Search

The assembly and build-up of neutral atomic hydrogen (HI) in galaxies is one of the most fundamental processes in galaxy formation and evolution. Studying this process directly in the early universe is hindered by the weakness of the hyperfine 21-cm HI line transition, impeding direct detections and measurements of the HI gas masses ($M_{\rm HI}$). Here we present a new method to infer $M_{\rm HI}$ of high-redshift galaxies using neutral, atomic oxygen as a proxy. Specifically, we derive metallicity-dependent conversion factors relating the far-infrared [OI]-$63\mu$m and [OI]-$145\mu$m emission line luminosities and $M_{\rm HI}$ in star-forming galaxies at $z\approx 2-6$ using gamma-ray bursts (GRBs) as probes. We substantiate these results by observations of galaxies at $z\approx 0$ with direct measurements of $M_{\rm HI}$ and [OI]-$63\mu$m and [OI]-$145\mu$m in addition to hydrodynamical simulations at similar epochs. We find that the [OI]$_{\rm 63\mu m}$-to-HI and [OI]$_{\rm 145\mu m}$-to-HI conversion factors universally appears to be anti-correlated with the gas-phase metallicity. The high-redshift GRB measurements further predict a mean ratio of $L_{\rm [OI]-63\mu m} / L_{\rm [OI]-145\mu m}=1.55\pm 0.12$ and reveal generally less excited [CII]. The $z \approx 0$ galaxy sample also shows systematically higher $\beta_{\rm [OI]-63\mu m}$ and $\beta_{\rm [OI]-145\mu m}$ conversion factors than the GRB sample, indicating either suppressed [OI] emission in local galaxies or more extended, diffuse HI gas reservoirs traced by the HI 21-cm. Finally, we apply these empirical calibrations to the few high-redshift detections of [OI]-$63\mu$m and [OI]-$145\mu$m line transitions from the literature and further discuss the applicability of these conversion factors to probe the HI gas content in the dense, star-forming ISM of galaxies at $z\gtrsim 6$, well into the epoch of reionization., Comment: Submitted to A&A. Comments welcome

We present high-resolution 1.5--6 GHz Karl G. Jansky Very Large Array (VLA) and $\textit{Hubble Space Telescope}$ ($\textit{HST}$) optical and infrared observations of the extremely active repeating fast radio burst (FRB) FRB$\,$20201124A and its barred spiral host galaxy. We constrain the location and morphology of star formation in the host and search for a persistent radio source (PRS) coincident with FRB$\,$20201124A. We resolve the morphology of the radio emission across all frequency bands and measure a star formation rate SFR $\approx 8.9\,M_{\odot}$ yr$^{-1}$, a factor of $\approx 4-6$ larger than optically-inferred SFRs, demonstrating dust-obscured star formation throughout the host. Compared to a sample of all known FRB hosts with radio emission, the host of FRB$\,$20201124A has the most significant obscured star formation. While ${\it HST}$ observations show the FRB to be offset from the bar or spiral arms, the radio emission extends to the FRB location. We propose that the FRB progenitor could have formed $\textit{in situ}$ (e.g., a magnetar central engine born from the explosion of a massive star). It is still plausible, although less likely, that the progenitor of FRB$\,$20201124A migrated from the central bar of the host, e.g., via a runaway massive star. We further place a limit on the luminosity of a putative PRS at the FRB position of $L_{\rm 6.0 \ GHz}$ $\lesssim$ 2.6 $\times$ $10^{27}$ erg s$^{-1}$ Hz$^{-1}$, two orders of magnitude below any PRS known to date. However, this limit is still broadly consistent with both magnetar nebulae and hypernebulae models assuming a constant energy injection rate of the magnetar and an age of $\gtrsim 10^{5}$ yr in each model, respectively., Comment: 21 pages, 6 figures, 3 tables, Submitted

The onset of galaxy formation is thought to be initiated by the infall of neutral, pristine gas onto the first protogalactic halos. However, direct constraints on the abundance of neutral atomic hydrogen (HI) in galaxies have been difficult to obtain at early cosmic times. Here we present spectroscopic observations with JWST of three galaxies at redshifts $z=8.8 - 11.4$, about $400-600$ Myr after the Big Bang, that show strong damped Lyman-$α$ absorption ($N_{\rm HI} > 10^{22}$ cm$^{-2}$) from HI in their local surroundings, an order of magnitude in excess of the Lyman-$α$ absorption caused by the neutral intergalactic medium at these redshifts. Consequently, these early galaxies cannot be contributing significantly to reionization, at least at their current evolutionary stages. Simulations of galaxy formation show that such massive gas reservoirs surrounding young galaxies so early in the history of the universe is a signature of galaxy formation in progress., Submitted

We present the results of a systematic search for candidate quiescent galaxies in the distant Universe in eleven $JWST$ fields with publicly available observations collected during the first three months of operations and covering an effective sky area of $\sim145$ arcmin$^2$. We homogeneously reduce the new $JWST$ data and combine them with existing observations from the $Hubble\,Space\,Telescope$. We select a robust sample of $\sim80$ candidate quiescent and quenching galaxies at $3 < z < 5$ using two methods: (1) based on their rest-frame $UVJ$ colors, and (2) a novel quantitative approach based on Gaussian Mixture Modeling of the $NUV-U$, $U-V$, and $V-J$ rest-frame color space, which is more sensitive to recently quenched objects. We measure comoving number densities of massive ($M_\star\geq 10^{10.6} M_\odot$) quiescent galaxies consistent with previous estimates relying on ground-based observations, after homogenizing the results in the literature with our mass and redshift intervals. However, we find significant field-to-field variations of the number densities up to a factor of $2-3$, highlighting the effect of cosmic variance and suggesting the presence of overdensities of red quiescent galaxies at $z>3$, as it could be expected for highly clustered massive systems. Importantly, $JWST$ enables the robust identification of quenching/quiescent galaxy candidates at lower masses and higher redshifts than before, challenging standard formation scenarios. All data products, including the literature compilation, are made publicly available., 15 pages, 6 Figures + Appendix. Accepted for publication in ApJ on Feb, 9. Data release: - Reduced HST+JWST mosaics + photometric catalogs and Eazy-py modeling: https://erda.ku.dk/archives/7166d013c1ca1371aac3c57b9e73190d/published-archive.html - Supplementary material and tables: https://zenodo.org/record/7614908#.Y-4ZruzMLmE - MAST: https://doi.org/10.17909/g3nt-a370 - See also Gould et al. 2023

We present the results of a systematic study of the rest-frame optical morphology of quiescent galaxies at $z \geq 3$ using the Near-Infrared Camera (NIRCam) onboard $JWST$. Based on a sample selected by $UVJ$ color or $NUVUVJ$ color, we focus on 26 quiescent galaxies with $9.810.3$ implies that our size - stellar mass relations are below those at lower redshifts, with the amplitude of $\sim0.6\, {\rm kpc}$ at $M_\star = 5\times 10^{10}\, M_\odot$. This value agrees with the extrapolation from the size evolution of quiescent galaxies at $z, Comment: 23 pages, 16 figures, 2 tables; submitted to ApJ

