X-ray Absorption and Reflection in Active Galactic Nuclei

X-ray spectroscopy offers an opportunity to study the complex mixture of emitting and absorbing components in the circumnuclear regions of active galactic nuclei, and to learn about the accretion process that fuels AGN and the feedback of material to their host galaxies. We describe the spectral signatures that may be studied and review the X-ray spectra and spectral variability of active galaxies, concentrating on progress from recent Chandra, XMM-Newton and Suzaku data for local type 1 AGN. We describe the evidence for absorption covering a wide range of column densities, ionization and dynamics, and discuss the growing evidence for partial-covering absorption from data at energies > 10 keV. Such absorption can also explain the observed X-ray spectral curvature and variability in AGN at lower energies and is likely an important factor in shaping the observed properties of this class of source. Consideration of self-consistent models for local AGN indicates that X-ray spectra likely comprise a combination of absorption and reflection effects from material originating within a few light days of the black hole as well as on larger scales. It is likely that AGN X-ray spectra may be strongly affected by the presence of disk-wind outflows that are expected in systems with high accretion rates, and we describe models that attempt to predict the effects of radiative transfer through such winds, and discuss the prospects for new data to test and address these ideas.Comment: Accepted for publication in the Astronomy and Astrophysics Review. 58 pages, 9 figures. V2 has fixed an error in footnote

The evolution of galaxies from primeval irregulars to present-day ellipticals

The current understanding of galaxy formation is that it proceeds in a 'bottom up' way, with the formation of small clumps of gas and stars that merge hierarchically until giant galaxies are built up. The baryonic gas loses the thermal energy by radiative cooling and falls towards the centres of the new galaxies, while supernovae (SNe) blow gas out. Any realistic model therefore requires a proper treatment of these processes, but hitherto this has been far from satisfactory. Here we report an ultra-high-resolution simulation that follows evolution from the earliest stages of galaxy formation through the period of dynamical relaxation. The bubble structures of gas revealed in our simulation ($< 3\times10^8$ years) resemble closely the high-redshift Lyman $\alpha$ emitters (LAEs). After $10^9$ years these bodies are dominated by stellar continuum radiation and look like the Lyman break galaxies (LBGs) known as the high-redshift star-forming galaxies at which point the abundance of elements heavier than helium ("metallicity") appears to be solar. After $1.3\times10^{10}$ years, these galaxies resemble present-day ellipticals.Comment: 27 pages and 4 figures, Supplementary Information included, movie available on http://www.isc.senshu-u.ac.jp/~thj0613/natur

Past, Present, and Future X-Ray and Gamma-Ray Missions

X- and -ray astronomy began in the early sixties of the last century with balloons flights, sounding rocket experiment and satellites. Long before space satellite detected X- and -rays emitted by cosmic sources, scientists had known that the Universe should be producing these photons. In this chapter we provided an overview of past and present missions that has made the X- and -ray astronomy an integral part of astronomical research, and prospects of future developments

Risk factors for failure of the 36 mm metal-on-metal Pinnacle total hip replacement system: a retrospective single-centre cohort study

Aims: To determine 10-year failure rates following 36mm metal-on-metal (MoM) Pinnacle total hip replacement (THR), and identify predictors of failure. Methods: We retrospectively assessed a single-centre cohort of 569 primary 36mm MoM Pinnacle THRs (all Corail stems) followed up since 2012 according to MHRA recommendations. Allcause failure rates (all-cause revision, and non-revised cross-sectional imaging failures) were calculated, with predictors for failure identified using multivariable Cox regression. Results: Failure occurred in 97 hips (17.0%). The 10-year cumulative failure rate was 27.1% (95% CI=21.6%-33.7%). Primary implantation from 2006 onwards (Hazard Ratio (HR)=4.30; CI=1.82-10.1; p=0.001) and bilateral MoM hip arthroplasty (HR=1.59; CI=1.03-2.46; p=0.037) predicted failure. The effect of implantation year on failure varied over time. From 4-years onwards following surgery, hips implanted since 2006 had significantly higher failure rates (8-years=28.3%; CI=23.1%-34.5%) compared to hips implanted before 2006 (8- years=6.3%; CI=2.4%-15.8%) (HR=15.2; CI=2.11-110.4; p=0.007). Conclusion: We observed that 36mm MoM Pinnacle THRs have an unacceptably high 10-year failure rate, especially if implanted from 2006 onwards or in bilateral MoM patients. Our findings regarding implantation year and failure support recent concerns about the device manufacturing process. We recommend all patients undergoing implantation since 2006 and those with bilateral MoM hips undergo regular investigation, regardless of symptoms

