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N. Vale Asari

Bio: N. Vale Asari is an academic researcher from Universidade Federal de Santa Catarina. The author has contributed to research in topics: Galaxy & Star formation. The author has an hindex of 23, co-authored 50 publications receiving 2998 citations. Previous affiliations of N. Vale Asari include Paris Diderot University & University of St Andrews.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the authors used the W Hα versus [NII]/Hα (WHAN) diagram to provide a comprehensive emission-line classification of Sloan Digital Sky Survey galaxies.
Abstract: We use the W Hα versus [NII]/Hα (WHAN) diagram introduced by us in previous work to provide a comprehensive emission-line classification of Sloan Digital Sky Survey galaxies. This classification is able to cope with the large population of weak line galaxies that do not appear in traditional diagrams due to a lack of some of the diagnostic lines. A further advantage of the WHAN diagram is to allow the differentiation between two very distinct classes that overlap in the low-ionization nuclear emission-line region (LINER) region of traditional diagnostic diagrams. These are galaxies hosting a weakly active galactic nucleus (wAGN) and 'retired galaxies' (RGs), i.e. galaxies that have stopped forming stars and are ionized by their hot low-mass evolved stars. A useful criterion to distinguish true from fake AGN (i.e. the RGs) is the value of ξ, which measures the ratio of the extinction-corrected Hα luminosity with respect to the Hα luminosity expected from photoionization by stellar populations older than 10 8 yr. We find that ξ follows a markedly bimodal distribution, with a ξ≫1 population composed by systems undergoing star formation and/or nuclear activity, and a peak at ξ~1 corresponding to the prediction of the RG model. We base our classification scheme not on ξ but on a more readily available and model-independent quantity which provides an excellent observational proxy for ξ: the equivalent width of Hα. Based on the bimodal distribution of W Hα , we set the practical division between wAGN and RGs at W Hα = 3 A. Five classes of galaxies are identified within the WHAN diagram: (i) pure star-forming galaxies: log[N II]/Hα 3 A; (ii) strong AGN (i.e. Seyferts): log[NII]/Hα > -0.4 and W Hα > 6A; (iii) weak AGN: log[N n]/Hα > -0.4 and W Hα between 3 and 6 A; (iv) RGs (i.e. fake AGN): W Hα < 3 A; (v) passive galaxies (actually, lineless galaxies): W Hα and W [NII] < 0.5 A. A comparative analysis of star formation histories and of other physical and observational properties in these different classes of galaxies corroborates our proposed differentiation between RGs and wAGN in the LINER-like family. This analysis also shows similarities between strong and weak AGN on the one hand, and retired and passive galaxies on the other.

461 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used the W_Ha versus [NII]/Ha (WHAN) diagram to provide a comprehensive emission-line classification of SDSS galaxies.
Abstract: We use the W_Ha versus [NII]/Ha (WHAN) diagram to provide a comprehensive emission-line classification of SDSS galaxies. This classification is able to cope with the large population of weak line galaxies that do not appear in traditional diagrams due to a lack of some of the diagnostic lines. A further advantage of the WHAN diagram is to allow the differentiation between two very distinct classes that overlap in the LINER region of traditional diagnostic diagrams. These are galaxies hosting a weakly active nucleus (wAGN) and "retired galaxies" (RGs), i.e. galaxies that have stopped forming stars and are ionized by their hot evolved low-mass stars. A useful criterion to distinguish true from fake AGN (i.e. the RGs) is the ratio (\xi) of the extinction-corrected L_Ha with respect to the Ha luminosity expected from photoionization by stellar populations older than 100 Myr. This ratio follows a markedly bimodal distribution, with a \xi >> 1 population composed by systems undergoing star-formation and/or nuclear activity, and a peak at \xi ~ 1 corresponding to the prediction of the RG model. We base our classification scheme on the equivalent width of Ha, an excellent observational proxy for \xi. Based on the bimodal distribution of W_Ha, we set the division between wAGN and RGs at W_Ha = 3 A. Five classes of galaxies are identified within the WHAN diagram: (a) Pure star forming galaxies: log [NII]/Ha 3 A. (b) Strong AGN (i.e., Seyferts): log [NII]/Ha > -0.4 and W_Ha > 6 A. (c) Weak AGN: log [NII]/Ha > -0.4 and W_Ha between 3 and 6 A. (d) RGs: W_Ha < 3 A. (e) Passive galaxies (actually, line-less galaxies): W_Ha and W_[NII] < 0.5 A. A comparative analysis of star formation histories and of other properties in these different classes of galaxies corroborates our proposed differentiation between RGs and weak AGN in the LINER-like family. (Abridged)

