124 research outputs found

    Evidence that the Bursting Component of the X-ray Radiation From 3C 111 Originates in the PC-Scale Jet

    Full text link
    Evidence is presented indicating that the bursting component of the X-ray radiation detected in the nuclear region of the active radio galaxy 3C 111 comes from the blobs ejected in the pc-scale jet and not from the accretion disc. After each new outburst the radio flux density associated with it increases to a peak in ~1 year and then subsides over a period of 1-2 years with the flux falling off exponentially as the blob moves outward and dissipates. Similar peaks (bursts) are seen in the X-ray light curve and a cross-correlation between the two shows a very high correlation with the X-ray peaks leading the radio peaks by ~100 days. A second cross-correlation, this time between the radio event start times and the X-ray light curve, also shows a significant correlation. When this is taken together with the long (~1 yr) delay between the start of each ejection event and its associated X-ray peak it indicates that this bursting component of the X-ray flux must be associated with the ejected blobs in the pc-scale jet and not with the accretion disc. Because X-ray telescopes do not have the resolution required to resolve the accretion disc area from the pc-scale jet, this paper is the first to present observational evidence that can pinpoint the point of origin of at least those long-timescale X-ray bursts with durations of 1-3 yrs.Comment: 11 pages, 8 Figures. Accepted for publication in Astrophysics and Space Scienc

    Finding Faint Intermediate-mass Black Holes in the Radio Band

    Full text link
    We discuss the prospects for detecting faint intermediate-mass black holes, such as those predicted to exist in the cores of globular clusters and dwarf spheroidal galaxies. We briefly summarize the difficulties of stellar dynamical searches, then show that recently discovered relations between black hole mass, X-ray luminosity and radio luminosity imply that in most cases, these black holes should be more easily detected in the radio than in the X-rays. Finally, we show upper limits from some radio observations of globular clusters, and discuss the possibility that the radio source in the core of the Ursa Minor dwarf spheroidal galaxy might be a 10,000100,000M\sim 10,000-100,000 M_\odot black hole.Comment: 10 pages, no figures, to appear in From X-ray Binaries to Quasars: Black Hole Accretion on All Mass Scales, ed. T. J. Maccarone, R. P. Fender, and L. C. Ho (Dordrecht: Kluwer

    Apolipoprotein E genotypes among diverse middle-aged and older Latinos: Study of Latinos-Investigation of Neurocognitive Aging results (HCHS/SOL)

    Get PDF
    The apoE4 isoform is associated with increased cholesterol, cardiovascular risk, and Alzheimer’s Disease risk, however, its distribution is not well-understood among US Latinos. Latinos living in the US are highly Amerindian, European and African admixed, which varies by region and country of origin. However, Latino genetic diversity is understudied and consequently poorly understood, which has significant implications for understanding disease risk in nearly one-fifth of the US population. In this report we describe apoE distributions in a large and representative sample of diverse, genetically determined US Latinos

    The association of acculturation with accelerometer-assessed and self-reported physical activity and sedentary behavior: The Hispanic Community Health Study/Study of Latinos

    Get PDF
    The adoption of US culture among immigrants has been associated with higher leisure-time physical activity and sedentary behavior. However, most research to date assesses this association using single measures of acculturation and physical activity. Our objective was to describe the cross-sectional association between acculturation and both physical activity and sedentary behavior among US Hispanic/Latino adults. Participants included Hispanic/Latinos 18–74 years living in four US locations enrolled in the Hispanic Community Health Study/Study of Latinos from 2008 to 2011. Acculturation was measured using acculturation scales (language and social), years in the US, language preference, and age at immigration. Physical activity and sedentary behavior were measured using the Global Physical Activity Questionnaire (N = 15,355) and Actical accelerometer (N = 11,954). Poisson, logistic, and linear regression were used, accounting for complex design and sampling weights. English-language preference was positively associated with self-reported leisure-time and transportation physical activity and accelerometer-assessed moderate-to-vigorous physical activity (MVPA). Social acculturation was positively associated with self-reported leisure-time and transportation physical activity and MVPA. Years in the US and age at immigration were positively associated with accelerometer-assessed MVPA. Language acculturation, years in the US, and age at immigration were associated with occupational physical activity among those who reported employment. Most acculturation measures were associated with self-reported sitting but not with accelerometer-assessed sedentary behavior. Different measures of acculturation, capturing various domains acculturation, were associated with physical activity and sedentary behavior. However, the direction of the association was dependent on the measures of acculturation physical activity/sedentary behavior, highlighting the complexity of these relationships