We report on the stellar content, half-light radii and star formation rates of a sample of 10 known high-redshift ($z\gtrsim 2$) galaxies selected on strong neutral hydrogen (HI) absorption (log(N(HI)/cm$^{-2})>19$) toward background quasars. We use observations from the {\it Hubble Space Telescope} (HST) Wide Field Camera 3 in three broad-band filters to study the spectral energy distribution(SED) of the galaxies. Using careful quasar point spread function subtraction, we study their galactic environments, and perform the first systematic morphological characterisation of such absorption-selected galaxies at high redshifts. Our analysis reveals complex, irregular hosts with multiple star-forming clumps. At a spatial sampling of 0.067 arcsec per pixel (corresponding to 0.55 kpc at the median redshift of our sample), 40% of our sample requires multiple S��rsic components for an accurate modelling of the observed light distributions. Placed on the mass-size relation and the `main sequence' of star-forming galaxies, we find that absorption-selected galaxies at high redshift extend known relations determined from deep luminosity-selected surveys to an order of magnitude lower stellar mass, with objects primarily composed of star-forming, late-type galaxies. We measure half-light radii in the range $r_{1/2} \sim$ 0.4 to 2.6 kpc based on the reddest band (F160W) to trace the oldest stellar populations, and stellar masses in the range $\log (\mathrm{M}_{\star}/\mathrm{M}_{\odot}) \sim$ 8 to 10 derived from fits to the broad-band SED. Spectroscopic and SED-based star formation rates are broadly consistent, and lie in the range log(SFR/M$_{\odot} $yr$^{-1}$) $\sim$0.0 to 1.7., 17 pages, Accepted for publication in MNRAS. This revision has minor text changes

With just a month of data, JWST is already transforming our view of the universe, revealing and resolving starlight in unprecedented populations of galaxies. Although “HST-dark” galaxies have previously been detected at long wavelengths, these observations generally suffer from a lack of spatial resolution, which limits our ability to characterize their sizes and morphologies. Here we report on a first view of starlight from a subset of the HST-dark population that is bright with JWST/NIRCam (4.4 μm < 24.5 mag) and very faint or even invisible with HST (μm). In this Letter we focus on a dramatic and unanticipated population of physically extended galaxies (≳0.″25). These 12 galaxies have photometric redshifts 2 < z < 6, high stellar masses M ⋆ ≳ 1010 M ⊙, and significant dust-attenuated star formation. Surprisingly, the galaxies have elongated projected axis ratios at 4.4 μm, suggesting that the population is disk dominated or prolate and we hence refer to them as ultrared flattened objects. Most of the galaxies appear red at all radii, suggesting significant dust attenuation throughout. With R e (F444W) ∼ 1–2 kpc, the galaxies are similar in size to compact massive galaxies at z ∼ 2 and the cores of massive galaxies and S0s at z ∼ 0. The stellar masses, sizes, and morphologies of the sample suggest that some could be progenitors of lenticular or fast-rotating galaxies in the local universe. The existence of this population suggests that our previous censuses of the universe may have missed massive, dusty edge-on disks, in addition to dust-obscured starbursts.

We present the results of a systematic search for candidate quiescent galaxies in the distant Universe in eleven $JWST$ fields with publicly available observations collected during the first three months of operations and covering an effective sky area of $\sim145$ arcmin$^2$. We homogeneously reduce the new $JWST$ data and combine them with existing observations from the $Hubble\,Space\,Telescope$. We select a robust sample of $\sim80$ candidate quiescent and quenching galaxies at $3 < z < 5$ using two methods: (1) based on their rest-frame $UVJ$ colors, and (2) a novel quantitative approach based on Gaussian Mixture Modeling of the $NUV-U$, $U-V$, and $V-J$ rest-frame color space, which is more sensitive to recently quenched objects. We measure comoving number densities of massive ($M_\star\geq 10^{10.6} M_\odot$) quiescent galaxies consistent with previous estimates relying on ground-based observations, after homogenizing the results in the literature with our mass and redshift intervals. However, we find significant field-to-field variations of the number densities up to a factor of $2-3$, highlighting the effect of cosmic variance and suggesting the presence of overdensities of red quiescent galaxies at $z>3$, as it could be expected for highly clustered massive systems. Importantly, $JWST$ enables the robust identification of quenching/quiescent galaxy candidates at lower masses and higher redshifts than before, challenging standard formation scenarios. All data products, including the literature compilation, are made publicly available., Comment: 15 pages, 6 Figures + Appendix. Accepted for publication in ApJ on Feb, 9. Data release: - Reduced HST+JWST mosaics + photometric catalogs and Eazy-py modeling: https://erda.ku.dk/archives/7166d013c1ca1371aac3c57b9e73190d/published-archive.html - Supplementary material and tables: https://zenodo.org/record/7614908#.Y-4ZruzMLmE - MAST: https://doi.org/10.17909/g3nt-a370 - See also Gould et al. 2023

With just a month of data, JWST is already transforming our view of the Universe, revealing and resolving starlight in unprecedented populations of galaxies. Although ``HST-dark" galaxies have previously been detected at long wavelengths, these observations generally suffer from a lack of spatial resolution which limits our ability to characterize their sizes and morphologies. Here we report on a first view of starlight from a subset of the HST-dark population that are bright with JWST/NIRCam (4.4$μ$m

We report the archival discovery of Lyman-$α$ emission from the bright ultraviolet galaxy Y002 at $z=7.677$, spectroscopically confirmed by its ionized carbon [CII] 158$μ$m emission line. The Ly$α$ line is spatially associated with the rest-frame UV stellar emission ($M_{\rm UV}$~-22, 2x brighter than $M^\star_{\rm UV}$) and it appears offset from the peak of the extended [CII] emission at the current ~1" spatial resolution. We derive an estimate of the unobscured SFR(UV)=$(22\pm1)\,M_\odot$ yr$^{-1}$ and set an upper limit of SFR(IR)$, 10 pages, 4 figures. Accepted for publication in The Astrophysical Journal Letters

$JWST$'s first glimpse of the $z>10$ Universe has yielded a surprising abundance of luminous galaxy candidates. Here we present the most extreme of these systems: CEERS-1749. Based on $0.6-5\mu$m photometry, this strikingly luminous ($\approx$26 mag) galaxy appears to lie at $z\approx17$. This would make it an $M_{\rm{UV}}\approx-22$, $M_{\rm{\star}}\approx5\times10^{9}M_{\rm{\odot}}$ system that formed a mere $\sim220$ Myrs after the Big Bang. The implied number density of this galaxy and its analogues challenges virtually every early galaxy evolution model that assumes $\Lambda$CDM cosmology. However, there is strong environmental evidence supporting a secondary redshift solution of $z\approx5$: all three of the galaxy's nearest neighbors at $2\mu$m photometry, producing an apparent blue slope as well as a strong break in the SED. Such a perfectly disguised contaminant is possible only in a narrow redshift window ($\Delta z\lesssim0.1$), implying that the permitted volume for such interlopers may not be a major concern for $z>10$ searches, particularly when medium-bands are deployed. If CEERS-1749 is confirmed to lie at $z\approx5$, it will be the highest-redshift quiescent galaxy, or one of the lowest mass dusty galaxies of the early Universe detected to-date. Both redshift solutions of this intriguing galaxy hold the potential to challenge existing models of early galaxy evolution, making spectroscopic follow-up of this source critical., Comment: Submitted to ApJL. Fig. 1 shows the "superposed" state, Fig. 2 presents the potential z~5 protocluster, Fig. 3 shows some atypical z~5 SEDs, Fig. 4 studies the morphology, Fig. 5 summarizes the extraordinary situation at z~17, and Fig. 6 argues for why such interlopers may not be a major issue for z>10 searches. Comments warmly welcomed

