| 1. |
- Brennan, S. J., et al.
(författare)
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Photometric and spectroscopic evolution of the interacting transient AT 2016jbu(Gaia16cfr)
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 513:4, s. 5642-5665
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Tidskriftsartikel (refereegranskat)abstract
- We present the results from a high-cadence, multiwavelength observation campaign of AT 2016jbu (aka Gaia16cfr), an interacting transient. This data set complements the current literature by adding higher cadence as well as extended coverage of the light-curve evolution and late-time spectroscopic evolution. Photometric coverage reveals that AT 2016jbu underwent significant photometric variability followed by two luminous events, the latter of which reached an absolute magnitude of MV ∼ −18.5 mag. This is similar to the transient SN 2009ip whose nature is still debated. Spectra are dominated by narrow emission lines and show a blue continuum during the peak of the second event. AT 2016jbu shows signatures of a complex, non-homogeneous circumstellar material (CSM). We see slowly evolving asymmetric hydrogen line profiles, with velocities of 500 km s−1 seen in narrow emission features from a slow-moving CSM, and up to 10 000 km s−1 seen in broad absorption from some high-velocity material. Late-time spectra (∼+1 yr) show a lack of forbidden emission lines expected from a core-collapse supernova and are dominated by strong emission from H, He I, and Ca II. Strong asymmetric emission features, a bumpy light curve, and continually evolving spectra suggest an inhibit nebular phase. We compare the evolution of H α among SN 2009ip-like transients and find possible evidence for orientation angle effects. The light-curve evolution of AT 2016jbu suggests similar, but not identical, circumstellar environments to other SN 2009ip-like transients.
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| 2. |
- Roy, Rupak, et al.
(författare)
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SN 2012aa : A transient between Type Ibc core-collapse and superluminous supernovae
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 596
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Tidskriftsartikel (refereegranskat)abstract
- Context. Research on supernovae (SNe) over the past decade has confirmed that there is a distinct class of events which are much more luminous (by similar to 2 mag) than canonical core-collapse SNe (CCSNe). These events with visual peak magnitudes less than or similar to-21 are called superluminous SNe (SLSNe). The mechanism that powers the light curves of SLSNe is still not well understood. The proposed scenarios are circumstellar interaction, the emergence of a magnetar after core collapse, or disruption of a massive star through pair production. Aims. There are a few intermediate events which have luminosities between these two classes. They are important for constraining the nature of the progenitors of these two different populations and their environments and powering mechanisms. Here we study one such object, SN 2012aa. Methods. We observed and analysed the evolution of the luminous Type Ic SN 2012aa. The event was discovered by the Lick Observatory Supernova Search in an anonymous galaxy (z approximate to 0.08). The optical photometric and spectroscopic follow-up observations were conducted over a time span of about 120 days. Results. With an absolute V-band peak of similar to-20 mag, the SN is an intermediate-luminosity transient between regular SNe Ibc and SLSNe. SN 2012aa also exhibits an unusual secondary bump after the maximum in its light curve. For SN 2012aa, we interpret this as a manifestation of SN-shock interaction with the circumstellar medium (CSM). If we assume a Ni-56-powered ejecta, the quasi-bolometric light curve requires roughly 1.3 M-circle dot of Ni-56 and an ejected mass of similar to 14 M-circle dot. This also implies a high kinetic energy of the explosion, similar to 5.4 x 10(51) erg. On the other hand, the unusually broad light curve along with the secondary peak indicate the possibility of interaction with CSM. The third alternative is the presence of a central engine releasing spin energy that eventually powers the light curve over a long time. The host of SN 2012aa is a star-forming Sa/Sb/Sbc galaxy. Conclusions. Although the spectral properties of SN 2012aa and its velocity evolution are comparable to those of normal SNe Ibc, its broad light curve along with a large peak luminosity distinguish it from canonical CCSNe, suggesting that the event is an intermediate-luminosity transient between CCSNe and SLSNe at least in terms of peak luminosity. In comparison to other SNe, we argue that SN 2012aa belongs to a subclass where CSM interaction plays a significant role in powering the SN, at least during the initial stages of evolution.
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| 3. |
- Tartaglia, Leonardo, et al.
(författare)
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The long-lived Type IIn SN 2015da : Infrared echoes and strong interaction within an extended massive shell star star star
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 635
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we report the results of the first similar to four years of spectroscopic and photometric monitoring of the Type IIn supernova SN 2015da (also known as PSN J13522411+3941286, or iPTF16tu). The supernova exploded in the nearby spiral galaxy NGC 5337 in a relatively highly extinguished environment. The transient showed prominent narrow Balmer lines in emission at all times and a slow rise to maximum in all bands. In addition, early observations performed by amateur astronomers give a very well-constrained explosion epoch. The observables are consistent with continuous interaction between the supernova ejecta and a dense and extended H-rich circumstellar medium. The presence of such an extended and dense medium is difficult to reconcile with standard stellar evolution models, since the metallicity at the position of SN 2015da seems to be slightly subsolar. Interaction is likely the mechanism powering the light curve, as confirmed by the analysis of the pseudo bolometric light curve, which gives a total radiated energy greater than or similar to 10(51) erg. Modeling the light curve in the context of a supernova shock breakout through a dense circumstellar medium allowed us to infer the mass of the prexisting gas to be similar or equal to 8 M-circle dot, with an extreme mass-loss rate for the progenitor star similar or equal to 0.6 M-circle dot yr(-1), suggesting that most of the circumstellar gas was produced during multiple eruptive events. Near- and mid-infrared observations reveal a fluxexcess in these domains, similar to those observed in SN 2010jl and other interacting transients, likely due to preexisting radiatively heated dust surrounding the supernova. By modeling the infrared excess, we infer a mass greater than or similar to 0.4 x 10(-3) M-circle dot for the dust.
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| 4. |
- Arcavi, Iair, et al.
