The Age, Metallicity and Alpha-Element Abundance of Galactic Globular Clusters from Single Stellar Population Models

Establishing the reliability with which stellar population parameters can be measured is vital to extragalactic astronomy. Galactic GCs provide an excellent medium in which to test the consistency of Single Stellar Population (SSP) models as they should be our best analogue to a homogeneous (single) stellar population. Here we present age, metallicity and $\alpha$-element abundance measurements for 48 Galactic globular clusters (GCs) as determined from integrated spectra using Lick indices and SSP models from Thomas, Maraston & Korn, Lee & Worthey and Vazdekis et al. By comparing our new measurements to independent determinations we are able to assess the ability of these SSPs to derive consistent results -- a key requirement before application to heterogeneous stellar populations like galaxies. We find that metallicity determinations are extremely robust, showing good agreement for all models examined here, including a range of enhancement methods. Ages and $\alpha$-element abundances are accurate for a subset of our models, with the caveat that the range of these parameters in Galactic GCs is limited. We are able to show that the application of published Lick index response functions to models with fixed abundance ratios allows us to measure reasonable $\alpha$-element abundances from a variety of models. We also examine the age-metallicity and [$\alpha$/Fe]-metallicity relations predicted by SSP models, and characterise the possible effects of varied model horizontal branch morphology on our overall results.Comment: 22 pages, 19 figures, accepted for publication in MNRA

Agnotology: The Making and Unmaking of Ignorance

"This volume emerged from workshops held at Pennsylvania State University in 2003 and Stanford University in 2005"--P. vii

Agnotologia

Robert Proctor and Ian Bolin coined the term agnotology to designate the study of ignorance. This paper proposes to overcome the vision of ignorance as a void that can be filled by knowledge and invites us to think about the ways in which it is produced today, in a premeditated and structural way: through negligence, myopia, secrecy or suppression. The author shows that the deliberate creation of ignorance is a strategy to compromise and sow doubts about the observed facts and about scientific knowledge, taking as examples the role of trade secrets, the activity of tobacco companies to deny the causal relationship between the cigarette smoking and cancer and the role of military secret. Finally, some cases in ignorance is an expression of moral values, such as the prohibition, in some universities, of research whose sole purpose is the profit motive and, in some scientific journals, of publishing works financed by certain sources, as well as the rejection of certain technologies for well-founded intellectual and moral reasons.Robert Proctor e Ian Bolin acuñaron el término agnotología para designar el estudio de la ignorancia. Este escrito propone superar la visión de la ignorancia como un vacío que puede ser llenado por el conocimiento e invita a pensar en las formas en que hoy se produce, en forma premeditada y estructural: por negligencia, miopía, secreto o supresión. El autor muestra que la creación deliberada de la ignorancia es una estrategia para engañar y sembrar dudas sobre los hechos observados y sobre el conocimiento científico, tomando como ejemplos el papel de los secretos comerciales, la actividad de las tabacaleras para negar la relación causal entre el consumo de cigarrillos y el cáncer y el papel del secreto militar. Por último analiza algunos casos en que la ignorancia es una expresión de valores morales, como la prohibición, en algunas universidades, de investigaciones cuyo único fin es el afán de lucro y, en algunas revistas científicas, de publicar trabajos financiados por ciertas fuentes, así como el rechazo de ciertas tecnologías por razones intelectuales y morales bien fundadas.Robert Proctor e Ian Bolin cunharam o termo agnotologia para designar o estudo da ignorância. Este artigo propõe-se a superar a visão da ignorância como um vazio que pode ser preenchido pelo conhecimento e nos convida a pensar sobre as maneiras pelas quais é produzido hoje, de maneira premeditada e estrutural: por negligência, miopia, sigilo ou supressão. O autor mostra que a criação deliberada da ignorância é uma estratégia para enganar e semear dúvidas sobre os fatos observados e sobre o conhecimento científico, tomando como exemplo o papel dos segredos comerciais, a atividade das empresas de tabaco em negar a relação causal entre os tabagismo e câncer e o papel do segredo militar. Por fim, analisa alguns casos em que a ignorância é uma expressão de valores morais, como a proibição, em algumas universidades, de pesquisas cujo único objetivo é o lucro e, em algumas revistas científicas, a publicação de obras financiadas por determinadas fontes, como a rejeição de certas tecnologias por razões intelectuais e morais bem fundamentadas