We present ALMA deep spectroscopy for a lensed galaxy at $z_{\rm spec}=8.496$ with $\log(M_{\rm star}/M_{\odot})\sim7.8$ whose optical nebular lines and stellar continuum are detected by JWST/NIRSpec and NIRCam Early Release Observations in SMACS0723. Our ALMA spectrum shows [OIII]88$\mu$m and [CII]158$\mu$m line detections at $4.0\sigma$ and $4.5\sigma$, respectively. The redshift and position of the [OIII] line coincide with those of the JWST source, while the [CII] line is blue-shifted by 90 km s$^{-1}$ with a spatial offset of $0.''5$ ($\approx0.5$ kpc in source plane) from the JWST source. The NIRCam F444W image, including [OIII]$\lambda$5007 and H$\beta$ line emission, spatially extends beyond the stellar components by a factor of $>8$. This indicates that the $z=8.5$ galaxy has already experienced strong outflows whose oxygen and carbon produce the extended [OIII]$\lambda$5007 and the offset [CII] emission, which would promote ionizing photon escape and facilitate reionization. With careful slit-loss corrections and removals of emission spatially outside the galaxy, we evaluate the [OIII]88$\mu$m/$\lambda$5007 line ratio, and derive the electron density $n_{\rm e}$ by photoionization modeling to be $220^{+170}_{-100}$ cm$^{-3}$, which is comparable with those of $z\sim2-3$ galaxies. We estimate an [OIII]88$\mu$m/[CII]158$\mu$m line ratio in the galaxy of $>4$, as high as those of known $z\sim6-9$ galaxies. This high [OIII]88$\mu$m/[CII]158$\mu$m line ratio is generally explained by the high $n_{\rm e}$ as well as the low metallicity ($Z_{\rm gas}/Z_{\odot}=0.04^{+0.02}_{-0.02}$), high ionization parameter ($\log U > -2.27$), and low carbon-to-oxygen abundance ratio ($\log$(C/O) $=[-0.52:-0.24]$) obtained from the JWST/NIRSpec data; further [CII] follow-up observations will constrain the covering fraction of photodissociation regions., Comment: 27 pages, 11 figures, 5 tables. Submitted to ApJ

Fast Radio Bursts (FRBs) are extremely energetic pulses of millisecond duration and unknown origin. In order to understand the phenomenon that emits these pulses, targeted and untargeted searches have been performed for multi-wavelength counterparts, including the optical. The objective of this work is to search for optical transients at the position of 8 well-localized FRBs, after the arrival of the burst on different time-scales (typically at one day, several months, and one year after FRB detection) in order to compare with known transient optical light curves. We used the Las Cumbres Observatory Global Telescope Network (LCOGT), which allows us to promptly take images owing to its network of twenty-three telescopes working around the world. We used a template subtraction technique on all the images we collected at different epochs. We have divided the subtractions into two groups, in one group we use the image of the last epoch as a template and in the other group we use the image of the first epoch as a template. We have searched for bright optical transients at the localizations of the FRBs (, Accepted to Astronomy & Astrophysics on 27 June, 2021. 8 pages, 3 figures, 3 tables

We present a high-resolution analysis of the host galaxy of fast radio burst (FRB)~190608, an SB(r)c galaxy at $z=0.11778$ (hereafter HG 190608), to dissect its local environment and its contributions to the FRB properties. Our Hubble Space Telescope Wide Field Camera 3 ultraviolet and visible light image reveals that the subarcsecond localization of FRB~190608 is coincident with a knot of star-formation ($\Sigma_{\rm SFR} = 1.5 \times 10^{-2}~ M_{\odot} \, \rm \, yr^{-1} \, kpc^{-2}$) in the northwest spiral arm of HG~190608. Using H$\beta$ emission present in our Keck Cosmic Web Imager integral field spectrum of the galaxy with a surface brightness of $\mu_{\rm H\beta}= \mathrm{(3.36\pm0.21)\times10^{-17}\;erg\;s^{-1}\;cm^{-2}\;arcsec^{-2}}$, we infer an extinction-corrected H$\alpha$ surface brightness and compute a dispersion measure (DM) from the interstellar medium of HG 190608 of $\rm DM_{\rm Host,ISM} = 94 \pm 38~ \;pc\;cm^{-3}$. The galaxy rotates with a circular velocity $v_{\rm circ} = \rm 141 \pm 8~ km\;s^{-1}$ at an inclination $i_{\mathrm{gas}} = 37 \pm 3^\circ$, giving a dynamical mass $M_{\rm halo}^{\rm dyn} \approx 10^{11.96 \pm 0.08}~M_{\odot}$. This implies a halo contribution to the DM of $\rm DM_{\rm Host,Halo}= \rm 55\pm25 \;pc\;cm^{-3}$ subject to assumptions on the density profile and fraction of baryons retained. From the galaxy rotation curve, we infer a bar-induced pattern speed of $\Omega_p=34\pm 6\;\mathrm{km\;s^{-1}\;kpc^{-1}}$ using linear resonance theory. We then calculate the maximum time since star-formation for a progenitor using the furthest distance to the arm's leading edge within the localization, and find $t_{\mathrm{enc}} = 21_{-6}^{+25}$ Myr. Unlike previous high-resolution studies of FRB environments, we find no evidence of disturbed morphology, emission, or kinematics for FRB 190608., Comment: 21 pages, 11 figure files, 10 figures in paper, 3 tables. Accepted to ApJ on Sept. 16, 2021, published Nov. 29, 2021

The HI gas content is a key ingredient in galaxy evolution, the study of which has been limited to moderate cosmological distances for individual galaxies due to the weakness of the hyperfine HI 21-cm transition. Here we present a new approach that allows us to infer the HI gas mass $M_{\rm HI}$ of individual galaxies up to $z\approx 6$, based on a direct measurement of the [CII]-to-HI conversion factor in star-forming galaxies at $z\gtrsim 2$ using $\gamma$-ray burst afterglows. By compiling recent [CII]-158 $\mu$m emission line measurements we quantify the evolution of the HI content in galaxies through cosmic time. We find that the HI mass starts to exceed the stellar mass $M_\star$ at $z\gtrsim 1$, and increases as a function of redshift. The HI fraction of the total baryonic mass increases from around $20\%$ at $z = 0$ to about $60\%$ at $z\sim 6$. We further uncover a universal relation between the HI gas fraction $M_{\rm HI}/M_\star$ and the gas-phase metallicity, which seems to hold from $z\approx 6$ to $z=0$. The majority of galaxies at $z>2$ are observed to have HI depletion times, $t_{\rm dep,HI} = M_{\rm HI}/{\rm SFR}$, less than $\approx 2$ Gyr, substantially shorter than for $z\sim 0$ galaxies. Finally, we use the [CII]-to-HI conversion factor to determine the cosmic mass density of HI in galaxies, $\rho_{\rm HI}$, at three distinct epochs: $z\approx 0$, $z\approx 2$, and $z\sim 4-6$. These measurements are consistent with previous estimates based on 21-cm HI observations in the local Universe and with damped Lyman-$\alpha$ absorbers (DLAs) at $z\gtrsim 2$, suggesting an overall decrease by a factor of $\approx 5$ in $\rho_{\rm HI}(z)$ from the end of the reionization epoch to the present., Comment: Accepted for publication in ApJ

