Quasars: from the Physics of Line Formation to Cosmology

Quasars accreting matter at very high rates (known as extreme Population A [xA] or super-Eddington accreting massive black holes) provide a new class of distance indicators covering cosmic epochs from the present-day Universe up to less than 1 Gyr from the Big Bang. The very high accretion rate makes it possible that massive black holes hosted in xA quasars radiate at a stable, extreme luminosity-to-mass ratio. This in turns translates into stable physical and dynamical conditions of the mildly ionized gas in the quasar low-ionization line emitting region. In this contribution, we analyze the main optical and UV spectral properties of extreme Population A quasars that make them easily identifiable in large spectroscopic surveys at low-z (z < 1) and intermediate-z (2 < z < 2.6), and the physical conditions that are derived for the formation of their emission lines. Ultimately, the analysis supports the possibility of identifying a virial broadening estimator from low-ionization line widths, and the conceptual validity of the redshift-independent luminosity estimates based on virial broadening for a known luminosity-to-mass ratio.Comment: 13 pages, 5 figures. Invited lecture at SPIG 2018, Belgrade. To appear in Ato

Black hole mass estimates in quasars - A comparative analysis of high- and low-ionization lines

The inter-line comparison between high- and low-ionization emission lines has yielded a wealth of information on the quasar broad line region (BLR) structure and dynamics, including perhaps the earliest unambiguous evidence in favor of a disk + wind structure in radio-quiet quasars. We carried out an analysis of the CIV 1549 and Hbeta line profiles of 28 Hamburg-ESO high luminosity quasars and of 48 low-z, low luminosity sources in order to test whether the high-ionization line CIV 1549 width could be correlated with Hbeta and be used as a virial broadening estimator. We analyze intermediate- to high-S/N, moderate resolution optical and NIR spectra covering the redshifted CIV and H$\beta$ over a broad range of luminosity log L ~ 44 - 48.5 [erg/s] and redshift (0 - 3), following an approach based on the quasar main sequence. The present analysis indicates that the line width of CIV 1549 is not immediately offering a virial broadening estimator equivalent to H$\beta$. At the same time a virialized part of the BLR appears to be preserved even at the highest luminosities. We suggest a correction to FWHM(CIV) for Eddington ratio (using the CIV blueshift as a proxy) and luminosity effects that can be applied over more than four dex in luminosity. Great care should be used in estimating high-L black hole masses from CIV 1549 line width. However, once corrected FWHM(CIV) values are used, a CIV-based scaling law can yield unbiased MBH values with respect to the ones based on H$\beta$ with sample standard deviation ~ 0.3 dex.Comment: 43 pages, 15 Figures, submitted to A&

Donovanosis en mujeres indígenas

La donovanosis es una rara infección causada por la bacteriaCalymmatobacteriumgranulomatisque produce importantes lesiones ulcero-granulomatosas, preferentemente en la zonaanogenital.Considerada como enfermedad de trasmisión sexual, no es ésta la única vía detrasmisión, siendo también importantes las condiciones higiénicas, socioeconómicas y ambientalesen su etiopatogenia.Afecta áreas tropicales de varios continentes, incluido el americano, donde hayseries descriptas en varios países. En el Paraguay ha sido poco reportada, por lo que esta serie decuatro pacientes mujeres, jóvenes, indígenas de varias parcialidades, con lesiones exuberantes enzona anogenital, de larga evolución, tres de ellas embarazadas y dos con extensión a órganosinternos, es importante. El objetivo de este trabajo es llamar la atención sobre un problema de granmorbilidad y que exige mejorar la cobertura de salud y condiciones de vida de estas comunidadesindígenas

Narrow-line Seyfert 1s: what is wrong in a name?

