Low-Luminosity Active Galactic Nuclei: Are They UV-Faint and Radio Loud?

Low-luminosity AGNs are perceived to be radio loud and devoid of a ``big blue bump'', indicating a transition from a radiatively efficient, geometrically thin, accretion disc in high-luminosity AGNs, to a geometrically thick, radiatively inefficient accretion flow at low luminosities and accretion rates. I revisit the issue of the spectral energy distributions (SEDs) of low-luminosity AGNs using recently published, high-angular-resolution data at radio, UV, and X-ray wavelengths, for a sample of 13 nearby galaxies with LINER nuclei. I show that, contrary to common wisdom, low-luminosity AGNs have significant nonstellar UV flux, and UV/X-ray luminosity ratios similar, on average, to those of Seyfert 1 nuclei ~10^4 times more luminous. The alpha_ox index that quantifies this ratio is in the range between -0.8 to -1.4, and is below the extrapolation to low luminosities of the relation between alpha_ ox and UV luminosity observed at higher luminosities. In terms of radio loudness, most of the LINERs are indeed radio loud (or sometimes even ``super radio loud'') based on their radio/UV luminosity ratios, when compared to the most luminous quasars. However, the entire distribution of radio loudness has been shown to shift to higher radio/UV ratios at low AGN luminosities. In the context of this global shift, some LINERs (the majority) can be considered radio quiet, and some (from among those with black hole masses >~10^8.5 M_sun) are radio loud. The SEDs of low-luminosity (~10^40 erg/s) AGNs are thus quite similar to those of Seyferts up to luminosities of ~10^44erg/s, and there is no evidence for a sharp change in the SEDs at the lowest luminosities. Thin AGN accretion discs may therefore persist at low accretion rates, in analogy to some recent findings for Galactic stellar-mass accreting black holes.Comment: MNRAS, in pres

Borderless Boundaries – as Means of Death and Life: Wilderness Portraits in Patristic and Rabbinic Literature

This study examines the role played by environmental representation of an apparent borderless boundary, the desert, as presented in Scripture – the Hebrew Bible / First Testament. It considers lessons derived from “desert-thought” testified within Rabbinic and Patristic literature. In Scripture, the desert played a prominent role in both Exodus and Akedah, two narratives central to Jewish thought and Christian theology. Beyond this, desert fathers such as Antony of Egypt expressed profound spirituality through this desolate land (Chrysostom; Athanasius, Vita). The Rabbis repeatedly embellished, for virtue’s sake, lessons gained from this same bleak landscape (Midrash Bemidbar Rabbah). An early version of this article was presented at the Canadian Society for Patristic Studies annual conference, a part of the Canadian Congress for Social Sciences and Humanities (May 26, 2014) at Brock University, St. Catharines, Ontario

Investment under Uncertainty and the Recipient of the Entry Cost

A typical model of investment under uncertainty where firms incur an irreversible cost in order to produce is studied with a novel focus on the reciever of this cost ("the source"). The source is modeled as a firm or a government that sells a resource or a right that are necessary for the production of the final good. We study in detail how the source sets its resource's price. We find that this price is a decreasing function of the elasticity of the demand for the final good. We also find that when this demand is sufficiently low, the source does not lower its price accordingly, and the producers of the final good delay their purchases of the resource. The reason is that the source expects demand to be higher in the future and does not want to be committed then to a low price for its resource

Labor Hours in the U.S. and Europe - the Role of Different Preferences Towards Leisure

Since 1950, the quantity of working hours has been decreasing over time both in the U.S. and in the main European economies. The European economies have started this mutual decline process with longer working hours than in the U.S., but have ended it with less working hours than the U.S. This article presents a model in which this dynamic pattern for the joint dynamics of their working hours is shared by two economies that differ only in the weight that their individuals put on leisure in their utility function and are identical in every other respect.Working hours; Economic Growth