394 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed to use the BPT diagram for galaxy classification and showed that the W Hα versus [N II]/Hα diagram can be applied to the largest sample of galaxies without loss of discriminating power between Seyferts and LINERs.
Abstract: A numerous population of weak line galaxies (WLGs) is often left out of statistical studies on emission-line galaxies (ELGs) due to the absence of an adequate classification scheme, since classical diagnostic diagrams, such as [O III]/Hβ versus [N II]/Hα (the BPT diagram), require the measurement of at least four emission lines. This paper aims to remedy this situation by transposing the usual divisory lines between star-forming (SF) galaxies and active galactic nuclei (AGN) hosts and between Seyferts and LINERs to diagrams that are more economical in terms of line quality requirements. By doing this, we rescue from the classification limbo a substantial number of sources and modify the global census of ELGs. More specifically, (1) we use the Sloan Digital Sky Survey Data Release 7 to constitute a suitable sample of 280 000 ELGs, one-third of which are WLGs. (2) Galaxies with strong emission lines are classified using the widely applied criteria of Kewley et al., Kauffmann et al. and Stasinska et al. to distinguish SF galaxies and AGN hosts and Kewley et al. to distinguish Seyferts from LINERs. (3) We transpose these classification schemes to alternative diagrams keeping [N II]/Hα as a horizontal axis, but replacing Hβ by a stronger line (Hα or [O II]), or substituting the ionization-level sensitive [O III]/Hβ ratio with the equivalent width of Hα (W Hα ). Optimized equations for the transposed divisory lines are provided. (4) We show that nothing significant is lost in the translation, but that the new diagrams allow one to classify up to 50 per cent more ELGs. (5) Introducing WLGs in the census of galaxies in the local Universe increases the proportion of metal-rich SF galaxies and especially LINERs. In the course of this analysis, we were led to make the following points. (i) The Kewley et al. BPT line for galaxy classification is generally ill-used. (ii) Replacing [O III]/Hβ by W Hα in the classification introduces a change in the philosophy of the distinction between LINERs and Seyferts, but not in its results. Because the W Hα versus [N II]/Hα diagram can be applied to the largest sample of ELGs without loss of discriminating power between Seyferts and LINERs, we recommend its use in further studies. (iii) The dichotomy between Seyferts and LINERs is washed out by WLGs in the BPT plane, but it subsists in other diagnostic diagrams. This suggests that the right wing in the BPT diagram is indeed populated by at least two classes, tentatively identified with bona fide AGN and 'retired' galaxies that have stopped forming stars and are ionized by their old stellar populations.

