| 1. |
- Glasbey, JC, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
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| 3. |
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| 4. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 5. |
- Diego, J. M., et al.
(författare)
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JWST's PEARLS : A new lens model for ACT-CL J0102-4915, "El Gordo," and the first red supergiant star at cosmological distances discovered by JWST
- 2023
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 672
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Tidskriftsartikel (refereegranskat)abstract
- The first James Webb Space Telescope (JWST) data on the massive colliding cluster El Gordo allow for 23 known families of multiply lensed images to be confirmed and for eight new members of these families to be identified. Based on these families, which have been confirmed spectroscopically by MUSE, we derived an initial lens model. This model guided the identification of 37 additional families of multiply lensed galaxies, among which 28 are entirely new systems, and nine were previously known. The initial lens model determined geometric redshifts for the 37 new systems. The geometric redshifts agree reasonably well with spectroscopic or photometric redshifts when those are available. The geometric redshifts enable two additional models that include all 60 families of multiply lensed galaxies spanning a redshift range 2 z z > 0.8 and has an estimated virial mass close the maximum mass allowed by standard cosmological models. The JWST images also reveal the presence of small-mass perturbers that produce small lensing distortions. The smallest of these is consistent with being a dwarf galaxy at z = 0.87 and has an estimated mass of 3.8 x 10(9) M-circle dot, making it the smallest substructure found at z > 0.5. The JWST images also show several candidate caustic-crossing events. One of them is detected at high significance at the expected position of the critical curve and is likely a red supergiant star at z = 2.1878. This would be the first red supergiant found at cosmological distances. The cluster lensing should magnify background objects at z > 6, making more of them visible than in blank fields of a similar size, but there appears to be a deficiency of such objects.
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| 6. |
- Echelmeier, A., et al.
(författare)
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Segmented flow generator for serial crystallography at the European X-ray free electron laser
- 2020
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Ingår i: Nature Communications. - : Nature Research. - 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Serial femtosecond crystallography (SFX) with X-ray free electron lasers (XFELs) allows structure determination of membrane proteins and time-resolved crystallography. Common liquid sample delivery continuously jets the protein crystal suspension into the path of the XFEL, wasting a vast amount of sample due to the pulsed nature of all current XFEL sources. The European XFEL (EuXFEL) delivers femtosecond (fs) X-ray pulses in trains spaced 100 ms apart whereas pulses within trains are currently separated by 889 ns. Therefore, continuous sample delivery via fast jets wastes >99% of sample. Here, we introduce a microfluidic device delivering crystal laden droplets segmented with an immiscible oil reducing sample waste and demonstrate droplet injection at the EuXFEL compatible with high pressure liquid delivery of an SFX experiment. While achieving ~60% reduction in sample waste, we determine the structure of the enzyme 3-deoxy-D-manno-octulosonate-8-phosphate synthase from microcrystals delivered in droplets revealing distinct structural features not previously reported.
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| 7. |
- Tsiligiannis, Epameinondas, et al.
(författare)
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A Four Carbon Organonitrate as a Significant Product of Secondary Isoprene Chemistry
- 2022
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 49:11
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Tidskriftsartikel (refereegranskat)abstract
- Oxidation of isoprene by nitrate radicals (NO3) or by hydroxyl radicals (OH) under high NOx conditions forms a substantial amount of organonitrates (ONs). ONs impact NOx concentrations and consequently ozone formation while also contributing to secondary organic aerosol. Here we show that the ONs with the chemical formula C4H7NO5 are a significant fraction of isoprene-derived ONs, based on chamber experiments and ambient measurements from different sites around the globe. From chamber experiments we found that C4H7NO5 isomers contribute 5%-17% of all measured ONs formed during nighttime and constitute more than 40% of the measured ONs after further daytime oxidation. In ambient measurements C4H7NO5 isomers usually dominate both nighttime and daytime, implying a long residence time compared to C-5 ONs which are removed more rapidly. We propose potential nighttime sources and secondary formation pathways, and test them using a box model with an updated isoprene oxidation scheme.
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| 8. |
- Windhorst, Rogier A., et al.
