Runaway Eccentricity Growth: A Pathway for Binary Black Hole Mergers in AGN Disks

Binary black holes embedded within the accretion disks that fuel active galactic nuclei (AGN) are promising progenitors for the source of gravitational wave events detected by LIGO/VIRGO. Several recent studies have shown that when these binaries form they should be highly eccentric and retrograde. However, many uncertainties remain concerning the orbital evolution of these binaries as they either inspiral towards merger or disassociate. Previous hydrodynamical simulations exploring their orbital evolution have been predominantly two-dimensional, or have been restricted to binaries on nearly circular orbits. We present the first high-resolution, three-dimensional local shearing-box simulations of both prograde and retrograde eccentric binary black holes embedded in AGN disks. We find that retrograde binaries shrink several times faster than their prograde counterparts and exhibit significant orbital eccentricity growth, the rate of which monotonically increases with binary eccentricity. Our results suggest that retrograde binaries may experience runaway orbital eccentricity growth, which may bring them close enough together at pericenter for gravitational wave emission to drive them to coalescence. Although their eccentricity is damped, prograde binaries shrink much faster than their orbital eccentricity decays, suggesting they should remain modestly eccentric as they contract towards merger. Finally, binary precession driven by the AGN disk may dominate over precession induced by the supermassive black hole depending on the binary accretion rate and its location in the AGN disk, which can subdue the evection resonance and von Ziepel-Lidov-Kozai cycles.Comment: Corrected figures 11, 1

Mapping the Planetary Wake in HD 163296 with Kinematics

We map the planetary wake associated with the embedded protoplanet creating the CO kink in the disk of HD~163296. We show that the wake can be traced by a series of correlated perturbations in the peak velocity map. The sign change of the perturbations across the disk major axis confirm that the wake induces predominantly radial motion, as predicted by models of planet-disk interaction. These results provide the first direct confirmation of planet wakes generated by Lindblad resonances. Mapping the wake provides a constraint on the disk aspect ratio, which is required to measure the mass of the planet.Comment: 10 Pages, 6 figures. Accepted in ApJ

Signatures of an eccentric disc cavity: Dust and gas in IRS 48

We test the hypothesis that the disc cavity in the `transition disc' Oph IRS 48 is carved by an unseen binary companion. We use 3D dust-gas smoothed-particle hydrodynamics simulations to demonstrate that marginally coupled dust grains concentrate in the gas over-density that forms in in the cavity around a low binary mass ratio binary. This produces high contrast ratio dust asymmetries at the cavity edge similar to those observed in the disc around IRS 48 and other transition discs. This structure was previously assumed to be a vortex. However, we show that the observed velocity map of IRS 48 displays a peculiar asymmetry that is not predicted by the vortex hypothesis. We show the unusual kinematics are naturally explained by the non-Keplerian flow of gas in an eccentric circumbinary cavity. We further show that perturbations observed in the isovelocity curves of IRS 48 may be explained as the product of the dynamical interaction between the companion and the disc. The presence of a $\sim$0.4 M$_{\odot}$ companion at a $\sim$10 au separation can qualitatively explain these observations. High spatial resolution line and continuum imaging should be able to confirm this hypothesis.Comment: 9 pages, 7 figures, accepted for publication in MNRA

Kinematic and thermal signatures of the directly imaged protoplanet candidate around Elias 2-24

We report kinematic and thermal signatures associated with the directly imaged protoplanet candidate in the Elias 2-24 disc. Using the DSHARP ALMA observations of the $^{12}$CO J=2-1 line, we show that the disc kinematics are perturbed, with a detached CO emission spot at the location of the planet candidate and traces of spiral wakes, and also that the observed CO emission intensities require local heating. While the foreground extinction hides the velocity channels associated with the planet, preventing a planet mass estimate, the level of gas heating implied by the CO emission indicates the presence of a warm, embedded giant planet. Comparison with models show this could either be a $\gtrsim 5$M$_\mathrm{Jup}$, or a lower mass ( $\gtrsim 2$M$_\mathrm{Jup}$) but accreting proto-planet.Comment: 6 pages, 3 figures, accepted for publication in MNRAS Letter

Observational signatures of circumbinary discs - I. Kinematics

peer reviewedWe present five morphological and kinematic criteria to aid in asserting the binary nature of a protoplanetary disc, based on 3D hydrodynamical simulations of circumbinary discs post-processed with Monte Carlo radiative transfer. We find that circumbinary discs may be identified by (i) a central cavity, (ii) spiral arms both in and outside of their central cavities, (iii) non-localized perturbations in their iso-velocity curves, (iv) asymmetry between the lines of maximum speed of the blueshifted and redshifted wings, and (v) asymmetry between the area of the blueshifted and redshifted wings. We provide quantitative metrics for the last two criteria that can be used, in conjunction with the morphological criteria, to signal whether a protoplanetary disc is likely to be a circumbinary disc

Quasar accretion disk sizes from continuum reverberation mapping in the DES standard-star fields

