Mapeamento e descrição das áreas de ocorrência dos eventos de decoada no Pantanal.

Decoada ou dequada é o nome popular que se dá no Pantanal aos eventos anuais de alteração natural da qualidade da água durante a fase hidrológica de enchente, cuja intensidade varia de acordo com o clima e os padrões de inundação anuais. Ocorrem alterações das características físicas e químicas da água, que incluem mudanças para cor escura, depleção de oxigênio dissolvido (OD), chegando à anoxia, diminuição do pH (< 6,0) e aumento do CO2 Livre, de aproximadamente 20 mg/L para mais que 100 mg/L, podendo ocorrer expressivas mortandades de peixes dependendo da magnitude das alterações. Neste estudo mapeamos e descrevemos a área de ocorrência desses eventos no Pantanal, baseados nos dados de monitoramento de qualidade de água de 1988 a 2011, nas informações de técnicos e moradores da região e também fizemos uma estimativa da intensidade dos eventos. A concentração de OD nos rios e lagoas principais foi utilizada como indicador, em que OD< 3,0 mg/L durante a época de inundação foi considerado indicativo de ocorrência potencial do evento. De acordo com os registros obtidos, os eventos de decoada foram observados desde Cáceres, ao Norte, até Porto Murtinho, ao Sul, sendo de alta intensidade no rio Paraguai, principalmente abaixo de Bela Vista do Norte. No rio Cuiabá, os eventos são comuns desde Porto Cercado até a sua foz com o rio Paraguai, considerados de média a alta intensidade. No rio Taquari, os eventos foram considerados de baixa intensidade, sendo mais intensos somente próximo ao Paraguai-Mirim. No rio Miranda, a decoada pode ser observada desde a foz do rio Aquidauana até a confluência com o rio Paraguai, mas é no Passo do Lontra onde a intensidade pode ser alta a ponto de afetar os peixes. As lagoas (baías) Uberaba e Gaíva seriam os locais com menor probabilidade de ocorrência dos eventos de decoada. Já as baías Vermelha, Castelo e Tuiuiú, na área de alta inundação, são os locais onde eventos com alta frequência e intensidade foram registrados, ocorrendo anualmente.bitstream/item/83348/1/BP121.pd

VLA Observations of a New Population of Blazars

We present the first deep VLA radio images of flat-spectrum radio quasars (FSRQ) with multiwavelength emission properties similar to those of BL Lacs with synchrotron X-rays. Our observations of twenty-five of these sources show that their radio morphologies are similar to those of other radio quasars. However, their range of extended powers is more similar to that of BL Lacertae objects (BL Lacs) and extends down to the low values typical of FR I radio galaxies. Five out of our nine lobe-dominated sources have extended radio powers in the range typical of both FR I and FR II radio galaxies, but their extended radio structure is clearly FR II-like. Therefore, we have not yet found a large population of radio quasars hosted by FR Is. Two thirds of our sources have a core-dominated radio morpholgy and thus X-rays likely dominated by the jet. We find that their ratios of radio core to total X-ray luminosity are low and in the regime indicative of synchrotron X-rays. This result shows that also blazars with strong emission lines can produce jets of high-energy synchrotron emission and undermines at least in part the ``blazar sequence'' scenario which advocates that particle Compton cooling by an external radiation field governs the frequency of the synchrotron emission peak.Comment: 26 pages, 33 figures. Accepted for publication in Ap

Radio-loud Active Galaxies in the Northern ROSAT All-Sky Survey III: New Spectroscopic Identifications from the RGB BL Lac Survey

