| 11. |
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| 12. |
- Pursiainen, M., et al.
(author)
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Polarimetry of hydrogen-poor superluminous supernovae
- 2023
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In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 674
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Journal article (peer-reviewed)abstract
- We present linear polarimetry for seven hydrogen-poor superluminous supernovae (SLSNe-I) of which only one has previously published polarimetric data. The best-studied event is SN 2017gci, for which we present two epochs of spectropolarimetry at +3 d and +29 d post-peak in rest frame, accompanied by four epochs of imaging polarimetry up to +108 d. The spectropolarimetry at +3 d shows increasing polarisation degree P towards the redder wavelengths and exhibits signs of axial symmetry, but at +29 d, P similar to 0 throughout the spectrum, implying that the photosphere of SN 2017gci evolved from a slightly aspherical configuration to a more spherical one in the first month post-peak. However, an increase of P to similar to 0.5% at similar to+55 d accompanied by a different orientation of the axial symmetry compared to +3 d implies the presence of additional sources of polarisation at this phase. The increase in polarisation is possibly caused by interaction with circumstellar matter (CSM), as already suggested by a knee in the light curve and a possible detection of broad H alpha emission at the same phase. We also analysed the sample of all 16 SLSNe-I with polarimetric measurements to date. The data taken during the early spectroscopic phase show consistently low polarisation, indicating at least nearly spherical photospheres. No clear relation between the polarimetry and spectral phase was seen when the spectra resemble Type Ic SNe during the photospheric and nebular phases. The light-curve decline rate, which spans a factor of eight, also shows no clear relation with the polarisation properties. While only slow-evolving SLSNe-I have shown non-zero polarisation, the fast-evolving ones have not been observed at sufficiently late times to conclude that none of them exhibit changing P. However, the four SLSNe-I with increasing polarisation degree also have irregular light-curve declines. For up to half of them, the photometric, spectroscopic, and polarimetric properties are affected by CSM interaction. As such, CSM interaction clearly plays an important role in understanding the polarimetric evolution of SLSNe-I.
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| 13. |
- Pursiainen, M., et al.
(author)
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SN 2023emq : A Flash-ionized Ibn Supernova with Possible C iii Emission
- 2023
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In: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 959:1
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Journal article (peer-reviewed)abstract
- SN 2023emq is a fast-evolving transient initially classified as a rare Type Icn supernova (SN), interacting with a H- and He-free circumstellar medium (CSM) around maximum light. Subsequent spectroscopy revealed the unambiguous emergence of narrow He lines, confidently placing SN 2023emq in the more common Type Ibn class. Photometrically, SN 2023emq has several uncommon properties regardless of its class, including its extreme initial decay (faster than >90% of Type Ibn/Icn SNe) and sharp transition in the decline rate from 0.20 to 0.07 mag day−1 at +20 days. The bolometric light curve can be modeled as CSM interaction with 0.32M⊙ of ejecta and 0.12M⊙ of CSM, with 0.006M⊙ of nickel, as expected of fast, interacting SNe. Furthermore, broadband polarimetry at +8.7 days (P = 0.55% ± 0.30%) is consistent with spherical symmetry. A discovery of a transitional Type Icn/Ibn SN would be unprecedented and would give valuable insights into the nature of mass loss suffered by the progenitor just before death, but we favor an interpretation that SN 2023emq is a Type Ibn SN that exhibited flash-ionized features in the earliest spectrum, as the features are not an exact match with other Type Icn SNe to date. However, the feature at 5700 Å, in the region of C iii and N ii emission, is significantly stronger in SN 2023emq than in the few other flash-ionized Type Ibn SNe, and if it is related to C iii, it possibly implies a continuum of properties between the two classes.
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| 15. |
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IMPROVER D2.2 Report of criteria for evaluating resilience
- 2016
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Reports (other academic/artistic)abstract
- In the recent years, the focus has moved from critical infrastructure protection to that of resilience. But how do we know whether a critical infrastructure is resilient or not, how can it be evaluated, measured and enhanced? Drawing on, combining and developing the ideas of the existing literature and practices, the current report develops a holistic, easy-to-use and computable methodology to evaluate critical infrastructure resilience, called Critical Infrastructure Resilience Index (CIRI). The methodology is applicable to all types of critical infrastructure, including a possibility to tailor it to the specific needs of different sectors, facilities and hazard scenarios. The proposed methodology is especially suitable for organizational and technological resilience evaluation, but permits including also elements of societal resilience indicators to the evaluations. The methodology is based on four levels of hierarchically organized indicators. Level 1 consists of the phases well known from the so-called crisis management cycle. Under these phases, we find sets of Level 2 rather generic indicators. Thus under level 1 ‘Prevention’, for instance, we may find a Level 2 indicator such as ‘Resilient design’, further divided into Level 3 more detailed indicators such as ‘Physical robustness’, ‘Cyber robustness’, ‘Redundancy’, ‘Modularity’, and ‘Independency’. The task is to study these indicators on Level 4 in the context of concrete critical infrastructure facilities and hazard scenarios, that is, applying Level 3 indicators into concrete circumstances. The methodology then permits to transfer quantitative, semi-quantitative and qualitative evaluations of individual sector-specific resilience indicators into uniform metrics, based on process maturity levels. This in turn makes it possible to give a specific critical infrastructure, or its part, a resilience value on the scale 0-5. While the real resilience value becomes clear only when one engages in the analysis of several indicators, the methodology can be used also as a step-by-step measurement and development tool for resilience, without necessary immediately engaging in time-consuming total resilience analysis. The user of this methodology is supposed to be the operator of critical infrastructure, or part of it, in the spirit of self-auditing. In case it would be implemented in a wider scale, in cooperation between the operators and authorities, it would give the authorities a holistic picture about the respective society’s critical infrastructure resilience. In this report, we draw a concise picture of the methodology and illustrate how this methodology could be applied to a specific infrastructure and hazard scenario.
