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1. Blueshifted absorption lines from X-ray reflection in IRAS 13224−3809

Author

MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology. Department of Physics, Fabian, AC, Reynolds, CS, Jiang, J, Pinto, C, Gallo, LC, Parker, ML, Lasenby, AN, Alston, WN, Buisson, DJK, Cackett, EM, De Marco, B, Garcia, J, Kara, Erin A, Kosec, P, Middleton, MJ, Miller, JM, Miniutti, G, Walton, DJ, Wilkins, DR, Young, AJ, MIT Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology. Department of Physics, Fabian, AC, Reynolds, CS, Jiang, J, Pinto, C, Gallo, LC, Parker, ML, Lasenby, AN, Alston, WN, Buisson, DJK, Cackett, EM, De Marco, B, Garcia, J, Kara, Erin A, Kosec, P, Middleton, MJ, Miller, JM, Miniutti, G, Walton, DJ, Wilkins, DR, and Young, AJ

Abstract

ABSTRACT We explore a disc origin for the highly blueshifted, variable absorption lines seen in the X-ray spectrum of the narrow-line Seyfert 1 galaxy IRAS 13224−3809. The blueshift corresponds to a velocity of ∼0.25c. Such features in other active galactic nuclei are often interpreted as ultrafast outflows. The velocity is of course present in the orbital motions of the inner disc. The absorption lines in IRAS 13224−3809 are best seen when the flux is low and the reflection component of the disc is strong relative to the power-law continuum. The spectra are consistent with a model in which the reflection component passes through a thin, highly ionized absorbing layer at the surface of the inner disc, the blueshifted side of which dominates the flux due to relativistic aberration (the disc inclination is about 70°). No fast outflow need occurs beyond the disc.

Published
2022

2. Quasi-periodic dipping in the ultraluminous X-ray source, NGC 247 ULX-1

Author

Alston, WN, Pinto, C, Barret, D, D’Aì, A, Del Santo, M, Earnshaw, H, Fabian, AC, Fuerst, F, Kara, E, Kosec, P, Middleton, MJ, Parker, ML, Pintore, F, Robba, A, Roberts, TP, Sathyaprakash, R, Walton, D, Ambrosi, E, Alston, WN, Pinto, C, Barret, D, D’Aì, A, Del Santo, M, Earnshaw, H, Fabian, AC, Fuerst, F, Kara, E, Kosec, P, Middleton, MJ, Parker, ML, Pintore, F, Robba, A, Roberts, TP, Sathyaprakash, R, Walton, D, and Ambrosi, E

Abstract

ABSTRACT Most ultraluminous X-ray sources (ULXs) are believed to be stellar mass black holes or neutron stars accreting beyond the Eddington limit. Determining the nature of the compact object and the accretion mode from broad-band spectroscopy is currently a challenge, but the observed timing properties provide insight into the compact object and details of the geometry and accretion processes. Here, we report a timing analysis for an 800 ks XMM–Newton campaign on the supersoft ultraluminous X-ray source, NGC 247 ULX-1. Deep and frequent dips occur in the X-ray light curve, with the amplitude increasing with increasing energy band. Power spectra and coherence analysis reveals the dipping preferentially occurs on ∼5 and ∼10 ks time-scales. The dips can be caused by either the occultation of the central X-ray source by an optically thick structure, such as warping of the accretion disc, or from obscuration by a wind launched from the accretion disc, or both. This behaviour supports the idea that supersoft ULXs are viewed close to edge-on to the accretion disc.

Published
2022

3. The unusual broad-band X-ray spectral variability of NGC 1313 X-1 seen with XMM–Newton, Chandra , and NuSTAR

Author

MIT Kavli Institute for Astrophysics and Space Research, Walton, DJ, Pinto, C, Nowak, M, Bachetti, M, Sathyaprakash, R, Kara, E, Roberts, TP, Soria, R, Brightman, M, Canizares, CR, Earnshaw, HP, Fürst, F, Heida, M, Middleton, MJ, Stern, D, Tao, L, Webb, N, Alston, WN, Barret, D, Fabian, AC, Harrison, FA, Kosec, P, MIT Kavli Institute for Astrophysics and Space Research, Walton, DJ, Pinto, C, Nowak, M, Bachetti, M, Sathyaprakash, R, Kara, E, Roberts, TP, Soria, R, Brightman, M, Canizares, CR, Earnshaw, HP, Fürst, F, Heida, M, Middleton, MJ, Stern, D, Tao, L, Webb, N, Alston, WN, Barret, D, Fabian, AC, Harrison, FA, and Kosec, P

