Adrianne Slyz

Abstract:

This is an erratum to the paper 'Dark matter-deficient dwarf galaxies form via tidal stripping of dark matter in interactions with massive companions', which was published in MNRAS, 502, 1785 (Jackson et al. 2021). In the original version of the paper S. K. Yi's affiliation was incorrectly listed as 'School of Physics, Korea Institute for Advanced Study (KIAS), 85 Hoegiro, Dongdaemun-gu, Seoul 02455, Republic of Korea', whereas the correct affiliation is 'Department of Astronomy and Yonsei University Observatory, Yonsei University, Seoul 03722, Republic of Korea'. In addition S. K. Yi would also like to add the following acknowledgement: SKY acknowledges support from the Korean National Research Foundation (NRF-2020R1A2C3003769). The supercomputing time for numerical simulation was kindly provided by KISTI (KSC-2017-G2-003), and large data transfer was supported by KREONET.

Abstract:

We present the first results from SPHINX-MHD, a suite of cosmological radiation-magnetohydrodynamics simulations designed to study the impact of primordial magnetic fields (PMFs) on galaxy formation and the evolution of the intergalactic medium during the epoch of reionization. The simulations are among the first to employ on-the-fly radiation transfer and constrained transport ideal MHD in a cosmological context to simultaneously model the inhomogeneous process of reionization and the growth of PMFs. We run a series of $(5{\rm Mpc})^3$ cosmological volumes, varying both the strength of the seed magnetic field and its spectral index. We find that PMFs with a spectral index ($n_B$) and a comoving amplitude ($B_0$) that have $n_B>-0.562\log_{10}(B_0/1{\rm n}G) - 3.35$ produce electron optical depths ($\tau_e$) that are inconsistent with CMB constraints due to the unrealistically early collapse of low-mass dwarf galaxies. For $n_B\geq-2.9$, our constraints are considerably tighter than the $\sim{\rm n}G$ constraints from Planck. PMFs that do not satisfy our constraints have little impact on the reionization history or the shape of the UV luminosity function. Likewise, detecting changes in the Ly$\alpha$ forest due to PMFs will be challenging because photoionisation and photoheating efficiently smooth the density field. However, we find that the first absorption feature in the global 21cm signal is a particularly sensitive indicator of the properties of the PMFs, even for those that satisfy our $\tau_e$ constraint. Furthermore, strong PMFs can increase the escape of LyC photons by up to 25% and shrink the effective radii of galaxies by 44% which could increase the completeness fraction of galaxy surveys. Finally, our simulations show that surveys with a magnitude limit of ${\rm M_{UV,1500{\rm A}}=-13}$ can probe the sources that provide the 50% of photons for reionization out to $z=12$.

Abstract:

Despite their ubiquity, there are many open questions regarding galactic and cosmic magnetic fields. Specifically, current observational constraints cannot rule out whether magnetic fields observed in galaxies were generated in the early Universe or are of astrophysical nature. Motivated by this, we use our magnetic tracer algorithm to investigate whether the signatures of primordial magnetic fields persist in galaxies throughout cosmic time. We simulate a Milky Way-like galaxy down to z ∼ 2–1 in four scenarios: magnetized solely by primordial magnetic fields, magnetized exclusively by supernova (SN)-injected magnetic fields, and two combined primordial + SN magnetization cases. We find that once primordial magnetic fields with a comoving strength B0 > 10−12 G are considered, they remain the primary source of galaxy magnetization. Our magnetic tracers show that, even combined with galactic sources of magnetization, when primordial magnetic fields are strong, they source the large-scale fields in the warm metal-poor phase of the simulated galaxy. In this case, the circumgalactic medium and intergalactic medium can be used to probe B0 without risk of pollution by magnetic fields originated in the galaxy. Furthermore, whether magnetic fields are primordial or astrophysically sourced can be inferred by studying local gas metallicity. As a result, we predict that future state-of-the-art observational facilities of magnetic fields in galaxies will have the potential to unravel astrophysical and primordial magnetic components of our Universe.