(författare)
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JWST PEARLS. Prime extragalactic areas for reionization and lensing science : project overview and first results
- 2023
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Ingår i: Astronomical Journal. - : Institute of Physics (IOP). - 0004-6256 .- 1538-3881. ; 165:1
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Tidskriftsartikel (refereegranskat)abstract
- We give an overview and describe the rationale, methods, and first results from NIRCam images of the JWST “Prime Extragalactic Areas for Reionization and Lensing Science” (PEARLS) project. PEARLS uses up to eight NIRCam filters to survey several prime extragalactic survey areas: two fields at the North Ecliptic Pole (NEP); seven gravitationally lensing clusters; two high redshift protoclusters; and the iconic backlit VV 191 galaxy system to map its dust attenuation. PEARLS also includes NIRISS spectra for one of the NEP fields and NIRSpec spectra of two high-redshift quasars. The main goal of PEARLS is to study the epoch of galaxy assembly, active galactic nucleus (AGN) growth, and First Light. Five fields—the JWST NEP Time-Domain Field (TDF), IRAC Dark Field, and three lensing clusters—will be observed in up to four epochs over a year. The cadence and sensitivity of the imaging data are ideally suited to find faint variable objects such as weak AGN, high-redshift supernovae, and cluster caustic transits. Both NEP fields have sightlines through our Galaxy, providing significant numbers of very faint brown dwarfs whose proper motions can be studied. Observations from the first spoke in the NEP TDF are public. This paper presents our first PEARLS observations, their NIRCam data reduction and analysis, our first object catalogs, the 0.9–4.5 μm galaxy counts and Integrated Galaxy Light. We assess the JWST sky brightness in 13 NIRCam filters, yielding our first constraints to diffuse light at 0.9–4.5 μm. PEARLS is designed to be of lasting benefit to the community.
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| 9. |
- Caputi, K. I., et al.
(författare)
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ALMA Lensing Cluster Survey: An ALMA Galaxy Signposting a MUSE Galaxy Group at z=4.3 Behind "El Gordo"
- 2021
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 908:2
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of a Multi Unit Spectroscopic Explorer (MUSE) galaxy group at z = 4.32 lensed by the massive galaxy cluster ACT-CL J0102-4915 (aka El Gordo) at z = 0.87, associated with a 1.2 mm source that is at a 2.07 0.88 kpc projected distance from one of the group galaxies. Three images of the whole system appear in the image plane. The 1.2 mm source has been detected within the Atacama Large Millimetre/submillimetre Array (ALMA) Lensing Cluster Survey (ALCS). As this ALMA source is undetected at wavelengths lambda < 2 mu m, its redshift cannot be independently determined, however, the three lensing components indicate that it belongs to the same galaxy group at z = 4.32. The four members of the MUSE galaxy group have low to intermediate stellar masses (similar to 10(7)-10(10) M) and star formation rates (SFRs) of 0.4-24 M yr(-1), resulting in high specific SFRs (sSFRs) for two of them, which suggest that these galaxies are growing fast (with stellar mass doubling times of only similar to 2 x 10(7) yr). This high incidence of starburst galaxies is likely a consequence of interactions within the galaxy group, which is compact and has high velocity dispersion. Based on the magnification-corrected sub-/millimeter continuum flux density and estimated stellar mass, we infer that the ALMA source is classified as an ordinary ultra-luminous infrared galaxy (with associated dust-obscured SFR similar to 200-300 M yr(-1)) and lies on the star formation main sequence. This reported case of an ALMA/MUSE group association suggests that some presumably isolated ALMA sources are in fact signposts of richer star-forming environments at high redshifts.
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| 10. |
- Diego, Jose M., et al.
(författare)
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JWST's PEARLS : Mothra, a new kaiju star at z=2.091 extremely magnified by MACS0416, and implications for dark matter models
- 2023
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 679
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Tidskriftsartikel (refereegranskat)abstract
- We report the discovery of Mothra, an extremely magnified monster star, likely a binary system of two supergiant stars, in one of the strongly lensed galaxies behind the galaxy cluster MACS J0416.1-2403. Mothra is in a galaxy with spectroscopic redshift z = 2.091 in a portion of the galaxy that is parsecs away from the cluster caustic. The binary star is observed only on the side of the critical curve with negative parity but has been detectable for at least eight years, implying the presence of a small lensing perturber. Microlenses alone cannot explain the earlier observations of this object made with the Hubble Space Telescope. A larger perturber with a mass of at least 10(4 )M(circle dot) offers a more satisfactory explanation. Based on the lack of perturbation on other nearby sources in the same arc, the maximum mass of the perturber is 2.5 x 10(6) M-circle dot, making this the smallest substructure constrained by lensing at z > 0.3. The existence of this millilens is fully consistent with expectations from standard cold dark matter cosmology. On the other hand, the existence of such a small substructure in a cluster environment has implications for other dark matter models. In particular, warm dark matter models with particle masses below 8.7 keV are excluded by our observations. Similarly, axion dark matter models are consistent with the observations only if the axion mass is in the range 0.5 x 10(-22) eV < m(a )< 5 x 10(-22) eV.
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