Characteristics and risk factors of UCS fracture subtypes in periprosthetic fractures around the hip

Aims Periprosthetic fractures (PPFs) following hip arthroplasty are complex injuries. This study evaluates patient demographic characteristics, management, outcomes, and risk factors associated with PPF subtypes over a decade. Methods Using a multicentre collaborative study design, independent of registry data, we identified adults from 29 centres with PPFs around the hip between January 2010 and December 2019. Radiographs were assessed for the Unified Classification System (UCS) grade. Patient and injury characteristics, management, and outcomes were compared between UCS grades. A multinomial logistic regression was performed to estimate relative risk ratios (RRR) of variables on UCS grade

A review of current surgical practice in the operative treatment of proximal humeral fractures: Does the PROFHER trial demonstrate a need for change?

Objectives: The PROximal Fracture of the Humerus: Evaluation by Randomisation (PROFHER) trial has recently demonstrated that surgery is non-superior to non-operative treatment in the management of displaced proximal humeral fractures. The objective of this study was to assess current surgical practice in the context of the PROFHER trial in terms of patient demographics, injury characteristics and the nature of the surgical treatment. Methods: A total of ten consecutive patients undergoing surgery for the treatment of a proximal humeral fracture from each of 11 United Kingdom hospitals were retrospectively identified over a 15 month period between January 2014 and March 2015. Data gathered for the 110 patients included patient demographics, injury characteristics, mode of surgical fixation, the grade of operating surgeon and the cost of the surgical implants. Results: A majority of the patients were female (66%, 73 of 110). The mean patient age was 62 years (range 18 to 89). A majority of patients met the inclusion criteria for the PROFHER trial (75%, 83 of 110). Plate fixation was the most common mode of surgery (68%, 75 patients), followed by intramedullary fixation (12%, 13 patients), reverse shoulder arthroplasty (10%, 11 patients) and hemiarthroplasty (7%, eight patients). The consultant was either the primary operating surgeon or supervising the operating surgeon in a large majority of cases (91%, 100 patients). Implant costs for plate fixation were significantly less than both hemiarthroplasty (p &lt; 0.05) and reverse shoulder arthroplasty (p &lt; 0.0001). Implant costs for intramedullary fixation were significantly less than plate fixation (p &lt; 0.01), hemiarthroplasty (p &lt; 0.0001) and reverse shoulder arthroplasty (p &lt; 0.0001). Conclusions: Our study has shown that the majority of a representative sample of patients currently undergoing surgical treatment for a proximal humeral fracture in these United Kingdom centres met the inclusion criteria for the PROFHER trial and that a proportion of these patients may, therefore, have been effectively managed non-operatively.</p

A review of current surgical practice in the operative treatment of proximal humeral fractures: Does the PROFHER trial demonstrate a need for change?

Objectives: The PROximal Fracture of the Humerus: Evaluation by Randomisation (PROFHER) trial has recently demonstrated that surgery is non-superior to non-operative treatment in the management of displaced proximal humeral fractures. The objective of this study was to assess current surgical practice in the context of the PROFHER trial in terms of patient demographics, injury characteristics and the nature of the surgical treatment. Methods: A total of ten consecutive patients undergoing surgery for the treatment of a proximal humeral fracture from each of 11 United Kingdom hospitals were retrospectively identified over a 15 month period between January 2014 and March 2015. Data gathered for the 110 patients included patient demographics, injury characteristics, mode of surgical fixation, the grade of operating surgeon and the cost of the surgical implants. Results: A majority of the patients were female (66%, 73 of 110). The mean patient age was 62 years (range 18 to 89). A majority of patients met the inclusion criteria for the PROFHER trial (75%, 83 of 110). Plate fixation was the most common mode of surgery (68%, 75 patients), followed by intramedullary fixation (12%, 13 patients), reverse shoulder arthroplasty (10%, 11 patients) and hemiarthroplasty (7%, eight patients). The consultant was either the primary operating surgeon or supervising the operating surgeon in a large majority of cases (91%, 100 patients). Implant costs for plate fixation were significantly less than both hemiarthroplasty (p andlt; 0.05) and reverse shoulder arthroplasty (p andlt; 0.0001). Implant costs for intramedullary fixation were significantly less than plate fixation (p andlt; 0.01), hemiarthroplasty (p andlt; 0.0001) and reverse shoulder arthroplasty (p andlt; 0.0001). Conclusions: Our study has shown that the majority of a representative sample of patients currently undergoing surgical treatment for a proximal humeral fracture in these United Kingdom centres met the inclusion criteria for the PROFHER trial and that a proportion of these patients may, therefore, have been effectively managed non-operatively.</p

