35 research outputs found

    Super-solar N/C in the NLS1 Galaxy Markarian 1044

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    Narrow-Line Seyfert 1s (NLS1s) are known to have extreme values of a number of properties compared to Active Galactic Nuclei (AGN) as a class. In particular, previous emission-line studies have suggested that NLS1s are unusually metal rich compared to broad-line AGN of comparable luminosity. We present low- and medium-resolution spectroscopic observations of the NLS1 Markarian 1044 with the Hubble Space Telescope Imaging Spectrometer (STIS). We identify two blueshifted intrinsic absorption systems at -1145 and -295 km/s relative to the systemic velocity of the galaxy. Using a simple photoionization model of the absorbing gas, we find that the strongest and best-measured of the absorption systems has N/C approximately 6.96 times the solar value. We also report on the discovery of three new Ly-alpha forest lines with neutral Hydrogen column density log greater than 12.77 in the log. This number is consistent with the 2.6 expected in the path length to the source redshift of Mrk 1044.Comment: Submitted to ApJ. 21 pages including 4 figures & 5 table

    Chandra Observations of X-ray Weak Narrow-Line Seyfert 1 Galaxies

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    We present Chandra observations of 17 optically-selected, X-ray weak narrow-line Seyfert 1 (NLS1) galaxies. These objects were optically identified by Williams et al. (2002) in the Sloan Digital Sky Survey Early Data Release, but were not found in the ROSAT All-Sky Survey (RASS) despite having optical properties similar to RASS-detected NLS1s. All objects in this sample were detected by Chandra and exhibit a range of 0.5-2 keV photon indices Gamma=1.1-3.4. One object was not detected in the soft band, but has a best-fit Gamma=0.25 over the full 0.5-8 keV range. These photon indices extend to values far below what are normally observed in NLS1s. A composite X-ray spectrum of the hardest objects in this sample does not show any signs of absorption, although the data do not prohibit one or two of the objects from being highly absorbed. We also find a strong correlation between Gamma and L_1keV; this may be due to differences in L_bol/L_Edd among the NLS1s in this sample. Such variations are seemingly in conflict with the current paradigm that NLS1s accrete near the Eddington limit. Most importantly, this sample shows that strong, ultrasoft X-ray emission is not a universal characteristic of NLS1s; in fact, a substantial number may exhibit weak and/or low-Gamma X-ray emission.Comment: Minor changes, added section on X-ray weakness. 25 pages incl. 6 figures, 3 tables, accepted to Ap

    Narrow-line Seyfert 1 Galaxies from the Sloan Digital Sky Survey Early Data Release

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    We present a sample of 150 narrow-line Seyfert 1s (NLS1s) found within the Sloan Digital Sky Survey Early Data Release (EDR), only two of which were previously identified as such. This substantially increases the known number of NLS1s, and provides a basic method by which to identify many more with subsequent releases of SDSS data. With its large size and homogeneous, well-defined selection criteria, this sample will help alleviate two major problems which have plauged NLS1 research in the past; namely, their relative rarity and significant differences in selection algorithms between the known samples. 45 of these SDSS-selected NLS1s are detected at energies of 0.1-2 keV in the ROSAT All-Sky Survey (RASS), and are found to have ultrasoft X-ray spectra with photon indices of Gamma >~ 2, in agreement with previous results for NLS1s. However, about 10-20 of those NLS1s that were not detected by ROSAT have optical properties very similar to the detected objects, and so should also have been detected by the RASS. This may be due to either significant intrinsic absorption in many NLS1s, or a significant sub-class of NLS1s that have uncharacteristic, intrinsically flatter (hence harder) X-ray spectral energy distributions.Comment: Minor changes, accepted to AJ; 21 pages, 7 figures, AASTEX v5.

    Human rights and ethical reasoning : capabilities, conventions and spheres of public action

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    This interdisciplinary article argues that human rights must be understood in terms of opportunities for social participation and that social and economic rights are integral to any discussion of the subject. We offer both a social constructionist and a normative framework for a sociology of human rights which reaches beyond liberal individualism, combining insights from the work of Amartya Sen and from French convention theory. Following Sen, we argue that human rights are founded on the promotion of human capabilities as ethical demands shaped by public reasoning. Using French convention theory, we show how the terms of such deliberation are shaped by different constructions of collectively held values and the compromises reached between them. We conclude by demonstrating how our approach offers a new perspective on spheres of public action and the role these should play in promoting social cohesion, individual capabilities and human rights

    The Spectral Energy Distribution and Emission-Line properties of the NLS1 Galaxy Arakelian 564

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    We present the intrinsic spectral energy distribution (SED) of the NLS1 Arakelian 564, constructed with contemporaneous data obtained during a multi-wavelength, multi-satellite observing campaign in 2000 and 2001. We compare it with that of the NLS1 Ton S180 and with those obtained for BLS1s to infer how the relative accretion rates vary among the Sy1 population. Although the peak of the SED is not well constrained, most of the energy is emitted in the 10-100 eV regime, constituting roughly half of the emitted energy in the optical/X-ray ranges. This is consistent with a primary spectral component peaking in the extreme UV/soft X-ray band, and disk-corona models, hence high accretion rates. Indeed, we estimate that \dot{m}~1. We examine the emission lines in its spectrum, and we constrain the physical properties of the line-emitting gas through photoionization modeling. The line-emitting gas is characterized by log n~11 and log U~0, and is stratified around log U~0. Our estimate of the radius of the H\beta-emitting region ~10 \pm 2 lt-days is consistent with the radius-luminosity relationships found for Sy1 galaxies. We also find evidence for super-solar metallicity in this NLS1. We show that the emission lines are not good diagnostics for the underlying SEDs and that the absorption line studies offer a far more powerful tool to determine the ionizing continuum of AGNs, especially if comparing the lower- and higher-ionization lines.Comment: 15 pages, 10 figures; accepted for publication in The Astrophysical Journal, LaTeX emulateapj.st

    Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

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    Morality and World Hunger

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    Bittner R. Morality and World Hunger. In: Pogge TW, ed. Global Justice. Metaphilosophy series in Philosophy. Oxford: Blackwell; 2001: 24-31
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