Narrow-line Seyfert 1s (NLSy1s) are an ill-defined class. Work done over the past 20 years as well as recent analyses show a continuity in properties (e.g., Balmer line profiles, blueshifts of high-ionization lines) between sources with FWHM above and below 2000 km/s, the defining boundary of NLSy1s. This finding alone suggests that comparisons between samples of NLSy1s and rest of broad-line AGNs are most likely biased. NLSy1s can be properly contextualized by their location on the quasar main sequence originally defined by Sulentic et al 2000. At one end, NLSy1s encompass sources with strong FeII emission and associated with high Eddington ratio that hold the promise of becoming useful distance indicators; at the other end, at least some of them are sources with broad profiles seen face-on. Any rigid FWHM limit gives rise to some physical ambiguity, as the FWHM of low-ionization lines depends in a complex way on mass, Eddington ratio, orientation, and luminosity. In addition, if the scaling derived from luminosity and virial dynamics applies to the broad line regions, NLSy1s at luminosity higher than 1E47 erg/s become physically impossible. Therefore, in a broader context, a proper subdivision of two distinct classes of AGNs and quasars may be achieved by the distinction between Pop. A and B with boundary at = 4000 km/s in samples at z < 1, or on the basis of spectrophotometric properties which may ultimately be related to differences in accretion modes if high-luminosity quasars are considered.Comment: Contribution presented at the meeting Revisiting narrow-line Seyfert 1 galaxies and their place in the Universe, held at the Padova Botanical Garden, Italy, on 9-13 April 201

A main sequence for quasars

The last 25 years saw a major step forward in the analysis of optical and UV spectroscopic data of large quasar samples. Multivariate statistical approaches have led to the definition of systematic trends in observational properties that are the basis of physical and dynamical modeling of quasar structure. We discuss the empirical correlates of the so-called "main sequence" associated with the quasar Eigenvector 1, its governing physical parameters and several implications on our view of the quasar structure, as well as some luminosity effects associated with the virialized component of the line emitting regions. We also briefly discuss quasars in a segment of the main sequence that includes the strongest FeII emitters. These sources show a small dispersion around a well-defined Eddington ratio value, a property which makes them potential Eddington standard candles.Comment: Invited talk presented at the Padova Conference on "Quasars at all cosmic epochs"; to appear in Frontiers of Astrophysics and Space Scienc

Dark energy constraints from quasar observations

Recent measurements of the parameters of the Concordance Cosmology Model ($\Lambda$CDM) done in the low-redshift Universe with Supernovae Ia/Cepheids, and in the distant Universe done with Cosmic Microwave Background (CMB) imply different values for the Hubble constant (67.4 $\pm$ 0.5 km s$^{-1}$ Mpc$^{-1}$ from Planck vs 74.03 $\pm$ 1.42 km s$^{-1}$ Mpc$^{-1}$, Riess et al. 2019). This Hubble constant tension implies that either the systematic errors are underestimated, or the $\Lambda$CDM does not represent well the observed expansion of the Universe. Since quasars - active galactic nuclei - can be observed in the nearby Universe up to redshift z $\sim$ 7.5, they are suitable to estimate the cosmological properties in a large redshift range. Our group develops two methods based on the observations of quasars in the late Universe up to redshift z$\sim$4.5, with the objective to determine the expansion rate of the Universe. These methods do not yet provide an independent measurement of the Hubble constant since they do not have firm absolute calibration but they allow to test the $\Lambda$CDM model, and so far no departures from this model were found.Comment: 6 pages, 2 figures, contribution to the Proceedings of the 100 years of the Polish Physical Society Congress, 16-18 October 2020, Warsaw, Poland. http://info.ifpan.edu.pl/APP

Modelo Multifractal Aplicado al Riego

We define the binomial multifractal distribution as an expression of a law of small numbers. We studied a form of evaluation or design of a distribution system in an irrigation district by determining its conduction capacity with the desired flexibility knowing the following parameters: flow, frequency, and irrigation time. The method consists of the approximation of the binomial distribution through the Gaussian, an inverse relation of probability, two estimations of Gaussian parameters, and the application of the multifractal distribution. We present the mathematical reformulation of Boltzmann relation in the statistical mechanics, which gives origin to the multifractal model. In particular, we illustrate its application in the problems of irrigation,  pointing out that it is also possible to apply it to multifractal models: variogram, exponential, gamma, and Gaussian.Definimos la distribución multifractal binomial, como expresión de una ley de los pequeños números. Estudiamos una forma de evaluación o de diseño de un sistema de distribución en un distrito de riego, al determinar su capacidad de conducción con la flexibilidad deseada, conociendo los parámetros de gasto, frecuencia y tiempo de riego. El método es la aproximación de la distribución binomial por la Gaussiana, una relación inversa de probabilidad, dos estimaciones de parámetros Gaussianos, y la aplicación de la distribución multifractal. Presentamos la reformulación matemática de la relación de Boltzmann en la mecánica estadística, que da origen al modelo multifractal. En particular, ilustramos su aplicación en el problema del riego. Pero también es posible aplicarlo a los modelos multifractales: variograma, exponencial, gama, y Gaussiano