The power system is experiencing an increasing share of renewable and intermittent energy production and increasing electrification. However, these changes are creating high power peaks, are straining the grid and call for expensive investments in expansions and improvements. This paper examines how the operational strategy of shared battery energy storage systems (s-BESS) can address these issues for commercial buildings with relatively high power peaks. Due to the uncertainty in long-term costs when subject to a measured peak (MP) grid tariff, the scheduling of the battery is optimised with a receding horizon control algorithm. The optimisation model is used on a Norwegian real-life case study to find the best possible configuration with an already existing battery. Although current Norwegian regulations challenge the possibility for shared metering and billing for a s-BESS configuration, the results show that the total system cost was reduced by 19.2% compared to no battery. The community peak was reduced by 17.8% compared to no battery and 6.22-17.5% compared to individual storage, which indicates that s-BESS is of value for the DSO as well.

We present Hubble Space Telescope (HST/WFC3) ultraviolet and infrared observations of eight fast radio burst (FRB) host galaxies with sub-arcsecond localizations, including the hosts of three known repeating FRBs. We quantify their spatial distributions and locations with respect to their host galaxy light distributions, finding that they occur at moderate host normalized-offsets of 1.4 $r_e$ ([0.6,2.1] $r_e$; 68% interval), occur on fainter regions of their hosts in terms of IR light, but overall trace the radial distribution of IR light in their galaxies. The FRBs in our tested distribution do not clearly trace the distributions of any other transient population with known progenitors, and are statistically distinct from the locations of LGRBs, H-poor SLSNe, SGRBs, and Ca-rich transients. We further find that most FRBs are not in regions of elevated local star formation rate and stellar mass surface densities in comparison to the mean global values of their hosts. We also place upper limits to the IR flux at the FRB positions of $m_{\rm IR}\gtrsim\!24.8-27.6$~AB~mag, constraining both satellite and background galaxies to luminosities well below the host luminosity of FRB121102. We find that 5/8 FRB hosts exhibit clear spiral arm features in IR light, and that the positions of all well-localized FRBs located in such hosts are consistent with their spiral arms, although not on their brightest regions. Our results do not strongly support the primary progenitor channel of FRBs being connected either with the most massive (stripped-envelope) stars, or with events which require kicks and long delay times (neutron star mergers)., 21 pages, 9 figures, Accepted for publication in ApJ

We present deep Apache Point Observatory optical observations within seconds of the outburst of the periodic fast radio burst (FRB) 180916.J0158+65 obtained on 3 September 2020. FRB 180916.J0158+65 is located in a nearby spiral galaxy 150 Mpc away and has an "active phase" with a well-measured period of approximately 16.3 days. Targeting the FRB at the peak of its expected active phase and during a recent 30 minute observing window by the Canadian Hydrogen Intensity Mapping Experiment (CHIME), we did not detect any transient optical emission at m_i=24.7~mag (3-sigma) from 2.2 to 1938.1 seconds after the burst arrival time in optical bands (corrected for dispersion). Comparing our limiting magnitudes to models of a synchrotron maser formed in the circumburst environment of FRB 180916+J0158.65, we constrain scenarios where the burst energy was >1e44 erg and the circumburst density was >1e4 cm-3., submitted to ApJL

We explore the prompt magnetar progenitor scenario in the context of fast radio burst (FRB) host galaxies demographics and offset distributions. Magnetars are neutron stars with strong magnetic fields on the order of $10^{15}$ G with a short decay lifetime of less than $10^4$ years. Due to their extremely short lifetimes, magnetars should follow the demographics of galaxies according to their current star-formation rate (SFR). Moreover, we hypothesize that magnetars should follow the SFR profile within galaxies, which we assume to follow an exponential profile. We construct a simple model for the host galaxies of magnetars assuming these events track SFR in all galaxies and compare it to observed properties from a sample of \nsecure\ secure FRB hosts. We find the distribution of observed SFRs is inconsistent with the model at $>95\%$ c.l. The offset distribution is consistent with this scenario; however, this could be due to the limited sample size and the seeing limited estimates for the effective radii of the FRB host galaxies. Despite the recent association of an FRB with a magnetar in the Milky Way, magnetars may not be the only source of FRBs in the universe, yet any other successful model must account for the demographics of the FRB host in SFR and their observed galactocentric offsets., Accepted for publication at ApJ Letters

In the early Universe, most of the cold neutral gas that will later form into individual stars and galaxies is practically invisible to us. These neutral gas reservoirs can, however, be illuminated by bright cosmic lightsources such as gamma-ray bursts (GRBs) and quasars. The aim of this thesis is to use these luminous objects as tools to study the environments of intervening or host galaxy absorption systems through cosmic time. Part I is dedicated to examining the gas, dust and metals in the immediate region surrounding GRBs. Part II presents a search for and the study of cold and molecular gas in high-z GRB host galaxy absorption systems. Part III focuses on using quasars to examine gas-rich intervening galaxies in the line of sight, with specific focus on absorption systems rich in dust and metals. This thesis demonstrates the importance of observing large samples of GRB afterglows to 1) allow for statistical studies of the GRB phenomena itself and the associated host galaxy environments and 2) to obtain spectra of peculiar or unusual GRB afterglows, that is only observed rarely. In addition, it highlights that defining a complete and unbiased sample of quasars is vital to fully exploit the potential of quasars as probes of cosmic chemical evolution. In this version of the thesis only the title, author list and abstract for each published paper, presented as individual chapters, are provided. Principal supervisor: Prof. P\'all Jakobsson., Comment: PhD thesis, October 2019, University of Iceland, 83 pages. Abridged version from original 276 pp

