283 research outputs found

    The Hard X-Ray View of Reflection, Absorption, and the Disk-Jet Connection in the Radio-Loud AGN 3C 33

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    We present results from Suzaku and Swift observations of the nearby radio galaxy 3C 33, and investigate the nature of absorption, reflection, and jet production in this source. We model the 0.5-100 keV nuclear continuum with a power law that is transmitted either through one or more layers of pc-scale neutral material, or through a modestly ionized pc-scale obscurer. The standard signatures of reflection from a neutral accretion disk are absent in 3C 33: there is no evidence of a relativistically blurred Fe Kα\alpha emission line, and no Compton reflection hump above 10 keV. We find the upper limit to the neutral reflection fraction is R<0.41 for an e-folding energy of 1 GeV. We observe a narrow, neutral Fe Kα\alpha line, which is likely to originate at least 2,000 R_s from the black hole. We show that the weakness of reflection features in 3C 33 is consistent with two interpretations: either the inner accretion flow is highly ionized, or the black-hole spin configuration is retrograde with respect to the accreting material.Comment: 12 pages, 11 figures, 4 tables. Accepted for publication in Ap

    The Hard X-ray 20-40 keV AGN Luminosity Function

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    We have compiled a complete extragalactic sample based on 25,000 deg^2 to a limiting flux of 3E-11 ergs/cm**2/sec (7,000 deg^2 to a flux limit of 1E-11 ergs/cm**2/sec) in the 20 - 40 keV band with INTEGRAL. We have constructed a detailed exposure map to compensate for effects of non-uniform exposure. The flux-number relation is best described by a power-law with a slope of alpha = 1.66+-0.11. The integration of the cumulative flux per unit area leads to f = 2.6E-10 ergs/cm**2/sec/sr, which is about 1% of the known 20 - 40 keV X-ray background. We present the first luminosity function of AGNs in the 20-40 keV energy range, based on 38 extragalactic objects detected by the imager IBIS/ISGRI on-board INTEGRAL. The luminosity function shows a smoothly connected two power-law form, with an index of gamma_1 = 0.8 below, and gamma_2 = 2.1 above the turn-over luminosity of L* = 2.4E43 ergs/sec. The emissivity of all INTEGRAL AGNs per unit volume is W(> 1E41 ergs/sec) = 2.8E38 ergs/sec/Mpc**3. These results are consistent with those derived in the 2 - 20 keV energy band and do not show a significant contribution by Compton-thick objects. Because the sample used in this study is truly local (average z = 0.022), only limited conclusions can be drawn for the evolution of AGNs in this energy band.Comment: 16 pages, 10 figures, accepted for publication in Ap

    The Chandra X-ray Observatory Resolves the X-ray Morphology and Spectra of a Jet in PKS 0637-752

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    The core-dominated radio-loud quasar PKS 0637-752 (z = 0.654) was the first celestial object observed with the Chandra X-ray Observatory, offering the early surprise of the detection of a remarkable X-ray jet. Several observations with a variety of detector configurations contribute to a total exposure time with the Chandra Advanced CCD Imaging Spectrometer (ACIS; Garmire et al. 2000, in preparation) of about 100ks. A spatial analysis of all the available X-ray data, making use of Chandra's spatial resolving power of about 0.4 arcsec, reveals a jet that extends about 10 arcsec to the west of the nucleus. At least four X-ray knots are resolved along the jet, which contains about 5% of the overall X-ray luminosity of the source. Previous observations of PKS 0637-752 in the radio band (Tingay et al. 1998) had identified a kpc-scale radio jet extending to the West of the quasar. The X-ray and radio jets are similar in shape, intensity distribution, and angular structure out to about 9 arcsec, after which the X-ray brightness decreases more rapidly and the radio jet turns abruptly to the north. The X-ray luminosity of the total source is log Lx ~ 45.8 erg/s (2 - 10keV), and appears not to have changed since it was observed with ASCA in November 1996. We present the results of fitting a variety of emission models to the observed spectral distribution, comment on the non-existence of emission lines recently reported in the ASCA observations of PKS 0637-752, and briefly discuss plausible X-ray emission mechanisms.Comment: 24 pages, includes 8 figures, Accepted for publication in Ap

    A randomised control trial to compare quiet eye training efficacy to traditional technical training with undergraduate student nurses' peripheral intravenous cannulation performance: A protocol

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    Introduction: Peripheral intravenous cannulation (PIVC) is a common and complex procedure with low first-attempt success rates, causing patient suffering and increased healthcare costs. Quiet Eye (QE) training, a gaze-focused approach, has shown promise in improving procedural PIVC skills. We will examine the effectiveness of traditional technical training (TT) and QE (QET) training on student nurse PIVC performance. Methods: 44 participants will be randomly assigned to either the TT or QET groups using a blocked randomization method to ensure balanced group sizes. Blinded outcome assessments will minimize bias. Data will be collected using a structured questionnaire and a mobile eye tracker to simultaneously record gaze and hand movements. Participants will complete pre-intervention, post-intervention, and one-week retention tests using a light-skinned manikin arm. A transfer task, utilizing a dark-skinned manikin arm, will assess participants’ skills post trials. The TT group will receive traditional instruction on hand movement improvement; the QET group will receive feedback on their gaze behaviours. The primary outcome measure will be PIVC first attempt success defined as being able to flush the inserted catheter with 10 mL (maximum) normal saline into the vessel. A trial will be considered unsuccessful if more than gentle pressure on the syringe plunger is needed to flush the catheter or if the participant abandoned the attempt before attempting the flush. Other dependent variables will be QE duration (%), number of fixations, total movement time (s), and movement phase time (s). We will analyze data with descriptive and inferential statistics, including mixed model ANOVA and Chi-Square tests. Discussion: This study examines the significance of improving PIVC first attempt success rates and highlights QET potential as an intervention. Emphasis is placed on critical implications for healthcare, particularly the importance of integrating QETinto nursing education programs. Future research utilizing large-scale trials and longitudinal designs is recommended
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