5,586 research outputs found
Governance: A Soft Revolution with hard Political and Legal Effects
El supuesto básico de este artículo es que la gobernanza señala un alejamiento de los dos pilares del proyecto moderno: la democracia representativa y las instituciones legislativas. La gobernanza, como fenómeno institucional complejo, que va mucho mas allá de la participación, ha desestructurado sensiblemente los dos principales puntos de referencia de la democracia moderna: pueblo y territorio. Su trato inclusivo y abierto no ha impedido el surgimiento de un lado oscuro, hecho de modos exclusivos: un teatro sin publicidad. Desde la perspectiva de las transformaciones este artículo pone en evidencia la emergencia de una normatividad cambiante y fluida, capaz de adaptarse a las especificidades y a la variabilidad de situaciones y procesos, ofuscando inevitablemente la misma primacía de la legislación.The basic assumption of this article is that governance marks a departure from the two pillars of the project of modernity: representative democracy and legislative institutions. Governance, as a complex institutional phenomenon that goes far beyond participation, has significantly deconstructed the two main points of reference of modern democracy, that is, people and territory. Furthermore, its inclusive and open nature has not prevented the emergence of a dark side, made of exclusive modes: a theater without publicity. From the perspective of transformations, this article highlights the emergence of a changing and fluid normativity, one capable of adapting to the specificity and the variability of situations and processes, inevitably eclipsing the primacy of the legislation itself
Relationship of Black Holes to Bulges
Supermassive black holes appear to be uniquely associated with galactic
bulges. The mean ratio of black hole mass to bulge mass was until recently very
uncertain, with ground based, stellar kinematical data giving a value roughly
an order of magnitude larger than other techniques. The discrepancy was
resolved with the discovery of the M-sigma relation, which simultaneously
established a tight corrrelation between black hole mass and bulge velocity
dispersion, and confirmed that the stellar kinematical mass estimates were
systematically too large due to failure to resolve the black hole's sphere of
influence. There is now excellent agreement between the various techniques for
estimating the mean black hole mass, including dynamical mass estimation in
quiescent galaxies; reverberation mapping in active galaxies and quasars; and
computation of the mean density of compact objects based on integrated quasar
light. Implications of the M-sigma relation for the formation of black holes
are discussed.Comment: 29 pages, 12 postscript figures, uses newpasp.sty. To appear in "The
Central Kpc of Starbursts and AGN", ed. J. H. Knapen, J. E. Beckman, I.
Shlosman & T. J. Mahone
A Log-Quadratic Relation Between the Nuclear Black-Hole Masses and Velocity Dispersions of Galaxies
We demonstrate that a log-linear relation does not provide an adequate
description of the correlation between the masses of Super-Massive Black-Holes
(SMBH, M_bh) and the velocity dispersions of their host spheroid (sigma). An
unknown relation between log(M_bh) and log(sigma) may be expanded to second
order to obtain a log-quadratic relation of the form log(M_bh)=alpha+beta
log(sigma/200) + beta_2[log(sigma/200)]^2. We perform a Bayesian analysis using
the Nuker sample, and solve for beta, beta_2 and alpha, in addition to the
intrinsic scatter (delta). We find unbiased parameter estimates of
beta=4.2+/-0.37, beta_2=1.6+/-1.3 and delta=0.275+/-0.05. At the 80% level the
M_bh-sigma relation does not follow a uniform power-law. Indeed, over the
velocity range 70km/s<sigma<380km/s the logarithmic slope of the best fit
relation varies between 2.7 and 5.1, which should be compared with a power-law
estimate of 4.02+/-0.33. Assuming no systematic offset, single epoch virial
SMBH masses estimated for AGN follow the same log-quadratic M_bh-sigma relation
as the Nuker sample, but extend it downward in mass by an order of magnitude.
The log-quadratic term in the M_bh-sigma relation has a significant effect on
estimates of the local SMBH mass function at M_bh>10^9 solar masses, leading to
densities of SMBHs with M_bh>10^10 solar masses that are several orders of
magnitude larger than inferred from a log-linear relation. We also estimate
unbiased parameters for the SMBH-bulge mass relation. With a parameterisation
log(M_bh)=alpha_b + beta_b log(M_b/10^{11}) + beta_2b[log(M_b/10^{11})]^2, we
find beta_b=1.15+/-0.18 and beta_2b=0.12+/-0.14. We determined an intrinsic
scatter delta_b=0.41+/-0.07 which is ~50% larger than the scatter in the
M_bh-sigma relation.Comment: 21 pages, 14 figures. Replaced to correct errors in published versio
No Supermassive Black Hole in M33?
We analyze optical long-slit spectroscopy of the nucleus of M33 obtained from
the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope.
