5 research outputs found

    Revisiting X-ray-Bright-Optically-Normal-Galaxies with the Chandra Source Catalog

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    X-ray bright optically normal galaxies (XBONGs) are galaxies with X-ray luminosities consistent with those of active galactic nuclei (AGNs) but no evidence of AGN optical emission lines. Crossmatching the Chandra Source Catalog version 2 (CSC2) with the Sloan Digital Sky Survey (SDSS) sample of spectroscopically classified galaxies, we have identified 817 XBONG candidates with LX > 1042 erg s-1 and X-ray to optical flux ratio FXO > 0.1. Comparisons with WISE colors and NIR, optical, UV, and radio luminosities show that the loci of XBONGs are in-between those of control samples of normal galaxies and quasars and are consistent with low-luminosity quasars. We find that 43% of the XBONG sample have X-ray colors suggesting NH > 1022 cm-2, double the fraction in the QSO sample, suggesting that a large fraction of XBONG are highly obscured AGNs. However, ~50% of the XBONGs are not obscured and have X-ray colors harder than those of normal galaxies. Some of these XBONGs have spatially extended X-ray emission. These characteristics suggest that they may be unidentified galaxy groups and clusters. Using the X-ray luminosity functions of QSOs and galaxies/groups/clusters, we estimate the approximate fraction of extended XBONGs to be < 20%. We also assess the approximate fraction of XBONGs whose AGN signatures are diluted by stellar light of host galaxies to be ~30%, based on their redshift and deviation from the extrapolation of the QSO LX-Lr relation.Comment: Submitted ApJ. 29 pages, 17 figure

    The Chandra Source Catalog Normal Galaxy Sample

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    We present an extensive and well-characterized Chandra X-ray Galaxy Catalog (CGC) of 8557 galaxy candidates in the redshift range z ~ 0.04 - 0.7, optical luminosity 1010 - 1011 Lro, and X-ray luminosity (0.5-7 keV) LX = 2x1040 - 2x1043 erg s-1. We estimate ~5% false match fraction and contamination by QSOs. The CGC was extracted from the Chandra Source Catalog version 2 (CSC2) by cross-correlating with optical and IR all-sky survey data, including SDSS, PanSTARRS, DESI Legacy, and WISE. Our selection makes use of two main criteria that we have tested on the subsample with optical spectroscopical identification. (1) A joint selection based on X-ray luminosity (LX) and X-ray to optical flux ratio (FXO), which recovers 63% of the spectroscopically classified galaxies with a small contamination fraction (7%), a significant improvement over methods using LX or FXO alone (< 50% recovery). (2) A joint W1-W2 (W12) WISE color and LX selection that proves effective in excluding QSOs and improves our selection by recovering 72% of the spectroscopically classified galaxies and reducing the contamination fraction (4%). Of the CGC, 24% was selected by means of optical spectroscopy; 30% on the basis of LX, FXO, and W12; and 46% by using either the LX-FXO or the LX-W12 selection criteria. We have individually examined the data for galaxies with z < 0.1, which may include more than one CSC2 X-ray source, leading to the exclusion of 110 local galaxies. Our catalog also includes near-IR and UV data and galaxy morphological types.Comment: submitted ApJS, 35 pages, 11 figure

    Extremely bright x-ray pulsar breaks all the rules

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    Swift J0243.6+6124 is the first known ultraluminous X-ray pulsar in our Galaxy. This system is an interacting X-ray binary, composed of a rapidly spinning and highly magnetized (≈ 1012 G) neutron star accreting material from the disk of its massive Be companion. Be/X-ray binaries are highly variable and prone to frequent X-ray outbursts. The X-ray pulsar of Swift J0243 is ultraluminous, meaning that it emits at luminosities greater than the Eddington limit for a 1.4 Msun neutron star assuming spherical accretion, Ledd = 1.8 × 1038 erg s −1 . The system reached a peak luminosity L\u3e 1039 erg s−1 during its 2017 outburst. This luminosity is about 10× the Eddington limit for a 1.4 Msun neutron star. The Galactic location of this system allows for the study of super-Eddington accretion as an analog of distant ultraluminous X-ray sources. I used data from the Neil Gehrels Swift X-ray Telescope to investigate the evolution of the spectral and temporal properties of this system. The goal with this dataset was to understand how accretion onto the neutron star varies in and of out of the super-Eddington regime. I searched for characteristic transitions that could reveal changes in the accretion geometry with luminosity. During the super- Eddington outburst of Swift J0243, the spin period dropped by 0.7%, the pulsed fraction nearly doubled, the hardness ratio reached its lowest point, and the pulse shape changed from single-peaked to double-peaked. Such changes may reflect

    Positive Patient Postoperative Outcomes with Pharmacotherapy: A Narrative Review including Perioperative-Specialty Pharmacist Interviews

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    The influence of pharmacotherapy regimens on surgical patient outcomes is increasingly appreciated in the era of enhanced recovery protocols and institutional focus on reducing postoperative complications. Specifics related to medication selection, dosing, frequency of administration, and duration of therapy are evolving to optimize pharmacotherapeutic regimens for many enhanced recovery protocolized elements. This review provides a summary of recent pharmacotherapeutic strategies, including those configured within electronic health record (EHR) applications and functionalities, that are associated with the minimization of the frequency and severity of postoperative complications (POCs), shortened hospital length of stay (LOS), reduced readmission rates, and cost or revenue impacts. Further, it will highlight preventive pharmacotherapy regimens that are correlated with improved patient preparation, especially those related to surgical site infection (SSI), venous thromboembolism (VTE), nausea and vomiting (PONV), postoperative ileus (POI), and emergence delirium (PoD) as well as less commonly encountered POCs such as acute kidney injury (AKI) and atrial fibrillation (AF). The importance of interprofessional collaboration in all periprocedural phases, focusing on medication management through shared responsibilities for drug therapy outcomes, will be emphasized. Finally, examples of collaborative care through shared mental models of drug stewardship and non-medical practice agreements to improve operative throughput, reduce operative stress, and increase patient satisfaction are illustrated
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