(författare)
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Energetic eruptions leading to a peculiar hydrogen-rich explosion of a massive star
- 2017
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 551:7679, s. 210-213
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Tidskriftsartikel (refereegranskat)abstract
- Every supernova so far observed has been considered to be the terminal explosion of a star. Moreover, all supernovae with absorption lines in their spectra show those lines decreasing in velocity over time, as the ejecta expand and thin, revealing slower-moving material that was previously hidden. In addition, every supernova that exhibits the absorption lines of hydrogen has one main light-curve peak, or a plateau in luminosity, lasting approximately 100 days before declining(1). Here we report observations of iPTF14hls, an event that has spectra identical to a hydrogen-rich core-collapse supernova, but characteristics that differ extensively from those of known supernovae. The light curve has at least five peaks and remains bright for more than 600 days; the absorption lines show little to no decrease in velocity; and the radius of the line-forming region is more than an order of magnitude bigger than the radius of the photosphere derived from the continuum emission. These characteristics are consistent with a shell of several tens of solar masses ejected by the progenitor star at supernova-level energies a few hundred days before a terminal explosion. Another possible eruption was recorded at the same position in 1954. Multiple energetic pre-supernova eruptions are expected to occur in stars of 95 to 130 solar masses, which experience the pulsational pair instability(2-5). That model, however, does not account for the continued presence of hydrogen, or the energetics observed here. Another mechanism for the violent ejection of mass in massive stars may be required.
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| 5. |
- Halme, P., et al.
(författare)
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Challenges of ecological restoration : Lessons from forests in northern Europe
- 2013
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 167, s. 248-256
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Forskningsöversikt (refereegranskat)abstract
- The alarming rate of ecosystem degradation has raised the need for ecological restoration throughout different biomes and continents. North European forests may appear as one of the least vulnerable ecosystems from a global perspective, since forest cover is not rapidly decreasing and many ecosystem services remain at high level. However, extensive areas of northern forests are heavily exploited and have lost a major part of their biodiversity value. There is a strong requirement to restore these areas towards a more natural condition in order to meet the targets of the Convention on Biological Diversity. Several northern countries are now taking up this challenge by restoring forest biodiversity with increasing intensity. The ecology and biodiversity of boreal forests are relatively well understood making them a good model for restoration activities in many other forest ecosystems. Here we introduce northern forests as an ecosystem, discuss the historical and recent human impact and provide a brief status report on the ecological restoration projects and research already conducted there. Based on this discussion, we argue that before any restoration actions commence, the ecology of the target ecosystem should be established with the need for restoration carefully assessed and the outcome properly monitored. Finally, we identify the most important challenges that need to be solved in order to carry out efficient restoration with powerful and long-term positive impacts on biodiversity: coping with unpredictability, maintaining connectivity in time and space, assessment of functionality, management of conflicting interests and social restrictions and ensuring adequate funding. © 2013 Elsevier Ltd.
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| 6. |
- Lunnan, Ragnhild, et al.
(författare)
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A UV resonance line echo from a shell around a hydrogen-poor superluminous supernova
- 2018
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Ingår i: Nature Astronomy. - : Springer Science and Business Media LLC. - 2397-3366. ; 2:11, s. 887-895
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Tidskriftsartikel (refereegranskat)abstract
- Hydrogen-poor superluminous supernovae (SLSN-I) are a class of rare and energetic explosions that have been discovered in untargeted transient surveys in the past decade(1,2). The progenitor stars and the physical mechanism behind their large radiated energies (about 1O(51) erg or 1O(44) J) are both debated, with one class of models primarily requiring a large rotational energy(3,4) and the other requiring very massive progenitors that either convert kinetic energy into radiation through interaction with circumstellar material (CSM)(5-8 )or engender an explosion caused by pair-instability (loss of photon pressure due to particle-antiparticle production)(9,10). Observing the structure of the CSM around SLSN-I offers a powerful test of some scenarios, although direct observations are scarce(11,)(12). Here, we present a series of spectroscopic observations of the SLSN-I iPTF16eh, which reveal both absorption and time- and frequency-variable emission in the Mg n resonance doublet. We show that these observations are naturally explained as a resonance scattering light echo from a circumstellar shell. Modelling the evolution of the emission, we infer a shell radius of 0.1 pc and velocity of 3,300 km s(-1), implying that the shell was ejected three decades before the supernova explosion. These properties match theoretical predictions of shell ejections occurring because of pulsational pair-instability and imply that the progenitor had a helium core mass of about 50-55 M-circle dot, corresponding to an initial mass of about 115 M-circle dot.
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| 7. |
- Strandberg, G., et al.
(författare)
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Bespoke climate indicators for the Swedish energy sector − a stakeholder focused approach
- 2024
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Ingår i: Climate Services. - Göteborg : IVL Svenska Miljöinstitutet. - 2405-8807. ; 34, s. 100486-100486
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Tidskriftsartikel (refereegranskat)abstract
- Climate change concerns the energy sector to a high degree because the sector is sensitive both to changing conditions for power and heat production, and to changing demand for electricity, heating and cooling. In this study potential consequences of climate change on different parts of the Swedish energy sector were assessed in a series of workshops, where climate and energy scientists, energy systems experts and analysts met with representativesof the energy sector to assess the vulnerability of the sector and consider what climate indicators could be used to assess impacts of relevance. The impact of climate change depends on the energy type. Hydropower, for which production is naturally linked to weather and climate, is significantly impacted by climate change. For other forms of production, such as nuclear power, other factors such as e.g. policy and technology development are more important. The series of workshops held in this study, where different aspects of climate change and consequences were discussed, proved very successful and has increased our understanding of climate impacts on the energy system.
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| 8. |
- Fremling, Christoffer, et al.
