Beware of fake AGNs

In the BPT diagram, the distribution of the emission-line galaxies from the Sloan Digital Sky Survey (SDSS) evokes the wings of a seagull. Traditionally, galaxies in the right wing are considered to host AGNs. Our study of the stellar populations of SDSS galaxies showed that about1/4 of galaxies thought to host LINERS are in fact "retired galaxies", i.e. galaxies that stopped forming stars and are ionized by hot post-AGB stars and white dwarfs (Stasinska et al. 2008). When including the galaxies that lack some of the lines needed to place them in the BPT diagram the fraction of retired galaxies is even larger (Cid Fernandes et al., 2009, arXiv:0912.1376)Comment: to be published in "Co-evolution of central black holes and galaxies: feeding and feed-back" Proceedings IAU Symposium No. 267, Peterson, Rachel Somerville, & Thaisa Storchi-Bergmann ed

A comprehensive classification of galaxies in the SDSS: How to tell true from fake AGN?

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)Comment: Accepted for publication in MNRA

BOND: Bayesian Oxygen and Nitrogen abundance Determinations in giant H II regions using strong and semi-strong lines

We present BOND, a Bayesian code to simultaneously derive oxygen and nitrogen abundances in giant H II regions. It compares observed emission lines to a grid of photoionization models without assuming any relation between O/H and N/O. Our grid spans a wide range in O/H, N/O and ionization parameter U, and covers different starburst ages and nebular geometries. Varying starburst ages accounts for variations in the ionizing radiation field hardness, which arise due to the ageing of H II regions or the stochastic sampling of the initial mass function. All previous approaches assume a strict relation between the ionizing field and metallicity. The other novelty is extracting information on the nebular physics from semi-strong emission lines. While strong lines ratios alone ([O III]/Hbeta, [O II]/Hbeta and [N II]/Hbeta) lead to multiple O/H solutions, the simultaneous use of [Ar III]/[Ne III] allows one to decide whether an H II region is of high or low metallicity. Adding He I/Hbeta pins down the hardness of the radiation field. We apply our method to H II regions and blue compact dwarf galaxies, and find that the resulting N/O vs O/H relation is as scattered as the one obtained from the temperature-based method. As in previous strong-line methods calibrated on photoionization models, the BOND O/H values are generally higher than temperature-based ones, which might indicate the presence of temperature fluctuations or kappa distributions in real nebulae, or a too soft ionizing radiation field in the models.Comment: MNRAS in press; 21 pages, 22 figures, 2 tables; code, data and results available at http://bond.ufsc.b

The many faces of LINER-like galaxies: a WISE view

We use the SDSS and WISE surveys to investigate the real nature of galaxies defined as LINERs in the BPT diagram. After establishing a mid-infrared colour W2-W3 = 2.5 as the optimal separator between galaxies with and without star formation, we investigate the loci of different galaxy classes in the W_{Ha} versus W2-W3 space. We find that: (1) A large fraction of LINER-like galaxies are emission-line retired galaxies, i.e galaxies which have stopped forming stars and are powered by hot low-mass evolved stars (HOLMES). Their W2-W3 colours show no sign of star formation and their Ha equivalent widths, W_{Ha}, are consistent with ionization by their old stellar populations. (2) Another important fraction have W2-W3 indicative of star formation. This includes objects located in the supposedly `pure AGN' zone of the BPT diagram. (3) A smaller fraction of LINER-like galaxies have no trace of star formation from W2-W3 and a high W_{Ha}, pointing to the presence of an AGN. (4) Finally, a few LINERs tagged as retired by their W_{Ha} but with W2-W3 values indicative of star formation are late-type galaxies whose SDSS spectra cover only the old `retired' bulge. This reinforces the view that LINER-like galaxies are a mixed bag of objects involving different physical phenomena and observational effects thrusted into the same locus of the BPT diagram.Comment: Accepted for publication in MNRAS; 9 pages, 6 figure

Semi-empirical analysis of Sloan Digital Sky Survey galaxies III. How to distinguish AGN hosts

