58 research outputs found

    The first resolved imaging of milliarcsecond-scale jets in Circinus X-1

    Get PDF
    We present the first resolved imaging of the milliarcsecond-scale jets in the neutron star X-ray binary Circinus X-1, made using the Australian Long Baseline Array. The angular extent of the resolved jets is ~20 milliarcseconds, corresponding to a physical scale of ~150 au at the assumed distance of 7.8 kpc. The jet position angle is relatively consistent with previous arcsecond-scale imaging with the Australia Telescope Compact Array. The radio emission is symmetric about the peak, and is unresolved along the minor axis, constraining the opening angle to be less than 20 degrees. We observe evidence for outward motion of the components between the two halves of the observation. Constraints on the proper motion of the radio-emitting components suggest that they are only mildly relativistic, although we cannot definitively rule out the presence of the unseen, ultra-relativistic (Lorentz factor >15) flow previously inferred to exist in this system.Comment: Accepted for publication in MNRAS Letters. 6 pages, 4 figure

    Guiding cities under increased droughts: The limits to sustainable urban futures

    Get PDF
    Climate change is likely to increase droughts. The vulnerability of cities to droughts is increasing worldwide. Policy responses from cities to droughts lack consideration of long-term climatic and socio-economic scenarios, and focus on short-term emergency actions that disregard sustainability in the connected regional and river basin systems. We aim to explore the dynamics of the water-energy-land nexus in urban systems suffering increased climate change-related droughts, and their implications for sustainability. We complement a case study with a literature review providing cross-regional insights, and detail pervasive knowledge, policy and ambition gaps in the interaction between cities and droughts. We show that water availability with low emissions, without compromising ecosystems and with low costs to society, poses a local-scale limit to sustainable urban growth, a new concept delineating the limits to growth in cities. We conclude that urban and river basin planners need to institutionalize transparency and cross-sectoral integration in multi-sector partnerships, to consider long-term land use planning together with water and energy, and to apply integrated climate services to cities. Our study reveals the importance of including land, water and energy in long-term urban planning, and to connect them with the county, region, river basin and global scales. © 2021 The Author(s)The authors would like to express their gratitude for limited contributions, comments and discussions that helped to improve the manuscript to Muhamad Bahri, Jörg Cortekar, Mirabela Marin, Serban Octavian Davidescu, Iñaki Torres Cobián, and to two anonymous reviewers that helped to substantially improve the manuscript. Valuable feedback obtained in two conference sessions co‑lead by some of the authors (at Adaptation Futures 2018 in Cape Town, and at the 4th European Climate Change Adaptation conference, in Lisbon in 2019) is acknowledged. The authors acknowledge financial support from the project CLISWELN funded by ERA4CS. ERA4CS is an ERA-NET initiated by JPI Climate, and CLISWELN is funded by BMBF (DE), UEFISCDI (RO), BMBWF and FFG (AT), and MINECO (ES), with co-funding from the European Union (Grant 690462 ). This paper and the content included in it do not represent the opinion of the European Union, and the European Union is not responsible for any use that might be made of its content. Marta OlazabalThe authors would like to express their gratitude for limited contributions, comments and discussions that helped to improve the manuscript to Muhamad Bahri, Jörg Cortekar, Mirabela Marin, Serban Octavian Davidescu, Iñaki Torres Cobián, and to two anonymous reviewers that helped to substantially improve the manuscript. Valuable feedback obtained in two conference sessions co‑lead by some of the authors (at Adaptation Futures 2018 in Cape Town, and at the 4th European Climate Change Adaptation conference, in Lisbon in 2019) is acknowledged. The authors acknowledge financial support from the project CLISWELN funded by ERA4CS. ERA4CS is an ERA-NET initiated by JPI Climate, and CLISWELN is funded by BMBF (DE), UEFISCDI (RO), BMBWF and FFG (AT), and MINECO (ES), with co-funding from the European Union (Grant 690462 ). This paper and the content included in it do not represent the opinion of the European Union, and the European Union is not responsible for any use that might be made of its content. Marta Olazaba

    Radio emission from the X-ray pulsar Her X-1: a jet launched by a strong magnetic field neutron star?

    Get PDF
    Her X-1 is an accreting neutron star (NS) in an intermediate-mass X-ray binary. Like lowmass X-ray binaries (LMXBs), it accretes via Roche lobe overflow, but similar to many high-mass X-ray binaries containing a NS; Her X-1 has a strong magnetic field and slow spin. Here, we present the discovery of radio emission from Her X-1 with the Very Large Array. During the radio observation, the central X-ray source was partially obscured by a warped disc. We measure a radio flux density of 38.7 ± 4.8 µJy at 9 GHz but cannot constrain the spectral shape. We discuss possible origins of the radio emission, and conclude that coherent emission, a stellar wind, shocks and a propeller outflow are all unlikely explanations. A jet, as seen in LMXBs, is consistent with the observed radio properties. We consider the implications of the presence of a jet in Her X-1 on jet formation mechanisms and on the launching of jets by NSs with strong magnetic fields

    Compulsory admissions of patients with mental disorders : State of the art on ethical and legislative aspects in 40 European countries