(författare)
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PTF12os and iPTF13bvn. Two stripped-envelope supernovae from low-mass progenitors in NGC 5806
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 593
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Tidskriftsartikel (refereegranskat)abstract
- Context. We investigate two stripped-envelope supernovae (SNe) discovered in the nearby galaxy NGC 5806 by the (intermediate) Palomar Transient Factory [(i)PTF]. These SNe, designated PTF12os/SN 2012P and iPTF13bvn, exploded within ~520 days of one another at a similar distance from the host-galaxy center. We classify PTF12os as a Type IIb SN based on our spectral sequence; iPTF13bvn has previously been classified as Type Ib having a likely progenitor with zero age main sequence (ZAMS) mass below ~17 M⊙. Because of the shared and nearby host, we are presented with a unique opportunity to compare these two SNe.Aims. Our main objective is to constrain the explosion parameters of iPTF12os and iPTF13bvn, and to put constraints on the SN progenitors. We also aim to spatially map the metallicity in the host galaxy, and to investigate the presence of hydrogen in early-time spectra of both SNe.Methods. We present comprehensive datasets collected on PTF12os and iPTF13bvn, and introduce a new automatic reference-subtraction photometry pipeline (FPipe) currently in use by the iPTF. We perform a detailed study of the light curves (LCs) and spectral evolution of the SNe. The bolometric LCs are modeled using the hydrodynamical code hyde. We analyze early spectra of both SNe to investigate the presence of hydrogen; for iPTF13bvn we also investigate the regions of the Paschen lines in infrared spectra. We perform spectral line analysis of helium and iron lines to map the ejecta structure of both SNe. We use nebular models and late-time spectroscopy to constrain the ZAMS mass of the progenitors. We also perform image registration of ground-based images of PTF12os to archival HST images of NGC 5806 to identify a potential progenitor candidate.Results. We find that our nebular spectroscopy of iPTF13bvn remains consistent with a low-mass progenitor, likely having a ZAMS mass of ~12M⊙. Our late-time spectroscopy of PTF12os is consistent with a ZAMS mass of ~15M⊙. We successfully identify a source in pre-explosion HST images coincident with PTF12os. The colors and absolute magnitude of this object are consistent between pre-explosion and late-time HST images, implying it is a cluster of massive stars. Our hydrodynamical modeling suggests that the progenitor of PTF12os had a compact He core with a mass of 3.25+ 0.77-0.56M⊙ at the time of the explosion, which had a total kinetic energy of 0.54+ 0.41-0.25 × 1051 erg and synthesized 0.063+ 0.020-0.011M⊙ of strongly mixed 56Ni. Spectral comparisons to the Type IIb SN 2011dh indicate that the progenitor of PTF12os was surrounded by a thin hydrogen envelope with a mass lower than 0.02M⊙. We also find tentative evidence that the progenitor of iPTF13bvn could have been surrounded by a small amount of hydrogen prior to the explosion. This result is supported by possible weak signals of hydrogen in both optical and infrared spectra.
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| 9. |
- Urpelainen, S., et al.
(författare)
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FINEST:A high performance branch-line for VUV photon energy range gas phase studies at MAX-lab
- 2010
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X. - 9780735407824 ; 1234, s. 411-414
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Konferensbidrag (refereegranskat)abstract
- We present a dedicated beamline branch for high flux and ultra-high resolution (R>100000) gas and vapor phase studies in the vacuum-ultra-violet (VUV) region of light on the undulator beamline I3, located on the 700 MeV MAX-III storage ring. The mechanical and optical design of the branch-line, the differential pumping setup as well as performance characteristics are presented.
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| 10. |
- Appelgren, Patrik, et al.
(författare)
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Modelling of a small helical magnetic flux compression generator
- 2007
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Ingår i: PPPS-2007 - Pulsed Power Plasma Science 2007. - 1424409144 - 9781424409143 ; , s. 1155-1158
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Konferensbidrag (refereegranskat)abstract
- Helical flux-compression generators convert the chemical energy bond in explosives into electric energy. This paper briefly presents a model of, implemented in Matlab-Simulink, and simulation results for such a device. The simulation results are compared to experimental data from two experiments with identical generators but with different seed currents, influencing the resistive losses and thus the current amplification. The model is used to analyse the performance of the generator.
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| 11. |
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| 12. |
- Madar Johansson, Miralda, et al.
(författare)
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The binding mechanism of the virulence factor Streptococcus suis adhesin P subtype to globotetraosylceramide is associated with systemic disease
- 2020
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 295:42, s. 14305-14324
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus suis is part of the pig commensal microbiome but strains can also be pathogenic, causing pneumonia and meningitis in pigs as well as zoonotic meningitis. According to genomic analysis, S. suis is divided into asymptomatic carriage, respiratory and systemic strains with distinct genomic signatures. Because the strategies to target pathogenic S. suis are limited, new therapeutic approaches are needed. The virulence factor S. suis adhesin P (SadP) recognizes the galabiose Gal alpha 1-4Gal-oligosaccharide. Based on its oligosaccharide fine specificity, SadP can be divided into subtypes P-N and P-O. We show here that subtype P-N is distributed in the systemic strains causing meningitis, whereas type P-O is found in asymptomatic carriage and respiratory strains. Both types of SadP are shown to predominantly bind to pig lung globotriaosylceramide (Gb3). However, SadP adhesin from systemic subtype P-N strains also binds to globotetraosylceramide (Gb4). Mutagenesis studies of the galabiose-binding domain of type P-N SadP adhesin showed that the amino acid asparagine 285, which is replaced by an aspartate residue in type P-O SadP, was required for binding to Gb4 and, strikingly, was also required for interaction with the glycomimetic inhibitor phenylurea-galabiose. Molecular dynamics simulations provided insight into the role of Asn-285 for Gb4 and phenylurea-galabiose binding, suggesting additional hydrogen bonding to terminal GalNAc of Gb4 and the urea group. Thus, the Asn-285-mediated molecular mechanism of type P-N SadP binding to Gb4 could be used to selectively target S. suis in systemic disease without interfering with commensal strains, opening up new avenues for interventional strategies against this pathogen.
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| 13. |
- Marrinan, Sarah L, et al.
(författare)
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A randomized, double-blind, placebo-controlled trial of camicinal in Parkinson's disease.
- 2018
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Ingår i: Movement Disorders. - : Wiley. - 0885-3185 .- 1531-8257. ; 33:2, s. 329-332
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Delayed gastric emptying may impair l-dopa absorption, contributing to motor fluctuations. We evaluated the effect of camicinal (GSK962040), a gastroprokinetic, on the absorption of l-dopa and symptoms of PD.METHODS: Phase II, double-blind, placebo-controlled trial. Participants were randomized to receive camicinal 50 mg once-daily (n = 38) or placebo (n = 20) for 7 to 9 days.RESULTS: l-dopa exposure was similar with coadministration of camicinal compared to placebo. Median time to maximum l-dopa concentration was reduced, indicating more rapid absorption of l-dopa. Camicinal resulted in significant reduction in OFF time (-2.31 hours; 95% confidence interval: -3.71, -0.90), significant increase in ON time (+1.88 hours; 95% confidence interval: 0.28, 3.48) per day, and significant decrease in mean total MDS-UPDRS score (-12.5; 95% confidence interval: -19.67, -5.29). Camicinal treatment was generally well tolerated.CONCLUSIONS: PD symptom improvement with camicinal occurred in parallel with more rapid absorption of l-dopa. This study provides evidence of an improvement of the motor response to l-dopa in people with PD treated with camicinal 50 mg once-daily compared with placebo, which will require further evaluation.