The number of supernovae known to be connected with long-duration gamma-ray bursts (GRBs) is increasing and the link between these events is no longer exclusively found at low redshift (z less than or similar to 0.3) but is well established also at larger distances. We present a new case of such a liaison at z = 0.33 between GRB171010A and SN 2017htp. It is the second closest GRB with an associated supernova of only three events detected by Fermi-LAT. The supernova is one of the few higher redshift cases where spectroscopic observations were possible and shows spectral similarities with the well-studied SN 1998bw, having produced a similar Ni mass (M-Ni = 0.33 +/- 0.02 M-circle dot) with slightly lower ejected mass (M-ej = 4.1 +/- 0.7 M-circle dot) and kinetic energy (E-K = 8.1 +/- 2.5 x 10(51) erg). The host-galaxy is bigger in size than typical GRB host galaxies, but the analysis of the region hosting the GRB revealed spectral properties typically observed in GRB hosts and showed that the progenitor of this event was located in a very bright H II region of its face-on host galaxy, at a projected distance of similar to 10 kpc from its galactic centre. The star-formation rate (SFRGRB similar to 0.2 M-circle dot yr(-1)) and metallicity (12 + log(O/H) similar to 8.15 +/- 0.10) of the GRB star-forming region are consistent with those of the host galaxies of previously studied GRB-SN systems.© 2019 The Author(s).Published by Oxford University Press on behalf of the Royal Astronomical Society, We thank the anonymous referee for the valuable comments that contributed to improving the quality of the publication. AM, PDA, SCa, and GT acknowledge support from ASI grant INAFI/004/11/3. DBM is supported by research grant 19054 from Villum Fonden. This study is partly based on data acquired under the extended Public ESO Spectroscopic Survey for TransientObjects (ePESSTO; http://www.pessto.org, under programme 199.D-0143) and within the Stargate collaboration (under programme 0100.D-0649). The study is based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 199.D-0143. LI and DAK acknowledge the support from the Spanish research project AYA2014-58381-P. LI and DAK acknowledge support from Juan de la Cierva Incorporacion fellowship IJCI-2016-30940 and IJCI-2015-26153, respectively. The study is based on observations collected at the Centro Astronomico Hispano Aleman (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut fur Astronomie and the Instituto de Astrofisica de Andalucia (CSIC). AR acknowledges support from Premiale LBT 2013. The study is based on data collected with Large Binocular Cameras at the LBT. The LBT is an international collaboration among institutions in the United States, Italy, and Germany. The study is based on observations made with the Nordic Optical Telescope (thanks to the valuable support of D. Bettoni) under programme 51-504, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. The study is partially based on observations collected at Copernico Telescope (Asiago, Mt. Ekar, Italy) of the INAF Osservatorio Astronomico di Padova. LT is partially supported by the PRIN-INAF 2017 'Towards the SKA and CTA era: discovery, localization, and physics of transient sources'. MNis supported by a Royal Astronomical Society Research Fellowship. MGis supported by the Polish NCN MAESTRO grant 2014/14/A/ST9/00121. KM acknowledges support from H2020 ERC grant no. 58638. The Cosmic Dawn Center is funded by the DNRF. Support for FOE is provided by the Ministry of Economy, Development, and Tourism's Millennium Science Initiative through grant IC120009, awarded to The Millennium Institute of Astrophysics. FOE acknowledges support from the FONDECYT grant no. 1170953. DX acknowledges the supports by the One-Hundred-Talent Program of the Chinese Academy of Sciences (CAS) and by the Strategic Priority Research Program 'Multi-wavelength Gravitational Wave Universe of the CAS (no. XDB23000000).

Whether stars could have driven the reionization of the intergalactic medium depends critically on the proportion of ionizing radiation that escapes the galaxies in which it is produced. Spectroscopy of gamma-ray burst (GRB) afterglows can be used to estimate the opacity to extreme ultraviolet (EUV) radiation along the lines-of-sight to the bursts. Assuming that long-duration GRBs trace the locations of the massive stars dominating EUV production, the average escape fraction of ionizing radiation can be calculated independently of galaxy size or luminosity. Here we present a compilation of H i column density (N HI ) measures for 140 GRBs in the range 1.6 < z < 6.7. Although the sample is heterogeneous, in terms of spectral resolution and signal-to-noise ratio, fits to the Ly α absorption line provide robust constraints on N HI , even for spectra of insufficient quality for other purposes. Thus we establish an escape fraction at the Lyman limit of (f esc ) ≈ 0.005, with a 98 per cent confidence upper limit of (f esc ) ≈ 0.015. This analysis suggests that stars provide a small contribution to the ionizing radiation budget at z < 5. At higher redshifts firm conclusions are limited by the small size of the GRB sample (7/140), but any decline in average H i column density seems to be modest. We also find no significant correlation of N HI with galaxy UV luminosity or host stellar mass. We discuss in some detail potential biases and argue that, while not negligible, systematic errors in f esc are unlikely to be more than a factor ~2 in either direction, and so would not affect the primary conclusions. Given that many GRB hosts are low-metallicity dwarf galaxies with high specific star-formation rates, these results present a particular problem for the hypothesis that such galaxies dominated the reionization of the Universe. © 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society., JJ acknowledges support from Nederlandse Onderzoekschool Voor Astronomie(NOVA) and The Netherlands Organisation for Scientific Research (NWO) - The Sao Paulo Research Foundation (FAPESP) grant for advanced instrumentation in astronomy. KEH acknowledges support by a Project Grant (162948-051) from The Icelandic Research Fund. DAK acknowledges support from the Spanish research project AYA2014-58381-P and Juan de la Cierva Incorporacion IJCI-2015-26153. AJL and ERS acknowledge Science and Technology Facilities Council (STFC) consolidated grant ST/L000733/1. NRT and KW acknowledge Science and Technology Facilities Council (STFC) consolidated grant ST/N000757/1. AC acknowledges National Aeronautics and Space Administration (NASA) grant NNX15AP95A. AdUP acknowledges support from a Ramon y Cajal fellowship (RyC-2012-09975), a 2016 Banco Bilbao Vizcaya Argentaria (BBVA) Foundation Grant for Researchers and Cultural Creators, and from the Spanish research project AYA 2014-58381-P. RC acknowledges partial support from National Aeronautics and Space Administration (NASA) Swift grant NNX16AB04G.This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No. 725246).

Quasar lines of sight intersect intervening galaxy discs or circum-galactic environments at random impact parameters and potential well depths. Absorption line velocity widths ($\Delta v_{90}$) are known to scale with host galaxy stellar masses, and inversely with the projected separation from the quasar line of sight. Its dependence on stellar mass can be eliminated by normalising with the emission-line widths of the host galaxies, $\sigma_{em}$, so that absorbers with a range of $\Delta v_{90}$ values can be compared directly. Using a sample of DLA systems at 0.2 < z < 3.2 with spectroscopically confirmed host galaxies, we find that the velocity ratio $\Delta v_{90}/\sigma_{em}$ decreases with projected distances from the hosts. We compare the data with expectations of line-of-sight velocity dispersions derived for different dark matter halo mass distributions, and find that models with steeper radial dark matter profiles provide a better fit to the observations, although the scatter remains large. Gas outflows from the galaxies may cause an increased scatter, or scale radii of dark matter halo models may not be representative for the galaxies. We demonstrate by computing virial velocities, that metal-rich DLAs that belong to massive galaxy halos (M$_{halo} \approx 10^{12}$ M$_{\odot}$) mostly remain gravitationally bound to the halos., Comment: 10 pages, submitted for publication in MNRAS. [v1] includes 2.nd set of answers to the referee

