1,410 research outputs found
Constraints on the radio loud/radio quiet dichotomy from the fundamental plane
The fundamental plane for black hole activity constitutes a tight correlation
between jet power, X-ray luminosity, and black hole mass. Under the assumption
that a Blandford-Znajek-type mechanism, which relies on black hole spin,
contributes non-negligibly to jet production, the sufficiently small scatter in
the fundamental plane shows that black hole spin differences of
a1 are not typical among the active galactic nuclei
population. If as it seems radio loud and radio quiet objects are both
faithful to the fundamental plane, models of black hole accretion in which the
radio loud/radio quiet dichotomy is based on a spin dichotomy of
a1/a0, respectively, are difficult to reconcile with the
observations.
We show how recent theoretical work based on differences in accretion flow
orientation between retrograde and prograde, accommodates a small scatter in
the fundamental plane for objects that do have non-negligible differences in
black hole spin values. We also show that the dichotomy in spin between the
most radio loud and the most radio quiet involves a0. And, finally, we show how the picture that produces compatibility
with the fundamental plane, also allows one to interpret other otherwise
puzzling observations of jets across the mass scale including 1) the recently
observed inverse relation between radio and X-rays at higher Eddington ratios
in both black hole X-ray binaries as well as active galactic nuclei and 2) the
apparent contradiction between jet power and black hole spin observed in X-ray
hard and transitory burst states in X-ray binaries.Comment: 8 pages, 1 figure, accepted in MNRA
Constraints of the Radio-loud/Radio-quiet Dichotomy from the Fundamental Plane
The Fundamental Plane for black hole activity constitutes a tight correlation between jet power, X-ray luminosity, and black hole mass. Under the assumption that a Blandford–Znajek-type mechanism, which relies on black hole spin, contributes non-negligibly to jet production, the sufficiently small scatter in the Fundamental Plane shows that black hole spin differences of |Δa| ∼ 1 are not typical among the active galactic nuclei population. If – as it seems – radio-loud and radio-quiet objects are both faithful to the Fundamental Plane, models of black hole accretion in which the radio-loud/radio-quiet dichotomy is based on a spin dichotomy of a∼1/a∼0, respectively, are difficult to reconcile with the observations. We show how recent theoretical work based on differences in accretion flow orientation between retrograde and prograde, accommodates a small scatter in the Fundamental Plane for objects that do have non-negligible differences in black hole spin values. We also show that the dichotomy in spin between the most radio loud and the most radio quiet involves |Δa| ≈ 0. And, finally, we show how the picture that produces compatibility with the Fundamental Plane, also allows one to interpret other otherwise puzzling observations of jets across the mass scale including (1) the recently observed inverse relation between radio and X-rays at higher Eddington ratios in both black hole X-ray binaries as well as active galactic nuclei and (2) the apparent contradiction between jet power and black hole spin observed in X-ray hard and transitory burst states in X-ray binaries
Quantitative uniqueness for elliptic equations with singular lower order terms
We use a Carleman type inequality of Koch and Tataru to obtain quantitative
estimates of unique continuation for solutions of second order elliptic
equations with singular lower order terms. First we prove a three sphere
inequality and then describe two methods of propagation of smallness from sets
of positive measure.Comment: 23 pages, v2 small changes are done and some mistakes are correcte
Emotional, cognitive and behavioral self-regulation in forensic psychiatric patients:Changes over time and associations with childhood trauma, identity and personality pathology
The construct of self-regulation is of particular interest to the forensic psychiatric practice due to its associations with both clinical and criminal outcomes, as well as recidivism. However, research on different components of self-regulation within forensic psychiatric practice is rare. The current study aimed to gain knowledge on the construct of self-regulation in a sample of forensic psychiatric patients (N = 94). Firstly, by investigating change of emotional, behavioral and cognitive self-regulation over the course of 12 months in state-mandated care in a treatment facility. Secondly, by looking at the associations between these three elements of self-regulation and childhood trauma, identity dysfunction and personality pathology. Repeated measures ANOVA showed little to no difference in average self-regulation over time (only for behavioral regulation), and rank-order stability was relatively high in most cases. Path analysis showed that: emotion regulation was associated with all outcomes; behavioral regulation with all except childhood trauma and detachment; and cognitive regulation only with antagonism and negative affectivity. Findings suggest short-term changes are unlikely and indicate relative importance of emotional, and to some extent behavioral regulation for clinical practice. However, due to sample size restrictions, interpretations should be made with caution
Variable stars and stellar populations in Andromeda XXI: II. Another merged galaxy satellite of M31?