393 citations

Journal ArticleDOI
TL;DR: In this paper, the authors propose to use the SDSS DR7 data set for the classification of weak line galaxies (WLGs) by transposing the usual divisory lines between Star Forming (SF) and AGN hosts, and between Seyferts and LINERs to diagrams that are more economical in terms of line quality requirements.
Abstract: A numerous population of weak line galaxies (WLGs) is often left out of statistical studies on emission line galaxies (ELGs) due to the absence of an adequate classification scheme, since classical diagnostic diagrams, like [OIII]/Hb vs [NII]/Ha (the BPT diagram), require the measurement of at least 4 emission lines. This paper aims to remedy this situation by transposing the usual divisory lines between Star Forming (SF) and AGN hosts, and between Seyferts and LINERs to diagrams that are more economical in terms of line quality requirements. By doing this, we rescue from the classification limbo a substantial number of sources and modify the global census of ELGs. More specifically: (1) We use the SDSS DR7 to constitute a suitable sample of 280k ELGs, 1/3 of which are WLGs. (2) Galaxies with strong emission lines are classified using the widely applied criteria of Kewley et al (2001), Kauffmann et al (2003), Stasinska et al (2006) and Kewley et al (2006). (3) We transpose these classification schemes to alternative diagrams keeping [NII]/Ha as a horizontal axis, but replacing Hb by a stronger line (Ha or [OII]), or substituting [OIII]/Hb ratio with the equivalent width of Ha. Optimized equations for the transposed divisory lines are provided. (4) We show that nothing significant is lost in the translation, but that the new diagrams allow one to classify up to 50% more ELGs. (5) Introducing WLGs in the census of galaxies in the local Universe increases the proportion of metal-rich SF galaxies and especially LINERs. (abridged)

326 citations

Journal ArticleDOI
TL;DR: The second public data release (DR2) of the Calar Alto Legacy Integral Field Area (CALIFA) survey as discussed by the authors contains over 1.5 million spectra.
Abstract: This paper describes the Second Public Data Release (DR2) of the Calar Alto Legacy Integral Field Area (CALIFA) survey. The data for 200 objects are made public, including the 100 galaxies of the First Public Data Release (DR1). Data were obtained with the integral-field spectrograph PMAS /PPak mounted on the 3.5 m telescope at the Calar Alto observatory. Two different spectral setups are available for each galaxy, (i) a low-resolution V500 setup covering the wavelength range 3745-7500 A with a spectral resolution of 6.0 A (FWHM); and (ii) a medium-resolution V1200 setup covering the wavelength range 3650-4840 A with a spectral resolution of 2.3 A (FWHM). The sample covers a redshift range between 0.005 and 0.03, with a wide range of properties in the color-magnitude diagram, stellar mass, ionization conditions, and morphological types. All the cubes in the data release were reduced with the latest pipeline, which includes improved spectrophotometric calibration, spatial registration, and spatial resolution. The spectrophotometric calibration is better than 6% and the median spatial resolution is 2´´ 4. In total, the second data release contains over 1.5 million spectra.

218 citations


Cited by
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Journal ArticleDOI
TL;DR: The Virgo Consortium's EAGLE project as discussed by the authors is a suite of hydrodynamical simulations that follow the formation of galaxies and black holes in representative volumes, where thermal energy is injected into the gas, allowing winds to develop without predetermined speed or mass loading factors.
Abstract: We introduce the Virgo Consortium's EAGLE project, a suite of hydrodynamical simulations that follow the formation of galaxies and black holes in representative volumes. We discuss the limitations of such simulations in light of their finite resolution and poorly constrained subgrid physics, and how these affect their predictive power. One major improvement is our treatment of feedback from massive stars and AGN in which thermal energy is injected into the gas without the need to turn off cooling or hydrodynamical forces, allowing winds to develop without predetermined speed or mass loading factors. Because the feedback efficiencies cannot be predicted from first principles, we calibrate them to the z~0 galaxy stellar mass function and the amplitude of the galaxy-central black hole mass relation, also taking galaxy sizes into account. The observed galaxy mass function is reproduced to ≲0.2 dex over the full mass range, 108

2,828 citations

01 Jan 2005
TL;DR: The Monthly Notices as mentioned in this paper is one of the three largest general primary astronomical research publications in the world, published by the Royal Astronomical Society (RAE), and it is the most widely cited journal in astronomy.
Abstract: Monthly Notices is one of the three largest general primary astronomical research publications. It is an international journal, published by the Royal Astronomical Society. This article 1 describes its publication policy and practice.

