| 1. |
- Aros, Francisco I, et al.
(författare)
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Dynamical modelling of globular clusters: challenges for the robust determination of IMBH candidates
- 2020
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 499:4, s. 4646-4665
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Tidskriftsartikel (refereegranskat)abstract
- The presence or absence of intermediate-mass black holes (IMBHs) at the centre of Milky Way globular clusters (GCs) is still an open question. This is due to either observational restrictions or limitations in the dynamical modelling method; in this work, we explore the latter. Using a sample of high-end Monte Carlo simulations of GCs, with and without a central IMBH, we study the limitations of spherically symmetric Jeans models assuming constant velocity anisotropy and mass-to-light ratio. This dynamical method is one of the most widely used modelling approaches to identify a central IMBH in observations.With these models, we are able to robustly identify and recover the mass of the central IMBH in our simulation with a high-mass IMBH (MIMBH/MGC∼4 per cent). Simultaneously, we show that it is challenging to confirm the existence of a low-mass IMBH (MIMBH/MGC∼0.3 per cent), as both solutions with and without an IMBH are possible within our adopted error bars. For simulations without an IMBH, we do not find any certain false detection of an IMBH. However, we obtain upper limits that still allow for the presence of a central IMBH. We conclude that while our modelling approach is reliable for the high-mass IMBH and does not seem to lead towards a false detection of a central IMBH, it lacks the sensitivity to robustly identify a low-mass IMBH and to definitely rule out the presence of an IMBH when it is not there.
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| 2. |
- Aros, Francisco I, et al.
(författare)
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Using binaries in Globular Clusters to catch sight of Intermediate-Mass Black Holes
- 2021
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 1365-2966 .- 0035-8711. ; 508:3, s. 4385-4398
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Tidskriftsartikel (refereegranskat)abstract
- The dynamical evolution of globular clusters (GCs) is tied to their binary population, as binaries segregate to the cluster centre, leading to an increased binary fraction in the core. This central overabundance of mainly hard binaries can serve as a source of energy for the cluster and has a significant effect on the observed kinematics, such as artificially increasing the observed line-of-sight velocity dispersion. We analyse the binary fractions and distributions of 95 simulated GCs, with and without an intermediate-mass black hole (IMBH) in their centre. We show that an IMBH will not only halt the segregation of binaries towards the cluster centre, but also, directly and indirectly, disrupt the binaries that segregate, thus, depleting binaries in the cluster core. We illustrate this by showing that clusters with an IMBH have fewer binaries and flatter radial binary distributions than their counterparts without one. These differences in the binary fraction and distribution provide an additional indicator for the presence of a central IMBH in GCs. In addition, we analyse the effects of the binary fraction on the line-of-sight velocity dispersion in the simulated GCs and find that binaries can cause an overestimation of up to 70percent of the velocity dispersion within the core radius. Using recent VLT/MUSE observations of NGC 3201 by Giesers et al. (2019), we find an overestimation of 32.2±7.8percent in the velocity dispersion that is consistent with the simulations and illustrates the importance of accurately accounting for the binary population when performing kinematic or dynamical analysis.
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| 3. |
- Djuric, Olivera, et al.
(författare)
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Budget impact analysis of introducing digital breast tomosynthesis in breast cancer screening in Italy
- 2024
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Ingår i: Radiologia Medica. - 0033-8362. ; 129:9, s. 1288-1302
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study quantifies the impact on budget and cost per health benefit of implementing digital breast tomosynthesis (DBT) in place of digital mammography (DM) for breast cancer screening among asymptomatic women in Italy. Methods: A budget impact analysis and a cost consequence analysis were conducted using parameters from the MAITA project and literature. The study considered four scenarios for DBT implementation, i.e., DBT for all women, DBT for women aged 45–49 years, DBT based on breast density (BI-RADS C + D or D only), and compared these to the current DM screening. Healthcare provider's perspective was adopted, including screening, diagnosis, and cancer treatment costs. Results: Introducing DBT for all women would increase overall screening costs by 20%. Targeting DBT to women aged 45–49 years or with dense breasts would result in smaller cost increases (3.2% for age-based and 1.4–10.7% for density-based scenarios). The cost per avoided interval cancer was significantly higher when DBT was applied to all women compared to targeted approaches. The cost per gained early-detected cancer slightly increases in targeted approaches, while the assumptions on the clinical significance and overdiagnosis of cancers detected by DBT and not by DM have a strong impact. Conclusions: Implementing DBT as a primary breast cancer test in screening programs in Italy would lead to a substantial increase in costs. Tailoring DBT use to women aged 45–49 or with dense breasts could enhance the feasibility and sustainability of the intervention. Further research is needed to clarify the impact of DBT on overdiagnosis and the long-term outcomes.
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| 4. |
- Isaksson, Mats, 1961, et al.
(författare)
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Assessing 131I in thyroid by non-spectroscopic instruments - a European intercomparison exercise
- 2019
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 128:September
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Tidskriftsartikel (refereegranskat)abstract
- One of the issues of the Open Project for the European Radiation Research Area (OPERRA) was human thyroid monitoring in case of a large scale nuclear accident. This issue was covered in task 5.4 as project “CaThyMARA” (Child and Adult Thyroid Monitoring After Reactor Accident), which included several aspects of thyroid monitoring, e.g. screening of facilities able to perform thyroid monitoring in the European countries, dose estimation, modelling of detector response, and two intercomparison exercises. The intercomparison described in this paper focused on thyroid monitoring by non-spectrometric instruments, including gamma cameras and other instruments that were considered available for measurements made by members of the public. A total of 12 facilities from 7 European countries have participated and 43 various measuring devices have been evaluated. The main conclusion of this intercomparison is that the ability to make assessments of 131I activity in the thyroid to the exposed population after an accidental release must, on the average, be considered as good among the European laboratories taking part in this study. This intercomparison also gave the participants the possibility to calibrate the measuring devices for thyroid measurements of children where this procedure was not available before. A comprehensive report of the intercomparison is given.
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