The Properties of AGN in the context of X-ray Binaries

Black holes are undoubtedly the most fascinating and exciting objects in the Universe, capturing the imagination of scientists and film writers alike. It has been a long standing objective of the scientific community to understand how these objects work and whether the black holes seen in the centers of galaxies, including our own, show analogous physics to those seen in stellar mass binary systems in other parts of the galaxy. In this body of work I aim to introduce the reader to the many broad facets of the subject to which the first 4 chapters are dedicated. These explain the mechanisms allowing black holes to be seen, i.e. luminous accretion and reprocessing of radiation, the environments black holes are found in and the effect this can have on observations. The 5 chapters following the introduction are the papers that I have published from my studies in this field as I try to address the outstanding problems which present obstacles to our understanding of unified black hole accretion. I hope that you, the reader will find this work compelling in nature and an enjoyable insight into one of the greatest mysteries of the Universe

Global Three-Dimensional Radiation Magnetohydrodynamic Simulations of Accretion onto a Stellar Mass Black Hole at Sub- and Near-critical Accretion Rates

We present global 3D radiation magnetohydrodynamical simulations of accretion onto a 6.62 solar mass black hole with quasi-steady state accretion rates reaching 0.016 to 0.9 times the critical accretion rate, which is defined as the accretion rate to power the Eddington luminosity assuming a 10% radiative efficiency, in different runs. The simulations show no sign of thermal instability over hundreds of thermal timescales at 10 $r_{\rm g}$. The energy dissipation happens close to the mid-plane in the near-critical runs and near the disk surface in the low accretion rate run. The total radiative luminosity inside $\sim$20 $r_{\rm g}$ is about 1% to 30% the Eddington limit, with a radiative efficiency of about 6% and 3%, respectively, in the sub- and near-critical accretion regimes. In both cases, self-consistent turbulence generated by the magnetorotational instability (MRI) leads to angular momentum transfer, and the disk is supported by magnetic pressure. Outflows from the central low-density funnel with a terminal velocity of $\sim$0.1$c$ are seen only in the near-critical runs. We conclude that these magnetic pressure dominated disks are thermally stable and thicker than the $\alpha$ disk, and the effective temperature profiles are much flatter than that in the $\alpha$ disks. The magnetic pressure of these disks are comparable within an order of magnitude with the previous analytical magnetic pressure dominated disk model.Comment: 17 pages, 13 figures, 3 tables, accepted for publication in Ap

On the Spin of the Black Hole in IC 10 X-1

The compact X-ray source in the eclipsing X-ray binary IC 10 X–1 has reigned for years as ostensibly the most massive stellar-mass black hole, with a mass estimated to be about twice that of its closest rival. However, striking results presented recently by Laycock et al. reveal that the mass estimate, based on emission-line velocities, is unreliable and that the mass of the X-ray source is essentially unconstrained. Using Chandra and NuSTAR data, we rule against a neutron-star model and conclude that IC 10 X–1 contains a black hole. The eclipse duration of IC 10 X–1 is shorter and its depth shallower at higher energies, an effect consistent with the X-ray emission being obscured during eclipse by a Compton-thick core of a dense wind. The spectrum is strongly disk-dominated, which allows us to constrain the spin of the black hole via X-ray continuum fitting. Three other wind-fed black hole systems are known; the masses and spins of their black holes are high: M ~ 10 - 15M_☉ and ɑ_* > 0.8. If the mass of IC 10 X-1's black hole is comparable, then its spin is likewise high

THE OPTICAL-UV EMISSIVITY OF QUASARS: DEPENDENCE ON BLACK HOLE MASS AND RADIO LOUDNESS

We analyzed a large sample of radio-loud and radio-quiet quasar spectra at redshift 1.0 < z < 1.2 to compare the inferred underlying quasar continuum slopes (after removal of the host galaxy contribution) with accretion disk models. The latter predict redder (decreasing) alpha_3000 continuum slopes (L_\nu~\nu^alpha at 3000Ang) with increasing black hole mass, bluer alpha_3000 with increasing luminosity at 3000Ang, and bluer alpha_3000 with increasing spin of the black hole, when all other parameters are held fixed. We find no clear evidence for any of these predictions in the data. In particular we find that: (i) alpha_3000 shows no significant dependence on black hole mass or luminosity. Dedicated Monte Carlo tests suggest that the substantial observational uncertainties in the black hole virial masses can effectively erase any intrinsic dependence of alpha_3000 on black hole mass, in line with some previous studies. (ii) The mean slope alpha_3000 of radio-loud sources, thought to be produced by rapidly spinning black holes, is comparable to, or even redder than, that of radio-quiet quasars. Indeed, although quasars appear to become more radio loud with decreasing luminosity, we still do not detect any significant dependence of alpha_3000 on radio loudness. The predicted mean alpha_3000 slopes tend to be bluer than in the data. Disk models with high inclinations and dust extinction tend to produce redder slopes closer to empirical estimates. Our mean alpha_3000 values are close to the ones independently inferred at z<0.5 suggesting weak evolution with redshift, at least for moderately luminous quasars.This is the author accepted manuscript. The final version is available from the Institute of Physics via http://dx.doi.org/10.3847/2041-8205/818/1/L