We present new spectroscopic identifications for 169 objects in the RASS-Green Bank (RGB) catalog of radio- and X-ray-emitting AGN. These data significantly increase the fraction of bright RGB objects with classifications. Specifically, we report and discuss the classification of 66 radio-loud quasars, 53 BL Lacs, 33 Broad Line Radio Galaxies, 5 Narrow Line Radio Galaxies, 1 Seyfert I galaxy and 11 galaxies or galaxies in clusters. Over 78% of the identifications we present here are new. The observations we report were undertaken as part of our targeted search program to identify a new, large unbiased sample of BL Lac Objects and we therefore discuss the BL Lac sample extensively. Unlike many previous surveys, we impose no selection criteria based on optical morphology, color or broadband spectral energy distribution. Our classifications are based solely on a carefully defined set of self-consistent spectroscopic classification criteria. We show the 53 RGB presented here exhibit transitional properties between normal galaxies and BL Lacs discovered previously. We show there is no clear separation in CaII break strength between RGB BL Lacs and galaxies, with the distribution of break strengths varying smoothly between 0% and 50%. We also show that the newly discovered RGB BL Lacs reside in a "zone of avoidance" in the log(S_x/S_r) vs. log(S_o/S_r) diagram. This has important implications for BL Lac search strategies since it shows that RASS BL Lac samples will be severely incomplete if candidates are chosen only from among those objects with the highest S_x/S_r flux ratios.Comment: 21 pages text, 189 Figures, 4 tables, LaTeX2E, 4.2MB tar file (compressed); special style file paper.sty provide

A Viewing Angle - Kinetic Luminosity Unification Scheme For BL Lacertae Objects

We propose a unified classification for BL Lac objects (BLs), focusing on the synchrotron peak frequency of the spectral energy distribution. The unification scheme is based on the angle Theta that describes the orientation of the relativistic jet and on the electron kinetic luminosity Lambda of the jet. We assume that Lambda scales with the size of the jet r in a self-similar fashion (Lambda propto r^2), as supported by observational data. The jets are self-similar in geometry and have the same pressure and median magnetic field at the inlet, independent of size. The self-similarity is broken for the highest energy electrons, which radiate mainly at high frequencies, since for large sources they suffer more severe radiative energy losses over a given fraction of the jet length. We calculate the optically thin synchrotron spectrum using an accelerating inner jet model based on simple relativistic gas dynamics and show that it can fit the observed infrared to X-ray spectrum of PKS 2155--304. We couple the accelerating jet model to the unification scheme and compare the results to complete samples of BLs. The negative apparent evolution of X-ray selected BLs is explained as a result of positive evolution of the jet electron kinetic luminosity $\Lambda_{kin}$. We review observational arguments in favor of the existence of scaled-down accretion disks and broad emission-line regions in BLs. The proposed unification scheme can explain the lack of observed broad emission lines in X-ray selected BLs, as well as the existence of those lines preferentially in luminous radio-selected BLs. Finally, we review observational arguments that suggest the extension of this unification scheme to all blazars.Comment: 32 pages, 8 figures, to be published in the ApJ (Oct 20, 1998

The Pearson-Readhead Survey of Compact Extragalactic Radio Sources From Space. II. Analysis of Source Properties

We have performed a multi-dimensional correlation analysis on the observed properties of a statistically complete core-selected sample of compact radio-loud active galactic nuclei, based on data from the VLBI Space Observing Programme (Paper I) and previously published studies. Our sample is drawn from the well-studied Pearson-Readhead (PR) survey, and is ideally suited for investigating the general effects of relativistic beaming in compact radio sources. In addition to confirming many previously known correlations, we have discovered several new trends that lend additional support to the beaming model. These trends suggest that the most highly beamed sources in core-selected samples tend to have a) high optical polarizations; b) large pc/kpc-scale jet misalignments; c) prominent VLBI core components; d) one-sided, core, or halo radio morphology on kiloparsec scales; e) narrow emission line equivalent widths; and f) a strong tendency for intraday variability at radio wavelengths. We have used higher resolution space and ground-based VLBI maps to confirm the bi-modality of the jet misalignment distribution for the PR survey, and find that the sources with aligned parsec- and kiloparsec-scale jets generally have arcsecond-scale radio emission on both sides of the core. The aligned sources also have broader emission line widths. We find evidence that the BL Lacertae objects in the PR survey are all highly beamed, and have very similar properties to the high-optically polarized quasars, with the exception of smaller redshifts. A cluster analysis on our data shows that after partialing out the effects of redshift, the luminosities of our sample objects in various wave bands are generally well-correlated with each other, but not with other source properties.Comment: 21 pages, 10 figures. Accepted for publication in the Astrophysical Journal. Part I can be found at astro-ph/010227

Uso do solo e geração de sedimentos na Bacia do Rio São Lourenço, MT.

