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Black Hole

Lensing of space time around a black hole. At Oxford we study black holes observationally and theoretically on all size and time scales - it is some of our core work.

Credit: ALAIN RIAZUELO, IAP/UPMC/CNRS. CLICK HERE TO VIEW MORE IMAGES.

Adrianne Slyz

Professor of Astrophysics

Sub department

  • Astrophysics

Research groups

  • Beecroft Institute for Particle Astrophysics and Cosmology
Adrianne.Slyz@physics.ox.ac.uk
Telephone: 01865 (2)83013
Denys Wilkinson Building, room 555D
  • About
  • Publications

Impact of star formation models on the growth of simulated galaxies at high redshifts

Astronomy & Astrophysics EDP Sciences (2024)

Authors:

Cheonsu Kang, Taysun Kimm, Daniel Han, Harley Katz, Julien Devriendt, Adrianne Slyz, Romain Teyssier
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Evaluating the variance of individual halo properties in constrained cosmological simulations

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 534:4 (2024) 3120-3132

Authors:

Richard Stiskalek, Harry Desmond, Julien Devriendt, Adrianne Slyz
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Dwarf galaxies as a probe of a primordially magnetized Universe

Astronomy and Astrophysics EDP Sciences 690 (2024) A59

Authors:

Mahsa Sanati, Sergio Martin-Alvarez, Jennifer Schober, Yves Revaz, Adrianne Slyz, Julien Devriendt

Abstract:

Aims: The true nature of primordial magnetic fields (PMFs) and their role in the formation of galaxies still remains elusive. To shed light on these unknowns, we investigate their impact by varying two sets of properties: (i) accounting for the effect of PMFs on the initial matter power spectrum, and (ii) accounting for their magneto-hydrodynamical effects on the formation of galaxies. By comparing both we can determine the dominant agent in shaping galaxy evolution.

Methods: We use the magneto-hydrodynamics code RAMSES, to generate multiple new zoom-in simulations for eight different host halos of dwarf galaxies across a wide luminosity range of 103 − 106 L⊙. These halos are selected from a ΛCDM cosmological box, tracking their evolution down to redshift z = 0. We explore a variety of primordial magnetic field (comoving) strengths Bλ ranging from 0.05 to 0.50 nG.

Results: We find magnetic fields in the interstellar medium not only modify star formation in dwarf spheroidal galaxies but also completely prevent the formation of stars in less compact ultra-faints with halo mass and stellar mass below ∼ 2.5 · 109 and 3 · 106 M⊙, respectively. At high redshifts, the impact of PMFs on host halos of dwarf galaxies through the modification of the matter power spectrum is more dominant than the influence of magneto-hydrodynamics in shaping their gaseous structure. Through the amplification of small perturbations ranging in mass from 107 to 109 M⊙ in the ΛCDM+PMFs matter power spectrum, primordial fields expedite the formation of the first dark matter halos, leading to an earlier onset and a higher star formation rate at redshifts z > 12. We investigate the evolution of various energy components and demonstrate that magnetic fields with an initial strength of Bλ ≥ 0.05 nG exhibit a strong growth of magnetic energy, accompanied by a saturation phase, that starts quickly after the growth phase. These trends persist consistently, regardless of the initial conditions, whether it is the classical ΛCDM or modified by PMFs. Lastly, we investigate the impact of PMFs on the present-time observable properties of dwarf galaxies, namely, the half light radius, V-band luminosity, mean metallicity and velocity dispersion profile. We find that PMFs with moderate strengths of Bλ ≤ 0.10 nG show great agreement with the scaling relations of the observed Local group dwarfs. However, stronger fields lead to large sizes and high velocity dispersion.

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Impact of star formation models on the growth of galaxies at high redshifts

(2024)

Authors:

Cheonsu Kang, Taysun Kimm, Daniel Han, Harley Katz, Julien Devriendt, Adrianne Slyz, Romain Teyssier
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The great escape: understanding the connection between Ly α emission and LyC escape in simulated JWST analogues

Monthly Notices of the Royal Astronomical Society Oxford University Press 532:2 (2024) 2463-2484

Authors:

Nicholas Choustikov, Harley Katz, Aayush Saxena, Thibault Garel, Julien Devriendt, Adrianne Slyz, Taysun Kimm, Jeremy Blaizot, Joki Rosdahl

Abstract:

Constraining the escape fraction of Lyman Continuum (LyC) photons from high-redshift galaxies is crucial to understanding reionization. Recent observations have demonstrated that various characteristics of the Ly α emission line correlate with the inferred LyC escape fraction (f LyC esc ) of low-redshift galaxies. Using a data set of 9600 mock Ly α spectra of star-forming galaxies at 4.64 ≤ z ≤ 6 from the SPHINX20 cosmological radiation hydrodynamical simulation, we study the physics controlling the escape of Ly α and LyC photons. We find that our mock Ly α observations are representative of high-redshift observations and that typical observational methods tend to overpredict the Ly α escape fraction (f Ly α esc ) by as much as 2 dex. We investigate the correlations between f LyC esc and f Ly α esc , Ly α equivalent width (Wλ(Ly α)), peak separation (vsep), central escape fraction (fcen), and red peak asymmetry (Ared f ). We find that f Ly α esc and fcen are good diagnostics for LyC leakage, selecting for galaxies with lower neutral gas densities and less UV attenuation that have recently experienced supernova feedback. In contrast, Wλ(Ly α) and vsep are found to be necessary but insufficient diagnostics, while Ared f carries little information. Finally, we use stacks of Ly α, H α, and F150W mock surface brightness profiles to find that galaxies with high f LyC esc tend to have less extended Ly α and F150W haloes but larger H α haloes than their non-leaking counterparts. This confirms that Ly α spectral profiles and surface brightness morphology can be used to better understand the escape of LyC photons from galaxies during the epoch of reionization.
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