COVID-19: Third dose booster vaccine effectiveness against breakthrough coronavirus infection, hospitalisations and death in patients with cancer: A population-based study

Purpose: People living with cancer and haematological malignancies are at increased risk of hospitalisation and death following infection with acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronavirus third dose vaccine boosters are proposed to boost waning immune responses in immunocompromised individuals and increase coronavirus protection; however, their effectiveness has not yet been systematically evaluated. Methods: This study is a population-scale real-world evaluation of the United Kingdom’s third dose vaccine booster programme for cancer patients from 8th December 2020 to 7th December 2021. The cancer cohort comprises individuals from Public Health England’s national cancer dataset, excluding individuals less than 18 years. A test-negative case-control design was used to assess third dose booster vaccine effectiveness. Multivariable logistic regression models were fitted to compare risk in the cancer cohort relative to the general population. Results: The cancer cohort comprised of 2,258,553 tests from 361,098 individuals. Third dose boosters were evaluated by reference to 87,039,743 polymerase chain reaction (PCR) coronavirus tests. Vaccine effectiveness against breakthrough infections, symptomatic infections, coronavirus hospitalisation and death in cancer patients were 59.1%, 62.8%, 80.5% and 94.5% respectively. Lower vaccine effectiveness was associated with a cancer diagnosis within 12 months, lymphoma, recent systemic anti-cancer therapy (SACT) or radiotherapy. Lymphoma patients had low levels of protection from symptomatic disease. In spite of third dose boosters, following multivariable adjustment, individuals with cancer remain at increased risk of coronavirus hospitalisation and death compared to the population control (OR 3.38, 3.01 respectively. p<0.001 for both). Conclusions: Third dose boosters are effective for most individuals with cancer, increasing protection from coronavirus. However, their effectiveness is heterogenous, and lower than the general population. Many patients with cancer will remain at increased risk of coronavirus infections, even after 3 doses. In the case of patients with lymphoma, there is a particularly strong disparity of vaccine effectiveness against breakthrough infection and severe disease. Breakthrough infections will disrupt cancer care and treatment with potentially adverse consequences on survival outcomes. The data support the role of vaccine boosters in preventing severe disease, and further pharmacological intervention to prevent transmission and aid viral clearance to limit disruption of cancer care as the delivery of care continues to evolve during the coronavirus pandemic

Project overview and update on WEAVE: the next generation wide-field spectroscopy facility for the William Herschel Telescope

We present an overview of and status report on the WEAVE next-generation spectroscopy facility for the William Herschel Telescope (WHT). WEAVE principally targets optical ground-based follow up of upcoming ground-based (LOFAR) and space-based (Gaia) surveys. WEAVE is a multi-object and multi-IFU facility utilizing a new 2-degree prime focus field of view at the WHT, with a buffered pick-and-place positioner system hosting 1000 multi-object (MOS) fibres, 20 integral field units, or a single large IFU for each observation. The fibres are fed to a single spectrograph, with a pair of 8k(spectral) x 6k (spatial) pixel cameras, located within the WHT GHRIL enclosure on the telescope Nasmyth platform, supporting observations at R~5000 over the full 370-1000nm wavelength range in a single exposure, or a high resolution mode with limited coverage in each arm at R~20000. The project is now in the final design and early procurement phase, with commissioning at the telescope expected in 2017.Comment: 11 pages, 11 Figures, Summary of a presentation to Astronomical Telescopes and Instrumentation 201

The future of evapotranspiration : global requirements for ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources

The fate of the terrestrial biosphere is highly uncertain given recent and projected changes in climate. This is especially acute for impacts associated with changes in drought frequency and intensity on the distribution and timing of water availability. The development of effective adaptation strategies for these emerging threats to food and water security are compromised by limitations in our understanding of how natural and managed ecosystems are responding to changing hydrological and climatological regimes. This information gap is exacerbated by insufficient monitoring capabilities from local to global scales. Here, we describe how evapotranspiration (ET) represents the key variable in linking ecosystem functioning, carbon and climate feedbacks, agricultural management, and water resources, and highlight both the outstanding science and applications questions and the actions, especially from a space-based perspective, necessary to advance them

IL7 genetic variation and toxicity to immune checkpoint blockade in patients with melanoma

Treatment with immune checkpoint blockade (ICB) frequently triggers immune-related adverse events (irAEs), causing considerable morbidity. In 214 patients receiving ICB for melanoma, we observed increased severe irAE risk in minor allele carriers of rs16906115, intronic to IL7. We found that rs16906115 forms a B cell-specific expression quantitative trait locus (eQTL) to IL7 in patients. Patients carrying the risk allele demonstrate increased pre-treatment B cell IL7 expression, which independently associates with irAE risk, divergent immunoglobulin expression and more B cell receptor mutations. Consistent with the role of IL-7 in T cell development, risk allele carriers have distinct ICB-induced CD8+ T cell subset responses, skewing of T cell clonality and greater proportional repertoire occupancy by large clones. Finally, analysis of TCGA data suggests that risk allele carriers independently have improved melanoma survival. These observations highlight key roles for B cells and IL-7 in both ICB response and toxicity and clinical outcomes in melanoma