A carga de sedimentos para o Pantanal tem aumentado nas últimas décadas devido ao desmatamento para a agricultura e pecuária sem os devidos cuidados com a conservação dos solos nas sub-bacias que compõem o Pantanal, as quais têm suas cabeceiras no planalto. A Bacia do Rio São Lourenço é uma dessas bacias, sendo que, em 2012, 36% da sua área haviam sido convertidas a uso antrópico. O manejo de bacias hidrográficas para uso e conservação da água e dos solos se torna mais ágil com o uso de ferramentas de modelagem hidrológica, como o SWAT (Soil and Water Assessment Tool), tem sido amplamente usado, gerando centenas de trabalhos científicos publicados. Os objetivos deste trabalho foram: estruturar um protótipo de modelo hidrológico de chuva-vazão para aplicar a outras bacias da Bacia do Alto Paraguai; avaliar o efeito do uso e cobertura do solo sobre a produção de sedimentos; e comparar a geração de sedimentos na Bacia do Rio São Lourenço entre os usos e coberturas dos anos de 2002 e 2012. O trabalho foi realizado na Bacia do Rio São Lourenço, MT. Foram utilizados, na modelagem da relação chuva-vazão e produção de sedimentos, dois cenários de uso e cobertura do solo da área de estudo, sendo um do ano de 2002 e outro do ano de 2012. Também foram utilizados dados de relevo e solos da bacia; dados pluviométricos da região e dados fluviométricos da bacia. Utilizou-se o modelo hidrológico SWAT para realizar as simulações de geração de sedimentos nesses cenários de uso e cobertura. Os resultados foram avaliados de forma comparativa. Foi possível quantificar o impacto da alteração do uso do solo na Bacia do Rio São Lourenço. Foram mapeadas as regiões em que a mudança no uso e na ocupação acarretou em maiores contribuições para a geração de sedimentos. Os resultados obtidos permitem a tomada de decisão para o planejamento de ações prioritárias de conservação do solo. O protótipo de modelohidrológico desenvolvido pode ser adaptado para as demais bacias da Bacia do Alto Paraguai (BAP)

Dinâmica do balanço de energia em larga escala no pantanal mato-grossense, Brasil.

No Pantanal brasileiro, as inundações destacam a importância da quantificação dos processos de troca de energia e massa entre a superfície e a baixa atmosfera em largas escalas. Imagens MODIS em conjunto com dados agrometeorológicos para o ano de 2012 foram usadas na modelagem dos componentes do balanço de energia em todo o pantanal, extraindo-se posteriormente para análises as sub-regiões de Barão de Melgaço, Paiaguás e Nhecolândia. O algoritmo SAFER (Simple Algorithm For Evapotranspiration Retrieving) foi aplicado para a obtenção do fluxo de calor latente (&#955;E). O saldo de radiação (Rn) foi estimado através da radiação solar global (RG), do albedo da superfície (&#945;0) e da transmissividade atmosférica (&#964;). Com o fluxo de calor na superfície (G) obtido como uma fração de Rn, o fluxo de calor sensível (H) foi quantificado como resíduo na equação do balanço de energia. As frações da energia disponível (Rn - G) usada como &#955;E foram em média de 65, 50 e 49%, para Barão de Melgaço, Paiaguás e Nhecolândica. As mais elevadas condições de umidade na primeira sub região, juntamente com advecção horizontal de calor, detectada pelos valores negativos de H, fizeram com que vários pixels no período fora da estação chuvosa ficassem com valores de &#955;E acima de Rn. Tomando-se a fração evaporativa como indicador de umidade, o ecossistema mais úmido foi a Savana Arborizada (SA) com 58% da energia disponível sendo usada como &#955;E, enquanto que o mais seco foi o ecossistema modificado Alteração Antrópica (aa), sendo esta fração 46%

The Sedentary Multi-Frequency Survey. I. Statistical Identification and Cosmological Properties of HBL BL Lacs