The mass-metallicity gradient relation of early-type galaxies

We present a newly observed relation between galaxy mass and radial metallicity gradients of early-type galaxies. Our sample of 51 early-type galaxies encompasses a comprehensive mass range from dwarf to brightest cluster galaxies. The metallicity gradients are measured out to one effective radius by comparing nearly all of the Lick absorption-line indices to recent models of single stellar populations. The relation shows very different behaviour at low and high masses, with a sharp transition being seen at a mass of ~ 3.5 x 10^10 M_sun (velocity dispersion of ~140 km/s, M_B ~ -19). Low-mass galaxies form a tight relation with mass, such that metallicity gradients become shallower with decreasing mass and positive at the very low-mass end. Above the mass transition point several massive galaxies have steeper gradients, but a clear downturn is visible marked by a broad scatter. The results are interpreted in comparison with competing model predictions. We find that an early star-forming collapse could have acted as the main mechanism for the formation of low-mass galaxies, with star formation efficiency increasing with galactic mass. The high-mass downturn could be a consequence of merging and the observed larger scatter a natural result of different merger properties. These results suggest that galaxies above the mass threshold of ~ 3.5 x 10^10 M_sun might have formed initially by mergers of gas-rich disc galaxies and then subsequently evolved via dry merger events. The varying efficiency of the dissipative merger-induced starburst and feedback processes have shaped the radial metallicity gradients in these high-mass systems.Comment: 5 pageg, 3 figures, accepted by ApJ Lette

Spatially resolved stellar populations in the isolated elliptical NGC 821

We present the analysis of Lick absorption-line indices from three separate long-slit spectroscopic observations of the nearby isolated elliptical galaxy NGC 821. The three data sets present a consistent picture of the stellar population within one effective radius, in which strong gradients are evident in both luminosity-weighted age and metallicity. The central population exhibits a young age of ~4 Gyr and a metallicity ~3 times solar. At one effective radius the age has risen to ~12 Gyr and the metallicity fallen to less than 1/3 solar. The low metallicity population around one effective radius appears to have an exclusively red horizontal branch, with no significant contribution from the blue horizontal branch evident in some globular clusters of the same age and metallicity. Despite the strong central age gradient, we demonstrate that only a small fraction (<10%) of the galaxy's stellar mass can have been created in recent star formation events. We consider possible star formation histories for NGC 821 and find that the most likely cause of the young central population was a minor merger or tidal interaction that caused NGC 821 to consume its own gas in a centrally concentrated burst of star formation 1 to 4 Gyr ago.Comment: 11 pages. Accepted for publication in MNRA

‘The industry must be inconspicuous’: Japan Tobacco’s corruption of science and health policy via the Smoking Research Foundation

Objective: To investigate how and why Japan Tobacco, Inc. (JT) in 1986 established the Smoking Research Foundation (SRF), a research-funding institution, and to explore the extent to which SRF has influenced science and health policy in Japan.Methods: We analysed documents in the Truth Tobacco Industry Documents archive, along with recent Japanese litigation documents and published documents.Results: JT’s effort to combat effective tobacco control was strengthened in the mid-1980s, following privatisation of the company. While remaining under the protection of Japan’s Ministry of Finance, the semiprivatised company lost its ’access to politicos’, opening up a perceived need for collaboration with global cigarette makers. One solution, arrived at through clandestine planning with American companies, was to establish a third-party organisation, SRF, with the hope of capturing scientific and medical authority for the industry. Guarded by powerful people in government and academia, SRF was launched with the covert goal of influencing tobacco policy both inside and outside Japan. Scholars funded by SRF have participated in international conferences, national advisory committees and tobacco litigation, in most instances helping the industry to maintain a favourable climate for the continued sale of cigarettes.Conclusions: Contrary to industry claims, SRF was never meant to be independent or neutral. With active support from foreign cigarette manufacturers, SRF represents the expansion into Asia of the denialist campaign that began in the USA in 1953

