Browsing by Author "Theuns, Tom"
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- ItemOptical colours and spectral indices of z=0.1 EAGLE galaxies with the 3D dust radiative transfer code SKIRT(2017) Trayford, James W.; Camps, Peter; Theuns, Tom; Baes, Maarten; Bower, Richard G.; Crain, Robert A.; Gunawardhana, Madusha L. P.; Schaller, Matthieu; Schaye, Joop; Frenk, Carlos S.We present mock optical images, broad-band and H alpha fluxes, and D4000 spectral indices for 30 145 galaxies from the EAGLE hydrodynamical simulation at redshift z = 0.1, modelling dust with the SKIRT Monte Carlo radiative transfer code. The modelling includes a subgrid prescription for dusty star-forming regions, with both the subgrid obscuration of these regions and the fraction of metals in diffuse interstellar dust calibrated against far-infrared fluxes of local galaxies. The predicted optical colours as a function of stellar mass agree well with observation, with the SKIRT model showing marked improvement over a simple dust-screen model. The orientation dependence of attenuation is weaker than observed because EAGLE galaxies are generally puffier than real galaxies, due to the pressure floor imposed on the interstellar medium (ISM). The mock Ha luminosity function agrees reasonably well with the data, and we quantify the extent to which dust obscuration affects observed H alpha fluxes. The distribution of D4000 break values is bimodal, as observed. In the simulation, 20 per cent of galaxies deemed 'passive' for the SKIRT model, i.e. exhibiting D4000 > 1.8, are classified 'active' when ISM dust attenuation is not included. The fraction of galaxies with stellar mass greater than 10(10) M-circle dot that are deemed passive is slightly smaller than observed, which is due to low levels of residual star formation in these simulated galaxies. Colour images, fluxes and spectra of EAGLE galaxies are to be made available through the public EAGLE data base.
- ItemThe evolution of the oxygen abundance gradients in star-forming galaxies in the EAGLE simulations(2022) Tissera, Patricia B.; Rosas-Guevara, Yetli; Sillero, Emanuel; Pedrosa, Susana E.; Theuns, Tom; Bignone, LucasWe analyse the evolution of the oxygen abundance gradient of star-forming galaxies with stellar mass M-* >= 10(9)M(circle dot) in the EAGLE simulation over the redshift range z = [0, 2.5]. We find that the median metallicity gradient of the simulated galaxies is close to zero at all z, whereas the scatter around the median increases with z. The metallicity gradients of individual galaxies can evolve from strong to weak and vice versa, since mostly low-metallicity gas accretes on to the galaxy, resulting in enhanced star formation and ejection of metal-enriched gas by energy feedback. Such episodes of enhanced accretion, mainly dominated by major mergers, are more common at higher z and hence contribute to increasing the diversity of gradients. For galaxies with negative metallicity gradients, we find a redshift evolution of similar to -0.03 dex kpc(-1)/delta z. A positive mass dependence is found at z <= 0.5, which becomes slightly stronger for higher redshifts and, mainly, for M-* < 10(9.)(5) M-circle dot. Only galaxies with negative metallicity gradients define a correlation with galaxy size, consistent with an inside-out formation scenario. Our findings suggest that major mergers and/or significant gas accretion can drive strong negative or positive metallicity gradients. The first ones are preferentially associated with disc-dominated galaxies, and the second ones with dispersion-dominated systems. The comparison with forthcoming observations at high redshift will allow a better understanding of the potential role of metallicity gradients as a chemical probe of galaxy formation.
- ItemTowards the statistical detection of the warm–hot intergalactic medium in intercluster filaments of the cosmic web(2016) Tejos, Nicolás; Prochaska, J. Xavier; Crighton, Neil H.M.; Morris, Simon L.; Werk, Jessica K.; Theuns, Tom; Padilla, Nelson; Bielby, Rich M.; Finn, Charles W.