We consider the techniques to distinguish normal star forming (NSF) galaxies and active galactic nuclei (AGN) hosts using optical spectra. The observational data base is a set of 20000 galaxies extracted from the Sloan Digital Sky Survey, for which we have determined the emission line intensities after subtracting the stellar continuum obtained from spectral synthesis. Our analysis is based on photoionization models computed using the stellar ionizing radiation predicted by Starburst 99 and, for the AGNs, a broken power-law spectrum. We explain why, among the four classical emission line diagnostic diagrams, the [OIII]/Hb vs [NII]/Ha one works best. We show however, that none of these diagrams is efficient in detecting AGNs in metal poor galaxies, should such cases exist. We propose a new divisory line between ``pure'' NSF galaxies and AGN hosts. We also show that a classification into NSF and AGN galaxies using only [NII]/Ha is feasible and useful. Finally, we propose a new classification diagram, the DEW diagram, plotting D_n(4000) vs max(EW[OII],EW[NeIII]). This diagram can be used with optical spectra for galaxies with redshifts up to z = 1.3, meaning an important progress over classifications proposed up to now. Since the DEW diagram requires only a small range in wavelength, it can also be used at even larger redshifts in suitable atmospheric windows. It also has the advantage of not requiring stellar synthesis analysis to subtract the stars and of allowing one to see ALL the galaxies in the same diagram, including passive galaxies.Comment: 14 pages, 9 figures, accepted for publication in MNRAS (replaced on august 3, 2006, eqs 6 and 7 corrected

Retired galaxies: not to be forgotten in the quest of the star formation -- AGN connection

We propose a fresh look at the Main Galaxy Sample of the Sloan Digital Sky Survey by packing the galaxies in stellar mass and redshift bins. We show how important it is to consider the emission-line equivalent widths, in addition to the commonly used emission-line ratios, to properly identify retired galaxies (i.e. galaxies that have stopped forming stars and are ionized by their old stellar populations) and not mistake them for galaxies with low-level nuclear activity. We find that the proportion of star-forming galaxies decreases with decreasing redshift in each mass bin, while that of retired galaxies increases. Galaxies with $M_\star > 10^{11.5} M_\odot$ have formed all their stars at redshift larger than 0.4. The population of AGN hosts is never dominant for galaxy masses larger than $10^{10} M_\odot$. We warn about the effects of stacking galaxy spectra to discuss galaxy properties. We estimate the lifetimes of active galactic nuclei (AGN) relying entirely on demographic arguments --- i.e. without any assumption on the AGN radiative properties. We find upper-limit lifetimes of about 1--5 Gyr for detectable AGN in galaxies with masses between $10^{10}$--$10^{12} M_\odot$. The lifetimes of the AGN-dominated phases are a few $10^8$ yr. Finally, we compare the star-formation histories of star-forming, AGN and retired galaxies as obtained by the spectral synthesis code STARLIGHT. Once the AGN is turned on it inhibits star formation for the next $\sim$ 0.1 Gyr in galaxies with masses around $10^{10} M_\odot$, $\sim$ 1 Gyr in galaxies with masses around $10^{11} M_\odot$.Comment: accepted for MNRAS figure resolution has been degraded with respect to what will be published in MNRA

An atlas of Calcium triplet spectra of active galaxies

We present a spectroscopic atlas of active galactic nuclei covering the region around the 8498, 8542, 8662 Calcium triplet (CaT) lines. The sample comprises 78 objects, divided into 43 Seyfert 2s, 26 Seyfert 1s, 3 Starburst and 6 normal galaxies. The spectra pertain to the inner ~300 pc in radius, and thus sample the central kinematics and stellar populations of active galaxies. The data are used to measure stellar velocity dispersions (sigma_star) both with cross-correlation and direct fitting methods. These measurements are found to be in good agreement with each-other and with those in previous studies for objects in common. The CaT equivalent width is also measured. We find average values and sample dispersions of W_CaT of 4.6+/-2.0, 7.0 and 7.7+/-1.0 angstrons for Seyfert 1s, Seyfert 2s and normal galaxies, respectively. We further present an atlas of [SIII]\lambda 9069 emission line profiles for a subset of 40 galaxies. These data are analyzed in a companion paper which addresses the connection between stellar and Narrow Line Region kinematics, the behaviour of the CaT equivalent width as a function of sigma_star, activity type and stellar population properties.Comment: 18 pages, 10 figures, accepted for publication in MNRA

Pengaruh Model Kooperatif Tipe Numbered Heads Together terhadap Hasil Belajar Pkn di Sekolah Dasar

The effectiveness of Numbered Heads Together cooperative model to Civic Education learning Outcomes in Grade V Elementary School 36 South Pontianak. The purpose of this study was to describe the effect of Numbered Heads Together cooperative model to Civic Education learning Outcomes in Grade V Elementary School 36 South Pontianak. The method that used in this study is the pre-experimental design with experimental design one group pre-test post-test. Based on analysis of data obtained, the average results of pre-test is 61,36 and the average results of post-test is 72.64. Retrieved tcount 3.810 and ttable (α = 0,01) is 2.492, which means tcount> ttable (3.810> 2.4892), thus the hypothesis is accepted. And from the calculation of effect size (ES) ES obtained 0.96 with the criteria is high in the range of ES > 0.8. This means using Numbered Heads Together cooperative model to Civic Education learning Outcomes in Grade V Elementary School 36 South Pontianak