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| 14. |
- Nyholm, Tufve, et al.
(författare)
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MR and CT data with multiobserver delineations of organs in the pelvic areaPart of the Gold Atlas project
- 2018
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Ingår i: Med Phys. - : Wiley. - 0094-2405 .- 2473-4209. ; 45:3, s. 1295-1300
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Tidskriftsartikel (refereegranskat)abstract
- PurposeWe describe a public dataset with MR and CT images of patients performed in the same position with both multiobserver and expert consensus delineations of relevant organs in the male pelvic region. The purpose was to provide means for training and validation of segmentation algorithms and methods to convert MR to CT like data, i.e., so called synthetic CT (sCT). Acquisition and validation methodsT1- and T2-weighted MR images as well as CT data were collected for 19 patients at three different departments. Five experts delineated nine organs for each patient based on the T2-weighted MR images. An automatic method was used to fuse the delineations. Starting from each fused delineation, a consensus delineation was agreed upon by the five experts for each organ and patient. Segmentation overlap between user delineations with respect to the consensus delineations was measured to describe the spread of the collected data. Finally, an open-source software was used to create deformation vector fields describing the relation between MR and CT images to further increase the usability of the dataset. Data format and usage notesThe dataset has been made publically available to be used for academic purposes, and can be accessed from . Potential applicationsThe dataset provides a useful source for training and validation of segmentation algorithms as well as methods to convert MR to CT-like data (sCT). To give some examples: The T2-weighted MR images with their consensus delineations can directly be used as a template in an existing atlas-based segmentation engine; the expert delineations are useful to validate the performance of a segmentation algorithm as they provide a way to measure variability among users which can be compared with the result of an automatic segmentation; and the pairwise deformably registered MR and CT images can be a source for an atlas-based sCT algorithm or for validation of sCT algorithm. (c) 2018 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.
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| 15. |
- Pärna, R., et al.
(författare)
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FinEstBeaMS – A wide-range Finnish-Estonian Beamline for Materials Science at the 1.5 GeV storage ring at the MAX IV Laboratory
- 2017
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 859, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- The FinEstBeaMS beamline is under construction at the 1.5 GeV storage ring of the MAX IV Laboratory at Lund, Sweden. It has been designed to cover an unusually wide energy range from ultraviolet (4.3 eV) to soft X-rays (1000 eV) but experiments will also be possible at the Mg and Al Kα energies. Instead of having two different insertion devices and optical schemes for low and high photon energy regions, we have based our design on a single long-period, elliptically polarizing undulator and a plane grating monochromator. This solution will provide very good conditions for planned experiments in the whole photon energy region. The beamline will have two branches: one will mainly be used to investigate free atoms, molecules and clusters with photoelectron/photoion coincidence spectroscopy as well as solids with photoluminescence spectroscopy whereas the other one will be dedicated to ultra-high vacuum studies of surfaces and interfaces, utilizing X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. This paper focuses on the optical design of the beamline and general design concepts of the gas phase and solid state end stations.
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| 16. |
- Qvarford, M., et al.
(författare)
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Polarisation-dependent X-ray absorption in high- and low-Tc Bi2Sr2Can-1CunO4+2n superconductors
- 1993
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Ingår i: Physica C: Superconductivity and its Applications. - : Elsevier BV. - 0921-4534. ; 214:1-2, s. 119-126
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Tidskriftsartikel (refereegranskat)abstract
- Taking advantage of the linear polarisation of synchrotron radiation, the polarisation dependence of the O K and Cu L3 X-ray absorption edges has been compared for in situ cleaved Bi2Sr2CaCu2O8 and Bi2Sr2CuO6 single crystals. The X-ray absorption spectra were measured by means of total electron yield detection. The spectra show for both crystals that the lowest unoccupied Cu 3d and O 2p orbitals are dominantly oriented parallel to the a-b plane, but also the presence of a small amount of unoccupied orbitals oriented perpendicular to the a-b plane can be deduced from both the O K and Cu L3 absorption spectra. A shift of the order of 0.5 eV between absorption into the in-plane and the out-of-plane Cu 3d orbitals was measured for the Bi2Sr2CaCu2O8 crystal, but no such shift was found for the Bi2Sr2CuO6 crystal.
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| 17. |
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| 18. |
- Soderholm, S, et al.
(författare)
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A photoelectron spectroscopy and x-ray absorption study of Bi2Sr2CaCu2O8 single crystal with adsorbed Cs : On the origin of the states affected by electron doping and evidence for spatially resolved electron doping
- 1996
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 8:9, s. 1307-1320
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Tidskriftsartikel (refereegranskat)abstract
- The influence of electron doping, via deposition of small amounts of Cs, on the electronic structure of Bi2Sr2CaCu2O8 has been studied by high-resolution photoelectron spectroscopy (PES) and x-ray absorption spectroscopy (XAS), utilizing synchrotron radiation. The changes in the electronic structure were monitored by PES of the valence band and of the O Is, Bi 4f, Bi 5d, Ca 2p and Sr 3d core levels, and by XAS at the O Is, Cu 2p and Ca 2p edges. The experimental data suggest that the loss of the Fermi edge and the loss of spectral intensity down to about 2 eV below the Fermi level, and the substantial loss of spectral intensity of the pre-edge structure in the O 1s XAS spectrum are mainly due to annihilation of states with O 2p character in the Cu-O layer. It is evident from bulk- and surface-sensitive XAS spectra that the electron doping by Cs affects the electronic structure more strongly close to the surface. This implies that the doping occurs locally and that the charge transfer between the different layers in the unit cell is not uniform. Thus it seems possible to alter the electronic properties of Bi2Sr2CaCu2O8 locally through spatially resolved electron doping. When larger amounts of Cs are deposited, a chemical reaction occurs which causes a disruption of the Bi-O layer. This deposition regime is characterized by the presence of caesium oxide and reduced (metallic) Bi.
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| 19. |
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| 20. |
- Taddia, Francesco, et al.
