7,160 research outputs found
Quasar outflow energetics from broad absorption line variability
Quasar outflows have long been recognized as potential contributors to the
co-evolution between supermassive black holes (SMBHs) and their host galaxies.
The role of outflows in AGN feedback processes can be better understood by
placing observational constraints on wind locations and kinetic energies. We
utilize broad absorption line (BAL) variability to investigate the properties
of a sample of 71 BAL quasars with PV broad absorption. The
presence of PV BALs indicates that other BALs like CIV
are saturated, such that variability in those lines favours clouds crossing the
line of sight. We use these constraints with measurements of BAL variability to
estimate outflow locations and energetics. Our data set consists of
multiple-epoch spectra from the Sloan Digital Sky Survey and MDM Observatory.
We detect significant (4) BAL variations from 10 quasars in our sample
over rest frame time-scales between < 0.2-3.8 yr. Our derived distances for the
10 variable outflows are nominally < 1-10 pc from the SMBH using the
transverse-motion scenario, and < 100-1000 pc from the central source using
ionization-change considerations. These distances, in combination with the
estimated high outflow column densities (i.e. > 10
cm), yield outflow kinetic luminosities between ~ 0.001-1 times the
bolometric luminosity of the quasar, indicating that many absorber energies
within our sample are viable for AGN feedback.Comment: 19 pages, 3 figures, 4 tables, 1 supplementary figure, accepted to
MNRA
Constraining FeLoBAL outflows from absorption line variability
FeLoBALs are a rare class of quasar outflows with low-ionization broad
absorption lines (BALs), large column densities, and potentially large kinetic
energies that might be important for `feedback' to galaxy evolution. In order
to probe the physical properties of these outflows, we conducted a
multiple-epoch, absorption line variability study of 12 FeLoBAL quasars
spanning a redshift range between 0.7 and 1.9 over rest frame time-scales of
approximately 10 d to 7.6 yr. We detect absorption line variability with
greater than 8 sigma confidence in 3 out of the 12 sources in our sample over
time-scales of 0.6 to 7.6 yr. Variable wavelength intervals are associated with
ground and excited state Fe II multiplets, the Mg II 2796, 2803 doublet, Mg I
2852, and excited state Ni II multiplets. The observed variability along with
evidence of saturation in the absorption lines favors transverse motions of gas
across the line of sight (LOS) as the preferred scenario, and allows us to
constrain the outflow distance from the supermassive black hole (SMBH) to be
less than 69, 7, and 60 pc for our three variable sources. In combination with
other studies, these results suggest that the outflowing gas in FeLoBAL quasars
resides on a range of scales and includes matter within tens of parsecs of the
central source.Comment: 21 pages, 6 figures, 2 supplementary figures (attached at the end of
the manuscript), accepted to Monthly Notices of the Royal Astronomical
Societ
Child mental health and educational attainment: multiple observers and the measurement error problem
We examine the effect of survey measurement error on the empirical relationship between child mental health and personal and family characteristics, and between child mental health and educational progress. Our contribution is to use unique UK survey data that contain (potentially biased) assessments of each child's mental state from three observers (parent, teacher and child), together with expert (quasi-)diagnoses, using an assumption of optimal diagnostic behaviour to adjust for reporting bias. We use three alternative restrictions to identify the effect of mental disorders on educational progress. Maternal education and mental health, family income and major adverse life events are all significant in explaining child mental health, and child mental health is found to have a large influence on educational progress. Our preferred estimate is that a one-standard-deviation reduction in ?true? latent child mental health leads to a 2- to 5-month loss in educational progress. We also find a strong tendency for observers to understate the problems of older children and adolescents compared to expert diagnosi
Weakly Invertible Elements in the Space of SquareâSummable Holomorphic Functions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135229/1/jlms0183.pd
The rural mother's experience of caring for a child with a chronic health condition: An integrative review
© 2018 John Wiley & Sons Ltd Aims and objectives: To identify and review the literature on rural mothersâ experiences in caring for a child with a chronic health condition. Background: Families living with a child who has a chronic health condition experience many challenges; these are often amplified for families living in rural areas, where issues such as the distance from services add further challenges the family must manage. Like many children, rural children with chronic health conditions are primarily cared for by their mothers. The additional strain of geography creates its own unique experiences for mothers who need to access the high-quality care that their child requires. Design: Integrative literature review using the Equator PRISMA guidelines. Methods: A search of databases; Cochrane, CINAHL, Ovid, PubMed, ProQuest Health and Medicine, Informit and Scopus for studies published between 2005â2016 using an integrative review approach. A total of 1,484 studies were identified with an additional six studies found through snowballing. The search resulted in seven studies being meeting the inclusion criteria after using the Critical Appraisal Skills Programme. Results: Data from the seven articles were analysed, and the mothersâ experiences were synthesised into five themes: âstruggling for resources,â âbarriers in accessing services,â âstrain of decision-making,â âmother's physical and emotional breakdownâ and âthe daily management of family activitiesâ. These five themes formed the basis of this article. Conclusions: The findings indicate that mothers from rural areas face additional barriers related to their rurality, including transportation difficulties, socioeconomic status and social isolation, and are challenged by limited access to specialty medical services, educators and allied health professionals. The literature review outcome will assist in informing nursing practice through identifying and allocating resources to reduce these barriers; rural mother experience will assist in enabling the child to reach their full developmental potential. Relevance to clinical practice: There is a need for health professionals to understand the challenges and barriers rural mothers face in accessing services. Nurses can assist rural mothers to navigate and access the appropriate services in order to reduce health inequity, increase accessibility to services and reduce rural disadvantage for their child. Nurses and health professionals are in an ideal position to develop future models of care that optimise health outcomes and enable equity and access to services for rural children with chronic conditions similar to those experienced by their urban counterparts
The Quasar SDSS J105041.35+345631.3: Black Hole Recoil or Extreme Double-Peaked Emitter?
The quasar SDSS J105041.35+345631.3 (z = 0.272) has broad emission lines
blueshifted by 3500 km/s relative to the narrow lines and the host galaxy. Such
an object may be a candidate for a recoiling supermassive black hole, binary
black hole, a superposition of two objects, or an unusual geometry for the
broad emission-line region. The absence of narrow lines at the broad line
redshift argues against superposition. New Keck spectra of J1050+3546 place
tight constraints on the binary model. The combination of large velocity shift
and symmetrical H-beta profile, as well as aspects of the narrow line spectrum,
make J1050+3546 an interesting candidate for black hole recoil. Other aspects
of the spectrum, however, suggest that the object is most likely an extreme
case of a ``double-peaked emitter.'' We discuss possible observational tests to
determine the true nature of this exceptional object.Comment: 5 pages, 2 figures, LaTeX; substantial revision
Integrating Life Cycle Assessment and Other Tools for Ex Ante Integrated Sustainability Assessment in the Minerals Industry
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