Abstract

© 2020 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. We present results from the major coordinated X-ray observing programme on the ULX NGC 1313 X-1 performed in 2017, combining XMM-Newton, Chandra, and NuSTAR, focusing on the evolution of the broad-band (∼0.3-30.0 keV) continuum emission. Clear and unusual spectral variability is observed, but this is markedly suppressed above ∼10-15 keV, qualitatively similar to the ULX Holmberg IX X-1. We model the multi-epoch data with two-component accretion disc models designed to approximate super-Eddington accretion, allowing for both a black hole and a neutron star accretor. With regards to the hotter disc component, the data trace out two distinct tracks in the luminosity-temperature plane, with larger emitting radii and lower temperatures seen at higher observed fluxes. Despite this apparent anticorrelation, each of these tracks individually shows a positive luminosity-temperature relation. Both are broadly consistent with L ∝ T4, as expected for blackbody emission with a constant area, and also with L ∝ T2, as may be expected for an advection-dominated disc around a black hole. We consider a variety of possibilities for this unusual behaviour. Scenarios in which the innermost flow is suddenly blocked from view by outer regions of the super-Eddington disc/wind can explain the luminosity-temperature behaviour, but are difficult to reconcile with the lack of strong variability at higher energies, assuming this emission arises from the most compact regions. Instead, we may be seeing evidence for further radial stratification of the accretion flow than is included in the simple models considered, with a combination of winds and advection resulting in the suppressed high-energy variability.

Published
2021

4. Blueshifted absorption lines from X-ray reflection in IRAS 13224−3809

Author

Fabian, AC, Reynolds, CS, Jiang, J, Pinto, C, Gallo, LC, Parker, ML, Lasenby, AN, Alston, WN, Buisson, DJK, Cackett, EM, De Marco, B, Garcia, J, Kara, E, Kosec, P, Middleton, MJ, Miller, JM, Miniutti, G, Walton, DJ, Wilkins, DR, Young, AJ, Fabian, AC, Reynolds, CS, Jiang, J, Pinto, C, Gallo, LC, Parker, ML, Lasenby, AN, Alston, WN, Buisson, DJK, Cackett, EM, De Marco, B, Garcia, J, Kara, E, Kosec, P, Middleton, MJ, Miller, JM, Miniutti, G, Walton, DJ, Wilkins, DR, and Young, AJ

Abstract

ABSTRACT We explore a disc origin for the highly blueshifted, variable absorption lines seen in the X-ray spectrum of the narrow-line Seyfert 1 galaxy IRAS 13224−3809. The blueshift corresponds to a velocity of ∼0.25c. Such features in other active galactic nuclei are often interpreted as ultrafast outflows. The velocity is of course present in the orbital motions of the inner disc. The absorption lines in IRAS 13224−3809 are best seen when the flux is low and the reflection component of the disc is strong relative to the power-law continuum. The spectra are consistent with a model in which the reflection component passes through a thin, highly ionized absorbing layer at the surface of the inner disc, the blueshifted side of which dominates the flux due to relativistic aberration (the disc inclination is about 70°). No fast outflow need occurs beyond the disc.

