The MUSE-Wide survey: A measurement of the Lyα\alpha emitting fraction among z>3z>3 galaxies

We present a measurement of the fraction of Lyman $\alpha$ (Ly$\alpha$) emitters ($X_{\rm{Ly} \alpha}$) amongst HST continuum-selected galaxies at $3<z<6$ with the Multi-Unit Spectroscopic Explorer (MUSE) on the VLT. Making use of the first 24 MUSE-Wide pointings in GOODS-South, each having an integration time of 1 hour, we detect 100 Ly$\alpha$ emitters and find $X_{\rm{Ly} \alpha}\gtrsim0.5$ for most of the redshift range covered, with 29 per cent of the Ly$\alpha$ sample exhibiting rest equivalent widths (rest-EWs) $\leq$ 15\AA. Adopting a range of rest-EW cuts (0 - 75\AA), we find no evidence of a dependence of $X_{\rm{Ly} \alpha}$ on either redshift or UV luminosity.Comment: 10 pages, 5 figures (MNRAS, updated as per version in press

Forschung über Evaluation in der Schweiz: Stand und Aussichten

Seit einiger Zeit hat sich die Forschung, die sich mit Evaluation befasst, klar intensiviert. Dieser Beitrag soll einen Überblick zur Forschung über Evaluation in der Schweiz geben, wobei das Was und Wie der Forschung und nicht die Befunde im Zentrum stehen. Dazu werden die Forschungstätigkeiten in ausgewählten Evaluationsfeldern und zu feldübergreifenden Fragen (wie Nachfrage oder Nutzung) beschrieben. Der Überblick verdeutlicht die zentrale Bedeutung der Evaluationsfachlichkeit: Wird anerkannt, dass Evaluationen neben einer thematischen auch eine eigenständige evaluationsfachliche Expertise erfordern, erhält die Forschung über Evaluation einen höheren Stellenwert

The MUSE Extremely Deep Field: The cosmic web in emission at high redshift

We report the discovery of diffuse extended Lyα emission from redshift 3.1 to 4.5, tracing cosmic web filaments on scales of 2.5-4 cMpc. These structures have been observed in overdensities of Lyα emitters in the MUSE Extremely Deep Field, a 140 h deep MUSE observation located in the Hubble Ultra-Deep Field. Among the 22 overdense regions identified, five are likely to harbor very extended Lyα emission at high significance with an average surface brightness of 5  ×  10-20 erg s-1 cm-2 arcsec-2. Remarkably, 70% of the total Lyα luminosity from these filaments comes from beyond the circumgalactic medium of any identified Lyα emitter. Fluorescent Lyα emission powered by the cosmic UV background can only account for less than 34% of this emission at z  ≈  3 and for not more than 10% at higher redshift. We find that the bulk of this diffuse emission can be reproduced by the unresolved Lyα emission of a large population of ultra low-luminosity Lyα emitters (< 1040 erg s-1), provided that the faint end of the Lyα luminosity function is steep (α ⪅ -1.8), it extends down to luminosities lower than 1038 -  1037 erg s-1, and the clustering of these Lyα emitters is significant (filling factor < 1/6). If these Lyα emitters are powered by star formation, then this implies their luminosity function needs to extend down to star formation rates < 10-4M yr-1. These observations provide the first detection of the cosmic web in Lyα emission in typical filamentary environments and the first observational clue indicating the existence of a large population of ultra low-luminosity Lyα emitters at high redshift. © R. Bacon et al. 2021

Cellular activation, phagocytosis, and bactericidal activity against group B streptococcus involve parallel myeloid differentiation factor 88-dependent and independent signaling pathways

Group B streptococci (GBS) vigorously activate inflammatory responses. We reported previously that a secreted GBS factor activates phagocytes via Toll-like receptor (TLR)2 and TLR6, but that GBS cell walls activate cells independently of these receptors. We hypothesized that the phagocytic immune functions in response to GBS, such as inflammation, uptake, and elimination of bacteria, occur through a coordinated engagement of TLRs, along with the coreceptors CD14 and CD11b/CD18. Using various knockout mice we show that GBS-induced activation of p38 and NF-kappaB depends upon the expression of the cytoplasmic TLR adapter protein, myeloid differentiation factor 88 (MyD88), but not TLR2 and/or TLR4. Macrophages with deletions of CD14 and complement receptor 3 had a normal cytokine response to whole bacteria, although the response to GBS factor was abrogated in CD14-null cells. The intracellular formation of bactericidal oxygen species proved to be MyD88 dependent; however, uptake of GBS, a prerequisite for intracellular killing by O(2) radicals, occurred independently of MyD88. While deletion of complement receptor 3 greatly diminished the uptake of opsonized GBS, it did not affect the formation of bactericidal O(2) radicals or inflammatory signaling intermediates. We conclude that the inflammatory, bactericidal, and phagocytic responses to GBS occur via parallel but independent processes

The mean H

We present the first measurements of the Lyman-continuum photon production efficiency ξion, 0 at z ∼ 4–5 for galaxies fainter than 0.2 L* (−19 mag). ξion, 0 quantifies the production rate of ionizing photons with respect to the UV luminosity density assuming a fiducial escape fraction of zero. Extending previous measurements of ξion, 0 to the faint population is important, as ultra-faint galaxies are expected to contribute the bulk of the ionizing emissivity. We probe ξion, 0 to such faint magnitudes by taking advantage of 200-h depth Spitzer/IRAC observations from the GREATS program and ≈300 3 <  z <  6 galaxies with spectroscopic redshifts from the MUSE GTO Deep + Wide programs. Stacked IRAC [3.6]−[4.5] colors are derived and used to infer the Hα rest-frame equivalent widths, which range from 403 Å to 2818 Å. The derived ξion, 0 is log10(ξion,0/Hz erg−1) = 25.36 ± 0.08 over −20.5 <  MUV <  −17.5, similar to those derived for brighter galaxy samples at the same redshift and therefore suggesting that ξion shows no strong dependence on MUV. The ξion, 0 values found in our sample imply that the Lyman-continuum escape fraction for MUV ≈ −19 star-forming galaxies cannot exceed ≈8–20% in the reionization era