| 1. |
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| 2. |
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- 2017
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:2
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Tidskriftsartikel (refereegranskat)
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| 3. |
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| 4. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 5. |
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| 6. |
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- 2019
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Abazov, V. M., et al.
(författare)
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Search for Higgs bosons decaying to tau(+)tau(-) pairs in p(p)over-bar collisions at root s=1.96 TeV
- 2012
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 707:3-4, s. 323-329
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Tidskriftsartikel (refereegranskat)abstract
- We present a search for the production of neutral Higgs bosons decaying into tau(+)tau(-) pairs in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of 5.4 fb(-1), were collected by the DO experiment at the Fermilab Tevatron Collider. We set upper limits at the 95% C.L. on the product of production cross section and branching ratio for a scalar resonance decaying into tau(+)tau(-) pairs, and we interpret these limits as limits on the production of Higgs bosons in the minimal supersymmetric standard model (MSSM) and as constraints in the MSSM parameter space.
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| 8. |
- Abazov, V. M., et al.
(författare)
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Search for scalar bottom quarks and third-generation leptoquarks in p(p)over-bar collisions at root s=1.96 TeV
- 2010
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 693:2, s. 95-101
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Tidskriftsartikel (refereegranskat)abstract
- We report the results of a search for pair production of scalar bottom quarks ((b) over bar (1)) and scalar third-generation leptoquarks (LQ(3)) in 5.2 fb(-1) of p (p) over bar collisions at the D0 experiment of the Fermilab Tevatron Collider. Scalar bottom quarks are assumed to decay to a neutralino ((chi) over bar (1)(0)) and a b quark, and we set 95% C.L. lower limits on their production in the (m((b) over bar1), m((chi) over bar 10)) mass plane such as m((b) over bar1) > 247 GeV for m(<(chi)over) (bar>10) = 0 and m((chi) over bar 10) > 110 GeV for 160 m(<(b) over bar1) < 200 GeV. The leptoquarks are assumed to decay to a tau neutrino and a b quark, and we set a 95% C.L. lower limit of 247 GeV on the mass of a charge-1/3 third-generation scalar leptoquark.
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| 9. |
- Abazov, V. M., et al.
(författare)
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Search for the rare decay B-s(0) -> mu(+)mu(-)
- 2010
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 693:5, s. 539-544
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of a search for the flavor changing neutral current decay B-s(0) -> mu(+)mu(-) using 6.1 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron Collider. The observed number of B-s(0) candidates is consistent with background expectations. The resulting upper limit on the branching fraction is B(B-s(0) -> mu(+)mu(-)) < 5.1 x 10(-8) at the 95% C.L. This limit is a factor of 2.4 better than that of the previous DO analysis and the best limit to date. Published by Elsevier B.V.
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| 10. |
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| 11. |
- Silventoinen, Karri, et al.
(författare)
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Genetic and environmental variation in educational attainment : an individual-based analysis of 28 twin cohorts
- 2020
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the heritability of educational attainment and how it differed between birth cohorts and cultural–geographic regions. A classical twin design was applied to pooled data from 28 cohorts representing 16 countries and including 193,518 twins with information on educational attainment at 25 years of age or older. Genetic factors explained the major part of individual differences in educational attainment (heritability: a2 = 0.43; 0.41–0.44), but also environmental variation shared by co-twins was substantial (c2 = 0.31; 0.30–0.33). The proportions of educational variation explained by genetic and shared environmental factors did not differ between Europe, North America and Australia, and East Asia. When restricted to twins 30 years or older to confirm finalized education, the heritability was higher in the older cohorts born in 1900–1949 (a2 = 0.44; 0.41–0.46) than in the later cohorts born in 1950–1989 (a2 = 0.38; 0.36–0.40), with a corresponding lower influence of common environmental factors (c2 = 0.31; 0.29–0.33 and c2 = 0.34; 0.32–0.36, respectively). In conclusion, both genetic and environmental factors shared by co-twins have an important influence on individual differences in educational attainment. The effect of genetic factors on educational attainment has decreased from the cohorts born before to those born after the 1950s.