B and V time-series photometry of the M31 dwarf spheroidal satellite
Andromeda XXI (And XXI) was obtained with the Large Binocular Cameras at the
Large Binocular Telescope. We have identified 50 variables in And XXI, of which
41 are RR Lyrae stars (37 fundamental-mode RRab, and 4 first-overtone RRc,
pulsators) and 9 are Anomalous Cepheids (ACs). The average period of the RRab
stars ( = 0.64 days) and the period-amplitude diagram place And~XXI in the
class of Oosterhoff II - Oosterhoff-Intermediate objects. From the average
luminosity of the RR Lyrae stars we derived the galaxy distance modulus of
(m-M)= mag, which is smaller than previous literature
estimates, although still consistent with them within 1 . The galaxy
color-magnitude diagram shows evidence for the presence of three different
stellar generations in And~XXI: 1) an old ( 12 Gyr) and metal poor
([Fe/H]=1.7 dex) component traced by the RR Lyrae stars; 2) a slightly
younger (10-6 Gyr) and more metal rich ([Fe/H]=1.5 dex) component populating
the red horizontal branch, and 3) a young age ( 1 Gyr) component with
same metallicity, that produced the ACs. Finally, we provide hints that And~XXI
could be the result of a minor merging event between two dwarf galaxies.Comment: accepted for publications in Ap
Possible Evolution of Supermassive Black Holes from FRI quasars
We explore the question of the rapid buildup of black hole mass in the early
universe employing a growing black hole mass-based determination of both jet
and disk powers predicted in recent theoretical work on black hole accretion
and jet formation. Despite simplified, even artificial assumptions about
accretion and mergers, we identify an interesting low probability channel for
the growth of one billion solar mass black holes within hundreds of millions of
years of the Big Bang without appealing to super Eddington accretion. This
result is made more compelling by the recognition of a connection between this
channel and an end product involving active galaxies with FRI radio morphology
but weaker jet powers in mildly sub-Eddington accretion regimes. While FRI
quasars have already been shown to occupy a small region of the available
parameter space for black hole feedback in the paradigm, we further suggest
that the observational dearth of FRI quasars is also related to their
connection to the most massive black hole growth due to both these FRIs high
redshifts and relative weakness. Our results also allow us to construct the AGN
luminosity function at high redshift, that agree with recent studies. In short,
we produce a connection between the unexplained paucity of a given family of
active galactic nuclei and the rapid growth of supermassive black holes, two
heretofore seemingly unrelated aspects of the physics of active galactic
nuclei.Comment: Accepted for publication in MNRAS on 12-May-2016., 27 pages, 7
figures, 1 tabl
Reconciling AG-star Formation, the Soltan Argument, and Meier\u27s Paradox
We provide a theoretical context for understanding the recent work of Kalfountzou et al. showing that star formation is enhanced at lower optical luminosity in radio-loud quasars. Our proposal for coupling the assumption of collimated FRII quasar-jet-induced star formation with lower accretion optical luminosity also explains the observed jet power peak in active galaxies at higher redshift compared to the peak in accretion power, doing so in a way that predicts the existence of a family of radio-quiet active galactic nuclei associated with rapidly spinning supermassive black holes at low redshift, as mounting observations suggest. The relevance of this work lies in its promise to explain the observed cosmological evolution of accretion power, jet power, and star formation in a way that is both compatible with the Soltan argument and resolves the so-called Meier Paradox
Local behavior of p-harmonic Green's functions in metric spaces
We describe the behavior of p-harmonic Green's functions near a singularity
in metric measure spaces equipped with a doubling measure and supporting a
Poincar\'e inequality
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