The MUSE Hubble Ultra Deep Field Survey X. Lyα\alpha Equivalent Widths at 2.9<z<6.62.9 < z < 6.6

We present rest-frame Ly$\alpha$ equivalent widths (EW) of 417 Ly$\alpha$ emitters (LAEs) detected with Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT) at $2.9 < z < 6.6$ in the Hubble Ultra Deep Field. Based on the deep MUSE spectroscopy and ancillary Hubble Space Telescope (HST) photometry data, we carefully measured EW values taking into account extended Ly$\alpha$ emission and UV continuum slopes ($\beta$). Our LAEs reach unprecedented depths, both in Ly$\alpha$ luminosities and UV absolute magnitudes, from log($L_{\rm Ly\alpha}$/erg s$^{-1}$) $\sim$41.0 to 43.0 and from Muv $\sim$ -16 to -21 (0.01-1.0 $L^{*}_{\rm z=3}$). The EW values span the range of $\sim$ 5 to 240 \AA\ or larger, and their distribution can be well fitted by an exponential law $N = N_{\rm 0}$ exp($-$EW/$w_{\rm 0}$). Owing to the high dynamic range in Muv, we find that the scale factor, $w_{\rm 0}$, depends on Muv in the sense that including fainter Muv objects increases $w_{\rm 0}$, i.e., the Ando effect. The results indicate that selection functions affect the EW scale factor. Taking these effects into account, we find that our $w_{\rm 0}$ values are consistent with those in the literature within $1\sigma$ uncertainties at $2.9 < z < 6.6$ at a given threshold of Muv and $L_{\rm Ly\alpha}$. Interestingly, we find 12 objects with EW $>200$ \AA\ above $1\sigma$ uncertainties. Two of these 12 LAEs show signatures of merger or AGN activity: the weak CIV $\lambda 1549$ emission line. For the remaining 10 very large EW LAEs, we find that the EW values can be reproduced by young stellar ages ($< 100$ Myr) and low metallicities ($\lesssim 0.02$ $Z_{\rm \odot}$). Otherwise, at least part of the Ly$\alpha$ emission in these LAEs needs to arise from anisotropic radiative transfer effects, fluorescence by hidden AGN or quasi-stellar object activity, or gravitational cooling.Comment: 22 pages, 12 figures, 9 tables, accepted for publication in A&A (MUSE UDF Series Paper X

First Light and Reionisation Epoch Simulations (FLARES) - VI. The colour evolution of galaxies z=5-15

With its exquisite sensitivity, wavelength coverage, and spatial and spectral resolution, the James Webb Space Telescope (JWST) is poised to revolutionize our view of the distant, high-redshift (z > 5) Universe. While Webb's spectroscopic observations will be transformative for the field, photometric observations play a key role in identifying distant objects and providing more comprehensive samples than accessible to spectroscopy alone. In addition to identifying objects, photometric observations can also be used to infer physical properties and thus be used to constrain galaxy formation models. However, inferred physical properties from broad-band photometric observations, particularly in the absence of spectroscopic redshifts, often have large uncertainties. With the development of new tools for forward modelling simulations, it is now routinely possible to predict observational quantities, enabling a direct comparison with observations. With this in mind, in this work, we make predictions for the colour evolution of galaxies at z = 5-15 using the First Light And Reionisation Epoch Simulations (flares) cosmological hydrodynamical simulation suite. We predict a complex evolution with time, driven predominantly by strong nebular line emission passing through individual bands. These predictions are in good agreement with existing constraints from Hubble and Spitzer as well as some of the first results from Webb. We also contrast our predictions with other models in the literature: While the general trends are similar, we find key differences, particularly in the strength of features associated with strong nebular line emission. This suggests photometric observations alone should provide useful discriminating power between different models and physical states of galaxies.Peer reviewe

Mewt

Ġabra ta’ poeżiji u proża li tinkludi: Waħx il-baqar ta’ Peter A. Caruana – Żewġ ilħna ta’ Pawlu Aquilina – Il-bidla... ta’ Karmenu Mallia – Ġirja... ta’ C. Cassar – Fis-sikta ta’ Wied Magħlaq ta’ Anton Agius – Xewqat ta’ hena ta’ Rużar Briffa – Il-mewt ta’ Ġużè Chetcuti.peer-reviewe

First light and reionization epoch simulations (FLARES) V : the redshift frontier

JWST is set to transform many areas of astronomy, one of the most exciting is the expansion of the redshift frontier to z > 10. In its first year, alone JWST should discover hundreds of galaxies, dwarfing the handful currently known. To prepare for these powerful observational constraints, we use the First Light And Reionization Epoch simulations (flares) to predict the physical and observational properties of the z > 10 population of galaxies accessible to JWST. This is the first time such predictions have been made using a hydrodynamical model validated at low redshift. Our predictions at z = 10 are broadly in agreement with current observational constraints on the far-UV luminosity function and UV continuum slope beta, though the observational uncertainties are large. We note tension with recent constraints z similar to 13 from Harikane et al. () - compared to these constraints, flares predicts objects with the same space density should have an order-of-magnitude lower luminosity, though this is mitigated slightly if dust attenuation is negligible in these systems. Our predictions suggest that in JWST's first cycle alone, around 600 galaxies should be identified at z > 10, with the first small samples available at z > 13.Peer reviewe