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| 12. |
- Aksentijevich, Ivona, et al.
(författare)
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An Autoinflammatory Disease with Deficiency of the Interleukin-1-Receptor Antagonist
- 2009
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Ingår i: New England Journal of Medicine. - 0028-4793. ; 360:23, s. 2426-2437
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Autoinflammatory diseases manifest inflammation without evidence of infection, high-titer autoantibodies, or autoreactive T cells. We report a disorder caused by mutations of IL1RN, which encodes the interleukin-1-receptor antagonist, with prominent involvement of skin and bone. METHODS We studied nine children from six families who had neonatal onset of sterile multifocal osteomyelitis, periostitis, and pustulosis. Response to empirical treatment with the recombinant interleukin-1-receptor antagonist anakinra in the first patient prompted us to test for the presence of mutations and changes in proteins and their function in interleukin-1-pathway genes including IL1RN. RESULTS We identified homozygous mutations of IL1RN in nine affected children, from one family from Newfoundland, Canada, three families from the Netherlands, and one consanguineous family from Lebanon. A nonconsanguineous patient from Puerto Rico was homozygous for a genomic deletion that includes IL1RN and five other interleukin-1-family members. At least three of the mutations are founder mutations; heterozygous carriers were asymptomatic, with no cytokine abnormalities in vitro. The IL1RN mutations resulted in a truncated protein that is not secreted, thereby rendering cells hyperresponsive to interleukin-1 beta stimulation. Patients treated with anakinra responded rapidly. CONCLUSIONS We propose the term deficiency of the interleukin-1-receptor antagonist, or DIRA, to denote this autosomal recessive autoinflammatory disease caused by mutations affecting IL1RN. The absence of interleukin-1-receptor antagonist allows unopposed action of interleukin-1, resulting in life-threatening systemic inflammation with skin and bone involvement. (ClinicalTrials.gov number, NCT00059748.)
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| 13. |
- An, Junghwa, et al.
(författare)
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Permanent Genetic Resources added to Molecular Ecology Resources Database 1 October 2009-30 November 2009
- 2010
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Ingår i: Molecular Ecology Resources. - : Wiley. - 1755-098X .- 1755-0998. ; 10:2, s. 404-408
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Tidskriftsartikel (refereegranskat)abstract
- This article documents the addition of 411 microsatellite marker loci and 15 pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Acanthopagrus schlegeli, Anopheles lesteri, Aspergillus clavatus, Aspergillus flavus, Aspergillus fumigatus, Aspergillus oryzae, Aspergillus terreus, Branchiostoma japonicum, Branchiostoma belcheri, Colias behrii, Coryphopterus personatus, Cynogolssus semilaevis, Cynoglossus semilaevis, Dendrobium officinale, Dendrobium officinale, Dysoxylum malabaricum, Metrioptera roeselii, Myrmeciza exsul, Ochotona thibetana, Neosartorya fischeri, Nothofagus pumilio, Onychodactylus fischeri, Phoenicopterus roseus, Salvia officinalis L., Scylla paramamosain, Silene latifo, Sula sula, and Vulpes vulpes. These loci were cross-tested on the following species: Aspergillus giganteus, Colias pelidne, Colias interior, Colias meadii, Colias eurytheme, Coryphopterus lipernes, Coryphopterus glaucofrenum, Coryphopterus eidolon, Gnatholepis thompsoni, Elacatinus evelynae, Dendrobium loddigesii Dendrobium devonianum, Dysoxylum binectariferum, Nothofagus antarctica, Nothofagus dombeyii, Nothofagus nervosa, Nothofagus obliqua, Sula nebouxii, and Sula variegata. This article also documents the addition of 39 sequencing primer pairs and 15 allele specific primers or probes for Paralithodes camtschaticus.