Published
2021

5. Discovery of a soft X-ray lag in the ultraluminous X-ray source NGC 1313 X-1

Author

Kara, E, Pinto, C, Walton, DJ, Alston, WN, Bachetti, M, Barret, D, Brightman, M, Canizares, CR, Earnshaw, HP, Fabian, AC, Fürst, F, Kosec, P, Middleton, MJ, Roberts, TP, Soria, R, Tao, L, Webb, NA, Kara, E, Pinto, C, Walton, DJ, Alston, WN, Bachetti, M, Barret, D, Brightman, M, Canizares, CR, Earnshaw, HP, Fabian, AC, Fürst, F, Kosec, P, Middleton, MJ, Roberts, TP, Soria, R, Tao, L, and Webb, NA

Abstract

© 2019 The Author(s). Ultraluminous X-ray sources (ULXs) provide a unique opportunity to probe the geometry and energetics of super-Eddington accretion. The radiative processes involved in super-Eddington accretion are not well understood, and so studying correlated variability between different energy bands can provide insights into the causal connection between different emitting regions. We present a spectral-timing analysis of NGC 1313 X-1 from a recent XMM–Newton campaign. The spectra can be decomposed into two thermal-like components, the hotter of which may originate from the inner accretion disc, and the cooler from an optically thick outflow. We find correlated variability between hard (2–10 keV) and soft (0.3–2 keV) bands on kilosecond time-scales, and find a soft lag of ∼150 s. The covariance spectrum suggests that emission contributing to the lags is largely associated with the hotter of the two thermal-like components, likely originating from the inner accretion flow. This is only the third ULX to exhibit soft lags. The lags range over three orders of magnitude in amplitude, but all three are ∼5–20 per cent of the corresponding characteristic variability time-scales. If these soft lags can be understood in the context of a unified picture of ULXs, then lag time-scales may provide constraints on the density and extent of radiatively driven outflows.

Published
2021

6. A 78 Day X-Ray Period Detected from NGC 5907 ULX1 by $\textit{Swift}$

Author

Walton, DJ, Fürst, F, Bachetti, M, Barret, D, Brightman, M, Fabian, AC, Gehrels, N, Harrison, FA, Heida, M, Middleton, MJ, Rana, V, Roberts, TP, Stern, D, Tao, L, Webb, N, Walton, Dominic [0000-0001-5819-3552], Fabian, Andrew [0000-0002-9378-4072], and Apollo - University of Cambridge Repository

Subjects
X-rays: binaries, X-rays: individual (NGC 5907 ULX1), black hole physics
Abstract

We report the detection of a 78.1 ± 0.5 day period in the X-ray light curve of the extreme ultraluminous X-ray source NGC 5907 ULX1 (L$_\text{X,peak}$ ~ 5 × 10$^{40}$ erg s$^{-1}$), discovered during an extensive monitoring program with $\textit{Swift}$. These periodic variations are strong, with the observed flux changing by a factor of ~3-4 between the peaks and the troughs of the cycle; our simulations suggest that the observed periodicity is detected comfortably in excess of 3$\sigma$ significance. We discuss possible origins for this X-ray period, but conclude that at the current time we cannot robustly distinguish between orbital and super-orbital variations., A.C.F. acknowledges support from ERC Advanced Grant 340442. The work of D.J.W./D.S. was performed at JPL/Caltech, under contract with NASA. D.B. and N.W. acknowledge financial support from the French Space Agency (CNES), M.J.M. acknowledges support from an Ernest Rutherford STFC fellowship, and T.P.R. acknowledges support from the STFC consolidated grant ST/L00075X/1. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester, and also made use of the XRT Data Analysis Software (XRTDAS) developed under the responsibility of the ASI Science Data Center (ASDC), Italy. We acknowledge the use of public data from the Swift data archive. This research has also made use of a collection of ISIS functions (ISISscripts) provided by ECAP/Remeis observatory and MIT.

Published
2016

7. Caseous lymphadenitis on Flinders Island: prevalence and management surveys

Author

Middleton Mj, Gregory Gg, and Epstein Vm

Subjects
Clostridium, Male, medicine.medical_specialty, Sheep, General Veterinary, Vaccination, Sheep Diseases, Enzyme-Linked Immunosorbent Assay, General Medicine, Biology, Dermatology, Tasmania, Interviews as Topic, Lymphadenitis, Surveys and Questionnaires, Bacterial Vaccines, medicine, Prevalence, Caseous lymphadenitis, Animals, Female, Immunization Schedule
Published
1991