Measurements of the physical properties of accretion disks in active galactic nuclei are important for better understanding the growth and evolution of supermassive black holes. We present the accretion disk sizes of 22 quasars from continuum reverberation mapping with data from the Dark Energy Survey (DES) standard star fields and the supernova C fields. We construct continuum lightcurves with the \textit{griz} photometry that span five seasons of DES observations. These data sample the time variability of the quasars with a cadence as short as one day, which corresponds to a rest frame cadence that is a factor of a few higher than most previous work. We derive time lags between bands with both JAVELIN and the interpolated cross-correlation function method, and fit for accretion disk sizes using the JAVELIN Thin Disk model. These new measurements include disks around black holes with masses as small as $\sim10^7$ $M_{\odot}$, which have equivalent sizes at 2500\AA \, as small as $\sim 0.1$ light days in the rest frame. We find that most objects have accretion disk sizes consistent with the prediction of the standard thin disk model when we take disk variability into account. We have also simulated the expected yield of accretion disk measurements under various observational scenarios for the Large Synoptic Survey Telescope Deep Drilling Fields. We find that the number of disk measurements would increase significantly if the default cadence is changed from three days to two days or one day.Comment: 33 pages, 24 figure

Cardiovascular risk factors and evolution of patients attended with COVID-19 in a National Reference Hospital from Lima, Peru

Introduction: Coronavirus disease 2019 (COVID-19) fatal outcomes have been associated with multiple cardiovascular risk factors. In new epidemic areas, such as Latin America, there is a lack of studies about this. Objectives: To evaluate demographic data, signs and symptoms during emergency arrival, prevalence of cardiovascular risk factors, laboratory and ECG findings and their influence in mortality, in a retrospective cohort of patients in a national reference hospital of Lima, Peru. Methods: Review the clinical records of the patients attended at Hospital Rebagliati Hospital during March 6th and April 30th, 2020, using rRT-PCR was used for the detection of the RNA of SARS-CoV-2 following the protocol Charité, Berlin, Germany, from nasopharyngeal swabs at the National Institute of Health. Bivariate analysis and multivariate analysis using logistic regression was done. Values of p < 0.05 were considered significant for all analyses. Results: One hundred six hospitalized patients were evaluated. The mean age of patients was 61.58 years (SD 16.81). Cardiovascular risk factors among them were hypertension (46.2%), diabetes (28.3%), and obesity (28.3%), among others. Fifty-six patients died (52.8%). Mortality associated factors at the multivariate analysis were arterial hypertension (OR=1.343, 95% 1.089-1.667), myocardial injury (OR=1.303, 95% 1.031-1.642), and mechanical ventilation (OR 1.262, 95% 1.034-1.665), as associated factors. Conclusion: Cardiovascular risk factors and cardiovascular signs or symptoms are common during emergency arrival in patients with COVID-19. Arterial hypertension, myocardial injury and mechanical ventilation were associated with mortality in multivariate analysis, as observed in other regions of the world.Introducción: Los desenlaces fatales de la enfermedad por coronavirus 2019 (COVID-19) se han asociado con múltiples factores de riesgo cardiovascular. En nuevas áreas epidémicas, como América Latina, faltan estudios al respecto. Objetivos: Evaluar datos demográficos, signos y síntomas durante la ingreso a emergencia, prevalencia de factores de riesgo cardiovascular, hallazgos de laboratorio y ECG y su influencia en la mortalidad, en una cohorte retrospectiva de pacientes en un hospital nacional de referencia de Lima, Perú. Métodos: Se revisaron las historias clínicas de los pacientes atendidos en el Hospital Nacional Edgardo Rebagliati durante los días 6 de marzo y 30 de abril de 2020, se utilizó rRT-PCR para la detección del ARN del SARS-CoV-2 siguiendo el protocolo Charité, Berlín, Alemania de hisopos nasofaríngeos en el Instituto Nacional de Salud. Se realizó análisis bivariado y análisis multivariado mediante regresión logística. Los valores de p <0,05 se consideraron significativos para todos los análisis. Resultados: Se evaluaron ciento seis pacientes hospitalizados. La edad media de los pacientes fue de 61,58 años (DE 16,81). Los factores de riesgo cardiovascular entre ellos fueron hipertensión (46,2%), diabetes (28,3%) y obesidad (28,3%), entre otros. Fallecieron 56 pacientes (52,8%). Los factores asociados a la mortalidad en el análisis multivariado fueron hipertensión arterial (OR = 1.343, 95% 1.089-1.667), lesión miocárdica (OR = 1.303, 95% 1.031-1.642) y ventilación mecánica (OR 1.262, 95% 1.034-1.665), como factores asociados. Conclusión: Los factores de riesgo cardiovascular y los signos o síntomas cardiovasculares son comunes durante la llegada de emergencia en pacientes con COVID-19. La hipertensión arterial, la lesión miocárdica y la ventilación mecánica se asociaron con la mortalidad en el análisis multivariado, como se observó en otras regiones del mundo

Recreating the OSIRIS-REx Slingshot Manoeuvre from a Network of Ground-Based Sensors

Optical tracking systems typically trade-off between astrometric precision and field-of-view. In this work, we showcase a networked approach to optical tracking using very wide field-of-view imagers that have relatively low astrometric precision on the scheduled OSIRIS-REx slingshot manoeuvre around Earth on September 22nd, 2017. As part of a trajectory designed to get OSIRIS-REx to NEO 101955 Bennu, this flyby event was viewed from 13 remote sensors spread across Australia and New Zealand to promote triangulatable observations. Each observatory in this portable network was constructed to be as lightweight and portable as possible, with hardware based off the successful design of the Desert Fireball Network. Over a 4 hour collection window, we gathered 15,439 images of the night sky in the predicted direction of the OSIRIS-REx spacecraft. Using a specially developed streak detection and orbit determination data pipeline, we detected 2,090 line-of-sight observations. Our fitted orbit was determined to be within about 10~km of orbital telemetry along the observed 109,262~km length of OSIRIS-REx trajectory, and thus demonstrating the impressive capability of a networked approach to SSA