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| 14. |
- Zhao, Chaoyang, et al.
(författare)
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A massive expansion of effector genes underlies gall-formation in the wheat pest Mayetiola destructor
- 2015
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Ingår i: Current Biology. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 25:5, s. 613-620
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Tidskriftsartikel (refereegranskat)abstract
- Gall-forming arthropods are highly specialized herbivores that, in combination with their hosts, produce extended phenotypes with unique morphologies [1]. Many are economically important, and others have improved our understanding of ecology and adaptive radiation [2]. However, the mechanisms that these arthropods use to induce plant galls are poorly understood. We sequenced the genome of the Hessian fly (Mayetiola destructor; Diptera: Cecidomyiidae), a plant parasitic gall midge and a pest of wheat (Triticum spp.), with the aim of identifying genic modifications that contribute to its plant-parasitic lifestyle. Among several adaptive modifications, we discovered an expansive reservoir of potential effector proteins. Nearly 5% of the 20,163 predicted gene models matched putative effector gene transcripts present in the M. destructor larval salivary gland. Another 466 putative effectors were discovered among the genes that have no sequence similarities in other organisms. The largest known arthropod gene family (family SSGP-71) was also discovered within the effector reservoir. SSGP-71 proteins lack sequence homologies to other proteins, but their structures resemble both ubiquitin E3 ligases in plants and E3-ligase-mimicking effectors in plant pathogenic bacteria. SSGP-71 proteins and wheat Skp proteins interact in vivo. Mutations in different SSGP-71 genes avoid the effector-triggered immunity that is directed by the wheat resistance genes H6 and H9. Results point to effectors as the agents responsible for arthropod-induced plant gall formation.
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| 15. |
- Litchfield, Kevin, et al.
(författare)
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Escape from nonsense-mediated decay associates with anti-tumor immunogenicity
- 2020
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Frameshift insertion/deletions (fs-indels) are an infrequent but highly immunogenic mutation subtype. Although fs-indels are degraded through the nonsense-mediated decay (NMD) pathway, we hypothesise that some fs-indels escape degradation and elicit anti-tumor immune responses. Using allele-specific expression analysis, expressed fs-indels are enriched in genomic positions predicted to escape NMD, and associated with higher protein expression, consistent with degradation escape (NMD-escape). Across four independent melanoma cohorts, NMD-escape mutations are significantly associated with clinical-benefit to checkpoint inhibitor (CPI) therapy (Pmeta = 0.0039). NMD-escape mutations are additionally found to associate with clinical-benefit in the low-TMB setting. Furthermore, in an adoptive cell therapy treated melanoma cohort, NMD-escape mutation count is the most significant biomarker associated with clinical-benefit. Analysis of functional T cell reactivity screens from personalized vaccine studies shows direct evidence of fs-indel derived neoantigens eliciting immune response, particularly those with highly elongated neo open reading frames. NMD-escape fs-indels represent an attractive target for biomarker optimisation and immunotherapy design.
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| 16. |
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| 17. |
- Wu, H., et al.
(författare)
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Helical self-assembly-induced singlet-triplet emissive switching in a mechanically sensitive system
- 2017
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society. - 0002-7863 .- 1520-5126. ; 139:2, s. 785-791
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Tidskriftsartikel (refereegranskat)abstract
- In nanoscience, chirality has shown a significant ability to tune materials' electronic properties, whereas imposing macrochirality into the regulation of singlet-triplet features of organic optoelectronics remains a challenging research topic. Since the tuning for singlet and triplet excited-state properties in a single π-functional molecule connects to its multicolor luminescent application and potential improvement of internal quantum efficiency, we here report that supramolecular chirality can be employed to toggle the singlet and triplet emissions in a welldesigned asterisk-shaped molecule. Employing a hexathiobenzene-based single luminophore as a prototype and functionalizing it with chiral α-lipoiate side groups, we find that helical nanoarchitectures can accordingly form in mixed DMF/H20 solution. On this basis, switching between fluorescence and phosphorescence of the material can be realized upon helical self-assembly and dissociation. Such a behavior can be attributed to a helical-conformation-dependent manipulation of the intersystem crossing. Furthermore, reversible mechanoluminescence of the corresponding solid sample was also observed to rely on an analogous molecular self-assembly alternation. These results can probably provide new visions for the development of next-generation supramolecular chiral functional materials.