フィリップモリスから学ぶ：米たばこ企業の内部⽂書にみられる、たばこ健康害の証拠に関する⽇本たばこの戦略

日本では、第二次大戦後に喫煙率が急上昇し、それに伴い、現在、たばこ関連疾患による死亡率が急増している。20 世紀の大半において、日本のがんによる死亡原因第一位は胃がんだったが、1993 年に肺がんが胃がんを追い抜いた。日本では喫煙が肺がんの主原因であるが、政府が株式の2/3 を保有している日本たばこ産業（JT）は、たばこが疾病と死亡の大きな原因であるかどうかについて疑問を呈し続けている。日本の法廷には企業の内部文書を開示させる制度がないため、たばこと健康に関するJT の戦略について立証するのは困難である。しかし、オンラインアーカイブに保存されているアメリカのたばこ会社の内部文書によれば、JT は、喫煙による健康リスクについて長年知りながら、効果的なたばこ規制を妨害してきたことが明らかである。1980 年代半ばからは、アメリカのたばこメーカーとしばしば協力することで、このような妨害活動を進めてきた。〔アーカイブの〕証拠文書は、特に、フィリップモリスが、喫煙と健康に関するJT の対策や発表に対し助言、時には指導したこともあることを示している。JT の前身である専売公社が出版した論文のデータにおいて、報告された有害性指標値（空気中のニコチン濃度）が故意に低く変えられたという事例もある。国際協力により、JT を含むたばこ企業にとって、効果的な反禁煙（anti-antismoking）戦略の展開がより容易になっている。他の国々でも訴訟が始まれば、このような国際的な企業間協力の実態を明らかにする証拠が今後増えていくであろう

Galaxy and mass assembly (GAMA): End of survey report and data release 2

The Galaxy And Mass Assembly (GAMA) survey is one of the largest contemporary spectroscopic surveys of lowredshift galaxies. Covering an area of ~286 deg2 (split among five survey regions) down to a limiting magnitude of r < 19.8 mag, we have collected spectra and reliable redshifts for 238 000 objects using the AAOmega spectrograph on the Anglo-Australian Telescope. In addition, we have assembled imaging data from a number of independent surveys in order to generate photometry spanning the wavelength range 1 nm-1 m. Here, we report on the recently completed spectroscopic survey and present a series of diagnostics to assess its final state and the quality of the redshift data. We also describe a number of survey aspects and procedures, or updates thereof, including changes to the input catalogue, redshifting and re-redshifting, and the derivation of ultraviolet, optical and near-infrared photometry. Finally, we present the second public release ofGAMAdata. In this release, we provide input catalogue and targeting information, spectra, redshifts, ultraviolet, optical and near-infrared photometry, single-component Śersic fits, stellar masses, Hα-derived star formation rates, environment information, and group properties for all galaxies with r < 19.0 mag in two of our survey regions, and for all galaxies with r < 19.4 mag in a third region (72 225 objects in total). The data base serving these data is available at http://www.gama-survey.org/

Metallicity Gradients at Large Galactocentric Radii Using the Near-infrared Calcium Triplet

We describe a new spectroscopic technique for measuring radial metallicity gradients out to large galactocentric radii. We use the DEIMOS multi-object spectrograph on the Keck telescope and the galaxy spectrum extraction technique of Proctor et al. (2009). We also make use of the metallicity sensitive near-infrared (NIR) Calcium triplet (CaT) features together with single stellar population models to obtain metallicities. Our technique is applied as a pilot study to a sample of three relatively nearby (<30 Mpc) intermediate-mass to massive early-type galaxies. Results are compared with previous literature inner region values and generally show good agreement. We also include a comparison with profiles from dissipational disk-disk major merger simulations. Based on our new extended metallicity gradients combined with other observational evidence and theoretical predictions, we discuss possible formation scenarios for the galaxies in our sample. The limitations of our new technique are also discussed.Comment: 13 Pages, 9 Figures, 7 Tables, Accepted for publication in MNRA