8. Biology of four species of Whiting (Pisces: Sillaginidae) in Botany Bay, NSW

Author

Burchmore, JJ, Pollard, DA, Middleton, MJ, Bell, JD, and Pease, BC

Abstract

Four species of whiting (Family Sillaginidae) were collected from Botany Bay, New South Wales, between 1977 and 1979: Sillago ciliata (sand whiting), S. maculata maculata (trumpeter whiting), S. robusta (stout whiting) and S. bassensis flindersi (eastern school whiting). Sillago ciliata was the most abundant species over-all. Sillago ciliata was caught in greatest numbers in Zostera seagrass and shallow sandy habitats, whereas S. m. maculata, S. robusta and S. b. flindersi were most abundant over deeper muddy and sandy habitats. Sillago ciliata and S. b. flindersi were present mainly as juveniles. Gonosomatic indices and gonadal maturity stages of S. ciliata and S. m. maculata peaked around February. These species probably spawn within the Bay. Length to caudal fork at first maturity was 24 cm for male and female S. ciliata, 19 cm for male and female S. m. maculata, 17 cm for male and 18 cm for female S. robusta, and 14 cm for male and female S. b. flindersi. Although all species fed mainly on polychaetes and crustaceans, there was little overlap in specific dietary items between species. Variations observed in diet were due to fish size and temporal and spatial habitat differences within and among species.

Published
1988
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9. Structure of a fish community in a temperate tidal mangrove creek in Botany Bay, New South Wales

Author

Bell, JD, Pollard, DA, Burchmore, JJ, Pease, BC, and Middleton, MJ

Abstract

The fish assemblage in the lower reaches of a temperate tidal mangrove creek entering Botany Bay near Sydney, New South Wales, was sampled using rotenone every second month between December 1977 and October 1980. Almost 17 000 fish (weight ~ 115 kg), belonging to 46 species and 24 families, were collected. Six species dominated the assemblage and another four were relatively common. Fourteen species, including four of the above, were economically important. These fishes made up 38% of individuals and 32% of biomass and were represented only by small juveniles. Nineteen species (41%) were temporary residents; these mainly comprised juveniles of large species that live elsewhere as adults. Fifteen species (33%), most of which only attain a small size (< 100 mm), were assumed to be permanent residents. The remaining 12 species (26%) occurred in only one sample and were, therefore, classified as rare. The diversity (HI) and evenness (J') of the fish community were low and showed little seasonality because a few species dominated the assemblage on an irregular basis. Numbers of species and of individuals varied seasonally and were significantly correlated. Peaks in these parameters lagged behind those in water temperature by 4 months and were largely the result of the relatively restricted recruitment periods of several abundant temporary resident species. The large numbers of juveniles and small species in the mangrove creek habitat were attributed to the availability of suitable shelter and food for such small fishes. Concerted use of the mangrove habitat by several abundant temporary resident species during the same general period each year appeared to be facilitated by the occupation of otherwise vacant feeding niches and some staggering of their peak recruitment periods. Exclusive use of this habitat by small juveniles of several species in Botany Bay confirms that mangrove habitats in temperate Australia, like some of those studied in tropical and subtropical regions, are important nursery areas for fishes inhabiting adjacent estuarine and inshore marine habitats as adults.

Published
1984
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10. The Broadband Spectral Variability of Holmberg IX X-1

Author

Walton, DJ, Furst, F, Harrison, FA, Middleton, MJ, Fabian, AC, Bachetti, M, Barret, D, Miller, JM, Ptak, A, Rana, V, Stern, D, and Tao, L

Subjects
X-rays: binaries, Astrophysics::High Energy Astrophysical Phenomena, black hole physics, Astrophysics::Cosmology and Extragalactic Astrophysics, 7. Clean energy, Astrophysics::Galaxy Astrophysics, X-rays: individual (Holmberg IX X-1)
Abstract