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| 18. |
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| 19. |
- Aharonian, Felix, et al.
(författare)
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Atmospheric gas dynamics in the Perseus cluster observed with Hitomi
- 2018
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 70:2
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Tidskriftsartikel (refereegranskat)abstract
- Extending the earlier measurements reported in Hitomi collaboration (2016, Nature, 535, 117), we examine the atmospheric gas motions within the central 100 kpc of the Perseus cluster using observations obtained with the Hitomi satellite. After correcting for the point spread function of the telescope and using optically thin emission lines, we find that the line-of-sight velocity dispersion of the hot gas is remarkably low and mostly uniform. The velocity dispersion reaches a maxima of approximately 200 km s(-1) toward the central active galactic nucleus (AGN) and toward the AGN inflated northwestern ghost bubble. Elsewhere within the observed region, the velocity dispersion appears constant around 100 km s(-1). We also detect a velocity gradient with a 100 km s(-1) amplitude across the cluster core, consistent with large-scale sloshing of the core gas. If the observed gas motions are isotropic, the kinetic pressure support is less than 10% of the thermal pressure support in the cluster core. The well-resolved, optically thin emission lines have Gaussian shapes, indicating that the turbulent driving scale is likely below 100 kpc, which is consistent with the size of the AGN jet inflated bubbles. We also report the first measurement of the ion temperature in the intracluster medium, which we find to be consistent with the electron temperature. In addition, we present a new measurement of the redshift of the brightest cluster galaxy NGC 1275.
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| 20. |
- Aharonian, Felix, et al.
(författare)
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Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi
- 2018
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 70:2
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Tidskriftsartikel (refereegranskat)abstract
- The Hitomi Soft X-ray Spectrometer spectrum of the Perseus cluster, with similar to 5 eV resolution in the 2-9 keV band, offers an unprecedented benchmark of the atomic modeling and database for hot collisional plasmas. It reveals both successes and challenges of the current atomic data and models. The latest versions of AtomDB/APEC (3.0.8), SPEX (3.03.00), and CHIANTI (8.0) all provide reasonable fits to the broad-band spectrum, and are in close agreement on best-fit temperature, emission measure, and abundances of a few elements such as Ni. For the Fe abundance, the APEC and SPEX measurements differ by 16%, which is 17 times higher than the statistical uncertainty. This is mostly attributed to the differences in adopted collisional excitation and dielectronic recombination rates of the strongest emission lines. We further investigate and compare the sensitivity of the derived physical parameters to the astrophysical source modeling and instrumental effects. The Hitomi results show that accurate atomic data and models are as important as the astrophysical modeling and instrumental calibration aspects. Substantial updates of atomic databases and targeted laboratory measurements are needed to get the current data and models ready for the data from the next Hitomi-level mission.
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| 21. |
- Aharonian, Felix, et al.
