arXiv subjects

Valentin Mauerhofer

Publications and source records attributed to Valentin Mauerhofer.

21 records · Page 2Linked to original sources

arXiv2021

A partial Lyman limit system tracing intragroup gas at $z \approx 0.8$ towards HE1003+0149

We present an analysis of the galaxy environment and physical properties of a partial Lyman limit system at z = 0.83718 with HI and metal line components closely separated in redshift space ($|Δv| \approx 400$ km/s) towards the background quasar HE1003+0149. The HST/COS far-ultraviolet spectrum provides coverage of lines of oxygen ions from OI to OV. Comparison of observed spectral lines with synthetic profiles generated from Bayesian ionization modeling reveals the presence of two distinct gas phases in the absorbing medium. The low-ionization phase of the absorber has sub-solar metallicities (1/10-th solar) with indications of [C/O] < 0 in each of the components. The OIV and OV trace a more diffuse higher-ionization medium with predicted HI column densities that are $\approx 2$ dex lower. The quasar field observed with VLT/MUSE reveals three dwarf galaxies with stellar masses of $M^* \sim 10^{8} - 10^{9}$ M$_\odot$, and with star formation rates of $\approx 0.5 - 1$ M$_\odot$ yr$^{-1}$, at projected separations of $ρ/R_{\mathrm{vir}} \approx 1.8 - 3.0$ from the absorber. Over a wider field with projected proper separation of $\leq 5$ Mpc and radial velocity offset of $|Δv| \leq 1000$ km/s from the absorber, 21 more galaxies are identified in the $VLT$/VIMOS and Magellan deep galaxy redshift surveys, with 8 of them within $1$ Mpc and $500$ km/s, consistent with the line of sight penetrating a group of galaxies. The absorber presumably traces multiple phases of cool ($T \sim 10^4$ K) photoionized intragroup medium. The inferred [C/O] < 0 hints at preferential enrichment from core-collapse supernovae, with such gas displaced from one or more of the nearby galaxies, and confined to the group medium.

astro-ph.GA↗

arXiv2021

Constraining the cosmic UV background at z>3 with MUSE Lyman-α emission observations

The intensity of the Cosmic UV background (UVB), coming from all sources of ionising photons such as star-forming galaxies and quasars, determines the thermal evolution and ionization state of the intergalactic medium (IGM) and is, therefore, a critical ingredient for models of cosmic structure formation. Most of the previous estimates are based on the comparison between observed and simulated Lyman-$α$ forest. We present the results of an independent method to constrain the product of the UVB photoionisation rate and the covering fraction of Lyman limit systems (LLSs) by searching for the fluorescent Lyman-$α$ emission produced by self-shielded clouds. Because the expected surface brightness is well below current sensitivity limits for direct imaging, we developed a new method based on three-dimensional stacking of the IGM around Lyman-$α$ emitting galaxies (LAEs) between 2.9 3 that are consistent with previous measurements, with a preference for relatively low UVB intensities at z=3, and which suggest a non-monotonic decrease of $Γ$HI with increasing redshift between 3<z<5. This could suggest a possible tension between some UVB models and current observations which however require deeper and wider observations in Lyman-$α$ emission and absorption to be confirmed. Assuming instead a value of UVB from current models, our results constrain the covering fraction of LLSs at 3<z<4.5 to be less than 25% within 150kpc from LAEs.

astro-ph.GA↗

arXiv2016

Very Massive Tracers and Higher Derivative Biases

Most of the upcoming cosmological information will come from analyzing the clustering of the Large Scale Structures (LSS) of the universe through LSS or CMB observations. It is therefore essential to be able to understand their behavior with exquisite precision. The Effective Field Theory of Large Scale Structures (EFTofLSS) provides a consistent framework to make predictions for LSS observables in the mildly non-linear regime. In this paper we focus on biased tracers. We argue that in calculations at a given order in the dark matter perturbations, highly biased tracers will underperform because of their larger higher derivative biases. A natural prediction of the EFTofLSS is therefore that by simply adding higher derivative biases, all tracers should perform comparably well. We implement this prediction for the halo-halo and the halo-matter power spectra at one loop, and the halo-halo-halo, halo-halo-matter, and halo-matter-matter bispectra at tree-level, and compare with simulations. We find good agreement with the prediction: for all tracers, we are able to match the bispectra up to $k\simeq0.17\,h/$Mpc at $z=0$ and the power spectra to a higher wavenumber.

astro-ph.CO↗