The Gravity Collective: A Search for the Electromagnetic Counterpart to the Neutron Star-Black Hole Merger GW190814

We present optical follow-up imaging obtained with the Katzman Automatic Imaging Telescope, Las Cumbres Observatory Global Telescope Network, Nickel Telescope, Swope Telescope, and Thacher Telescope of the LIGO/Virgo gravitational wave (GW) signal from the neutron star-black hole (NSBH) merger GW190814. We searched the GW190814 localization region (19 deg$^{2}$ for the 90th percentile best localization), covering a total of 51 deg$^{2}$ and 94.6% of the two-dimensional localization region. Analyzing the properties of 189 transients that we consider as candidate counterparts to the NSBH merger, including their localizations, discovery times from merger, optical spectra, likely host-galaxy redshifts, and photometric evolution, we conclude that none of these objects are likely to be associated with GW190814. Based on this finding, we consider the likely optical properties of an electromagnetic counterpart to GW190814, including possible kilonovae and short gamma-ray burst afterglows. Using the joint limits from our follow-up imaging, we conclude that a counterpart with an $r$-band decline rate of 0.68 mag day$^{-1}$, similar to the kilonova AT 2017gfo, could peak at an absolute magnitude of at most $-17.8$ mag (50% confidence). Our data are not constraining for ''red'' kilonovae and rule out ''blue'' kilonovae with $M>0.5 M_{\odot}$ (30% confidence). We strongly rule out all known types of short gamma-ray burst afterglows with viewing angles $<$17$^{\circ}$ assuming an initial jet opening angle of $\sim$$5.2^{\circ}$ and explosion energies and circumburst densities similar to afterglows explored in the literature. Finally, we explore the possibility that GW190814 merged in the disk of an active galactic nucleus, of which we find four in the localization region, but we do not find any candidate counterparts among these sources.Comment: 86 pages, 9 figure

SN2017jgh: a high-cadence complete shock cooling light curve of a SN IIb with the Kepler telescope

SN 2017jgh is a type IIb supernova discovered by Pan-STARRS during the C16/C17 campaigns of the Kepler/K2 mission. Here, we present the Kepler/K2 and ground based observations of SN 2017jgh, which captured the shock cooling of the progenitor shock breakout with an unprecedented cadence. This event presents a unique opportunity to investigate the progenitors of stripped envelope supernovae. By fitting analytical models to the SN 2017jgh light curve, we find that the progenitor of SN 2017jgh was likely a yellow supergiant with an envelope radius of ∼50−290R⊙ ⁠, and an envelope mass of ∼0−1.7M⊙ ⁠. SN 2017jgh likely had a shock velocity of ∼7500−10 300 km s−1. Additionally, we use the light curve of SN 2017jgh to investigate how early observations of the rise contribute to constraints on progenitor models. Fitting just the ground based observations, we find an envelope radius of ∼50−330R⊙ ⁠, an envelope mass of ∼0.3−1.7M⊙ and a shock velocity of ∼9000−15 000 km s−1. Without the rise, the explosion time cannot be well constrained that leads to a systematic offset in the velocity parameter and larger uncertainties in the mass and radius. Therefore, it is likely that progenitor property estimates through these models may have larger systematic uncertainties than previously calculated

Parrhesia, eros, polis

L’intento di questa giornata di studi è promuovere un’interrogazione del nostro tempo a partire dalla rilettura della tragedia greca. La convinzione che motiva questa proposta è che la tragedia antica rappresenti una drammaturgia di condotte, dilemmi morali, problemi politici che segnano l’esistenza individuale e la convivenza sociale. Il combinarsi di una messa in atto di storie, che investono la parola e i corpi dei personaggi, con la riflessione sulla vita umana – non di rado col contributo decisivo del coro – offrono concetti, suscitano emozioni, indicano piste di pensiero dalla valenza etico-politica. Tale convinzione è suffragata dai numerosi riferimenti ai tragici greci presenti nel pensiero contemporaneo

Gli esperti

The peculiar role of experts in international investment arbitration is the result of the great differences among civil law and common law legal traditions in this regard. While the former grants judges the power to ap- point an independent expert acting as their auxiliary, the latter provides that they decide based on their free assessment of party-appointed experts. Though the second model is vastly predominant in the practice of investment arbi- tration, the principle of freedom of form that characterizes the evidentiary phase of these proceedings implies that both kinds of expertise may be ad- mitted even in the same arbitration procedure, the independent expert fol- lowing the party-appointed experts. The present contribution thus aims at tracing the provisions dealing with experts that may be found in interna- tional arbitration rules and soft law instruments, so as to identify their fea- tures and duties, as well as the tools that the arbitral tribunal may use, while making its decision, in assessing party-appointed expert evidence

Sull’(in)esistenza di un diritto all’udienza fisica negli arbitrati rituali con sede in Italia

Since the beginning of the Covid-19 pandemic, the arbitral community has made recourse to its celebrated flexibility in order to face the unprecedented challenge of delivering justice and respecting due process, while also complying with the emergency measures put in place to safeguard public health. This has translated into a surge in arbitral hearings conducted through video conference, raising however a new legal question: Does a right to a physical hearing exist in arbitration? The present essay aims at answering this question through an analysis of the relevant provisions of the law regulating arbitration proceedings in Italy, as well as the general rules of civil procedure. It further analyzes whether the failure to conduct a physical hearing, either against the parties’ agreement to hold one or over one party’s objection, may have an impact on the validity of the award and on the recognition and enforcement of foreign awards. Finally, it conducts a critical review of the emergency legislation that was recently enacted in Italy