(författare)
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Analysis of broad-lined Type Ic supernovae from the (intermediate) Palomar Transient Factory
- 2019
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 621
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Tidskriftsartikel (refereegranskat)abstract
- We study 34 Type Ic supernovae that have broad spectral features (SNe Ic-BL). This is the only SN type found in association with long-duration gamma-ray bursts (GRBs). We obtained our photometric data with the Palomar Transient Factory (PTF) and its continuation, the intermediate PTF (iPTF). This is the first large, homogeneous sample of SNe Ic-BL from an untargeted survey. Furthermore, given the high observational cadence of iPTF, most of these SNe Ic-BL were discovered soon after explosion. We present K-corrected Bgriz light curves of these SNe, obtained through photometry on template-subtracted images. We analyzed the shape of the r-band light curves, finding a correlation between the decline parameter Delta m(15) and the rise parameter Delta m-(10 ). We studied the SN colors and, based on g - r, we estimated the host-galaxy extinction for each event. Peak r-band absolute magnitudes have an average of -18.6 +/- 0.5 mag. We fit each r-band light curve with that of SN 1998bw (scaled and stretched) to derive the explosion epochs. We computed the bolometric light curves using bolometric corrections, r-band data, and g - r colors. Expansion velocities from Fen were obtained by fitting spectral templates of SNe Ic. Bolometric light curves and velocities at peak were fitted using the semianalytic Arnett model to estimate ejecta mass M-ej , explosion energy E-K and Ni-56 mass M( Ni-56) for each SN. We find average values of M-ej = 4 +/- 3 M-circle dot, E-K = (7 +/- 6) x 10(51) erg, and M( Ni-56) = 0.31 +/- 0.16 M-circle dot . The parameter distributions were compared to those presented in the literature and are overall in agreement with them. We also estimated the degree of Ni-56 mixing using scaling relations derived from hydrodynamical models and we find that all the SNe are strongly mixed. The derived explosion parameters imply that at least 21% of the progenitors of SNe Ic-BL are compatible with massive (>28 M-circle dot), possibly single stars, whereas at least 64% might come from less massive stars in close binary systems.
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| 21. |
- Taddia, Francesco, et al.
(författare)
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The Carnegie Supernova Project II : The shock wave revealed through the fog : The strongly interacting Type IIn SN 2013L
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 638
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Tidskriftsartikel (refereegranskat)abstract
- We present ultra-violet (UV) to mid-infrared (MIR) observations of the long-lasting Type IIn supernova (SN) 2013L obtained by the Carnegie Supernova Project II beginning two days after discovery and extending until +887 days (d). The SN reached a peak r-band absolute magnitude of approximate to -19 mag and an even brighter UV peak, and its light curve evolution resembles that of SN 1988Z. The spectra of SN 2013L are dominated by hydrogen emission features, characterized by three components attributed to different emission regions. A unique feature of this Type IIn SN is that, apart from the first epochs, the blue shifted line profile is dominated by the macroscopic velocity of the expanding shock wave of the SN. We are therefore able to trace the evolution of the shock velocity in the dense and partially opaque circumstellar medium (CSM), from similar to 4800 km s(-1) at +48 d, decreasing as t(-0.23) to similar to 2700 km s(-1) after a year. We performed spectral modeling of both the broad- and intermediate-velocity components of the H alpha line profile. The high-velocity component is consistent with emission from a radially thin, spherical shell located behind the expanding shock with emission wings broadened by electron scattering. We propose that the intermediate component originates from preionized gas from the unshocked dense CSM with the same velocity as the narrow component, similar to 100 km s(-1), but also that it is broadened by electron scattering. These features provide direct information about the shock structure, which is consistent with model calculations. The spectra exhibit broad OI and [OI] lines that emerge at greater than or similar to +144 d and broad CaII features. The spectral continua and the spectral energy distributions (SEDs) of SN 2013L after +132 d are well reproduced by a two-component black-body (BB) model; one component represents emitting material with a temperature between 5 x 10(3) and 1.5 x 10(4) K (hot component) and the second component is characterized by a temperature around 1-1.5 x 10(3) K (warm component). The warm component dominates the emission at very late epochs (greater than or similar to +400 d), as is evident from both the last near infrared (NIR) spectrum and MIR observations obtained with the Spitzer Space Telescope. Using the BB fit to the SEDs, we constructed a bolometric light curve that was modeled together with the unshocked CSM velocity and the shock velocity derived from the H alpha line modeling. The circumstellar-interaction model of the bolometric light curve reveals a mass-loss rate history with large values (1.7x10(-2)-0.15 M-circle dot yr(-1)) over the similar to 25-40 years before explosion, depending on the radiative efficiency and anisotropies in the CSM. The drop in the light curve at similar to 350 days and the presence of electron scattering wings at late epochs indicate an anisotropic CSM. The mass-loss rate values and the unshocked-CSM velocity are consistent with the characteristics of a massive star, such as a luminous blue variable (LBV) undergoing strong eruptions, similar to eta Carinae. Our analysis also suggests a scenario where pre-existing dust grains have a distribution that is characterized by a small covering factor.
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| 22. |
- Thiagarajan, Balasubramanian, et al.
(författare)
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The Normal Incidence Monochromator Beamline I3 on MAX III
- 2010
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Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. ; 1234, s. 661-664
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Konferensbidrag (refereegranskat)abstract
- On the 700 MeV MAX III ring at MAX-lab, a 6.65 m off-axis eagle type monochromator beamline has recently been commissioned. The beamline is sourced by an apple type variable polarization undulator. The energy range of the beamline is 4.6-50 eV and the resolving power achieved is more than 100,000. There are two branch lines, one for angle and spin resolved photoemission studies from solids and the other for gas phase and luminescence experiments. We present the design and performance of the beamline.
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| 23. |
- Appelgren, Patrik, et al.
(författare)
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Small helical magnetic flux compression generators : Experiments and analysis
- 2007
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Ingår i: PPPS-2007 - Pulsed Power Plasma Science 2007. - : IEEE. - 1424409144 - 9781424409143 ; , s. 1151-1154
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Konferensbidrag (refereegranskat)abstract
- This paper presents experimental results with helical magnetic flux-compression generators (FCGs). FCGs convert the chemical energy bond in explosives into electric energy. The generator had an initial inductance of 23 μH and was operated into a load of 0.2 μH. The generator is charged with 0.27 kg of high-explosives (PBXN-5). Various types of diagnostics were used to monitor the operation of the generator, including current probes, optical fibres, and piezo gauges. The results are analysed and the expansion of the armature compared with hydrodynamic simulations.