Epigrammi

Ġabra ta’ poeżiji u proża li tinkludi: Id-daqq tal-qanpiena ta’ għonq il-mogħża ħasbu l-vjatku ta’ Dun A. Tabone – Għaddejja l-purċissjoni ta’ Dun Frans Camilleri – Nazju jidħol baħri ta’ Alfie Guillaumier – Lil marti ta’ Pawlu Aquilina – In-nawfraġju ta’ Br. Henry – Orqod tfajjel, orqod ta’ Peter A. Caruana – Epigrammi ta’ E. Quattromani.peer-reviewe

Roti jduru

Ġabra ta’ poeżiji u proża li tinkludi: Kwartini ta’ C. Cassar – Dak li ħalla l-ħares ta’ Pawlu Cachia – Epigrammi ta’ Peter A. Caruana – Lill-Madonna tal-arju ta’ Mario Agius – Il-fatati li ħatfu lil Ġomu “Xewka” ta’ Ġużè Dimech Debono – Bla mħabba ta’ Ġorġ Borg – Il-bieb ta’ l-infern ta’ P. Jos. Cremona – Roti jduru ta’ C. Cassar.peer-reviewe

First Light And Reionization Epoch Simulations (FLARES) VII : The star formation and metal enrichment histories of galaxies in the early Universe

The star formation and metal enrichment histories of galaxies - at any epoch - constitute one of the key properties of galaxies, and their measurement is a core aim of observational extragalactic astronomy. The lack of deep rest-frame optical coverage at high redshift has made robust constraints elusive, but this is now changing thanks to JWST. In preparation for the constraints provided by JWST, we explore the star formation and metal enrichment histories of galaxies at z = 5-13 using the First Light And Reionization Epoch Simulations (FLARES) suite. Built on the EAGLE model, the unique strategy of FLARES allows us to simulate galaxies with a wide range of stellar masses (and luminosities) and environments. While we predict significant redshift evolution of average ages and specific star formation rates, our core result is mostly a flat relationship of age and specific star formation rate with stellar mass. We also find that galaxies in this epoch predominantly have strongly rising star formation histories, albeit with the normalization dropping with redshift and stellar mass. In terms of chemical enrichment, we predict a strong stellar mass-metallicity relation present at z = 10 and beyond alongside significant a-enhancement. Finally, we find no large-scale environmental dependence of the relationship between age, specific star formation rate, or metallicity with stellar mass.Peer reviewe

Cauli: a mouse strain with an Ift140 mutation that results in a skeletal ciliopathy modelling jeune syndrome

Cilia are architecturally complex organelles that protrude from the cell membrane and have signalling, sensory and motility functions that are central to normal tissue development and homeostasis. There are two broad categories of cilia; motile and non-motile, or primary, cilia. The central role of primary cilia in health and disease has become prominent in the past decade with the recognition of a number of human syndromes that result from defects in the formation or function of primary cilia. This rapidly growing class of conditions, now known as ciliopathies, impact the development of a diverse range of tissues including the neural axis, craniofacial structures, skeleton, kidneys, eyes and lungs. The broad impact of cilia dysfunction on development reflects the pivotal position of the primary cilia within a signalling nexus involving a growing number of growth factor systems including Hedgehog, Pdgf, Fgf, Hippo, Notch and both canonical Wnt and planar cell polarity. We have identified a novel ENU mutant allele of Ift140, which causes a mid-gestation embryonic lethal phenotype in homozygous mutant mice. Mutant embryos exhibit a range of phenotypes including exencephaly and spina bifida, craniofacial dysmorphism, digit anomalies, cardiac anomalies and somite patterning defects. A number of these phenotypes can be attributed to alterations in Hedgehog signalling, although additional signalling systems are also likely to be involved. We also report the identification of a homozygous recessive mutation in IFT140 in a Jeune syndrome patient. This ENU-induced Jeune syndrome model will be useful in delineating the origins of dysmorphology in human ciliopathies

Lil Marija Bambina

Ġabra ta’ poeżiji u proża li tinkludi: Xrar ta’ J. P. Vassallo – Awtonekroloġija ta’ Albert M. Cassola – Ħajja ta’ Peter A. Caruana – Ir-reġina tar-raħal ta’ Pawlu Mifsud – Lil Malta ta’ Oliver Friggieri – Taqbida ta’ Joseph Sciberras – Il-bejta ta’ Pawlu Aquilina – Lil Marija Bambina ta’ Ġużè Delia.peer-reviewe

Disa’ sinfonija ta’ Beethoven

Ġabra ta’ poeżiji u proża li tinkludi: It-trabokk ta’ W. Borg – Il-merħla tal-bnedmin ta’ Pawlu Aquilina – Versi ta’ Marċell Mizzi – Fuq ix-xmara Mersey, Manchester ta’ Wallace Ph. Gulia – Ħolma ta’ Peter A. Caruana – “Ma jiġix iżjed” ta’ A. Tabone – Id-dinja u l-bniedem ta’ Ġużè Chetcuti – Il-ġlied tal-ħbieb ta’ Marċell Mizzi – Lil ibni Danjel ta’ Manwel Cassar – Li kieku!!! ta’ C. Cassar – Id-disa’ sinfonija ta’ Beethoven ta’ Karmenu Mallia.peer-reviewe