2,091 citations

Journal ArticleDOI
Sebastián F. Sánchez1, Robert C. Kennicutt2, A. Gil de Paz3, G. van de Ven4, José M. Vílchez1, Lutz Wisotzki5, C. J. Walcher5, D. Mast1, J. A. L. Aguerri6, J. A. L. Aguerri1, Sergio Albiol-Pérez7, Almudena Alonso-Herrero1, João Alves8, J. Bakos1, J. Bakos6, T. Bartakova9, Joss Bland-Hawthorn10, Alessandro Boselli11, D. J. Bomans12, África Castillo-Morales3, C. Cortijo-Ferrero1, A. de Lorenzo-Cáceres6, A. de Lorenzo-Cáceres1, A. del Olmo1, Ralf-Jürgen Dettmar12, Angeles I. Díaz13, Simon Ellis10, Simon Ellis14, Jesús Falcón-Barroso6, Jesús Falcón-Barroso1, Hector Flores15, Anna Gallazzi16, Begoña García-Lorenzo6, Begoña García-Lorenzo1, R. M. González Delgado1, Nicolas Gruel, Tim Haines17, C. Hao18, Bernd Husemann5, J. Iglesias-Páramo1, Knud Jahnke4, Benjamin D. Johnson19, Bruno Jungwiert20, Bruno Jungwiert21, Veselina Kalinova4, C. Kehrig5, D. Kupko5, Angel R. Lopez-Sanchez14, Angel R. Lopez-Sanchez22, Mariya Lyubenova4, R. A. Marino3, R. A. Marino1, E. Mármol-Queraltó3, E. Mármol-Queraltó1, I. Márquez1, J. Masegosa1, Sharon E. Meidt4, Jairo Méndez-Abreu1, Jairo Méndez-Abreu6, Ana Monreal-Ibero1, C. Montijo1, A. Mourao23, G. Palacios-Navarro7, Polychronis Papaderos24, Anna Pasquali25, Reynier Peletier, Enrique Pérez1, I. Pérez26, Andreas Quirrenbach, M. Relaño26, F. F. Rosales-Ortega1, F. F. Rosales-Ortega13, Martin Roth5, T. Ruiz-Lara26, Patricia Sanchez-Blazquez13, C. Sengupta1, R. Singh4, Vallery Stanishev23, Scott Trager27, Alexandre Vazdekis6, Alexandre Vazdekis1, Kerttu Viironen1, Vivienne Wild28, Stefano Zibetti16, Bodo L. Ziegler8 
TL;DR: The Calar Alto Legacy Integral Field Area (CALIFA) survey as discussed by the authors was designed to provide a first step in this direction by obtaining spatially resolved spectroscopic information of a diameter selected sample of similar to 600 galaxies in the Local Universe.
Abstract: The final product of galaxy evolution through cosmic time is the population of galaxies in the local universe. These galaxies are also those that can be studied in most detail, thus providing a stringent benchmark for our understanding of galaxy evolution. Through the huge success of spectroscopic single-fiber, statistical surveys of the Local Universe in the last decade, it has become clear, however, that an authoritative observational description of galaxies will involve measuring their spatially resolved properties over their full optical extent for a statistically significant sample. We present here the Calar Alto Legacy Integral Field Area (CALIFA) survey, which has been designed to provide a first step in this direction. We summarize the survey goals and design, including sample selection and observational strategy. We also showcase the data taken during the first observing runs (June/July 2010) and outline the reduction pipeline, quality control schemes and general characteristics of the reduced data. This survey is obtaining spatially resolved spectroscopic information of a diameter selected sample of similar to 600 galaxies in the Local Universe (0.005 < z < 0.03). CALIFA has been designed to allow the building of two-dimensional maps of the following quantities: (a) stellar populations: ages and metallicities; (b) ionized gas: distribution, excitation mechanism and chemical abundances; and (c) kinematic properties: both from stellar and ionized gas components. CALIFA uses the PPAK integral field unit (IFU), with a hexagonal field-of-view of similar to 1.3 square', with a 100% covering factor by adopting a three-pointing dithering scheme. The optical wavelength range is covered from 3700 to 7000 angstrom, using two overlapping setups (V500 and V1200), with different resolutions: R similar to 850 and R similar to 1650, respectively. CALIFA is a legacy survey, intended for the community. The reduced data will be released, once the quality has been guaranteed. The analyzed data fulfill the expectations of the original observing proposal, on the basis of a set of quality checks and exploratory analysis: (i) the final datacubes reach a 3 sigma limiting surface brightness depth of similar to 23.0 mag/arcsec(2) for the V500 grating data (similar to 22.8 mag/arcsec(2) for V1200); (ii) about similar to 70% of the covered field-of-view is above this 3 sigma limit; (iii) the data have a blue-to-red relative flux calibration within a few percent in most of the wavelength range; (iv) the absolute flux calibration is accurate within similar to 8% with respect to SDSS; (v) the measured spectral resolution is similar to 85 km s(-1) for V1200 (similar to 150 km s(-1) for V500); (vi) the estimated accuracy of the wavelength calibration is similar to 5 km s(-1) for the V1200 data (similar to 10 km s(-1) for the V500 data); (vii) the aperture matched CALIFA and SDSS spectra are qualitatively and quantitatively similar. Finally, we show that we are able to carry out all measurements indicated above, recovering the properties of the stellar populations, the ionized gas and the kinematics of both components. The associated maps illustrate the spatial variation of these parameters across the field, reemphasizing the redshift dependence of single aperture spectroscopic measurements. We conclude from this first look at the data that CALIFA will be an important resource for archaeological studies of galaxies in the Local Universe.