We present results from four new broadband X-ray observations of the extreme ultraluminous X-ray source Holmberg IX X-1 (L$_{x}$ > 10$^{40}$ erg s$^{-1}$), performed by $\textit{Suzaku}$ and $\textit{Nu}$STAR in coordination. Combined with the archival data, we now have broadband observations of this remarkable source from six separate epochs. Two of these new observations probe lower fluxes than seen previously, allowing us to extend our knowledge of the broadband spectral variability exhibited. The spectra are well fit by two thermal blackbody components that dominate the emission below 10 keV, as well as a steep ($\Gamma$ $\sim$ 3.5) power-law tail that dominates above ~15 keV. Remarkably, while the 0.3–10.0 keV flux varies by a factor of ~3 between all these epochs, the 15–40 keV flux varies by only ~20%. Although the spectral variability is strongest in the ~1–10 keV band, both of the thermal components are required to vary when all epochs are considered. We also revisit the search for iron absorption features by leveraging the high-energy NuSTAR data to improve our sensitivity to extreme velocity outflows in light of the ultra-fast outflow recently detected in NGC 1313 X-1. Iron absorption from a similar outflow along our line of sight can be ruled out in this case. We discuss these results in the context of super-Eddington accretion models that invoke a funnel-like geometry for the inner flow, and propose a scenario in which we have an almost face-on view of a funnel that expands to larger radii with increasing flux, resulting in an increasing degree of geometrical collimation for the emission from intermediate-temperature regions., D.J.W. and M.J.M. acknowledge support from STFC through Ernest Rutherford fellowships, A.C.F. acknowledges support from ERC Advanced Grant 340442, and D.B. acknowledges financial support from the French Space Agency (CNES). This research has made use of data obtained with NuSTAR, a project led by Caltech, funded by NASA and managed by NASA/JPL, and has utilized the NUSTARDAS software package, jointly developed by the ASDC (Italy) and Caltech (USA). This research has also made use of data obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States, and with Suzaku, a collaborative mission between the space agencies of Japan (JAXA) and the USA (NASA).

11. Living on a Flare: Relativistic Reflection in V404 Cyg Observed by NuSTAR during Its Summer 2015 Outburst

Author

Walton, DJ, Mooley, K, King, AL, Tomsick, JA, Miller, JM, Dauser, T, García, JA, Bachetti, M, Brightman, M, Fabian, AC, Forster, K, Fürst, F, Gandhi, P, Grefenstette, BW, Harrison, FA, Madsen, KK, Meier, DL, Middleton, MJ, Natalucci, L, Rahoui, F, Rana, V, and Stern, D

Subjects
X-rays: binaries, 13. Climate action, Astrophysics::High Energy Astrophysical Phenomena, black hole physics, Astrophysics::Solar and Stellar Astrophysics, X-rays: individual (V404 Cyg)
Abstract

We present first results from a series of $\textit{NuSTAR}$ observations of the black hole X-ray binary V404 Cyg obtained during its summer 2015 outburst, primarily focusing on observations during the height of this outburst activity. The $\textit{NuSTAR}$ data show extreme variability in both the flux and spectral properties of the source. This is partly driven by strong and variable line-of-sight absorption, similar to previous outbursts. The latter stages of this observation are dominated by strong flares, reaching luminosities close to Eddington. During these flares, the central source appears to be relatively unobscured and the data show clear evidence for a strong contribution from relativistic reflection, providing a means to probe the geometry of the innermost accretion flow. Based on the flare properties, analogies with other Galactic black hole binaries, and also the simultaneous onset of radio activity, we argue that this intense X-ray flaring is related to transient jet activity during which the ejected plasma is the primary source of illumination for the accretion disk. If this is the case, then our reflection modeling implies that these jets are launched in close proximity to the black hole (as close as a few gravitational radii), consistent with expectations for jet launching models that tap either the spin of the central black hole, or the very innermost accretion disk. Our analysis also allows us to place the first constraints on the black hole spin for this source, which we find to be ${a}^{* }\gt 0.92$ (99% statistical uncertainty, based on an idealized lamp-post geometry)., D.J.W., P.G., and M.J.M. acknowledge support from STFC Ernest Rutherford fellowships (grant ST/J003697/2). K.P.M. acknowledges support from the Hintze Foundation. A.L.K. acknowledges support from NASA through an Einstein Postdoctoral Fellowship (grant number PF4-150125) awarded by the Chandra X-ray Center, operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060. A.C.F. acknowledges support from ERC Advanced Grant 340442. L.N. wishes to acknowledge the Italian Space Agency (ASI) for Financial support by ASI/INAF grant I/037/12/0-011/13. This research has made use of data obtained with NuSTAR, a project led by Caltech, funded by NASA and managed by NASA/JPL, and has utilized the NUSTARDAS software package, jointly developed by the ASDC (Italy) and Caltech (USA). This research has also made use of data from AMI, which is supported by the ERC, and we thank the AMI staff for scheduling these radio observations.

