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- Algaba, Juan-Carlos, et al.
(författare)
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Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign
- 2021
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1
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Forskningsöversikt (refereegranskat)abstract
- In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.
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- Abe, H., et al.
(författare)
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Gamma-ray observations of MAXI J1820+070 during the 2018 outburst
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press. - 0035-8711 .- 1365-2966. ; 517:4, s. 4736-4751
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Tidskriftsartikel (refereegranskat)abstract
- MAXIJ1820+070 is a low-mass X-ray binary with a black hole (BH) as a compact object. This binary underwent an exceptionally bright X-ray outburst from 2018 March to October, showing evidence of a non-thermal particle population through its radio emission during this whole period. The combined results of 59.5 h of observations of the MAXI J1820+070 outburst with the H.E.S.S., MAGIC and VERITAS experiments at energies above 200 GeV are presented, together with Fermi-LAT data between 0.1 and 500 GeV, and multiwavelength observations from radio to X-rays. Gamma-ray emission is not detected from MAXI J1820+070, but the obtained upper limits and the multiwavelength data allow us to put meaningful constraints on the source properties under reasonable assumptions regarding the non-thermal particle population and the jet synchrotron spectrum. In particular, it is possible to show that, if a high-energy (HE) gamma-ray emitting region is present during the hard state of the source, its predicted flux should be at most a factor of 20 below the obtained Fermi-LAT upper limits, and closer to them for magnetic fields significantly below equipartition. During the state transitions, under the plausible assumption that electrons are accelerated up to similar to 500 GeV, the multiwavelength data and the gamma-ray upper limits lead consistently to the conclusion that a potential HE and very-HE gamma-ray emitting region should be located at a distance from the BH ranging between 10(11) and 10(13) cm. Similar outbursts from low-mass X-ray binaries might be detectable in the near future with upcoming instruments such as CTA.
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- Acharyya, A., et al.
(författare)
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Multiwavelength Observations of the Blazar PKS 0735+178 in Spatial and Temporal Coincidence with an Astrophysical Neutrino Candidate IceCube-211208A
- 2023
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Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 954:1
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Tidskriftsartikel (refereegranskat)abstract
- We report on multiwavelength target-of-opportunity observations of the blazar PKS 0735+178, located 2 degrees .2 away from the best -fit position of the IceCube neutrino event IceCube-211208A detected on 2021 December 8. The source was in a high -flux state in the optical, ultraviolet, X-ray, and GeV ?-ray bands around the time of the neutrino event, exhibiting daily variability in the soft X-ray flux. The X-ray data from Swift-XRT and NuSTAR characterize the transition between the low-energy and high-energy components of the broadband spectral energy distribution (SED), and the ?-ray data from Fermi-LAT, VERITAS, and H.E.S.S. require a spectral cutoff near 100 GeV. Both the X-ray and ?-ray measurements provide strong constraints on the leptonic and hadronic models. We analytically explore a synchrotron self-Compton model, an external Compton model, and a lepto-hadronic model. Models that are entirely based on internal photon fields face serious difficulties in matching the observed SED. The existence of an external photon field in the source would instead explain the observed ?-ray spectral cutoff in both the leptonic and lepto-hadronic models and allow a proton jet power that marginally agrees with the Eddington limit in the lepto-hadronic model. We show a numerical lepto-hadronic model with external target photons that reproduces the observed SED and is reasonably consistent with the neutrino event despite requiring a high jet power.
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- Baker, Laura, et al.
(författare)
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Resting heart rate and the development of antisocial behavior from age 9 to 14 : genetic and environmental influences
- 2009
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Ingår i: Development and psychopathology (Print). - 0954-5794 .- 1469-2198. ; 21:3, s. 939-960
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Tidskriftsartikel (refereegranskat)abstract
- The genetic and environmental basis of a well-replicated association between antisocial behavior (ASB) and resting heart rate was investigated in a longitudinal twin study, based on two measurements between the ages of 9 and 14 years. ASB was defined as a broad continuum of externalizing behavior problems, assessed at each occasion through a composite measure based on parent ratings of trait aggression, delinquent behaviors, and psychopathic traits in their children. Parent ratings of ASB significantly decreased across age from childhood to early adolescence, although latent growth models indicated significant variation and twin similarity in the growth patterns, which were explained almost entirely by genetic influences. Resting heart rate at age 9-10 years old was inversely related to levels of ASB but not change patterns of ASB across age or occasions. Biometrical analyses indicated significant genetic influences on heart rate during childhood, as well as ASB throughout development from age 9 to 14. Both level and slope variation were significantly influenced by genetic factors. Of importance, the low resting heart rate and ASB association was significantly and entirely explained by their genetic covariation, although the heritable component of heart rate explained only a small portion (1-4%) of the substantial genetic variance in ASB. Although the effect size is small, children with low resting heart rate appear to be genetically predisposed toward externalizing behavior problems as early as age 9 years old.
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- Bannon, Brittany L., et al.
(författare)
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Confirmatory factor analysis of illness behavior in the Swedish Adoption/Twin Study of Aging (SATSA)
- 2017
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Ingår i: Annals of Behavioral Medicine. - : Springer. - 0883-6612 .- 1532-4796. ; 51:Suppl. 1, s. S2654-S2655
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Tidskriftsartikel (refereegranskat)abstract
- Background: Illness behaviors—or affective, cognitive, and behavioral responses to symptoms of illness—predict patient outcomes, including symptom exacerbation and functional recovery, and they account for a large proportion of U.S. healthcare costs. Although priorcross-sectional work has examined illness behaviors like symptom reporting in isolation, the measurement of illness behavior using a longitudinal, multi-indicator approach has yet to be explored.Aim: We evaluated illness behavior as a latent, developmental construct in the Swedish Adoption/Twin Study of Aging (SATSA).Method: Participants were up to 1,886 individuals (from 1,223 twin pairs) ages 29 to 102 years (Mage baseline = 62.32 years; SD =13.69; 59% Female). Illness behavior indicators included somatic complaints, non-prescription medication use, pain-related disability and perceived illness complications. The psychomotor retardation subscale of the CES-D was used to index somatic complaints, and medication use was a simple composite of 9 dichotomous items on participants’ use of non-prescription medications, such as over-the-counter analgesics, in the previous month. Pain-related disability included a simple composite of three dichotomous items on the presence of neck,back, or shoulder pain that prevented participants from performing daily tasks or activities. Perceived illness disability was a composite of difference scores, calculated from subtracting a physician panel’s objective ratings of disability for each of 35 medical conditions (on a 3-pointscale; 1= Little or no disability; 3= Severe disability) from participants’ self-ratings of how much each of the same endorsed medical conditions interfered with their daily lives (on the same 3-point scale; 1= Not at all; 3= A lot). Positive composite scores reflected higher perceived disability relative to what was expected from the objective ratings, whereas a composite score of zero reflected “accuracy” or agreement in perceived illness complications. Confirmatory Factor Analysis (CFA) was used to evaluate invariance in the loadings of these four indicatorson a latent illness behavior factor across four questionnaire waves (1987-2004).Findings: Confirmatory factor analyses revealed moderate factor loadings of the four indicators (standardized loadings ranged from .49 to .52, all ps < .0001). Also, practical fit indices from the nested model comparisons suggested strong factorial invariance in the loadings across time (CFI = .96; TLI = .95, RMSEA= .03, 90% CI: [.026, .035]).Conclusion: Illness behavior as a latent, multi-indicator construct represents a promising focus for longitudinal work on behavior change and maintenance.
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