We have assembled a multi-frequency database by cross-correlating the NVSS catalog of radio sources with the RASSBSC list of soft X-ray sources, obtaining optical magnitude estimates from the Palomar and UK Schmidt surveys as provided by the APM and COSMOS on-line services. By exploiting the nearly unique broad-band properties of High-Energy Peaked (HBL) BL Lacs we have statistically identified a sample of 218 objects that is expected to include about 85% of BL Lacs and that is therefore several times larger than all other published samples of HBLs. Using a subset (155 objects) that is radio flux limited and statistically well-defined we have derived the \vovm distribution and the LogN-LogS of extreme HBLs (fx/fr >= 3E-10 erg/cm2/s/Jansky) down to 3.5 mJy. We find that the LogN-LogS flattens around 20 mJy and that = 0.42 +/- 0.02. This extends to the radio band earlier results, based on much smaller X-ray selected samples, about the anomalous cosmological observational properties of HBL BL Lacs. A comparison with the expected radio LogN-LogS of all BL Lacs (based on a beaming model) shows that extreme HBLs make up roughly 2% of the BL Lac population, independently of radio flux. This result, together with the flatness of the radio logN-logS at low fluxes, is in contrast with the predictions of a recent model which assumes an anti-correlation between peak frequency and bolometric luminosity. The extreme fx/fr flux ratios and high X-ray fluxes of these BL Lacs makes them good candidate TeV sources, some of the brighter (and closer) ones possibly detectable with the current generation of Cerenkov telescopes.Comment: 11 pages, LaTeX, 6 ps figures. Accepted for publication in MNRA

Testing the Blazar Paradigm: ASCA Observations of FSRQs with Steep Soft X-ray Spectra

We present the first observations at medium-hard X-rays with ASCA in 1998 August--November of four Flat Spectrum Radio Quasars (FSRQs), characterized by unusually steep soft X-ray spectra (photon index, \Gamma_{0.2-2.4 keV} \sim 2-2.5), as previously measured with ROSAT. Such steep X-ray slopes are similar to those observed in synchrotron-dominated BL Lacs and are unexpected in the context of the recent blazar paradigm, where sources with strong emission lines (such as FSRQs) are dominated in soft X-rays by a flat inverse Compton tail. We find that the ASCA spectra of the four FSRQs are consistent with a power law model with \Gamma_{2-10 keV} \sim 1.8, flatter than their ROSAT spectra. This indicates the onset of an inverse Compton component at energies \gtrsim 2 keV, in agreement with the blazar unification scheme. However, these objects are still anomalous within the blazar class for their steep soft X-ray continua which, together with non-simultaneous data at longer wavelengths, hint at the possibility that the synchrotron emission extends to soft X-rays. This would imply an anomalously high synchotron peak frequency for a quasar with luminous broad lines, challenging current blazar unification schemes. Alternatively, a plausible explanation for the steep optical-to-soft X-ray continua of the four FSRQs is thermal emission from the accretion disk, similar to the blazars 3C~273 and 3C~345. In the Appendix, we present fits to the SIS data in an effort to contribute to the ongoing calibration of the the time-dependence of the SIS response at low energies.Comment: accepted for publication in The Astrophysical Journa

ASCA and contemporaneous ground-based observations of the BL Lacertae objects 1749+096 and 2200+420 (BL Lac)

We present ASCA observations of the radio-selected BL Lacertae objects 1749+096 (z=0.32) and 2200+420 (BL Lac, z=0.069) performed in 1995 Sept and Nov, respectively. The ASCA spectra of both sources can be described as a first approximation by a power law with photon index Gamma ~ 2. This is flatter than for most X-ray-selected BL Lacs observed with ASCA, in agreement with the predictions of current blazar unification models. While 1749+096 exhibits tentative evidence for spectral flattening at low energies, a concave continuum is detected for 2200+420: the steep low-energy component is consistent the high-energy tail of the synchrotron emission responsible for the longer wavelengths, while the harder tail at higher energies is the onset of the Compton component. The spectral energy distributions from radio to gamma-rays are consistent with synchrotron-self Compton emission from a single homogeneous region shortward of the IR/optical wavelengths, with a second component in the radio domain related to a more extended emission region. For 2200+420, comparing the 1995 Nov state with the optical/GeV flare of 1997 July, we find that models requiring inverse Compton scattering of external photons provide a viable mechanism for the production of the highest (GeV) energies during the flare. An increase of the external radiation density and of the power injected in the jet can reproduce the flat gamma-ray continuum observed in 1997 July. A directly testable prediction of this model is that the line luminosity in 2200+420 should vary shortly after (~1 month) a non-thermal synchrotron flare.Comment: 28 pages,6 figures, 5 tables; LaTeX document. accepted for publication in the Astrophysical Journa