The black hole transient MAXI J1348-630: evolution of the compact and transient jets during its 2019/2020 outburst

Monthly Notices of the Royal Astronomical Society Oxford University Press 504:1 (2021) 444-468

Authors:

F Carotenuto, S Corbel, E Tremou, Td Russell, A Tzioumis, Robert Fender, Pa Woudt, Sara Motta, Jca Miller-Jones, J Chauhan, Aj Tetarenko, Gr Sivakoff, Ian Heywood, A Horesh, Aj van der Horst, E Koerding, Kunal Mooley

Abstract:

We present the radio and X-ray monitoring campaign of the 2019/2020 outburst of MAXI J1348-630, a new black hole X-ray binary (BH XRB) discovered in 2019 January. We observed MAXI J1348-630 for ∼14 months in the radio band with MeerKAT and the Australia Telescope Compact Array, and in the X-rays with MAXI and Swift/XRT. Throughout the outburst, we detected and tracked the evolution of compact and transient jets. Following the main outburst, the system underwent at least four hard-state-only re-flares, during which compact jets were again detected. For the major outburst, we observed the rise, quenching and reactivation of compact jets, as well as two single-sided discrete ejecta travelling away from the BH, launched ∼2 months apart. These ejecta displayed the highest proper motion (≳100 mas d-1) ever measured for an accreting BH binary. From the jet motion, we constrain the ejecta inclination and speed to be ≤46° and ≥0.69 c, and the opening angle and transverse expansion speed of the first component to be ≤6° and ≤0.05 c. We also infer that the first ejection happened at the hard-to-soft state transition, before a strong radio flare, while the second ejection was launched during a short excursion from the soft to the intermediate state. After travelling with constant speed, the first component underwent a strong deceleration, which was covered with unprecedented detail and suggested that MAXI J1348-630 could be located inside a low-density cavity in the interstellar medium, as already proposed for XTE J1550-564 and H1743-322.

Hubble spectroscopy of LB-1: comparison with B+black-hole and Be+stripped-star models

(2021)

Authors:

DJ Lennon, J Maíz Apellániz, A Irrgang, R Bohlin, S Deustua, PL Dufton, S Simón-Díaz, A Herrero, J Casares, T Muñoz-Darias, SJ Smartt, JI González Hernández, A de Burgos

Linear anisotropies in dispersion-measure-based cosmological observables

(2021)

The novel Mechanical Ventilator Milano for the COVID-19 pandemic

Physics of Fluids AIP Publishing 33:3 (2021) 037122

Authors:

A Abba, C Accorsi, P Agnes, Jeffrey Tseng

Abstract:

This paper presents the Mechanical Ventilator Milano (MVM), a novel intensive therapy mechanical ventilator designed for rapid, large-scale, low-cost production for the COVID-19 pandemic. Free of moving mechanical parts and requiring only a source of compressed oxygen and medical air to operate, the MVM is designed to support the long-term invasive ventilation often required for COVID-19 patients and operates in pressure-regulated ventilation modes, which minimize the risk of furthering lung trauma. The MVM was extensively tested against ISO standards in the laboratory using a breathing simulator, with good agreement between input and measured breathing parameters and performing correctly in response to fault conditions and stability tests. The MVM has obtained Emergency Use Authorization by U.S. Food and Drug Administration (FDA) for use in healthcare settings during the COVID-19 pandemic and Health Canada Medical Device Authorization for Importation or Sale, under Interim Order for Use in Relation to COVID-19. Following these certifications, mass production is ongoing and distribution is under way in several countries. The MVM was designed, tested, prepared for certification, and mass produced in the space of a few months by a unique collaboration of respiratory healthcare professionals and experimental physicists, working with industrial partners, and is an excellent ventilator candidate for this pandemic anywhere in the world.

Cosmic shear power spectra in practice

Journal of Cosmology and Astroparticle Physics IOP Publishing 2021:3 (2021) 067

Authors:

A Nicola, Carlos Garcia-Garcia, David Alonso, J Dunkley, Pedro Ferreira, A Slosar, Dn Spergel

Abstract:

Cosmic shear is one of the most powerful probes of Dark Energy, targeted by several current and future galaxy surveys. Lensing shear, however, is only sampled at the positions of galaxies with measured shapes in the catalog, making its associated sky window function one of the most complicated amongst all projected cosmological probes of inhomogeneities, as well as giving rise to inhomogeneous noise. Partly for this reason, cosmic shear analyses have been mostly carried out in real-space, making use of correlation functions, as opposed to Fourier-space power spectra. Since the use of power spectra can yield complementary information and has numerical advantages over real-space pipelines, it is important to develop a complete formalism describing the standard unbiased power spectrum estimators as well as their associated uncertainties. Building on previous work, this paper contains a study of the main complications associated with estimating and interpreting shear power spectra, and presents fast and accurate methods to estimate two key quantities needed for their practical usage: the noise bias and the Gaussian covariance matrix, fully accounting for survey geometry, with some of these results also applicable to other cosmological probes. We demonstrate the performance of these methods by applying them to the latest public data releases of the Hyper Suprime-Cam and the Dark Energy Survey collaborations, quantifying the presence of systematics in our measurements and the validity of the covariance matrix estimate. We make the resulting power spectra, covariance matrices, null tests and all associated data necessary for a full cosmological analysis publicly available.