Development Of Community Based Ecotourism In Bahoi Village, West Likupang District, North Minahasa Regency

In the spatial development of North Sulawesi Province, Bahoi Village is one of the coral reef conservation development areas developed into community based ecotourism village. One area that has the potential is Bahoi Village District West Likupang North Minahasa District with the concept of marine community-based ecotourism. This potential is supported by Regional Regulation No. 1 of 2014 in North Sulawesi Province Spatial Planning. This study aims to determine the status of ecotourism development in Bahoi Village and evaluate the principles and concepts of ecotourism using a qualitative descriptive method. In this research, the data were taken by conducting literature study, verification, field survey, and an interview. Interviews were conducted using questionnaires as many as 18 questions/statements containing topics on the management of ecotourism in Bahoi Village, ecotourism concepts, and principles. Questions are presented and analyzed using R and SPSS programs. R is an integrated software unit with several facilities for manipulation, calculation, and reliable graphics performance. SPSS is an application that has a high enough statistical analysis capability and data management systems in the graphical environment by using descriptive menus in simple dialog boxes and easy to understand how to operate. Based on the results of the analysis, there are several problems concerning the management of ecotourism that still overlap, ecotourism principles that have not been reached, especially on economic principles, and the lack of community empowerment. Through this research it can be concluded that ecotourism of Bahoi Village has not given full impact, ecotourism management which is not good can, in turn, forget the economic interest of the local community, and there is urgent need to make Standard Operational Procedure (SOP) of ecotourism for community-based ecotourism management. Furthermore, the concept and principles of ecotourism that has not been applied thoroughly then need to be reviewed for better future.Keywords: development, marine ecotourism, ecotourism management, Bahoi villageABSTRAKDalam pengembangan tata ruang Wilayah Provinsi Sulawesi Utara. Desa Bahoi merupakan salah satu kawasan pengembangan koservasi terumbu karang yang dikembangkan menjadi Desa Ekowisata Berbasis Masyarakat.Salah satu wilayah yang memiliki potensi tersebut yaitu Desa Bahoi Kecamatan Likupang Barat Kabupaten Minahasa Utara dengan konsep ekowisata bahari berbasis masyarakat. Potensi ini didukung dengan Peraturan Daerah Nomor 1 Tahun 2014 tentang Rencana Tata Ruang Wilayah Provinsi Sulawesi Utara yaitu Desa Bahoi merupakan salah satu kawasan pengembangan konservasi terumbu karang.Penelitian ini bertujuan untuk mengetahui status pengembangan ekowisata yang ada di Desa Bahoi dan mengevaluasi prinsip-prinsip dan konsep ekowisata menggunakan metode deskriptif kualitatif. Dalam penelitian ini data di ambil dengan studi literature, verifikasi, survei lapangan dan wawancara. Wawancara dilakukan dengan menggunakan kuesioner sebanyak 18 Pertanyaan/pernyataan yang berisisi tentang pengelolaan ekowisata di Desa Bahoi, konsep dan prinsip-prinsip ekowisata. Pertanyaan disajikan dan di analisis menggunakan program R dan SPSS. R adalah suatu kesatuan software yang terintegrasi dengan beberapa fasilitas untuk manipulasi, perhitungan dan penampilan grafik yang handal. SPSS adalah sebuah program aplikasi yang memiliki kemampuan analisis statistik cukup tinggi serta sistem manajemen data pada lingkungan grafis dengan menggunakan menu-menu deskriptif dan kotak-kotak dialog yang sederhana sehingga mudah untuk dipahami cara pengoperasiannya. Berdasarkan hasil analisis yang dilakukan terdapat beberapa masalah mengenai pengelolaan ekowisata yang masih tumpang tindih, peinsip-prinsip ekowisata yang belum tercapai terutama pada prinsip ekonomi, kurangnya pemberdayaan masyarakat .Dari penelitian ini dapat ditarik kesimpulan ekowisata Desa Bahoi belum memeberi dampak secara menyeluruh, pengolaan ekowisata yang kurang baik dapat melupakan kepentingan ekonomi masyarakat lokal untuk itu perlu di buat Standar Operasional Prosedur ekowisata yang mengatur manajemen ekowisata,. Kosep dan prinsip-prinsip ekowisata yang belum diterapkan secara menyeluruh  maka perlu di kaji kembali.Kata Kunci: Kajian pengembangan, ekowisata bahari, pengelolaan Ekowisata, Desa BahoiÂ