    Get PDF
    Background. Compulsory admission procedures of patients with mental disorders vary between countries in Europe. The Ethics Committee of the European Psychiatric Association (EPA) launched a survey on involuntary admission procedures of patients with mental disorders in 40 countries to gather information from all National Psychiatric Associations that are members of the EPA to develop recommendations for improving involuntary admission processes and promote voluntary care. Methods. The survey focused on legislation of involuntary admissions and key actors involved in the admission procedure as well as most common reasons for involuntary admissions. Results. We analyzed the survey categorical data in themes, which highlight that both medical and legal actors are involved in involuntary admission procedures. Conclusions. We conclude that legal reasons for compulsory admission should be reworded in order to remove stigmatization of the patient, that raising awareness about involuntary admission procedures and patient rights with both patients and family advocacy groups is paramount, that communication about procedures should be widely available in lay-language for the general population, and that training sessions and guidance should be available for legal and medical practitioners. Finally, people working in the field need to be constantly aware about the ethical challenges surrounding compulsory admissions.Peer reviewe

    Accreting Millisecond X-Ray Pulsars

    Full text link
    Accreting Millisecond X-Ray Pulsars (AMXPs) are astrophysical laboratories without parallel in the study of extreme physics. In this chapter we review the past fifteen years of discoveries in the field. We summarize the observations of the fifteen known AMXPs, with a particular emphasis on the multi-wavelength observations that have been carried out since the discovery of the first AMXP in 1998. We review accretion torque theory, the pulse formation process, and how AMXP observations have changed our view on the interaction of plasma and magnetic fields in strong gravity. We also explain how the AMXPs have deepened our understanding of the thermonuclear burst process, in particular the phenomenon of burst oscillations. We conclude with a discussion of the open problems that remain to be addressed in the future.Comment: Review to appear in "Timing neutron stars: pulsations, oscillations and explosions", T. Belloni, M. Mendez, C.M. Zhang Eds., ASSL, Springer; [revision with literature updated, several typos removed, 1 new AMXP added

    Discovery of radio emission from the symbiotic X-ray binary system GX 1+4

    Get PDF
    We report the discovery of radio emission from the accreting X-ray pulsar and symbiotic X-ray binary GX 1+4 with the Karl G. Jansky Very Large Array. This is the first radio detection of such a system, wherein a strongly magnetized neutron star accretes from the stellar wind of an M-type giant companion. We measure a 9 GHz radio flux density of 105.3 ± 7.3 μJy, but cannot place meaningful constraints on the spectral index due to a limited frequency range. We consider several emission mechanisms that could be responsible for the observed radio source. We conclude that the observed properties are consistent with shocks in the interaction of the accretion flow with the magnetosphere, a synchrotron-emitting jet, or a propeller-driven outflow. The stellar wind from the companion is unlikely to be the origin of the radio emission. If the detected radio emission originates from a jet, it would show that strong magnetic fields (≥1012 G) do not necessarily suppress jet formation

    Jet quenching in the neutron star low-mass X-ray binary 1RXS J180408.9-342058

    Get PDF
    We present quasi-simultaneous radio (VLA) and X-ray (Swift) observations of the neutron star low-mass X-ray binary (NS-LMXB) 1RXS J180408.9-342058 (J1804) during its 2015 outburst. We found that the radio jet of J1804 was bright (232 ± 4 µJy at 10 GHz) during the initial hard X-ray state, before being quenched by more than an order of magnitude during the soft X-ray state (19 ± 4 µJy). The source then was undetected in radio ( < 13 µJy) as it faded to quiescence. In NS-LMXBs, possible jet quenching has been observed in only three sources and the J1804 jet quenching we show here is the deepest and clearest example to date. Radio observations when the source was fading towards quiescence (L X = 10 34-35 erg s -1 ) show that J1804 must follow a steep track in the radio/X-ray luminosity plane with ß > 0.7 (where L R a L X ß ). Few other sources have been studied in this faint regime, but a steep track is inconsistent with the suggested behaviour for the recently identified class of transitional millisecond pulsars. J1804 also shows fainter radio emission at L X < 10 35 erg s -1 than what is typically observed for accreting millisecond pulsars. This suggests that J1804 is likely not an accreting X-ray or transitional millisecond pulsar. © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society

    Future Science Prospects for AMI

    Get PDF
    The Arcminute Microkelvin Imager (AMI) is a telescope specifically designed for high sensitivity measurements of low-surface-brightness features at cm-wavelength and has unique, important capabilities. It consists of two interferometer arrays operating over 13.5-18 GHz that image structures on scales of 0.5-10 arcmin with very low systematics. The Small Array (AMI-SA; ten 3.7-m antennas) couples very well to Sunyaev-Zel'dovich features from galaxy clusters and to many Galactic features. The Large Array (AMI-LA; eight 13-m antennas) has a collecting area ten times that of the AMI-SA and longer baselines, crucially allowing the removal of the effects of confusing radio point sources from regions of low surface-brightness, extended emission. Moreover AMI provides fast, deep object surveying and allows monitoring of large numbers of objects. In this White Paper we review the new science - both Galactic and extragalactic - already achieved with AMI and outline the prospects for much more

    Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF

    Get PDF
    M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe
    corecore