither neutral hydrogen nor Lyα radiative transfer is directly incorporated in eagle , we compute these quantities in post-processing as explained next. 4.1.1 Identifying DLAs in the <sc>eagle</sc> simulations The ionizing background in eagle is implemented in the optically thin limit. Self-shielding of gas, allowing for the appearance of DLAs, is computed in post-processing using the urchin radiative transfer code described by Altay Theuns ( 2013 ). Briefly, this algorithm allows each gas particle to estimate the local ionizing intensity it is subject to by sampling the radiation field in 12 directions, with neutral gas in neighbouring gas particles potentially decreasing the local photo-ionization rate below the Haardt Madau ( 2001 ) optically thin value. Assuming the neutral fraction of a particle is set by the balance between photo- and collisional ionization versus recombinations, a reduced ionization rate increases the particle’s neutral fraction, which in turn affects the ionization rate determined by the particle’s neighbours. The impact of a change in the neutral fraction on the photo-ionization rate and vice versa is iterated until the neutral fraction of each particle converges from one iteration to the next. This post-process step thus yields the neutral hydrogen fraction of each SPH particle. Further details on how radiative transfer affects the neutral fraction as a function of column density and physical processes (e.g. the relative importance of collisional ionisation and photoionsation) can be found in the literature (e.g. Fumagalli et al. 2011 ; Rahmati et al. 2013 ). The resulting H i volume density is then projected onto an 8192 2 grid along the coordinate z -axis of the simulation box, using the Gaussian smoothing described by Altay Theuns ( 2013 ). Applying a column density threshold of allows us to identify DLAs. 2 We also calculate the -weighted z -coordinate and velocity of particles along each DLA line of sight to obtain the 3D position of each DLA (two spatial coordinates x and y , and a redshift coordinate z ). The redshift of each DLA allows us to compare DLAs to galaxies in redshift space, although we note that observed DLA redshifts are derived from low-ionization metal lines rather than H i directly, yet these elements are believed to trace the same phase of the gas. To compare to the muse observations, we analyse the L0025N0752 eagle snapshot at z = 3.027, which is closest in redshift to the data. Similarly to the