ORCID Profile
0000-0001-5252-9561
Current Organisations
The University of Edinburgh
,
University of Heidelberg Ruperto-Carola
,
Durham University
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Publisher: Oxford University Press (OUP)
Date: 21-10-2023
Publisher: Oxford University Press (OUP)
Date: 06-09-2022
Abstract: The relation between the integrated thermal Sunyaev–Zeldovich (tSZ) y-decrement versus halo mass (Y–M) can potentially constrain galaxy formation models, if theoretical and observational systematics can be properly assessed. We investigate the Y–M relation in the simba and IllustrisTNG-100 cosmological hydrodynamic simulations, quantifying the effects of feedback, line-of-sight projection, and beam convolution. We find that simba’s active galactic nucleus (AGN) jet feedback generates strong deviations from self-similar expectations for the Y–M relation, especially at $M_{\\rm 500}\\lesssim10^{13}M_\\odot$. In simba, this is driven by suppressed in-halo y contributions owing to lowered halo baryon fractions. IllustrisTNG results more closely resemble simba without jets. Projections of line-of-sight structures weaken these model differences slightly, but they remain significant – particularly at group and lower halo masses. In contrast, beam smearing at Planck resolution makes the models indistinguishable, and both models appear to agree well with Planck data down to the lowest masses probed. We show that the arcminute resolution expected from forthcoming facilities would retain the differences between model predictions, and thereby provide strong constraints on AGN feedback.
Publisher: Oxford University Press (OUP)
Date: 09-01-2023
Abstract: We study the nature of the low-redshift circumgalactic medium (CGM) in the Simba cosmological simulations as traced by ultraviolet absorption lines around galaxies in bins of stellar mass ($\\mbox{$M_\\star $}\\, & 10^{10}{\\rm M}_\\odot$) for star-forming, green valley and quenched galaxies at impact parameters r⊥ ≤ 1.25r200. We generate synthetic spectra for H i , Mg ii , C ii , Si iii , C iv , and O vi , fit Voigt profiles to obtain line properties, and estimate the density, temperature, and metallicity of the absorbing gas. We find that CGM absorbers are most abundant around star-forming galaxies with $\\mbox{$M_\\star $}\\, & 10^{11}\\,\\,{\\rm M}_{\\odot }$, while the abundance of green valley galaxies show similar behaviour to those of quenched galaxies, suggesting that the CGM ‘quenches’ before star formation ceases. H i absorbing gas exists across a broad range of cosmic phases [condensed gas, diffuse gas, hot halo gas, and Warm-Hot Intergalactic Medium (WHIM)], while essentially all low ionization metal absorption arises from condensed gas. O vi absorbers are split between hot halo gas and the WHIM. The fraction of collisionally ionized CGM absorbers is $\\sim 25{\\text{--}}55{{\\ \\rm per\\ cent}}$ for C iv and $\\sim 80{\\text{--}}95{{\\ \\rm per\\ cent}}$ for O vi , depending on stellar mass and impact parameter. In general, the highest column density absorption features for each ion arise from dense gas. Satellite gas, defined as that within 10r1/2,⋆, contributes $\\sim 3{{\\ \\rm per\\ cent}}$ of overall H i absorption but $\\sim 30{{\\ \\rm per\\ cent}}$ of Mg ii absorption, with the fraction from satellites decreasing with increasing ion excitation energy.
Publisher: Oxford University Press (OUP)
Date: 10-08-2022
Abstract: Using the state-of-the-art suite of hydrodynamic simulations Simba, as well as its dark-matter-only counterpart, we study the impact of the presence of baryons and of different stellar/AGN feedback mechanisms on large-scale structure, halo density profiles, and on the abundance of different baryonic phases within haloes and in the intergalactic medium (IGM). The unified picture that emerges from our analysis is that the main physical drivers shaping the distribution of matter at all scales are star formation-driven galactic outflows at z & 2 for lower mass haloes and AGN jets at z & 2 in higher mass haloes. Feedback suppresses the baryon mass function with time relative to the halo mass function, and it even impacts the halo mass function itself at the ∼20 per cent level, particularly evacuating the centres and enhancing dark matter just outside haloes. At early epochs baryons pile up in the centres of haloes, but by late epochs and particularly in massive systems gas has mostly been evacuated from within the inner halo. AGN jets are so efficient at such evacuation that at low redshifts the baryon fraction within ∼1012–1013 M⊙ haloes is only 25 per cent of the cosmic baryon fraction, mostly in stars. The baryon fraction enclosed in a sphere around such haloes approaches the cosmic value Ωb/Ωm only at 10–20 virial radii. As a result, 87 per cent of the baryonic mass in the Universe lies in the IGM at z = 0, with 67 per cent being in the form of warm-hot IGM (T & 105K).
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Daniele Sorini.