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📄 Simulating galaxy formation with the IllustrisTNG model

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Pillepich, Annalisa et al. (2018) · Monthly Notices of the Royal Astronomical Society
Reads: 526 · Citations: 1936
DOI: 10.1093/mnras/stx2656

🔗 https://ui.adsabs.harvard.edu/abs/2018MNRAS.473.4077P/abstract

#Astronomy #Astrophysics #Cosmology #MethodsNumerical #GalaxiesEvolution

Simulating galaxy formation with the IllustrisTNG model

We introduce an updated physical model to simulate the formation and evolution of galaxies in cosmological, large-scale gravity+magnetohydrodynamical simulations with the moving mesh code AREPO. The overall framework builds upon the successes of the Illustris galaxy formation model, and includes prescriptions for star formation, stellar evolution, chemical enrichment, primordial and metal-line cooling of the gas, stellar feedback with galactic outflows, and black hole formation, growth and multimode feedback. In this paper, we give a comprehensive description of the physical and numerical advances that form the core of the IllustrisTNG (The Next Generation) framework. We focus on the revised implementation of the galactic winds, of which we modify the directionality, velocity, thermal content and energy scalings, and explore its effects on the galaxy population. As described in earlier works, the model also includes a new black-hole-driven kinetic feedback at low accretion rates, magnetohydrodynamics and improvements to the numerical scheme. Using a suite of (25 Mpc h-1)3 cosmological boxes, we assess the outcome of the new model at our fiducial resolution. The presence of a self-consistently amplified magnetic field is shown to have an important impact on the stellar content of 1012 M⊙ haloes and above. Finally, we demonstrate that the new galactic winds promise to solve key problems identified in Illustris in matching observational constraints and affecting the stellar content and sizes of the low-mass end of the galaxy population.

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📄 The JWST EXCELS survey: A spectroscopic investigation of the ionizing…

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Begley, R. et al. (2026) · Monthly Notices of the Royal Astronomical Society
Reads: 12182 · Citations: 3
DOI: 10.1093/mnras/staf1995

🔗 https://ui.adsabs.harvard.edu/abs/2026MNRAS.545f1995B/abstract

#Astronomy #Astrophysics #Cosmology #GalaxiesEvolution #GalaxiesHighredshift

The JWST EXCELS survey: A spectroscopic investigation of the ionizing properties of star-forming galaxies at 1<z<8

Charting the Epoch of Reionization demands robust assessments of what drives the production of ionizing photons in high-redshift star-forming galaxies (SFGs) and requires better predictive capabilities from current observations. Using a sample of <inline-formula><tex-math>$N=159$</tex-math></inline-formula> SFGs at <inline-formula><tex-math>$1\lesssim z \lesssim 8$</tex-math></inline-formula>, observed with ultra-deep medium-resolution spectroscopy from the JWST/NIRSpec EXCELS survey, we perform a statistical analysis of their ionizing photon production efficiencies (<inline-formula><tex-math>$\xi _\mathrm{ion}$</tex-math></inline-formula>). We consider <inline-formula><tex-math>$\xi _\mathrm{ion}$</tex-math></inline-formula>, accurately measured with spectroscopic Balmer line measurements, in relation to a number of key galaxy observables including; nebular emission line equivalent widths (<inline-formula><tex-math>$W_\lambda (\mathrm{H\alpha })$</tex-math></inline-formula> and <inline-formula><tex-math>$W_\lambda$</tex-math></inline-formula>([O III])), UV luminosity (<inline-formula><tex-math>$M_\mathrm{UV}$</tex-math></inline-formula>) and spectral slope (<inline-formula><tex-math>$\beta _\mathrm{UV}$</tex-math></inline-formula>), as well as dust attenuation (<inline-formula><tex-math>$E(B-V)_\mathrm{neb}$</tex-math></inline-formula>) and redshift. Implementing a Bayesian linear regression methodology, we fit <inline-formula><tex-math>$\xi _\mathrm{ion}$</tex-math></inline-formula> against the principal observables while fully marginalizing over all measurement uncertainties, mitigating against the impact of outliers and determining the intrinsic scatter. Significant relations between <inline-formula><tex-math>$\xi _\mathrm{ion}$</tex-math></inline-formula> and <inline-formula><tex-math>$W_\lambda (\mathrm{H\alpha })$</tex-math></inline-formula>, <inline-formula><tex-math>$W_\lambda$</tex-math></inline-formula>([O III]) and <inline-formula><tex-math>$\beta _\mathrm{UV}$</tex-math></inline-formula> are recovered. Moreover, the weak trends with <inline-formula><tex-math>$M_\mathrm{UV}$</tex-math></inline-formula> and redshift can be fully explained by the remaining property dependencies. Expanding our analysis to multivariate regression, we determine that <inline-formula><tex-math>$W_\lambda (\mathrm{H\alpha })$</tex-math></inline-formula> or <inline-formula><tex-math>$W_\lambda$</tex-math></inline-formula>([O III]), along with <inline-formula><tex-math>$\beta _\mathrm{UV}$</tex-math></inline-formula> and <inline-formula><tex-math>$E(B-V)_\mathrm{neb}$</tex-math></inline-formula>, are the most important observables for accurately predicting <inline-formula><tex-math>$\xi _\mathrm{ion}$</tex-math></inline-formula>. The latter identifies the most common outliers as SFGs with relatively high <inline-formula><tex-math>$E(B-V)_\mathrm{neb}\gtrsim 0.5$</tex-math></inline-formula>, possibly indicative of intense obscured star-formation or strong differential attenuation. Combining these properties enable <inline-formula><tex-math>$\xi _\mathrm{ion,0}$</tex-math></inline-formula> to be inferred with an accuracy of <inline-formula><tex-math>$\simeq 0.15\,$</tex-math></inline-formula> dex, with a population intrinsic scatter of <inline-formula><tex-math>$\sigma _\mathrm{int}\simeq 0.035\,$</tex-math></inline-formula> dex.

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