12. A rapidly changing jet orientation in the stellar-mass black-hole system V404 Cygni.

Author

Miller-Jones JCA, Tetarenko AJ, Sivakoff GR, Middleton MJ, Altamirano D, Anderson GE, Belloni TM, Fender RP, Jonker PG, Körding EG, Krimm HA, Maitra D, Markoff S, Migliari S, Mooley KP, Rupen MP, Russell DM, Russell TD, Sarazin CL, Soria R, and Tudose V

Abstract

Powerful relativistic jets are one of the main ways in which accreting black holes provide kinetic feedback to their surroundings. Jets launched from or redirected by the accretion flow that powers them are expected to be affected by the dynamics of the flow, which for accreting stellar-mass black holes has shown evidence for precession 1 due to frame-dragging effects that occur when the black-hole spin axis is misaligned with the orbital plane of its companion star 2 . Recently, theoretical simulations have suggested that the jets can exert an additional torque on the accretion flow 3 , although the interplay between the dynamics of the accretion flow and the launching of the jets is not yet understood. Here we report a rapidly changing jet orientation-on a time scale of minutes to hours-in the black-hole X-ray binary V404 Cygni, detected with very-long-baseline interferometry during the peak of its 2015 outburst. We show that this changing jet orientation can be modelled as the Lense-Thirring precession of a vertically extended slim disk that arises from the super-Eddington accretion rate 4 . Our findings suggest that the dynamics of the precessing inner accretion disk could play a role in either directly launching or redirecting the jets within the inner few hundred gravitational radii. Similar dynamics should be expected in any strongly accreting black hole whose spin is misaligned with the inflowing gas, both affecting the observational characteristics of the jets and distributing the black-hole feedback more uniformly over the surrounding environment 5,6 .

Published
2019
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13. The response of relativistic outflowing gas to the inner accretion disk of a black hole.

Author

Parker ML, Pinto C, Fabian AC, Lohfink A, Buisson DJ, Alston WN, Kara E, Cackett EM, Chiang CY, Dauser T, De Marco B, Gallo LC, Garcia J, Harrison FA, King AL, Middleton MJ, Miller JM, Miniutti G, Reynolds CS, Uttley P, Vasudevan R, Walton DJ, Wilkins DR, and Zoghbi A

Abstract

The brightness of an active galactic nucleus is set by the gas falling onto it from the galaxy, and the gas infall rate is regulated by the brightness of the active galactic nucleus; this feedback loop is the process by which supermassive black holes in the centres of galaxies may moderate the growth of their hosts. Gas outflows (in the form of disk winds) release huge quantities of energy into the interstellar medium, potentially clearing the surrounding gas. The most extreme (in terms of speed and energy) of these-the ultrafast outflows-are the subset of X-ray-detected outflows with velocities higher than 10,000 kilometres per second, believed to originate in relativistic (that is, near the speed of light) disk winds a few hundred gravitational radii from the black hole. The absorption features produced by these outflows are variable, but no clear link has been found between the behaviour of the X-ray continuum and the velocity or optical depth of the outflows, owing to the long timescales of quasar variability. Here we report the observation of multiple absorption lines from an extreme ultrafast gas flow in the X-ray spectrum of the active galactic nucleus IRAS 13224-3809, at 0.236 ± 0.006 times the speed of light (71,000 kilometres per second), where the absorption is strongly anti-correlated with the emission of X-rays from the inner regions of the accretion disk. If the gas flow is identified as a genuine outflow then it is in the fastest five per cent of such winds, and its variability is hundreds of times faster than in other variable winds, allowing us to observe in hours what would take months in a quasar. We find X-ray spectral signatures of the wind simultaneously in both low- and high-energy detectors, suggesting a single ionized outflow, linking the low- and high-energy absorption lines. That this disk wind is responding to the emission from the inner accretion disk demonstrates a connection between accretion processes occurring on very different scales: the X-ray emission from within a few gravitational radii of the black hole ionizing the disk wind hundreds of gravitational radii further away as the X-ray flux rises.