(författare)
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Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector
- 2018
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 70:6
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Tidskriftsartikel (refereegranskat)abstract
- We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrometer, is capable of measuring polarization of gamma-ray photons. The Crab nebula is one of the brightest X-ray / gamma-ray sources on the sky, and, the only source from which polarized X-ray photons have been detected. SGD observed the Crab nebula during the initial test observation phase of Hitomi. We performed the data analysis of the SGD observation, the SGD background estimation and the SGD Monte Carlo simulations, and, successfully detected polarized gamma-ray emission from the Crab nebula with only about 5 ks exposure time. The obtained polarization fraction of the phase-integrated Crab emission (sum of pulsar and nebula emissions) is (22.1% +/- 10.6%), and, the polarization angle is 110.degrees 7 + 13.degrees 2 /-13.degrees 0 in the energy range of 60-160 keV (The errors correspond to the 1 sigma deviation). The confidence level of the polarization detection was 99.3%. The polarization angle measured by SGD is about one sigma deviation with the projected spin axis of the pulsar, 124.degrees 0 +/- 0.degrees 1.
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| 22. |
- Aharonian, Felix, et al.
(författare)
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Glimpse of the highly obscured HMXB IGR J16318-4848 with Hitomi
- 2018
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 70:2
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Tidskriftsartikel (refereegranskat)abstract
- We report on a Hitomi observation of IGR J16318-4848, a high-mass X-ray binary system with an extremely strong absorption of N-H similar to 10(24) cm(-2). Previous X-ray studies revealed that its spectrum is dominated by strong fluorescence lines of Fe as well as continuum emission lines. For physical and geometrical insight into the nature of the reprocessing material, we utilized the high spectroscopic resolving power of the X-ray microcalorimeter (the soft X-ray spectrometer: SXS) and the wide-band sensitivity by the soft and hard X-ray imagers (SXI and HXI) aboard Hitomi. Even though the photon counts are limited due to unintended off-axis pointing, the SXS spectrum resolves Fe K alpha(1) and K alpha(2) lines and puts strong constraints on the line centroid and line width. The line width corresponds to a velocity of 160(-70)(+300) km s(-1). This represents the most accurate, and smallest, width measurement of this line made so far from the any X-ray binary, much less than the Doppler broadening and Doppler shift expected from speeds that are characteristic of similar systems. Combined with the K-shell edge energy measured by the SXI and HXI spectra, the ionization state of Fe is estimated to be in the range of Fe I-IV. Considering the estimated ionization parameter and the distance between the X-ray source and the absorber, the density and thickness of the materials are estimated. The extraordinarily strong absorption and the absence of a Compton shoulder component have been confirmed. These characteristics suggest reprocessing materials that are distributed in a narrow solid angle or scattering, primarily by warm free electrons or neutral hydrogen. This measurement was achieved using the SXS detection of 19 photons. It provides strong motivation for follow-up observations of this and other X-ray binaries using the X-ray Astrophysics Recovery Mission and other comparable future instruments.
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| 23. |
- Aharonian, Felix, et al.
(författare)
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Hitomi observation of radio galaxy NGC 1275 : The first X-ray microcalorimeter spectroscopy of Fe-K alpha line emission from an active galactic nucleus
- 2018
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 70:2
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Tidskriftsartikel (refereegranskat)abstract
- The origin of the narrow Fe-K alpha fluorescence line at 6.4 keV from active galactic nuclei has long been under debate; some of the possible sites are the outer accretion disk, the broad line region, a molecular torus, or interstellar/intracluster media. In 2016 February-March, we performed the first X-ray microcalorimeter spectroscopy with the Soft X-ray Spectrometer (SXS) on board the Hitomi satellite of the Fanaroff-Riley type I radio galaxy NGC 1275 at the center of the Perseus cluster of galaxies. With the high-energy resolution of similar to 5 eV at 6 keV achieved by Hitomi/SXS, we detected the Fe-K alpha line with similar to 5.4 sigma significance. The velocity width is constrained to be 500-1600 km s(-1) (FWHM for Gaussian models) at 90% confidence. The SXS also constrains the continuum level from the NGC 1275 nucleus up to similar to 20 keV, giving an equivalent width of similar to 20 eV for the 6.4 keV line. Because the velocity width is narrower than that of the broad H alpha line of similar to 2750 km s(-1), we can exclude a large contribution to the line flux from the accretion disk and the broad line region. Furthermore, we performed pixel map analyses on the Hitomi/SXS data and image analyses on the Chandra archival data, and revealed that the Fe-K alpha line comes from a region within similar to 1.6 kpc of the NGC 1275 core, where an active galactic nucleus emission dominates, rather than that from intracluster media. Therefore, we suggest that the source of the Fe-K alpha line from NGC 1275 is likely a low-covering-fraction molecular torus or a rotating molecular disk which probably extends from a parsec to hundreds of parsecs scale in the active galactic nucleus system.