The amount of cold, molecular gas in high-redshift galaxies is typically inferred from proxies of molecular hydrogen (H$_2$), such as carbon monoxide (CO) or neutral atomic carbon ([CI]) and molecular gas mass conversion factors. The use of these proxies, however, relies on modeling and observations that have not been directly measured outside the local universe. Here, we use recent samples of high-redshift gamma-ray burst (GRB) and quasar molecular gas absorbers to determine this conversion factor $\alpha_{\rm [CI]}$ from the column density of H$_2$, which gives us the mass per unit column, and the [CI]($J=1$) column density, which provides the luminosity per unit column. This technique allows us to make direct measurements of the relative abundances in high-redshift absorption-selected galaxies. Our sample spans redshifts of z=1.9-3.4 and covers two orders of magnitude in gas-phase metallicity. We find that $\alpha_{\rm [CI]}$ scales linearly with the metallicity: $\log \alpha_{\rm [CI]} = -1.13\times \log(Z/Z_{\odot}) + 1.33$, with a scatter of $\sigma_{\alpha_{\rm [CI]}} = 0.2$ dex. Using a sample of emission-selected galaxies at z~0-5, with both [CI] and CO line detections, we apply the $\alpha_{\rm [CI]}$ conversion to derive independent estimates of the molecular gas mass and $\alpha_{\rm CO}$. We find a remarkable agreement between the molecular gas masses inferred from the absorption-derived $\alpha_{\rm [CI]}$ compared to typical $\alpha_{\rm CO}$-based estimates, and an inferred metallicity evolution of $\alpha_{\rm CO}$ that is consistent with $\alpha_{\rm [CI]}$ and previous estimates from the literature. These results thus support the use of the absorption-derived $\alpha_{\rm [CI]}$ conversion factor for emission-selected star-forming galaxies and demonstrate that both methods probe the same universal properties of molecular gas in the local and high-redshift universe., Comment: 8 pages, 4 figures, 1 table. Abstract abridged. Accepted for publication in ApJL

We present a comprehensive study of the relations between gas kinematics, metallicity, and stellar mass in a sample of 82 GRB-selected galaxies using absorption and emission methods. We find the velocity widths of both emission and absorption profiles to be a proxy of stellar mass. We also investigate the velocity-metallicity correlation and its evolution with redshift and find the correlation derived from emission lines to have a significantly smaller scatter compared to that found using absorption lines. Using 33 GRB hosts with measured stellar mass and metallicitiy, we study the mass-metallicity relation for GRB host galaxies in a stellar mass range of $10^{8.2} M_{\odot}$ to $10^{11.1} M_{\odot}$ and a redshift range of $ z\sim 0.3-3.4$. The GRB-selected galaxies appear to track the mass-metallicity relation of star forming galaxies but with an offset of 0.15 towards lower metallicities. This offset is comparable with the average error-bar on the metallicity measurements of the GRB sample and also the scatter on the MZ relation of the general population. It is hard to decide whether this relatively small offset is due to systematic effects or the intrinsic nature of GRB hosts. We also investigate the possibility of using absorption-line metallicity measurements of GRB hosts to study the mass-metallicity relation at high redshifts. Our analysis shows that the metallicity measurements from absorption methods can significantly differ from emission metallicities and assuming identical measurements from the two methods may result in erroneous conclusions., Accepted for publication in MNRAS

We have mimicked the biofilm formation with highly stable biocompatible poly(2-methyl-2-oxazoline)-based polymersomes by simple spreading-drying of a droplet of the sample solution onto a glass support. The diffusion-limited aggregation process of polymersomes onto the surface was analyzed within a fractal framework. The different examples analyzed and presented together indicate one means by which the aggregation process can be controlled and predicted. The anti-bacterial adhesion properties of poly(2-methyl-2-oxazoline) allow potential uses in surface modification for biofouling prevention improving stability and response time.

The study of self-assembling nano-cones induced by irradiation of nanosecond Nd:YAG laser pulses on a surface of a Si1-xGe(x) solid solution is reported. It is shown that dynamics of nano-cones formation depends on concentration of Ge atoms (x) in Si lattice and on the intensity of laser radiation. Two different processes of nano-cones formation depending on x are observed. The first one-at higher concentration of Ge atoms x = 0.3-0.4 and the second one-at lower concentration of Ge atoms at x = 0.15 take place. At the first stage, similar processes of nano-cones formation occur. It means, at low intensity of laser radiation 1 2.0 MW/cm2 nano-cones formation takes place by Stransky-Krastanov mode. On the same time, at lower concentration of Ge atoms cones look like "tree ring" growth due to melting of Ge separated islands on the irradiated surface at intensity of laser radiation 1 = 20 MW/cm2.

Gamma-ray bursts (GRBs) are powerful probes of early stars and galaxies, during and potentially even before the era of reionization. Although the number of GRBs identified at z 6 remains small, they provide a unique window on typical star-forming galaxies at that time, and thus are complementary to deep field observations. We report the identification of the optical drop-out afterglow of Swift GRB 120923A in near-infrared Gemini-North imaging, and derive a redshift of from Very Large Telescope/X-shooter spectroscopy. At this redshift the peak 15-150 keV luminosity of the burst was 3.2 × 10 erg s, and in this sense it was a rather typical long-duration GRB in terms of rest frame luminosity. This burst was close to the Swift/Burst Alert Telescope detection threshold, and the X-ray and near-infrared afterglow were also faint. We present ground- and space-based follow-up observations spanning from X-ray to radio, and find that a standard external shock model with a constant-density circumburst environment of density n ≈ 4 × 10 cm gives a good fit to the data. The near-infrared light curve exhibits a sharp break at t ≈ 3.4 days in the observer frame which, if interpreted as being due to a jet, corresponds to an opening angle of . The beaming-corrected γ-ray energy is then erg, while the beaming-corrected kinetic energy is lower, erg, suggesting that GRB 120923A was a comparatively low kinetic energy event. We discuss the implications of this event for our understanding of the high-redshift population of GRBs and their identification. © 2018. The American Astronomical Society. All rights reserved., This work is based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO12558. Support for Program number GO12558 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. This work is based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), Chile under programme 089.A-0067, and on observations obtained at the Gemini Observatory (acquired through the Gemini Science Archive and processed using the Gemini IRAF package), which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministerio da Ciencia, Tecnologia e Inovacao (Brazil) and Ministerio de Ciencia, Tecnologia e Innovacion Productiva (Argentina). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Based on data obtained with the VLA under program 12A-394. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The Dark Cosmology Centre was funded by the DNRF. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Program (FP7/2007-2013)/ERC Grant agreement no. EGGS-278202. E.R.S. acknowledges support from UK STFC consolidated grant ST/L000733/1. D.M. thanks the Instrument Center for Danish Astrophysics (IDA) for support. A.d.U.P. acknowledges support from a Ramon y Cajal fellowship. R.S.R. and A.d.U.P. acknowledge support from a 2016 BBVA Foundation Grant for Researchers and Cultural Creators. D.A.K., Z.C., R.S.R., and A.d.U.P. acknowledge support from the Spanish research project AYA 2014-58381-P. D.X. acknowledges the support by the One-Hundred-Talent Program of the Chinese Academy of Sciences (CAS), by the Strategic Priority Research Program Multi-wavelength Gravitational Wave Universe of the CAS (No. XDB23000000), and by the National Natural Science Foundation of China under grant 11533003. T.K. acknowledges support through the Sofja Kovalevskaja Award to Patricia Schady from the Alexander von Humboldt Foundation of Germany. D.A.K. thanks TLS Tautenburg for funding. N.R.T. and K.W. acknowledge support from the UK STFC under consolidated grant ST/N000757/1.