    Project momo: Multiwavelength observations and modeling of oj 287

    Get PDF
    Our project MOMO (Multiwavelength observations and modeling of OJ 287) consists of dedicated, dense, long-term flux and spectroscopic monitoring, and deep follow-up observations of the blazar OJ 287 at >13 frequencies from the radio to the X-ray band since late 2015. In particular, we are using Swift to obtain optical-UV-X-ray spectral energy distributions (SEDs) and the Effelsberg telescope to obtain radio measurements between 2 and 40 GHz. MOMO is the densest long-term monitoring of OJ 287 involving X-rays and broad-band SEDs. The theoretical part of the project aims at understanding jet and accretion physics of the blazar central engine in general and the supermassive binary black hole scenario in particular. Results are presented in a sequence of publications and so far included: detection and detailed analysis of the bright 2016/17 and 2020 outbursts and the long-term light curve; Swift, XMM, and NuSTAR spectroscopy of the 2020 outburst around maximum; and interpretation of selected events in the context of the binary black hole scenario of OJ 287 (papers I–IV). Here, we provide a description of the project MOMO, a summary of previous results, the latest results, and we discuss future prospects. View Full-TextKeywords: active galactic nuclei; blazars; jets; black holes; supermassive binary black holes; OJ 287; spectral energy distributions; Neil Gehrels Swift observatory; XMM-Newton; NuSTAR</p

    Physical Activity and Sedentary Behavior among US Hispanic/Latino Youth: The SOL Youth Study

    Get PDF
    Purpose: Physical activity and sedentary behavior among diverse Hispanic/Latino youth in the United States is not well documented. The aim of this study was to describe physical activity and sedentary behavior among a representative sample of Hispanic/Latino youth from four US communities using accelerometry and self-reported measures. Methods: From 2012 to 2014, 1466 Hispanic/Latino youth ages 8 to 16 yr, children of participants in the Hispanic Community Health Study/Study of Latinos, enrolled in the SOL youth. Physical activity and sedentary behavior were assessed by interview. After this, youth wore an Actical accelerometer for 1 wk. All statistical analyses accounted for the complex survey design and used sampling weights. Results: The accelerometer wear time adjusted mean minutes per day was: 604.6, sedentary; 178.9, light; 25.4, moderate; and 10.2, vigorous. Generally, higher levels of moderate and vigorous activity occurred among males, Mexican backgrounds, and youth age 8 to 10 yr compared with older age groups. Higher levels of sedentary behavior occurred among youth age 15 to 16 yr compared with younger age groups. The most common activities (reported, ≥1 per month) were of lower intensity, including listening to music (91.9%), homework (87.0%), riding in car/bus (84.3%), and hanging out with friends (83.4%). Common active pursuits included travel by walking (74.6%), physical education class (71.7%), running (71.4%), and recess (71.3%). Conclusions: Time, intensity, and type of physical activity and sedentary behavior varied among Hispanic/Latino youth. These findings can inform efforts to increase physical activity and reduce sedentary behavior among US Hispanic/Latino youth

    Measuring Black Hole Spin using X-ray Reflection Spectroscopy

    Full text link
    I review the current status of X-ray reflection (a.k.a. broad iron line) based black hole spin measurements. This is a powerful technique that allows us to measure robust black hole spins across the mass range, from the stellar-mass black holes in X-ray binaries to the supermassive black holes in active galactic nuclei. After describing the basic assumptions of this approach, I lay out the detailed methodology focusing on "best practices" that have been found necessary to obtain robust results. Reflecting my own biases, this review is slanted towards a discussion of supermassive black hole (SMBH) spin in active galactic nuclei (AGN). Pulling together all of the available XMM-Newton and Suzaku results from the literature that satisfy objective quality control criteria, it is clear that a large fraction of SMBHs are rapidly-spinning, although there are tentative hints of a more slowly spinning population at high (M>5*10^7Msun) and low (M<2*10^6Msun) mass. I also engage in a brief review of the spins of stellar-mass black holes in X-ray binaries. In general, reflection-based and continuum-fitting based spin measures are in agreement, although there remain two objects (GROJ1655-40 and 4U1543-475) for which that is not true. I end this review by discussing the exciting frontier of relativistic reverberation, particularly the discovery of broad iron line reverberation in XMM-Newton data for the Seyfert galaxies NGC4151, NGC7314 and MCG-5-23-16. As well as confirming the basic paradigm of relativistic disk reflection, this detection of reverberation demonstrates that future large-area X-ray observatories such as LOFT will make tremendous progress in studies of strong gravity using relativistic reverberation in AGN.Comment: 19 pages. To appear in proceedings of the ISSI-Bern workshop on "The Physics of Accretion onto Black Holes" (8-12 Oct 2012). Revised version adds a missing source to Table 1 and Fig.6 (IRAS13224-3809) and corrects the referencing of the discovery of soft lags in 1H0707-495 (which were in fact first reported in Fabian et al. 2009
    corecore