Identification of a new European rabbit IgA with a serine-rich hinge region

<div><p>In mammals, the most striking IgA system belongs to Lagomorpha. Indeed, 14 IgA subclasses have been identified in European rabbits, 11 of which are expressed. In contrast, most other mammals have only one IgA, or in the case of hominoids, two IgA subclasses. Characteristic features of the mammalian IgA subclasses are the length and amino acid sequence of their hinge regions, which are often rich in Pro, Ser and Thr residues and may also carry Cys residues. Here, we describe a new IgA that was expressed in New Zealand White domestic rabbits of <i>IGHV</i>a1 allotype. This IgA has an extended hinge region containing an intriguing stretch of nine consecutive Ser residues and no Pro or Thr residues, a motif exclusive to this new rabbit IgA. Considering the amino acid properties, this hinge motif may present some advantage over the common IgA hinge by affording novel functional capabilities. We also sequenced for the first time the IgA14 CH2 and CH3 domains and showed that IgA14 and IgA3 are expressed.</p></div

Cosmic CARNage I: on the calibration of galaxy formation models

We present a comparison of nine galaxy formation models, eight semi-analytical, and one halo occupation distribution model, run on the same underlying cold dark matter simulation (cosmological box of comoving width 125h−1 Mpc, with a dark-matter particle mass of 1.24 × 109h−1M) and the same merger trees. While their free parameters have been calibrated to the same observational data sets using two approaches, they nevertheless retain some ‘memory’ of any previous calibration that served as the starting point (especially for the manually tuned models). For the first calibration, models reproduce the observed z = 0 galaxy stellar mass function (SMF) within 3σ. The second calibration extended the observational data to include the z = 2 SMF alongside the z ∼ 0 star formation rate function, cold gas mass, and the black hole–bulge mass relation. Encapsulating the observed evolution of the SMF from z = 2 to 0 is found to be very hard within the context of the physics currently included in the models. We finally use our calibrated models to study the evolution of the stellar-to-halo mass (SHM) ratio. For all models, we find that the peak value of the SHM relation decreases with redshift. However, the trends seen for the evolution of the peak position as well as the mean scatter in the SHM relation are rather weak and strongly model dependent. Both the calibration data sets and model results are publicly available

Equivalent widths of Lyman α\alpha emitters in MUSE-Wide and MUSE-Deep

The aim of this study is to better understand the connection between the Lyman $\alpha$ rest-frame equivalent width (EW$_0$) and spectral properties as well as ultraviolet (UV) continuum morphology by obtaining reliable EW$_0$ histograms for a statistical sample of galaxies and by assessing the fraction of objects with large equivalent widths. We used integral field spectroscopy from MUSE combined with broad-band data from the Hubble Space Telescope (HST) to measure EW$_0$. We analysed the emission lines of $1920$ Lyman $\alpha$ emitters (LAEs) detected in the full MUSE-Wide (one hour exposure time) and MUSE-Deep (ten hour exposure time) surveys and found UV continuum counterparts in archival HST data. We fitted the UV continuum photometric images using the Galfit software to gain morphological information on the rest-UV emission and fitted the spectra obtained from MUSE to determine the double peak fraction, asymmetry, full-width at half maximum, and flux of the Lyman $\alpha$ line. The two surveys show different histograms of Lyman $\alpha$ EW$_0$. In MUSE-Wide, $20\%$ of objects have EW$_0 > 240$ \r{A}, while this fraction is only $11\%$ in MUSE-Deep and $\approx 16\%$ for the full sample. This includes objects without HST continuum counterparts (one-third of our sample), for which we give lower limits for EW$_0$. The object with the highest securely measured EW$_0$ has EW$_0=589 \pm 193$ \r{A} (the highest lower limit being EW$_0=4464$ \r{A}). We investigate the connection between EW$_0$ and Lyman $\alpha$ spectral or UV continuum morphological properties. The survey depth has to be taken into account when studying EW$_0$ distributions. We find that in general, high EW$_0$ objects can have a wide range of spectral and UV morphological properties, which might reflect that the underlying causes for high EW$_0$ values are equally varied. (abridged)Comment: 28 pages, 21 + 1 figures, 7 + 1 tables, accepted for publication in A&

The Lensed Lyman-Alpha MUSE Arcs Sample (LLAMAS): I. Characterisation of extended Lyman-alpha halos and spatial offsets