The All-Wavelength Extended Groth Strip International Survey (AEGIS) data sets

In this the first of a series of Letters, we present a panchromatic data set in the Extended Groth Strip region of the sky. Our survey, the All-Wavelength Extended Groth Strip International Survey (AEGIS), aims to study the physical properties and evolutionary processes of galaxies at z ∼ 1. It includes the following deep, wide-field imaging data sets: Chandra/ACIS X-ray, GALEX ultraviolet, CFHT/MegaCam Legacy Survey optical, CFHT/CFH12K optical, Hubble Space Telescope/ACS optical and NICMOS near-infrared, Palomar/WIRC near-infrared, Spitzer/IRAC mid-infrared, Spitzer/MIPS far-infrared, and VLA radio continuum. In addition, this region of the sky has been targeted for extensive spectroscopy using the Deep Imaging Multi-Object Spectrograph (DEIMOS) on the Keck II 10 m telescope. Our survey is compared to other large multiwavelength surveys in terms of depth and sky coverage. © 2007. The American Astronomical Sociey, All rights reserved

Multiwavelength observations of short-timescale variability in NGC 4151 .4. Analysis of multiwavelength continuum variability

This paper combines data from the three preceding papers in order to analyze the multi-wave-band variability and spectral energy distribution of the Seyfert 1 galaxy NGC 4151 during the 1993 December monitoring campaign. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and optical wavelengths. The strongest variations were seen in medium-energy (similar to 1.5 keV) X-rays, with a normalized variability amplitude (NVA) of 24%. Weaker (NVA = 6%) variations (uncorrelated with those at lower energies) were seen at soft gamma-ray energies of similar to 100 keV. No significant variability was seen in softer (0.1-1 keV) X-ray bands. In the ultraviolet/optical regime, the NVA decreased from 9% to 1% as the wavelength increased from 1275 to 6900 Angstrom These data do not probe extreme ultraviolet (1200 Angstrom to 0.1 keV) or hard X-ray (2-50 keV) variability. The phase differences between variations in different bands were consistent with zero lag, with upper limits of less than or similar to 0.15 day between 1275 Angstrom and the other ultraviolet bands, less than or similar to 0,3 day between 1275 Angstrom and 1.5 keV, and less than or similar to 1 day between 1275 and 5125 Angstrom These tight limits represent more than an order of magnitude improvement over those determined in previous multi-wave-band AGN monitoring campaigns. The ultraviolet fluctuation power spectra showed no evidence for periodicity, but were instead well fitted with a very steep, red power law (a less than or equal to -2.5). If photons emitted at a ''primary'' wave band are absorbed by nearby material and ''reprocessed'' to produce emission at a secondary wave band, causality arguments require that variations in the secondary band follow those in the primary band. The tight interband correlation and limits on the ultraviolet and medium-energy X-ray lags indicate that the reprocessing region is smaller than similar to 0.15 it-day in size. After correcting for strong (a factor of greater than or similar to 15) line-of-sight absorption, the medium-energy X-ray luminosity variations appear adequate to drive the ultraviolet/optical variations. However, the medium-energy X-ray NVA is 2-4 times that in the ultraviolet, and the single-epoch, absorption-corrected X-ray/gamma-ray luminosity is only about one-third of that of the ultraviolet/optical/infrared, suggesting that at most about a third of the total low-energy flux could be reprocessed high-energy emission. The strong wavelength dependence of the ultraviolet NVAs is consistent with an origin in an accretion disk, with the variable emission coming from the hotter inner regions and nonvariable emission from the cooler outer regions. These data, when combined with the results of disk fits, indicate a boundary between these regions near a radius of order R approximate to 0.07 1t-day. No interband lag would be expected, as reprocessing (and thus propagation between regions) need not occur, and the orbital timescale of similar to 1 day is consistent with the observed variability timescale. However, such a model does not immediately explain the good correlation between ultraviolet and X-ray variations