The study is focused on formation and optical properties of nanostructures induced by laser radiation on the surface of Si1-xGe(x)/Si hetero-structures. Formation of self-assembling nanohills induced by irradiation of nanosecond Nd:YAG laser pulses on the Si0.7Ge0.3/Si hetero-epitaxial structures is reported. The atomic force microscope study of the irradiated surface morphology has shown a start of nanohills formation after laser irradiation of the intensity I = 7.0 MW/cm2. The huge "blue shift" of photoluminescence spectra with maximum intensity in region of 700-800 nm (1.76-1.54 eV) is explained by the quantum confinement effect in the nanohills. The maximum of this photoluminescence band slightly shifts to shorter wavelengths with the increase of the intensity of laser pulses used for sample treatment. Appearance of the 300 cm(-1) Ge-Ge vibration band in Raman scattering spectra for sample irradiated with I = 20.0 MW/cm2 is explained by Ge phase formation. Formation of the Ge-rich phase is explained by localization of Ge atoms drifting toward the irradiated surface under the thermal gradient due to strong absorption of laser radiation. Ellipsometric data confirm appearance of Ge-rich phase precipitates amounting to 7.1%, 6.4% of the total Ge content induced by laser radiation of intensities I1 = 20.0 MW/cm2, I2 = 7.0 MW/cm2 respectively.

In this multicenter study, we investigated a possible association between the APOE ε4 allele and white matter (WM) integrity in Alzheimer's disease (AD) using diffusion tensor imaging (DTI).We analyzed fractional anisotropy (FA) and mean diffusivity (MD) as indices of WM integrity in 70 AD patients (35 APOE ε4 carriers, 35 noncarriers) and 56 healthy control (HC) subjects (28 APOE ε4 carriers, 28 noncarriers). APOE ε4 carriers and noncarriers were matched for age and gender within each diagnostic group.We found significant effects of diagnosis (Pcorrected.05 [FWE]; i.e., smaller FA values and larger MD values in AD patients compared with HCs) and significant effects (P.001) of APOE ε4 carrier status on MD in HCs but not in AD subjects.The results indicate that APOE ε4 has a moderate effect on WM integrity in HCs, but no effect on WM integrity in manifest AD.

We present the results of a new spectroscopic survey for dusty intervening absorption systems, particularly damped Ly$\alpha$ absorbers (DLAs), towards reddened quasars. The candidate quasars are selected from mid-infrared photometry from the Wide-field Infrared Survey Explorer combined with optical and near-infrared photometry. Out of 1073 candidates, we secure low-resolution spectra for 108 using the Nordic Optical Telescope on La Palma, Spain. Based on the spectra, we are able to classify 100 of the 108 targets as quasars. A large fraction (50 %) is observed to have broad absorption lines (BALs). Moreover, we find 6 quasars with strange breaks in their spectra, which are not consistent with regular dust reddening. Using template fitting we infer the amount of reddening along each line of sight ranging from A(V)$\approx$0.1 mag to 1.2 mag (assuming an SMC extinction curve). In four cases, the reddening is consistent with dust exhibiting the 2175{\AA} feature caused by an intervening absorber, and for two of these, a MgII absorption system is observed at the best-fit absorption redshift. In the rest of the cases, the reddening is most likely intrinsic to the quasar. We observe no evidence for dusty DLAs in this survey. However, the large fraction of BAL quasars hampers the detection of absorption systems. Out of the 50 non-BAL quasars only 28 have sufficiently high redshift to detect Ly$\alpha$ in absorption., Comment: 45 pages containing a large set of 100 figures and 2 long tables. Accepted for publication in ApJS

The sub-population of quasars reddened by intrinsic or intervening clouds of dust are known to be underrepresented in optical quasar surveys. By defining a complete parent sample of the brightest and spatially unresolved quasars in the COSMOS field, we quantify to which extent this sub-population is fundamental to our understanding of the true population of quasars. By using the available multiwavelength data of various surveys in the COSMOS field, we built a parent sample of 33 quasars brighter than $J=20$ mag, identified by reliable X-ray to radio wavelength selection techniques. Spectroscopic follow-up with the NOT/ALFOSC was carried out for four candidate quasars that had not been targeted previously to obtain a 100\% redshift completeness of the sample. The population of high $A_V$ quasars (HAQs), a specific sub-population of quasars selected from optical/near-infrared photometry, is found to contribute $21\%^{+9}_{-5}$ of the parent sample. The full population of bright spatially unresolved quasars represented by our parent sample consists of $39\%^{+9}_{-8}$ reddened quasars defined by having $A_V>0.1$, and $21\%^{+9}_{-5}$ of the sample having $E(B-V)>0.1$ assuming the extinction curve of the Small Magellanic Cloud. We show that the HAQ selection works well for selecting reddened quasars, but some are missed because their optical spectra are too blue to pass the $g-r$ color cut in the HAQ selection. This is either due to a low degree of dust reddening or anomalous spectra. We find that the fraction of quasars with contributing light from the host galaxy is most dominant at $z \lesssim 1$. At higher redshifts the population of spatially unresolved quasars selected by our parent sample is found to be representative of the full population at $J, 22 pages, 10 figures, accepted for publication in A&A. The ArXiv abstract has been shortened for it to be printable

The increased attention towards the use of calcined clays as supplementary cementitious materials (SCM’s) has prompted several studies of calcined kaolinite (metakaolin) and to a lesser extent also of heat-treated montmorillonite. However, a major part of these studies does not pay specific attention to the calcination process itself. Furthermore, most studies have been performed on phase-pure clays and such clays are not economically viable for applications as SCM’s at an industrial scale. In this work we investigate the reactivity of SCM’s produced by flash calcination of a natural kaolinite sample and a natural mixed smectite/illite sample. Several key properties of the flash calcined materials are tested and compared to calcined clays obtained by a conventional soak-calcination method. The analyses include characterization of physical properties such as BET surface area, specific density and particle fineness and of the microstructure and degree of reaction by powder XRD as well as 29Si and 27Al MAS NMR. Moreover, the pozzolanic reactivity of the SCM’s are investigated by a Chapelle-like test combined with NMR studies of Portland cement—SCM paste samples at different hydration times. Finally, the performance of mortar samples produced with a 35 wt% SCM substitution level is tested with respect to compressive strength and water requirement following the ASTM standard.