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| 16. |
- Maguire, Kate, et al.
(author)
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SN 2020udy : an SN Iax with strict limits on interaction consistent with a helium-star companion
- 2023
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In: Monthly notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 525:1, s. 1210-1228
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Journal article (peer-reviewed)abstract
- Early observations of transient explosions can provide vital clues to their progenitor origins. In this paper, we present the nearby Type Iax (02cx-like) supernova (SN), SN 2020udy, that was discovered within hours (∼7 h) of estimated first light. An extensive data set of ultra-violet, optical, and near-infrared observations was obtained, covering out to ∼150 d after explosion. SN 2020udy peaked at −17.86 ± 0.43 mag in the r band and evolved similarly to other ‘luminous’ SNe Iax, such as SNe 2005hk and 2012Z. Its well-sampled early light curve allows strict limits on companion interaction to be placed. Main-sequence companion stars with masses of 2 and 6 M⊙ are ruled out at all viewing angles, while a helium-star companion is allowed from a narrow range of angles (140–180° away from the companion). The spectra and light curves of SN 2020udy are in good agreement with those of the ‘N5def’ deflagration model of a near Chandrasekhar-mass carbon–oxygen white dwarf. However, as has been seen in previous studies of similar luminosity events, SN 2020udy evolves slower than the model. Broad-band linear polarization measurements taken at and after peak are consistent with no polarization, in agreement with the predictions of the companion-star configuration from the early light-curve measurements. The host galaxy environment is low metallicity and is consistent with a young stellar population. Overall, we find the most plausible explosion scenario to be the incomplete disruption of a CO white dwarf near the Chandrasekhar-mass limit, with a helium-star companion.
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| 17. |
- Perley, Daniel A., et al.
(author)
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Real-time discovery of AT2020xnd : a fast, luminous ultraviolet transient with minimal radioactive ejecta
- 2021
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In: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 508:4, s. 5138-5147
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Journal article (peer-reviewed)abstract
- The many unusual properties of the enigmatic AT2018cow suggested that at least some subset of the empirical class of fast blue optical transients (FBOTs) represents a genuinely new astrophysical phenomenon. Unfortunately, the intrinsic rarity and fleeting nature of these events have made it difficult to identify additional examples early enough to acquire the observations necessary to constrain theoretical models. We present here the Zwicky Transient Facility discovery of AT2020xnd (ZTF20acigmel, the 'Camel') at z = 0.243, the first unambiguous AT2018cow analogue to be found and confirmed in real time. AT2018cow and AT2020xnd share all key observational properties: a fast optical rise, sustained high photospheric temperature, absence of a second peak attributable to ejection of a radioactively heated stellar envelope, extremely luminous radio, millimetre, and X-ray emission, and a dwarf-galaxy host. This supports the argument that AT2018cow-like events represent a distinct phenomenon from slower-evolving radio-quiet supernovae, likely requiring a different progenitor or a different central engine. The sample properties of the four known members of this class to date disfavour tidal disruption models but are consistent with the alternative model of an accretion powered jet following the direct collapse of a massive star to a black hole. Contextual filtering of alert streams combined with rapid photometric verification using multiband imaging provides an efficient way to identify future members of this class, even at high redshift.
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| 18. |
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| 19. |
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| 20. |
- Taioli, E, et al.
(author)
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Polymorphisms in CYP1A1, GSTM1, GSTT1 and lung cancer below the age of 45 years
- 2003
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In: International Journal of Epidemiology. - : Oxford University Press (OUP). - 1464-3685 .- 0300-5771. ; 32:1, s. 60-63
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Journal article (peer-reviewed)abstract
- Background A genetic component of early-onset lung cancer has been suggested. The role of metabolic gene polymorphisms has never been studied in young lung cancer cases. Phase 1 and Phase 2 gene polymorphisms are involved in tobacco carcinogens' metabolism and therefore in lung cancer risk. Methods The effect of metabolic gene polymorphisms on lung cancer at young ages was studied by pooling data from the Genetic Susceptibility to Environmental Carcinogens (GSEC) database. All primary lung cancer cases of both sexes who were Caucasian and less than or equal to45 years of age at diagnosis, and the corresponding controls were selected. We obtained 261 cases and 1452 controls. Results There was a marginally significant association between lung cancer and GST1 null genotype (OR = 1.2; 95% Cl: 1.0-1.6), and a significant association between lung cancer and the homozygous CYP1A1 Msp1 variant allele (CYP1A1*2A and *2B) genotype (OR = 4.7 95% Cl: 1.2-19.0). When data were stratified by smoking status, the association between CYP1A1 genotype and lung cancer was confined to never smokers. Conclusions These results suggest that metabolic genetic factors play a role in lung cancer developing at young ages.
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