Observational effects of strong gravity

It is now a century since Einstein tore down the edifice of classical physics, ultimately replacing it with his crowning achievement, the General Theory of Relativity, the most remarkable prediction of which is the black hole. There are many astrophysical examples of black holes, understanding which has long been a goal of high-energy astronomy. We review how these observations can be explained in terms of a two-phase accretion flow. Hard X-ray photons produced in an optically thin gas are reflected from a cool accretion disk, resulting in a complex reflection spectra, which are dominated by a narrow Iron Кα fluorescence feature at 6.4 keV (dependent on the ionisation state of the cool disk). The photons that form this spectral feature originate in rapidly moving material, close to the black event horizon. They are therefore subject to the combined dynamical effects of the accretion disk and those of General Relativity, resulting in a highly broadened line Profile. The observed form of the line can then, in principle, be used as a test of the strong gravitational field of the black hole. We have developed a new, extremely fast strong gravity code that accurately calculates the effect of strong gravity on photons originating close to the black hole event horizon, including the ability to calculate the trajectories of photons that perform multiple orbits of the black hole. We compare results from the code to the standard models describing relativistic smeared lines available to the community, finding that they match to within ~ 5%. We apply this code to the observed shape of the Iron Κα line and show that the (poorly understood) vertical structure of the accretion disk strongly affects the derived radial emissivity profile, which has important consequences for the interpretation of observational data. Following on from this, we consider the spectral and imaging properties of thin Keplerian accretion disks, fully including the effects of photons that perform multiple orbits of the black hole. Viewed at high inclinations, these photons can carry as much as ~ 60% of the total luminosity of the system, which returns to the disk at a range of radii. At low inclinations, the multiple orbit photons re-intercept the disk plane close to the black hole. For a Schwarzschild black hole, this lies within the plunging region and so the photons need not be absorbed by the disk. The resultant ring is bright it may well be possible to use these as a future test of strong gravity via X-ray interferometrie images of accreting black holes. Finally, we examine the observational properties of accretion flows where angular momentum transport is provided by the Magneto-Rotational Instability. It is shown that the dissipation profile derived from the magnetic 4-current density in these simulations provides a remarkably close match to that derived from the standard relativistic disk model at large radii. At small radii however, the descriptions of dissipation in the two models are rather different, which has important observational consequences. With this model of dissipation, we examine the observed properties of optically thin accretion flows, discussing the implications of these calculations for the low I hard state of Galactic Black Holes, Additionally, we describe a simple reflection geometry for Iron Kα fluorescence, assuming that this MHD flow is optically thick in the equatorial plane. The resultant line shapes are markedly different to those predicted in the standard relativistic disk model, showing that the (currently unknown) flow dynamics are also important in shaping the line

State School Finance in the Mountain West, 2019

This fact sheet examines K-12 school finance indicators drawing from an original report by Albert Shanker Institute and Rutgers University Graduate School of Education. These indicators show whether states are funding school districts to national standards. This fact sheet examines state-level data for the Mountain West (Arizona, Colorado, Nevada, New Mexico, and Utah) from the State School Finance Profiles report for the 2018-2019 school year

A framework for experimental-data-driven assessment of Magnetized Liner Inertial Fusion stagnation image metrics

A variety of spherical crystal x-ray imager (SCXI) diagnostics have been developed and fielded on Magnetized Liner Inertial Fusion (MagLIF) experiments at the Sandia National Laboratories Z-facility. These different imaging modalities provide detailed insight into different physical phenomena such as mix of liner material into the hot fuel, cold liner emission, or reduce impact of liner opacity. However, several practical considerations ranging from the lack of a consistent spatial fiducial for registration to different point-spread-functions and tuning crystals or using filters to highlight specific spectral regions make it difficult to develop broadly applicable metrics to compare experiments across our stagnation image database without making significant unverified assumptions. We leverage experimental data for a model-free assessment of sensitivities to instrumentation-based features for any specified image metric. In particular, we utilize a database of historical and recent MagLIF data including $N_{\text{scans}} = 139$ image plate scans gathered across $N_{\text{exp}} = 67$ different experiments to assess the impact of a variety of features in the experimental observations arising from uncertainties in registration as well as discrepancies in signal-to-noise ratio and instrument resolution. We choose a wavelet-based image metric known as the Mallat Scattering Transform for the study and highlight how alternate metric choices could also be studied. In particular, we demonstrate a capability to understand and mitigate the impact of signal-to-noise, image registration, and resolution difference between images. This is achieved by utilizing multiple scans of the same image plate, sampling random translations and rotations, and applying instrument specific point-spread-functions found by ray tracing to high-resolution datasets, augmenting our data in an effectively model-free fashion.Comment: 17 pages, 14 figure

Housing Affordability for Top Occupations in Nevada Metros, 2022

This fact sheet combines housing and employment data from the National Housing Conference (NHC) and the Bureau of Labor Statistics (BLS) to examine housing affordability for the 10 most common occupations in the Las Vegas-Henderson-Paradise, NV and the Reno-Sparks, NV metropolitan statistical areas (MSAs) in Quarter 1 of 2022

Toll-Like Receptor 8 Is a Major Sensor of Group B Streptococcus But Not Escherichia coli in Human Primary Monocytes and Macrophages