To fully exploit the potential of quasars as probes of cosmic chemical evolution and the internal gas dynamics of galaxies it is important to understand the selection effects behind the quasar samples and in particular if the selection criteria exclude foreground galaxies with certain properties (most importantly a high dust content). Here we present spectroscopic follow-up from the 10.4-m GTC telescope of a dust-reddened quasar, eHAQ0111+0641, from the extended High A_V Quasar (HAQ) survey. We find that the z=3.21 quasar has a foreground Damped Lyman-alpha Absorber (DLA) at z=2.027 along the line of sight. The DLA has very strong metal lines due to a moderately high metallicity (with an inferred lower limit of 25% of the solar metallicity), but a very large gas column density along the line-of-sight in its host galaxy. This discovery is further evidence that there is a dust bias affecting the census of metals, caused by the combined effect of dust obscuration and reddening, in existing samples of z>2 DLAs. The case of eHAQ0111+0641 illustrates that dust bias is not only caused by dust obscuration, but also dust reddening., 7 pages, 4 figures. Accepted for publication in A&A. A few typos have been corrected

Since the first discovery of a broad-lined type Ic supernova (SN) with a long-duration gamma-ray burst (GRB) in 1998, fewer than fifty GRB-supernovae (SNe) have been discovered. The intermediate-luminosity Swift GRB 161219B and its associated supernova SN 2016jca, which occurred at a redshift of z = 0.1475, represents only the seventh GRB-SN to have been discovered within 1 Gpc, and hence provides an excellent opportunity to investigate the observational and physical properties of these very elusive and rare type of SN. As such, we present optical to near-infrared photometry and optical spectroscopy of GRB 161219B and SN 2016jca, spanning the first three months since its discovery. GRB 161219B exploded in the disk of an edge-on spiral galaxy at a projected distance of 3.4 kpc from the galactic centre. GRB 161219B itself is an outlier in the E - E plane, while SN 2016jca had a rest-frame, peak absolute V-band magnitude of M = - 19.0 ± 0.1, which it reached after 12.3 ± 0.7 rest-frame days. We find that the bolometric properties of SN 2016jca are inconsistent with being powered solely by a magnetar central engine, and demonstrate that it was likely powered exclusively by energy deposited by the radioactive decay of nickel and cobalt into their daughter products, which were nucleosynthesised when its progenitor underwent core collapse. We find that 0.22 ± 0.08M of nickel is required to reproducethe peak luminosity of SN 2016jca, and we constrain an ejecta mass of 5.8 ± 0.3M and a kinetic energy of 5.1 ± 0.8 × 10 erg. Finally, we report on a chromatic, pre-maximum bump in the g-band light curve, and discuss its possible origin.© ESO, 2017., L.I., C.T., Z.C., A.d.U.P. and D.A.K. acknowledge support from the Spanish research project AYA 2014-58381-P. C.T. and A.d.U.P. furthermore acknowledge support from Ramon y Cajal fellowships RyC-2012-09984 and RyC-2012-09975. D.A.K. and Z.C. acknowledge support from Juan de la Cierva Incorporacion fellowships IJCI-2015-26153 and IJCI-2014-21669. R.S.R. is supported by a 2016 BBVA Foundation Grant for Researchers and Cultural Creators. T.-W. Chen and T. Kruhler acknowledge the support through the Sofia Kovalevskaja Award to P. Schady from the Alexander von Humboldt Foundation of Germany. D.M. acknowledges support from the Instrument center for Danish Astrophysics (IDA).

Biological membranes are often subject to large voltages compared to their small thickness, especially true in nerves where fluxes of ions and corresponding voltage changes are thought to be the main mechanism behind the nerve signal. Yet the effects that these voltages have on the phospholipids that makes up the membrane are largely unknown. Lipids of biological membranes are often charged or swittterionic, high electrical fields should be expected to have a large effect on their organization and thermodynamical properties. Fluorescence microscopy is utilized to image the effects of high voltage fields on the domain structure of a model system consisting of a Langmuir-Blodgett monolayer of phospholipids.

Selection of extragalactic point sources, e.g. QSOs, is often hampered by significant selection effects causing existing samples to have rather complex selection functions. We explore whether a purely astrometric selection of extragalactic point sources, e.g. QSOs, is feasible with the ongoing Gaia mission. Such a selection would be interesting as it would be unbiased in terms of colours of the targets and hence would allow selection also with colours in the stellar sequence. We have analyzed a total of 18 representative regions of the sky by using GUMS, the simulator prepared for ESAs Gaia mission, both in the range of $12\le G \le 20$ mag and $12\le G \le 18$ mag. For each region we determine the density of apparently stationary stellar sources, i.e. sources for which Gaia cannot measure a significant proper motion. The density is contrasted with the density of extragalactic point sources, e.g. QSOs, in order to establish in which celestial directions a pure astrometric selection is feasible. When targeting regions at galactic latitude $|b| \ge 30^\mathrm{o}$ the ratio of QSOs to apparently stationary stars is above 50\% and when observing towards the poles the fraction of QSOs goes up to about $\sim80$\%. We show that the proper motions from the proposed Gaia successor mission in about 20 years would dramatically improve these results at all latitudes. Detection of QSOs solely from zero proper motion, unbiased by any assumptions on spectra, might lead to the discovery of new types of QSOs or new classes of extragalactic point sources., Comment: 4 pages, 4 figures, sent in and accepted for publishing to A&A

In order to gain a deeper understanding of the molecular underpinnings of sperm–egg interaction and early development, we have used two-dimensional (2D) electrophoresis, avidin blotting and tandem mass spectrometry to identify, clone and characterise abundant molecules from the mouse egg proteome. Two-dimensional avidin blots of biotinylated zona-free eggs revealed an abundant approximately 75-kDa surface-labelled heterogeneous protein possessing a staining pattern similar to that of the zona pellucida glycoprotein, mouse ZP3 (mZP3). In light of this observation, we investigated whether mZP3 specifically localises to the plasma membrane of mature eggs. Zona pellucidae of immature mouse oocytes and mature eggs were removed using acid Tyrode’s solution, chymotrypsin or mechanical shearing. Indirect immunofluorescence using the mZP3 monoclonal antibody (mAb) IE-10 demonstrated strong continuous staining over the entire surface of immature oocytes and weak microvillar staining on ovulated eggs, regardless of the method of zona removal. Interestingly, in mature eggs, increased fluorescence intensity was observed following artificial activation and fertilisation, whereas little to no fluorescence was observed in degenerated eggs. The surface localisation of ZP3 on mature eggs was supported by the finding that the IE-10 mAb immunoprecipitated an approximate 75-kDa protein from lysates of biotinylated zona-free eggs. To further investigate the specificity of the localisation of mZP3 to the oolemma, indirect immunofluorescence was performed using the IE-10 mAb on both CV-1 and CHO cells transfected with full-length recombinant mZP3 (re-mZP3). Plasma membrane targeting of the expressed re-mZP3 protein was observed in both cell lines. The membrane association of re-mZP3 was confirmed by the finding that biotinylated re-mZP3 (approximately 75 kDa) is immunoprecipitated from the hydrophobic phase of Triton X-114 extracts of transfected cells following phase partitioning. Immunoprecipitation assays also demonstrated that surface re-mZP3 was released from transfected CV-1 in a time-dependent manner. These results demonstrate that ZP3 is specifically associated with the surface of mature eggs and its subsequent release from the cell surface may represent one mechanism by which ZP3 is secreted. Furthermore, the increase in ZP3 surface expression following fertilisation suggests that ZP3 may have a functional role during sperm–oolemma binding and fusion. These results also validate the usefulness of using the 2D proteomic approach to identify and characterise egg-surface proteins.

High resolution and analytical transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to characterize short-period strained-layer Sim-Gen superlattices ( m monolayers Si, n monolayers Ge, total number of periods N≤ 145, total thickness ≃ 200 nm). The superlattices were grown by low-temperature molecular beam epitaxy (T = 300–400°C) on different SiGe alloy buffer layers on Si (100)substrates. The combination of these two methods shows that detailed informations can be obtained about superlattice periodicity, interface roughness, strain, and average composition.