Published
2017
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14. Resolved atomic lines reveal outflows in two ultraluminous X-ray sources.

Author

Pinto C, Middleton MJ, and Fabian AC

Abstract

Ultraluminous X-ray sources are extragalactic, off-nucleus, point sources in galaxies, and have X-ray luminosities in excess of 3 × 10(39) ergs per second. They are thought to be powered by accretion onto a compact object. Possible explanations include accretion onto neutron stars with strong magnetic fields, onto stellar-mass black holes (of up to 20 solar masses) at or in excess of the classical Eddington limit, or onto intermediate-mass black holes (10(3)-10(5) solar masses). The lack of sufficient energy resolution in previous analyses has prevented an unambiguous identification of any emission or absorption lines in the X-ray band, thereby precluding a detailed analysis of the accretion flow. Here we report the presence of X-ray emission lines arising from highly ionized iron, oxygen and neon with a cumulative significance in excess of five standard deviations, together with blueshifted (about 0.2 times light velocity) absorption lines of similar significance, in the high-resolution X-ray spectra of the ultraluminous X-ray sources NGC 1313 X-1 and NGC 5408 X-1. The blueshifted absorption lines must occur in a fast-outflowing gas, whereas the emission lines originate in slow-moving gas around the source. We conclude that the compact object in each source is surrounded by powerful winds with an outflow velocity of about 0.2 times that of light, as predicted by models of accreting supermassive black holes and hyper-accreting stellar-mass black holes.

Published
2016
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15. Differences in Drinking Patterns Between Female Nursing and Nonnursing Students.

Author

Hensel D, Engs RC, and Middleton MJ

Subjects
Cross-Sectional Studies, Female, Humans, Nursing Education Research, Risk-Taking, Students statistics & numerical data, Students, Nursing statistics & numerical data, United States, Universities, Young Adult, Alcohol Drinking psychology, Students psychology, Students, Nursing psychology
Abstract

This study compared the drinking patterns of 123 female nursing students with those of 185 female students of other majors enrolled beyond the freshman year at a large public university. High-risk drinking patterns did not vary significantly between the 2 groups, suggesting that students' drinking patterns reflected the norms of their institution. Prevention strategies geared at campus culture and that target students still enrolled in prerequisites may be needed to reduce alcohol abuse in nursing students.

Published
2016
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16. Examining the Effects of Self-reported Posttraumatic Stress Disorder Symptoms and Positive Relations With Others on Self-regulated Learning for Student Service Members/Veterans.

Author

Ness BM, Middleton MJ, and Hildebrandt MJ

Subjects
Adult, Female, Humans, Male, Stress Disorders, Post-Traumatic diagnosis, Surveys and Questionnaires, Universities, Interpersonal Relations, Self Report, Stress Disorders, Post-Traumatic complications, Stress Disorders, Post-Traumatic psychology, Students psychology, Veterans psychology
Abstract

Objectives: To examine the relationships between self-reported posttraumatic stress disorder (PTSD) symptoms, perceived positive relations with others, self-regulation strategy use, and academic motivation among student service members/veterans (SSM/V) enrolled in postsecondary education., Participants: SSM/V (N = 214), defined as veterans, active duty, or National Guard/Reservists of the US military, enrolled at 5 different institutions in Fall 2012., Methods: Data were collected using an online questionnaire that included standardized measures of PTSD symptoms, perceived quality of personal relations, academic self-regulation strategy use, and academic motivation., Results: PTSD symptoms were associated with lower self-efficacy for learning and maladaptive academic goal orientation. Additionally, PTSD symptoms were associated with lower effort regulation (ie, persistence) during academic work. Endorsement of more positive relations moderated the deleterious relationship between PTSD symptoms and maladaptive goal orientation., Conclusion: The results suggest that postsecondary personnel adopt a social-cognitive framework to develop social, mental health, and academic supports for SSM/V with PTSD.