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| 24. |
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| 25. |
- Berg, C., et al.
(författare)
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Observation of a low-binding-energy peak in the 2p core-level photoemission from oxidized Al(111)
- 1993
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Ingår i: Physical Review B (Condensed Matter). - 0163-1829. ; 47:19, s. 13063-13066
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution photoemission studies of oxidation of the Al(111) surface have been performed. The appearance of a component at lower binding energy than the metallic bulk Al emission in the Al 2p spectrum at oxygen exposures above ∼50 langmuir (1 L = 10-6 Torr s) is argued to be due to Al atoms which do not bond directly to oxygen atoms at the oxide-metal interface. Low-energy electron diffraction initially shows a 1×1 structure, which subsequently fades away at higher oxygen exposures, 400 L.
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| 26. |
- Denecke, R., et al.
(författare)
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Beamline 1511 at MAX II, capabilities and performance
- 1999
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 101-103, s. 971-977
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Tidskriftsartikel (refereegranskat)abstract
- The new undulator beamline 1511 at MAX-lab, now under commissioning, has been optimized for X-ray emission and photoelectron spectroscopies. Using an SX-700 high flux monochromator the accessible photon energy range is from 90 eV to about 1500 eV. The performance of the undulator agrees very well with the specifications, as shown by measurements using a photodiode. The energy resolution of the monochromator has been checked using absorption measurements in a gas cell. It was found to meet the expectations and exceeds a resolving power of 10 000 at 244 eV. The photon flux as a function of energy has been recorded as well and gives a maximum flux of 3×1013 photons/s/100 mA/0.1% BW. Beamlines 1511 and 1411 will be the first synchrotron beamlines making use of a so-called beam waist phenomenon, known from laser physics. We show results of ray-tracing calculations to determine the ultimate spot size on the sample location. The endstations to be used at this new beamline and their capabilities will be discussed as an example of the future use of this facility.
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| 27. |
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| 28. |
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| 29. |
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| 30. |
- Lindblom, A., et al.
(författare)
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First Trials with a 45 GW Cable-Based Pulsed-Power Generator
- 2009
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Ingår i: Acta Physica Polonica. A. - 0587-4246 .- 1898-794X. ; 115:6, s. 976-977
-
Tidskriftsartikel (refereegranskat)abstract
- The output from narrow-band high-power microwave (HPM) sources, such as the virtual cathode oscillator (vircator) and the magnetically insulated line oscillator (MILO), is strongly dependent on the voltage pulse feed. A rectangular, flat-top voltage pulse can be achieved by the use of a transmission line as a pulse-forming unit. The development in high-voltage cable technology has made them useful as parts of high-voltage and high-power generator systems. The generator is designed to deliver a 200 ns voltage pulse of 500 kV into a 10 Omega unmatched load with an electric power of 25 GW. The generator has an impedance of 2 Q. The primary energy storage of the generator consists of a 50 kV, 20 U capacitor bank. The 50 kV is discharged into a transformer that charges a pulse-forming line to 550 kV. When charged, the pulse-forming line is discharged into the load via a spark gap. This paper presents results from initial testing of the generator.
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| 31. |
- Lindblom, Adam, et al.
(författare)
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High-voltage pulsed-power cable generator
- 2009
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Ingår i: IEEE Transactions on Plasma Science. - USA : IEEE. - 0093-3813 .- 1939-9375. ; 37:1, s. 236-242
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Tidskriftsartikel (refereegranskat)abstract
- A cable-based 25-GW pulsed-power generator with output impedance of 2 is presented. It is designed to deliver a 200-ns-long 500-kV pulse into a 10 load. The primary energy storage of the generator consists of a 50-kV 20-kJ capacitor bank. The 50-kV capacitor bank is discharged into a 1 : 12 transformer. The transformer is designed to charge a pulse-forming line (PFL) to 600 kV. When charged, the PFL is discharged into a load via a spark gap. The spark gap is located in a coaxial system containing deionized water together with the cable endings of the PFL and transformer. The electric field at the cable endings is refractively graded by the high permittivity of the surrounding water. The primary and secondary windings consist of high-voltage cables that are interleaved and wound together. The PFL consists of eight 40-m-long 110-kV coaxial cables with both ends connected to the load. Each cable screen is grounded in the middle and connected in parallel. The cables have a characteristic impedance of 30 . The parallel cable setup gives the PFL an impedance of 2 . The total length, height, and width of the pulse generator are 4, 2, and 1.2 m, respectively.
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| 32. |
- Lundgren, E., et al.
(författare)
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Unified behavior of alkali core-level binding-energy shifts induced by sp metals
- 1997
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Ingår i: Physical Review B (Condensed Matter). - 0163-1829. ; 56:19, s. 12560-12565
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Tidskriftsartikel (refereegranskat)abstract
- Thin overlayers of Na, K. Rb, and Cs on different sp-metal substrates have been investigated using photo-electron spectroscopy. The alkali core levels show clearly resolved binding-energy shifts between the surface layer, the intermediate layer(s), and the interface layer. The magnitude of these shifts depends on sp metal and on alkali metal. The layer-resolved core-level binding-energy shifts are well reproduced by models based on a thermodynamical description. For three-layer alkali films the core-level binding energy of the intermediate layer is found to exhibit a small but significant shift between different sp-metal substrates. A simple relationship between the core-level binding-energy shift for the interface layer and the difference in rs value between the sp substrate and the adsorbate is shown to exist.
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| 33. |
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| 34. |
- Nordgren, J., et al.
