Neutral gas in Lyman-alpha emitting galaxies Haro 11 and ESO 338-IG04 measured through sodium absorption

Context. The Lyman alpha emission line of galaxies is an important tool for finding galaxies at high redshift, and thus probe the structure of the early universe. However, the resonance nature of the line and its sensitivity to dust and neutral gas is still not fully understood. Aims. We present measurements of the velocity, covering fraction and optical depth of neutral gas in front of two well known local blue compact galaxies that show Lyman alpha in emission: ESO 338-IG 04 and Haro 11. We thus test observationally the hypothesis that Lyman alpha can escape through neutral gas by being Doppler shifted out of resonance. Methods. We present integral field spectroscopy from the GIRAFFE/Argus spectrograph at VLT/FLAMES in Paranal, Chile. The excellent wavelength resolution allows us to accurately measure the velocity of the ionized and neutral gas through the H-alpha emission and Na D absorption, which traces the ionized medium and cold interstellar gas, respectively. We also present independent measurements with the VLT/X-shooter spectrograph which confirm our results. Results. For ESO 338-IG04, we measure no significant shift of neutral gas. The best fit velocity is -15 (16) km/s. For Haro 11, we see an outflow from knot B at 44 (13) km/s and infalling gas towards knot C with 32 (12) km/s. Based on the relative strength of the Na D absorption lines, we estimate low covering fractions of neutral gas (down to 10%) in all three cases. Conclusions. The Na D absorption likely occurs in dense clumps with higher column densities than where the bulk of the Ly-alpha scattering takes place. Still, we find no strong correlation between outflowing neutral gas and a high Lyman alpha escape fraction. The Lyman alpha photons from these two galaxies are therefore likely escaping due to a low column density and/or covering fraction.Comment: 9 pages, 3 figure

I konflikt eller balanse - ulike prediktorer av betydning for lederes partilfredshet

Hovedhensikten med denne studien var å undersøke hvilke psykologiske prosesser som var av betydning for lederes partilfredshet. I en stadig mer krevende hverdag hvor det forventes at ledere skal fylle flere roller, kan stress, krav og frustrasjoner bli en del av hverdagen. Dobbeltrollen mellom arbeid og privatliv kan bli dermed bli en kamp om ressurser og energi, hvor motivasjon for jobben og i parforholdet kan redusere den negative effekten av stress og utbrenthet. Ideen til studien ble basert på teorier og tidligere forskning om intraprosessene selvregulerende evne og motivasjon, av betydning for interpersonlige prosesser. Utvalget besto av 452 ledere fra små og mellomstore bedrifter i Norge hvor data var innhentet spesifikt for denne studien i et selvstendig forskningsprosjekt. Spørreskjemaet besto av tidligere skalaer fra psykologisk forskning, som ble tilpasset denne studien. En skala om selvregulerende evne i forholdet til partner ble utarbeidet spesifikt. Studien ble gjennomført som en survey, hvor data ble analysert i et korrelasjonelt design og gjennom ulike regresjonsanalyser. En empirisk modell dannet grunnlag for plassering av de ulike prediktorer i grupper etter en distal – proksimal tilnærming til fenomenet partilfredshet. Resultatet viste at evnen til global selvregulerende evne ikke påviste partilfredshet direkte, men førte til at ledere ble flinkere til å håndtere en rollekonflikt mellom arbeid og partner som igjen bidro til økt partilfredshet. De proksimale parrelaterte prediktorene, var av størst betydning for partilfredshet, hvor global selvregulerende evne førte til mindre krangling i parforholdet som igjen bidro til økt partilfredshet. Selvbestemmelse i parforhold, bestående av komponentene autonomi, kompetanse og tilhørighet, var den beste prediktoren for lederes partilfredshet. Studiens nytteverdi vil være å forstå lederes intrapersonlige og interpersonlige prosesser av betydning for partilfredshet for å forhindre brutte forhold og skilsmisser

Gravitational lensing reveals ionizing ultraviolet photons escaping from a distant galaxy

During the epoch of reionisation, neutral gas in the early Universe was ionized by hard ultraviolet radiation emitted by young stars in the first galaxies. To do so, ionizing ultraviolet photons must escape from the host galaxy. We present Hubble Space Telescope observations of the gravitationally lensed galaxy PSZ1-ARC G311.6602-18.4624, revealing bright, multiply-imaged ionizing photon escape from a compact star-forming region through a narrow channel in an optically thick gas. The gravitational lensing magnification shows how ionizing photons escape this galaxy, contributing to the re-ionization of the Universe. The multiple sight lines to the source probe absorption by intergalactic neutral hydrogen on scales of no more than a few hundred, perhaps even less than ten, parsec.Comment: 17 pages, 9 figures. Published in Scienc

Interaction between Cape hake spawning and the circulation in the northern Benguela upwelling ecosystem

Cape hake in Namibian waters are demersal and mesopelagic spawners, spawning peaking offshore between 100 and 400 m deep, depending on local environmental conditions. The cross-shelf circulation, low-oxygen layers and mesoscale gyres are three important environmental factors influencing hake spawning behaviour and subsequent transport of the spawning products. Normally, hake spawn offshore near the bottom at depths of 150–400 m. However, during one cruise, spawning was concentrated below several subsurface mesoscale gyres, resulting in reduced dispersion of the eggs and larvae. When the low-oxygen layer above the bottom is pronounced, hake spawning has been observed close to the top of the layer at oxygen concentrations as low as 0.2–0.3 ml l-1. The relatively small size of the eggs and their high specific gravity make them ascend quite slowly from the spawning depths, 10–40 m per day. Consequently, hake eggs spawned deeper than 200 m hatch before they reach the upper mixed layer. The newly hatched larvae are relatively undeveloped, without functional eyes or mouth, and display little swimming activity during their first hours, but laboratory observations have revealed subsequent periods of downward swimming activity. Based on current field observations, on buoyancy measurements of eggs and larvae and on observed larval behaviour, it is concluded that hake eggs and larvae are transported onshore by features of the upwelling subsurface circulation that compensate for offshore movement of surface water. This may be the basic mechanism concentrating early juvenile hake nearshore. Spawning activity near the low-oxygen layer might be a behavioural adaptation to minimize egg predation, because few other species are expected to survive such low concentrations of oxygen.Keywords: buoyancy, eggs, larvae, recruitment processes, retention, vertical distributionAfrican Journal of Marine Science 2001, 23: 317–33