Legendre expansion of the neutrino-antineutrino annihilation kernel: Influence of high order terms

We calculate the Legendre expansion of the rate of the process $\nu + \bar{\nu} \leftrightarrow e^+ + e^-$ up to 3rd order extending previous results of other authors which only consider the 0th and 1st order terms. Using different closure relations for the moment equations of the radiative transfer equation we discuss the physical implications of taking into account quadratic and cubic terms on the energy deposition outside the neutrinosphere in a simplified model. The main conclusion is that 2nd order is necessary in the semi-transparent region and gives good results if an appropriate closure relation is used.Comment: 14 pages, 4 figures. To be published in A&A Supplement Serie

The paradoxes of applying ethnography at a distance: Dürer’s Rhinoceros

In 1515, Albrecht Dürer received news of an animal encased in armour: it was an Indian rhinoceros which was being transported towards Rome as a present for Pope Leo X. The description and a sketch of the animal, arrived in Dürer’s hands, he made a woodcut that Europeans came to adopt as the true depiction of the rhinoceros. Dürer would never see an actual rhinoceros in his life. Nevertheless, this legendary woodcut creature shaped the public perception of a rhinoceros for the next two centuries. Is it art’s idealisation of the natural world the answer to overcoming distance? Or are metaphors just another type of truth? Prevented by the Covid-19 circumstances from going out to the field, Dürer’s Rhinoceros has become more than a metaphor for my project. My research included the production of a documentary in-situ, which soon changed for the production of a documentary at a distance. The different narratives created by the socio-cultural context and the documentary filmmaker’s commitment to truth hang over her like a sword of Damocles. I attempted to find solutions and other ways to reproduce the same proximity at a distance resourcing to online/research. In a moment of enthusiasm, and encouraged by early investigations, I wrote: ‘To recreate the proximity that this research needs, it is necessary to devise a new methodology, incorporating a strong network of collaborators, between researchers in the field, leaders of organisations and individuals prepared to communicate at a distance in a collective and polyphonic way’. This paper will analyse the different methods of conducting an online research in times of pandemic and crisis, to determine how narratives are created. As with Dürer’s woodcut, Rhinoceros, reality is very different

Maya women contest online narratives in action: creating equality through horizontal communication

Feminist Maya women have been contesting the narrative imposed by the state, social prejudices and media-imposed perceptions in contemporary Guatemala, reclaiming their place in society. This has been documented from an indigenous perspective (Chirix, 2008; Hernández-Castillo, 2010; Tzul Tzul, 2018; Cumes, 2019). In the long thread of history the indigenous population of Guatemala has resisted colonial imposition through the use of multiple strategies of adaptation, sometimes utilising elements of the dominant culture. In this case the creation of an online/virtual place in social media to defend and fight for their rights during the Covid-19 pandemic. By studying the case of the Guatemalan National Midwives Movement from a decolonial perspective and analysing the online development of: horizontal communication theory (Beltrán, 1979), in exceptional pandemic circumstances, will allow us to uncover: how indigenous women define their identity in relation to their knowledge, world-views and philosophies in their own voices, beyond any type of discrimination social or economic. This will enable a better understanding of how their communal organisational and communication strategies differ from Western individualism. However, social media cannot be fully representative of the indigenous midwives’ culture. The process of conveying meanings by words in a language that it is not your own and in contested media, such as an online/virtual place, certainly implies a process of surrendering. As Rivera Cusicanqui (2020) argues ‘in colonialism there is a very particular function for words, they do not name, they mask.’ This paper concludes that feminist decolonisation, cannot solely be rhetoric, but needs to be put to practice in every action

Beyond the pale?: the implications of the RSLG Report for non-CURL modern university libraries: Perspectives on the support libraries group: Final report

We have shown that the cluster-mass reconstruction method which combines strong and weak gravitational lensing data, developed in the first paper in the series, successfully reconstructs the mass distribution of a simulated cluster. In this paper we apply the method to the ground-based high-quality multi-colour data of RX J1347.5-114

Population Synthesis of Isolated Neutron Stars with magneto-rotational evolution II: from radio-pulsars to magnetars

Population synthesis studies constitute a powerful method to reconstruct the birth distribution of periods and magnetic fields of the pulsar population. When this method is applied to populations in different wavelengths, it can break the degeneracy in the inferred properties of initial distributions that arises from single-band studies. In this context, we extend previous works to include $X$-ray thermal emitting pulsars within the same evolutionary model as radio-pulsars. We find that the cumulative distribution of the number of X-ray pulsars can be well reproduced by several models that, simultaneously, reproduce the characteristics of the radio-pulsar distribution. However, even considering the most favourable magneto-thermal evolution models with fast field decay, log-normal distributions of the initial magnetic field over-predict the number of visible sources with periods longer than 12 s. We then show that the problem can be solved with different distributions of magnetic field, such as a truncated log-normal distribution, or a binormal distribution with two distinct populations. We use the observational lack of isolated NSs with spin periods P>12 s to establish an upper limit to the fraction of magnetars born with B > 10^{15} G (less than 1\%). As future detections keep increasing the magnetar and high-B pulsar statistics, our approach can be used to establish a severe constraint on the maximum magnetic field at birth of NSs.Comment: 12 pages, 11 figures, 5 table