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| 24. |
- Aharonian, Felix, et al.
(författare)
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Hitomi observations of the LMC SNR N 132 D : Highly redshifted X-ray emission from iron ejecta
- 2018
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 70:2
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Tidskriftsartikel (refereegranskat)abstract
- We present Hitomi observations of N 132 D, a young, X-ray bright, O-rich core-collapse supernova remnant in the Large Magellanic Cloud (LMC). Despite a very short observation of only 3.7 ks, the Soft X-ray Spectrometer (SXS) easily detects the line complexes of highly ionized S K and Fe K with 16-17 counts in each. The Fe feature is measured for the first time at high spectral resolution. Based on the plausible assumption that the Fe K emission is dominated by He-like ions, we find that the material responsible for this Fe emission is highly redshifted at similar to 800 km s(-1) compared to the local LMC interstellar medium (ISM), with a 90% credible interval of 50-1500 km s(-1) if a weakly informative prior is placed on possible line broadening. This indicates (1) that the Fe emission arises from the supernova ejecta, and (2) that these ejecta are highly asymmetric, since no blueshifted component is found. The S K velocity is consistent with the local LMC ISM, and is likely from swept-up ISM material. These results are consistent with spatial mapping that shows the He-like Fe concentrated in the interior of the remnant and the S tracing the outer shell. The results also show that even with a very small number of counts, direct velocity measurements from Doppler-shifted lines detected in extended objects like supernova remnants are now possible. Thanks to the very low SXS background of similar to 1 event per spectral resolution element per 100 ks, such results are obtainable during short pointed or slew observations with similar instruments. This highlights the power of high-spectral-resolution imaging observations, and demonstrates the new window that has been opened with Hitomi and will be greatly widened with future missions such as the X-ray Astronomy Recovery Mission (XARM) and Athena.
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| 25. |
- Aharonian, Felix, et al.
(författare)
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Hitomi X-ray observation of the pulsar wind nebula G21.5-0.9
- 2018
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Ingår i: Publications of the Astronomical Society of Japan. - : Oxford University Press (OUP). - 0004-6264 .- 2053-051X. ; 70:3
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Tidskriftsartikel (refereegranskat)abstract
- We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5-0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8-80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager, and Hard X-ray Imager (HXI) show a significant break in the continuum as previously found with the NuSTAR observation. After taking into account all known emissions from the SNR other than the PWN itself, we find that the Hitomi spectra can be fitted with a broken power law with photon indices of Gamma(1) = 1.74 +/- 0.02 and Gamma(2) = 2.14 +/- 0.01 below and above the break at 7.1 +/- 0.3 keV, which is significantly lower than the NuSTAR result (similar to 9.0 keV). The spectral break cannot be reproduced by time-dependent particle injection one-zone spectral energy distribution models, which strongly indicates that a more complex emission model is needed, as suggested by recent theoretical models. We also search for narrow emission or absorption lines with the SXS, and perform a timing analysis of PSR J1833-1034 with the HXI and the Soft Gamma-ray Detector. No significant pulsation is found from the pulsar. However, unexpectedly, narrow absorption line features are detected in the SXS data at 4.2345 keV and 9.296 keV with a significance of 3.65 sigma. While the origin of these features is not understood, their mere detection opens up a new field of research and was only possible with the high resolution, sensitivity, and ability to measure extended sources provided by an X-ray microcalorimeter.
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