Aims. We present the Lensed Lyman-Alpha MUSE Arcs Sample (LLAMAS) selected from MUSE and HST observations of 17 lensing clusters. The sample consists of 603 continuum-faint (23 < MUV<-14) lensed Lyman-α emitters (producing 959 images) with secure spectroscopic redshifts between 2.9 and 6.7. Combining the power of cluster magnification with 3D spectroscopic observations, we were able to reveal the resolved morphological properties of 268 Lyman-α emitters. Methods. We used a forward-modeling approach to model both Lyman-α and rest-frame UV continuum emission profiles in the source plane and measure spatial extent, ellipticity, and spatial offsets between UV and Lyman-α emission. Results. We find a significant correlation between UV continuum and Lyman-α spatial extent. Our characterization of the Lyman-α halos indicates that the halo size is linked to the physical properties of the host galaxy (SFR, Lyman-α equivalent width, Lyman-α line FWHM). We find that 48% of Lyman-α halos are best fit by an elliptical emission distribution with a median axis ratio of q =0.48. We observe that 60% of galaxies detected both in UV and Lyman-α emission show a significant spatial offset (ΔLyα-UV). We measure a median offset of ΔLyα-UV=0.58± 0.14 kpc for the entire sample. By comparing the spatial offset values with the size of the UV component, we show that 40% of the offsets could be due to star-forming sub-structures in the UV component, while the larger offsets (60%) are more likely due to greater-distance processes such as scattering effects inside the circumgalactic medium or emission from faint satellites or merging galaxies. Comparisons with a zoom-in radiative hydrodynamics simulation of a typical Lyman-α emitting galaxy show a very good agreement with LLAMAS galaxies and indicate that bright star-formation clumps and satellite galaxies could produce a similar spatial offset distribution

Probing the faint end Luminosity Function of Lyman Alpha Emitters at 3<z<7 behind 17 MUSE lensing clusters

We present a study of the galaxy Lyman-alpha luminosity function (LF) using a sample of 17 lensing clusters observed by the MUSE/VLT. Magnification from strong gravitational lensing by clusters of galaxies and MUSE apabilities allow us to blindly detect LAEs without any photometric pre-selection, reaching the faint luminosity regime. 600 lensed LAEs were selected behind these clusters in the redshift range 2.9<$z$< 6.7, covering four orders of magnitude in magnification-corrected Lyman-alpha luminosity (39.0<log$L$< 43.0). The method used in this work ($V_{\text{max}}$) follows the recipes originally developed by arXiv:1905.13696(N) (DLV19) with some improvements to better account for the effects of lensing when computing the effective volume. The total co-moving volume at 2.9<$z$<6.7 is $\sim$50 $10^{3}Mpc^{3}$. Our LF points in the bright end (log L)>42 are consistent with those obtained from blank field observations. In the faint luminosity regime, the density of sources is well described by a steep slope, $\alpha\sim-2$ for the global redshift range. Up to log(L)$\sim$41, the steepening of the faint end slope with redshift, suggested by the earlier work of DLV19 is observed, but the uncertainties remain large. A significant flattening is observed towards the faintest end, for the highest redshift bins (log$L$<41). Using face values, the steep slope at the faint-end causes the SFRD to dramatically increase with redshift, implying that LAEs could play a major role in the process of cosmic reionization. The flattening observed towards the faint end for the highest redshift bins still needs further investigation. This turnover is similar to the one observed for the UV LF at $z\geq6$ in lensing clusters, with the same conclusions regarding the reliability of current results (e.g.arXiv:1803.09747(N); arXiv:2205.11526(N)).Comment: 20 pages, 15 figures, 6 tables. Accepted for publication in A\&

A new species of Schoutedenichia Jadin & Vercammen-Grandjean, 1954 from Madagascar and a re-description of S. dutoiti (Radford, 1948) from South Africa (Acariformes: Trombiculidae)

A new chigger mite species, Schoutedenichia microcebi n. sp. is described from the grey mouse lemur Microcebus murinus (J.F. Miller) from Madagascar. The new species is closely related to S. dutoiti (Radford, 1948), a species described from a single specimen collected on a rodent in South Africa. Examination of the holotype and new material on S. dutoiti from South Africa enabled us to re-describe this species and provide new data on its hosts and geographical distribution

The JWST Emission Line Survey (JELS): the sizes and merger fraction of star-forming galaxies during the Epoch of Reionization

We used observations from the JWST Emission Line Survey (JELS) to measure the half-light radii () of 23 H-emitting star-forming (SF) galaxies at in the PRIMER/COSMOS field. Galaxy sizes were measured in JWST near-infrared camera observations in rest-frame H (tracing recent star formation) with the F466N and F470N narrow-band filters from JELS, and compared against rest-- and -band (tracing established stellar populations) and near-ultraviolet sizes. We find a size–stellar mass () relationship with a slope that is consistent with literature values at lower redshifts, though offset to lower sizes. We observe a large scatter in at low stellar mass ( ) which we believe is the result of bursty star formation histories (SFHs) of SF galaxies at the Epoch of Reionization (EoR). We find that the stellar and ionized gas components are similar in size at . The evidence of already-established stellar components in these H emitters (HAEs) indicates previous episodes of star formation have occurred. As such, following other JELS studies finding our HAEs are undergoing a current burst of star formation, we believe our results indicate that SF galaxies at the end of the EoR have already experienced a bursty SFH. From our relationship, we find for fixed stellar mass , which is in agreement with other observations and simulations of SF galaxies in the literature. We find a close-pair (major) merger fraction of () for galaxy separations , which is in agreement with other studies