Rather than the steep rise expected within the radius of influence of a
supermassive black hole, the velocity dispersion drops significantly within the
inner parsec. Dynamical modelling yields an estimated upper limit of 3000 solar
masses for the mass of a central compact object. This upper limit is however
consistent within the uncertainties with the mass predicted by the M-sigma
relation, which is between 2000 and 20,000 solar masses. We therefore can not
conclude that the presence of a massive black hole in the nucleus of M33 would
require a different formation mechanism from that of the black holes detected
in galaxies with more luminous bulges.Comment: 10 pages, 4 postscript figure
Extraction of main levels of a building from a large point cloud
Horizontal levels are references entities, the base of man-made environments. Their creation is the first step for various applications including the BIM (Building Information Modelling). BIM is an emerging methodology, widely used for new constructions, and increasingly applied to existing buildings (scan-to-BIM). The as-built BIM process is still mainly manual or semi-automatic and therefore is highly time-consuming. The automation of the as-built BIM is a challenging topic among the research community. This study is part of an ongoing research into the scan-to-BIM process regarding the extraction of the principal structure of a building. More specifically, here we present a strategy to automatically detect the building levels from a large point cloud obtained with a terrestrial laser scanner survey. The identification of the horizontal planes is the first indispensable step to produce an as-built BIM model. Our algorithm, developed in C++, is based on plane extraction by means of the RANSAC algorithm followed by the minimization of the quadrate sum of points-plane distance. Moreover, this paper will take an in-depth look at the influence of data resolution in the accuracy of plane extraction and at the necessary accuracy for the construction of a BIM model. A laser scanner survey of a three floors building composed by 36 scan stations has produced a point cloud of about 550 million points. The estimated plane parameters at different data resolution are analysed in terms of distance from the full points cloud resolution
Narrow-line Seyfert 1 Galaxies and the M_BH - sigma Relation
We have studied the location of narrow-line Seyfert 1 (NLS1) galaxies and
broad-line Seyfert 1 (BLS1) galaxies on the M_BH - sigma relation of non-active
galaxies. We find that NLS1 galaxies as a class - as well as the BLS1 galaxies
of our comparison sample - do follow the M_BH-sigma relation of non-active
galaxies if we use the width of the [SII]6716,6731 emission lines as surrogate
for stellar velocity dispersion, sigma_*. We also find that the width of
[OIII]5007 is a good surrogate for sigma_*, but only after (a) removal of
asymmetric blue wings, and, more important, after (b) excluding core [OIII]
lines with strong blueshifts (i.e., excluding galaxies which have their [OIII]
velocity fields dominated by radial motions, presumably outflows). The same
galaxies which are extreme outliers in [OIII] still follow the M_BH - sigma
relation in [SII]. We confirm previous findings that NLS1 galaxies are
systematically off-set from the M_BH - sigma relation if the full [OIII]
profile is used to measure sigma. We systematically investigate the influence
of several parameters on the NSL1 galaxies' location on the M_BH - sigma plane:
[OIII]_core blueshift, L/L_Edd, intensity ratio FeII/H_beta, NLR density, and
absolute magnitude. Implications for NLS1 models and for their evolution along
the M_BH - sigma relation are discussed.Comment: ApJ Letters, in press (3 figures, one in colour
Supermassive Black Holes and Their Host Galaxies - I. Bulge luminosities from dedicated near-infrared data
In an effort to secure, refine and supplement the relation between central
Supermassive Black Hole masses (Mbh), and the bulge luminosities of their host
galaxies, (Lbul), we obtained deep, high spatial resolution K-band images of 35
nearby galaxies with securely measured Mbh, using the wide-field WIRCam imager
at the Canada-France-Hawaii-Telescope (CFHT). A dedicated data reduction and
sky subtraction strategy was adopted to estimate the brightness and structure
of the sky, a critical step when tracing the light distribution of extended
objects in the near-infrared. From the final image product, bulge and total
magnitudes were extracted via two-dimensional profile fitting. As a first order
approximation, all galaxies were modeled using a simple Sersic-bulge +
exponential-disk decomposition. However, we found that such models did not
adequately describe the structure that we observe in a large fraction of our
sample galaxies which often include cores, bars, nuclei, inner disks, spiral
arms, rings and envelopes. In such cases, we adopted profile modifications
and/or more complex models with additional components. The derived bulge
magnitudes are very sensitive to the details and number of components used in
the models, although total magnitudes remain almost unaffected. Usually, but
not always, the luminosities and sizes of the bulges are overestimated when a
simple bulge+disk decomposition is adopted in lieu of a more complex model.
Furthermore we found that some spheroids are not well fit when the ellipticity
of the Sersic model is held fixed. This paper presents the details of the image
processing and analysis, while in a companion paper we discuss how
model-induced biases and systematics in bulge magnitudes impact the Mbh-Lbul
relation.Comment: 48 pages, 40 Figures, 5 tables; high-resolution figures and a
corresponding version of the .pdf are available at
https://www.dropbox.com/sh/lx0xqn89wa3y320/2hS-zZ12Y
The Low End of the Supermassive Black Hole Mass Function: Constraining the Mass of a Nuclear Black Hole in NGC 205 via Stellar Kinematics
Hubble Space Telescope (HST) images and spectra of the nucleated dwarf
elliptical galaxy NGC 205 are combined with 3-integral axisymmetric dynamical
models to constrain the mass (M_BH) of a putative nuclear black hole. This is
only the second attempt, after M33, to use resolved stellar kinematics to
search for a nuclear black hole with mass below 10^6 solar masses. We are
unable to identify a best-fit value of M_BH in NGC 205; however, the data
impose a upper limit of 2.2x10^4 M_sun (1sigma confidence) and and upper limit
of 3.8x10^4 M_sun (3sigma confidence). This upper limit is consistent with the
extrapolation of the M_BH-sigma relation to the M_BH < 10^6 M_sunregime. If we
assume that NGC 205 and M33 both contain nuclear black holes, the upper limits
on M_BH in the two galaxies imply a slope of ~5.5 or greater for the M_BH-sigma
relation. We use our 3-integral models to evaluate the relaxation time (T_r)
and stellar collision time (T_coll) in NGC 205; T_r~10^8 yr or less in the
nucleus and T_coll~10^11 yr. The low value of T_r is consistent with core
collapse having already occurred, but we are unable to draw conclusions from
nuclear morphology about the presence or absence of a massive black hole.Comment: Latex emulateapj, 15 pages, 16 figures, Version accepted for
Publication in ApJ, 20 July 2005, v628. Minor changes to discussion
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