1,143 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a picture in which the population of active galactic nuclei (AGNs) can be divided into two distinct populations: radiative-mode AGNs are associated with black holes that produce radiant energy powered by accretion at rates in excess of ∼ 1% of the Eddington limit.
Abstract: We summarize what large surveys of the contemporary Universe have taught us about the physics and phenomenology of the processes that link the formation and evolution of galaxies with their central supermassive black holes. We present a picture in which the population of active galactic nuclei (AGNs) can be divided into two distinct populations. The radiative-mode AGNs are associated with black holes (BHs) that produce radiant energy powered by accretion at rates in excess of ∼1% of the Eddington limit. They are primarily associated with less massive BHs growing in high-density pseudobulges at a rate sufficient to produce the total mass budget in these BHs in ∼10 Gyr. The circumnuclear environment contains high-density cold gas and associated star formation. Major mergers are not the primary mechanism for transporting this gas inward; secular processes appear dominant. Stellar feedback is generic in these objects, and strong AGN feedback is seen only in the most powerful AGNs. In jet-mode AGNs the bulk of...

898 citations

Journal ArticleDOI
TL;DR: A review of recent developments related to the unified model of active galactic nuclei (AGNs) can be found in this paper, where the authors focus on new ideas about the origin and properties of the central obscurer (torus) and the connection to its surroundings.
Abstract: This review describes recent developments related to the unified model of active galactic nuclei (AGNs). It focuses on new ideas about the origin and properties of the central obscurer (torus) and the connection to its surroundings. The review does not address radio unification. AGN tori must be clumpy but uncertainties about their properties persist. Today's most promising models involve disk winds of various types and hydrodynamic simulations that link the large-scale galactic disk to the inner accretion flow. Infrared (IR) studies greatly improved our understanding of the spectral energy distribution of AGNs, but they are hindered by various selection effects. X-ray samples are more complete. The dependence of the covering factor of the torus on luminosity is a basic relationship that remains unexplained. There is also much confusion regarding real type-II AGNs, which do not fit into a simple unification scheme. The most impressive recent results are due to IR interferometry, which is not in accord wit...

610 citations