(författare)
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Soft x-ray emission spectroscopy using monochromatized synchrotron radiation (invited)
- 1989
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 60:7, s. 1690-1696
-
Tidskriftsartikel (refereegranskat)abstract
- Soft x-ray emission spectroscopy is a common tool for the study of the electronic structure of molecules and solids. However, the interpretation of spectra is sometimes made difficult by overlaying lines due to satellite transitions or close-lying core holes. Also, irrelevant inner core transitions may accidentally fall in the wavelength region under study. These problems, which often arise for spectra excited with electrons or broadband photon sources can be removed by using monochromatized synchrotron radiation. In addition, one achieves other advantages as well, such as the ability to study resonant behavior. Another important aspect is the softness of this excitation agent, which allows chemically fragile compounds to be investigated. In this work we demonstrate the feasibility of using monochromatized synchrotron radiation to excite soft x-ray spectra. We also show new results which have been accomplished as a result of the selectivity of the excitation. The work has been carried out using the Flipper I wiggler beamline at HASYLAB in Hamburg using a new grazing incidence instrument designed specifically for this experiment. The photon flux at the Flipper I station (typically 5×1012 photons per second on the sample with a 1% bandpass) is enough to allow soft x-ray fluorescence spectra to be recorded at relatively high resolution and within reasonable accumulation times (typically, the spectra presented in this work were recorded in 30 min). The spectrometer is based on a new concept which allows the instrument to be quite small, still covering a large wavelength range (10-250 Å). The basic idea involves the use of several fixed mounted gratings and a large two-dimensional detector. The grating arrangement provides simple mounting within a limited space and, in particular, large spectral range. The detector can be moved in a three-axis coordinate system in order to cover the different Rowland curves defined by the different gratings. The arrangement permits the use of gratings with different radii, which further facilitate the achievement of optimum performance over a large range. Two-dimensional detection is used to allow a large solid angle, without suffering from loss of resolution due to imaging errors. The detector is based on five 2-in. MCPs with resistive anode read out. The sensitivity of the detector, which is normally very low for soft x rays, especially at grazing angles, is enhanced by CsI coating and by using an entrance electrode.
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| 35. |
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| 36. |
- Nyholm, Tufve, et al.
(författare)
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A national approach for automated collection of standardized and population-based radiation therapy data in Sweden
- 2016
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Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 0167-8140 .- 1879-0887. ; 119:2, s. 344-350
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To develop an infrastructure for structured and automated collection of interoperable radiation therapy (RT) data into a national clinical quality registry. Materials and methods: The present study was initiated in 2012 with the participation of seven of the 15 hospital departments delivering RT in Sweden. A national RT nomenclature and a database for structured unified storage of RT data at each site (Medical Information Quality Archive, MIQA) have been developed. Aggregated data from the MIQA databases are sent to a national RT registry located on the same IT platform (INCA) as the national clinical cancer registries. Results: The suggested naming convention has to date been integrated into the clinical workflow at 12 of 15 sites, and MIQA is installed at six of these. Involvement of the remaining 3/15 RT departments is ongoing, and they are expected to be part of the infrastructure by 2016. RT data collection from ARIA (R), Mosaiq (R), Eclipse (TM), and Oncentra (R) is supported. Manual curation of RT-structure information is needed for approximately 10% of target volumes, but rarely for normal tissue structures, demonstrating a good compliance to the RT nomenclature. Aggregated dose/volume descriptors are calculated based on the information in MIQA and sent to INCA using a dedicated service (MIQA2INCA). Correct linkage of data for each patient to the clinical cancer registries on the INCA platform is assured by the unique Swedish personal identity number. Conclusions: An infrastructure for structured and automated prospective collection of syntactically inter operable RT data into a national clinical quality registry for RT data is under implementation. Future developments include adapting MIQA to other treatment modalities (e.g. proton therapy and brachytherapy) and finding strategies to harmonize structure delineations. How the RT registry should comply with domain-specific ontologies such as the Radiation Oncology Ontology (ROO) is under discussion.
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| 37. |
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| 38. |
- Pålhagen, S. E., et al.
(författare)
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Interim analysis of long-term intraduodenal levodopa infusion in advanced Parkinson disease
- 2012
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Ingår i: Acta Neurologica Scandinavica. - : John Wiley & Sons. - 0001-6314 .- 1600-0404. ; 126:6, s. e29-e33
-
Tidskriftsartikel (refereegranskat)abstract
- Background - This interim 12-month analysis is a part of an open-label, observational, prospective study on health outcomes and cost impact of levodopa/carbidopa intestinal gel (LCIG, Duodopa) in Parkinson disease (PD). The specific aim was to investigate clinical and health-related quality of life (HRQoL) effects in routine care. Methods - Unified PD rating scale (UPDRS) was the primary efficacy measurement. PD QoL questionnaire 39 (PDQ-39) assessed HRQoL. Subjects were assessed at baseline, andgt;= 3 months after surgery, and then every 3 months. Results - Twenty-seven treatment-naive subjects when started with LCIG showed a decrease in UPDRS score that was statistically significant throughout the year: UPDRS total score (mean +/- SD), baseline = 52.1 +/- 16.1, N = 27, month 0 (first visit; at least 3 months after permanent LCIG) = 43.1 +/- 16.7, N = 27, P = 0.003; month 12 = 42.5 +/- 22.6, n = 25, P = 0.017. PDQ-39 results also showed a tendency for improvement: PDQ-39 (mean +/- SD), baseline = 33.6 +/- 10.8, N = 27, month 0 = 27.1 +/- 11.8, N = 27, P = 0.001; 12 months = 28.8 +/- 12.8, n = 23, P = 0.126. Conclusions - LCIG provides functional improvement beginning at first visit that is sustained for 12 months.
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| 39. |
- Pålhagen, Sven E., et al.