Published
2015
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17. A cross-sectional study of drinking patterns, prelicensure nursing education, and professional identity formation.

Author

Hensel D, Middleton MJ, and Engs RC

Subjects
Adult, Cross-Sectional Studies, Female, Humans, Male, Young Adult, Alcohol Drinking, Education, Nursing
Abstract

Background: Professional identity has been described as being an important outcome of nursing education, but how this identity forms is not well understood. Even less is known about how students' personal substance use/abuse patterns factor into their professional identity formation., Objectives: The purpose of this study was to describe drinking behaviors and professional identity formation among baccalaureate of nursing students., Design: This cross-sectional, descriptive study used a survey design., Setting: The study took place on three campuses of a large system university in the Midwestern United States., Participants: The convenience sample consisted of 333 students enrolled in the first semester of the second, third, and last year of a traditional baccalaureate of nursing program., Methods: Data were collected using the Nurse Self-Concept Questionnaire and the Student Alcohol Questionnaire. ANOVA and Pearson r statistical tests were used to analyze data., Results: Self-perceptions related to leadership were found to be the weakest aspect of the students' self-concepts, and the only dimensions of professional self-concept that differed significantly among students enrolled at varying program levels were knowledge and communication. A negative relationship was found between increased alcohol use and general self-concept and communication, but the associations were very weak., Conclusions: More research is needed to understand how best to facilitate the acquisition of an identity consistent with the profession's values and how to recruit candidates that embody nursing's preferred future., (© 2013.)

Published
2014
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18. Bright radio emission from an ultraluminous stellar-mass microquasar in M 31.

Author

Middleton MJ, Miller-Jones JC, Markoff S, Fender R, Henze M, Hurley-Walker N, Scaife AM, Roberts TP, Walton D, Carpenter J, Macquart JP, Bower GC, Gurwell M, Pietsch W, Haberl F, Harris J, Daniel M, Miah J, Done C, Morgan JS, Dickinson H, Charles P, Burwitz V, Della Valle M, Freyberg M, Greiner J, Hernanz M, Hartmann DH, Hatzidimitriou D, Riffeser A, Sala G, Seitz S, Reig P, Rau A, Orio M, Titterington D, and Grainge K

Abstract

A subset of ultraluminous X-ray sources (those with luminosities of less than 10(40) erg s(-1); ref. 1) are thought to be powered by the accretion of gas onto black holes with masses of ∼5-20M cicled dot, probably by means of an accretion disk. The X-ray and radio emission are coupled in such Galactic sources; the radio emission originates in a relativistic jet thought to be launched from the innermost regions near the black hole, with the most powerful emission occurring when the rate of infalling matter approaches a theoretical maximum (the Eddington limit). Only four such maximal sources are known in the Milky Way, and the absorption of soft X-rays in the interstellar medium hinders the determination of the causal sequence of events that leads to the ejection of the jet. Here we report radio and X-ray observations of a bright new X-ray source in the nearby galaxy M 31, whose peak luminosity exceeded 10(39) erg s(-1). The radio luminosity is extremely high and shows variability on a timescale of tens of minutes, arguing that the source is highly compact and powered by accretion close to the Eddington limit onto a black hole of stellar mass. Continued radio and X-ray monitoring of such sources should reveal the causal relationship between the accretion flow and the powerful jet emission.

Published
2013
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19. Is atropine always necessary before general anesthesia?

Author

Middleton MJ, Zitzer JM, and Urbach KF

Subjects
Adolescent, Adult, Aged, Anesthesia, General, Clinical Trials as Topic, Cyclopropanes pharmacology, Ethyl Ethers pharmacology, Halothane pharmacology, Humans, Male, Middle Aged, Nitrous Oxide pharmacology, Thiopental pharmacology, Arrhythmias, Cardiac chemically induced, Atropine pharmacology, Preanesthetic Medication
Published
1967

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