TLR8 is the major endosomal sensor of degraded RNA in human monocytes and macrophages. It has been implicated in the sensing of viruses and more recently also bacteria. We previously identified a TLR8-IFN regulatory factor 5 (IRF5) signaling pathway that mediates IFNβ and interleukin-12 (IL-12) induction by Staphylococcus aureus and is antagonized by TLR2. The relative importance of TLR8 for the sensing of various bacterial species is however still unclear. We here compared the role of TLR8 and IRF5 for the sensing of Group B Streptococcus (GBS), S. aureus, and Escherichia coli in human primary monocytes and monocyte-derived macrophages (MDM). GBS induced stronger IFNβ and TNF production as well as IRF5 nuclear translocation compared to S. aureus grown to the stationary phase, while S. aureus in exponential growth appeared similarly potent to GBS. Cytokine induction in primary human monocytes by GBS was not dependent on hemolysins, and induction of IFNβ and IL-12 as well as IRF5 activation were reduced with TLR2 ligand costimulation. Heat inactivation of GBS reduced IRF5 and NF-kB translocation, while only the viable E. coli activated IRF5. The attenuated stimulation correlated with loss of bacterial RNA integrity. The E. coli-induced IRF5 translocation was not inhibited by TLR2 costimulation, suggesting that IRF5 was activated via a TLR8-independent mechanism. Gene silencing of MDM using siRNA revealed that GBS-induced IFNβ, IL-12-p35, and TNF production was dependent on TLR8 and IRF5. In contrast, cytokine induction by E. coli was TLR8 independent but still partly dependent on IRF5. We conclude that TLR8-IRF5 signaling is more important for the sensing of GBS than for stationary grown S. aureus in human primary monocytes and MDM, likely due to reduced resistance of GBS to phagosomal degradation and to a lower production of TLR2 activating lipoproteins. TLR8 does not sense viable E. coli, while IRF5 still contributes to E. coli-induced cytokine production, possibly via a cytosolic nucleic acid sensing mechanism

Toll-Like Receptor 8 Is a Major Sensor of Group B Streptococcus But Not Escherichia coli in Human Primary Monocytes and Macrophages

TLR8 is the major endosomal sensor of degraded RNA in human monocytes and macrophages. It has been implicated in the sensing of viruses and more recently also bacteria. We previously identified a TLR8-IFN regulatory factor 5 (IRF5) signaling pathway that mediates IFNβ and interleukin-12 (IL-12) induction by Staphylococcus aureus and is antagonized by TLR2. The relative importance of TLR8 for the sensing of various bacterial species is however still unclear. We here compared the role of TLR8 and IRF5 for the sensing of Group B Streptococcus (GBS), S. aureus, and Escherichia coli in human primary monocytes and monocyte-derived macrophages (MDM). GBS induced stronger IFNβ and TNF production as well as IRF5 nuclear translocation compared to S. aureus grown to the stationary phase, while S. aureus in exponential growth appeared similarly potent to GBS. Cytokine induction in primary human monocytes by GBS was not dependent on hemolysins, and induction of IFNβ and IL-12 as well as IRF5 activation were reduced with TLR2 ligand costimulation. Heat inactivation of GBS reduced IRF5 and NF-kB translocation, while only the viable E. coli activated IRF5. The attenuated stimulation correlated with loss of bacterial RNA integrity. The E. coli-induced IRF5 translocation was not inhibited by TLR2 costimulation, suggesting that IRF5 was activated via a TLR8-independent mechanism. Gene silencing of MDM using siRNA revealed that GBS-induced IFNβ, IL-12-p35, and TNF production was dependent on TLR8 and IRF5. In contrast, cytokine induction by E. coli was TLR8 independent but still partly dependent on IRF5. We conclude that TLR8-IRF5 signaling is more important for the sensing of GBS than for stationary grown S. aureus in human primary monocytes and MDM, likely due to reduced resistance of GBS to phagosomal degradation and to a lower production of TLR2 activating lipoproteins. TLR8 does not sense viable E. coli, while IRF5 still contributes to E. coli-induced cytokine production, possibly via a cytosolic nucleic acid sensing mechanism

Toll-Like Receptor 8 Is a Major Sensor of Group B Streptococcus But Not Escherichia coli in Human Primary Monocytes and Macrophages

TLR8 is the major endosomal sensor of degraded RNA in human monocytes and macrophages. It has been implicated in the sensing of viruses and more recently also bacteria. We previously identified a TLR8-IFN regulatory factor 5 (IRF5) signaling pathway that mediates IFNβ and interleukin-12 (IL-12) induction by Staphylococcus aureus and is antagonized by TLR2. The relative importance of TLR8 for the sensing of various bacterial species is however still unclear. We here compared the role of TLR8 and IRF5 for the sensing of Group B Streptococcus (GBS), S. aureus, and Escherichia coli in human primary monocytes and monocyte-derived macrophages (MDM). GBS induced stronger IFNβ and TNF production as well as IRF5 nuclear translocation compared to S. aureus grown to the stationary phase, while S. aureus in exponential growth appeared similarly potent to GBS. Cytokine induction in primary human monocytes by GBS was not dependent on hemolysins, and induction of IFNβ and IL-12 as well as IRF5 activation were reduced with TLR2 ligand costimulation. Heat inactivation of GBS reduced IRF5 and NF-kB translocation, while only the viable E. coli activated IRF5. The attenuated stimulation correlated with loss of bacterial RNA integrity. The E. coli-induced IRF5 translocation was not inhibited by TLR2 costimulation, suggesting that IRF5 was activated via a TLR8-independent mechanism. Gene silencing of MDM using siRNA revealed that GBS-induced IFNβ, IL-12-p35, and TNF production was dependent on TLR8 and IRF5. In contrast, cytokine induction by E. coli was TLR8 independent but still partly dependent on IRF5. We conclude that TLR8-IRF5 signaling is more important for the sensing of GBS than for stationary grown S. aureus in human primary monocytes and MDM, likely due to reduced resistance of GBS to phagosomal degradation and to a lower production of TLR2 activating lipoproteins. TLR8 does not sense viable E. coli, while IRF5 still contributes to E. coli-induced cytokine production, possibly via a cytosolic nucleic acid sensing mechanism