(författare)
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Levodopa-carbidopa intestinal gel (LCIG) treatment in routine care of patients with advanced Parkinsons disease: An open-label prospective observational study of effectiveness, tolerability and healthcare costs
- 2016
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Ingår i: Parkinsonism & Related Disorders. - : ELSEVIER SCI LTD. - 1353-8020 .- 1873-5126. ; 29, s. 17-23
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Continuous infusion of levodopa-carbidopa intestinal gel (LCIG) can effectively manage motor and non-motor complications in advanced Parkinsons disease (PD). Healthcare costs, quality of life (QoL), effectiveness, and tolerability were assessed in routine care treatment with LCIG. Methods: The seventy-seven patients enrolled in this prospective, open-label, 3-year study in routine medical care were LCIG-naive (N = 37), or had previous LCIG treatment for amp;lt;2 (N = 22), or amp;gt;= 2 (N = 18) years. Healthcare costs were collected monthly. PD symptoms and QoL were assessed with the Unified Parkinsons Disease Rating Scale (UPDRS), 39-item Parkinsons Disease Questionnaire (PDQ-39), and EuroQoL 5-Dimension Visual Analog Scale (EQ-5D VAS); LCIG dose, safety, and tolerability were monitored. Results: Mean monthly costs per patient ( 8226 5952) were similar across cohorts, remained steady during 3-year follow-up, and increased with PD severity and QoL impairment. In LCIG-naive patients, significant improvements compared to baseline were observed on the UPDRS total score and PDQ-39 summary index score through 18 months (n = 24; UPDRS, p = 0.033; PDQ-39, p = 0.049). Symptom control was maintained during 3-year follow-up in LCIG-experienced cohorts. Small changes in mean daily LCIG dose were observed. Adverse events were common and generally related to the device, procedure, levodopa, or laboratory evaluations. Conclusions: Costs in LCIG-treated patients were stable over 3 years. LCIG treatment led to significant improvements in motor function and QoL over 18 months in LCIG-naive patients and no worsening was observed in LCIG-experienced patients over 3 years despite natural PD progression over time. The longterm safety was consistent with the established LCIG profile. (C) 2016 AbbVie Inc. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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| 40. |
- QVARFORD, M, et al.
(författare)
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X-RAY-ABSORPTION AND RESONANT-PHOTOEMISSION STUDY OF CA IN THE HIGH-TEMPERATURE SUPERCONDUCTOR BI2SR2CACU2O8
- 1992
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 46:21, s. 14126-14133
-
Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of Ca in the high-temperature superconductor Bi2Sr2CaCu2O8 has been studied by x-ray-absorption spectroscopy and resonant-photoemission at the Ca L2,3 absorption edge. In the x-ray-absorption spectrum no edge structure is seen at the energy corresponding to the Ca 2p3/2 core-level binding energy, in agreement with the very low Ca density of states at the Fermi level predicted by band-structure calculations. Furthermore, the crystal-field splitting of the Ca 3d level, which is characteristic of ionic Ca compounds, is clearly observed in the x-ray-absorption spectrum. The photoemission spectra display strong resonant enhancements of the Ca 3s and 3p core levels as well as strong changes in the intensity and the line shape of the Ca L2,3M2,3M2,3 Auger structure at the Ca L2,3 threshold, showing the localized nature of the 3d states in core ionized Ca. The 3d induced spectator shift of the Ca L2,3M2,3M2,3 complex is fairly small as compared to what has been reported for CaF2, indicating that the screening of the normal Auger final state by the charge carriers in the surrounding Cu-O2 layers is quite efficient. From the Ca L2,3M2,3M2,3 data it is also suggested that, at the Ca L2 threshold, the excited 3d electron participates in a Coster-Kronig-type decay resulting in a 2p3/2 core hole followed by a normal L3M2,3M2,3 Auger decay.
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| 41. |
- Rubensson, J. E., et al.
(författare)
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Resonant behavior in soft x-ray fluorescence excited by monochromatized synchrotron radiation
- 1988
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Ingår i: Physical Review Letters. - 0031-9007. ; 60:17, s. 1759-1762
-
Tidskriftsartikel (refereegranskat)abstract
- Soft x-ray emission spectra of TiN, excited by monochromatized synchrotron radiation, have been recorded in a grazing-incidence spectrometer. The tunability of the excitation energy has allowed the pure N K and Ti LIII emission spectra to be isolated for the first time. A new type of resonance is observed in the Ti L emission spectrum, and interpreted as due to the decay of a quasiatomic intermediate state. The results call for a reinterpretation of Ti L spectra and a revision of the interpretation of 3d-metal L-emission spectra in general.
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| 42. |
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| 43. |
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| 44. |
- Schulze, Steve, et al.
(författare)
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The Palomar Transient Factory Core-collapse Supernova Host-galaxy Sample. I. Host-galaxy Distribution Functions and Environment Dependence of Core-collapse Supernovae
- 2021
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 255:2
-
Tidskriftsartikel (refereegranskat)abstract
- Several thousand core-collapse supernovae (CCSNe) of different flavors have been discovered so far. However, identifying their progenitors has remained an outstanding open question in astrophysics. Studies of SN host galaxies have proven to be powerful in providing constraints on the progenitor populations. In this paper, we present all CCSNe detected between 2009 and 2017 by the Palomar Transient Factory. This sample includes 888 SNe of 12 distinct classes out to redshift z approximate to 1. We present the photometric properties of their host galaxies from the far-ultraviolet to the mid-infrared and model the host-galaxy spectral energy distributions to derive physical properties. The galaxy mass function of Type Ic, Ib, IIb, II, and IIn SNe ranges from 10(5) to 10(11.5) M (circle dot), probing the entire mass range of star-forming galaxies down to the least-massive star-forming galaxies known. Moreover, the galaxy mass distributions are consistent with models of star-formation-weighted mass functions. Regular CCSNe are hence direct tracers of star formation. Small but notable differences exist between some of the SN classes. Type Ib/c SNe prefer galaxies with slightly higher masses (i.e., higher metallicities) and star formation rates than Type IIb and II SNe. These differences are less pronounced than previously thought. H-poor superluminous supernovae (SLSNe) and SNe Ic-BL are scarce in galaxies above 10(10) M (circle dot). Their progenitors require environments with metallicities of < 0.4 and < 1 solar, respectively. In addition, the hosts of H-poor SLSNe are dominated by a younger stellar population than all other classes of CCSNe. Our findings corroborate the notion that low metallicity and young age play an important role in the formation of SLSN progenitors.
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| 45. |
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| 46. |
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| 47. |
- Wassdahl, N., et al.
(författare)
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Synchrotron-radiation-excited soft-x-ray-fluorescence studies of Cu and Zn : On the validity of the sudden approximation
- 1990
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Ingår i: Physical Review Letters. - 0031-9007. ; 64:23, s. 2807-2810
-
Tidskriftsartikel (refereegranskat)abstract
- The L23 x-ray-emission spectra of Cu and Zn have been recorded using tunable-synchrotron-radiation-excited fluorescence spectroscopy. The satellite structure was studied in detail by varying the excitation energy from threshold to several hundred eV above. Strong satellites are observed which can unambiguously be associated with the decay of multiply excited states. This disproves recent claims of a breakdown of the sudden approximation in this regime.
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