SDSS THIRTEENTH DATA RELEASE

This post is now in four languages: English, Chinese, Spanish and Portuguese! It is originally written by Anne-Marie Weijmans in English and translated by Zheng Zheng (to Chinese) ,  Andres Meza (to Spanish) and Ricardo Ogando (to Portuguese). 

This weekend, the Sloan Digital Sky Survey (SDSS) is celebrating its thirteenth public data release, or lucky DR13!

Data releases are an important part of the SDSS. All the data that are observed by the Sloan Telescope for the various surveys that are part of SDSS, get reduced and processed, and eventually are made publicly available. This means that everyone with access to the internet can download the data, use it for their research or teaching, or simply look at all the images and spectra that are available. You just have to go to the SDSS website, and you can start exploring the data for yourself!

So, what does DR13 have in store for you? Apart from including all the data that was released in previous data releases, there is also lots of new data:

  • DR13 is the first data release for the MaNGA survey! MaNGA stands for Mapping Nearby Galaxies at Apache Point Observatory, and it studies galaxies with integral-field spectroscopy. This allows us to study chemical elements and motions of stars and gas not just in the centre of the galaxies, but all over the galaxy outskirts too. MaNGA is releasing its spectra in datacubes for 1351 individual galaxies, making it the biggest integral-field galaxy survey available on-line so far!
  • APOGEE, or the APO Galaxy Evolution Experiment is taking infra-red spectra for hundreds of thousands of stars in the Milky Way. For this data release, they have improved the analysis of all their previously released spectra, and measured the abundances of various chemical elements of stars. This will help us understand how the Milky Way formed over time.
  • eBOSS, short for extended Baryon Oscillation Spectroscopic Survey, is mapping the structure of the Universe, by taking spectra of more than a million galaxies and quasars. Its goal is to measure the expansion rate of the Universe, and the nature of the mysterious Dark Energy that accelerates this expansion. eBOSS is releasing improved analysis of previously released spectra, as well as several catalogs with information on emission line galaxies and variable quasars.

Do you want to have a look at all of this data? Here are some places to get started:

  • The SDSS SkyServer has several tools to explore the data. You can for instance:
    • find stars and galaxies in the Navigate tool
    • look at images and spectra of stars and galaxies with the QuickLook tool
    • search for a particular sample of galaxies or stars with SQL
  • If you are interested in analyzing the data yourself, then you can find more information on how to download the data on the SDSS data access page
  • If you are a teacher and interested in activities that will help your students explore the Universe, then have a look at our SDSS education web page, with lots of resources for the class room.

Anne-Marie Weijmans
SDSS Data Release Coordinator
University of St Andrews

 

 

本周末(7月31日)斯隆数字化巡天(SDSS)迎来了它的第十三次数据释放(DR13)!

数据释放是SDSS的重要事件。所有由斯隆望远镜观测的SDSS各种巡天计划的数据,都会经过处理并对公众开放。这就意味着所有人都可以从网上找到和下载这些数据,并用来做研究、教学、或者仅仅是查看已有的图像和光谱。你只需点击进入SDSS的网站就可以查看这些数据啦!

那么,DR13里面到底都有什么呢?除了包含之前的数据释放中所有的数据以外,它还包含了很多新的数据:

  • DR13是MaNGA巡天的第一次数据释放!MaNGA是对近邻星系进行的积分场光谱巡天。有了MaNGA数据,我们还可以研究整个星系的 — 而不仅仅是星系中心的 — 元素丰度以及恒星和气体的运动。 MaNGA将释放1351个星系的IFU光谱,这也是现今在网上公开的最大的积分场星系巡天数据样本。
  • APOGEE是拍摄几十万颗银河系内恒星的红外光谱的巡天项目。在这次的数据释放中,我们改进了以前的数据处理方式,并且测量了恒星的各种元素丰度。这将会帮助我们理解银河系的形成过程
  • eBOSS巡天用拍摄一百多万个星系和类星体的光谱的方式来描绘宇宙的结构。它的目的是测量宇宙膨胀的速度以及探寻造成宇宙加速膨胀的神秘的暗能量的本质。eBOSS不光会释放经过改进处理的以前释放过的光谱,还会释放几个包含发射线星系和变源类星体信息的星表。

你是不是已经想要看一看这些数据啦?下面列出的这些网址可以帮助你开始探索:

  • 如果你希望自己来分析数据,那么你可以在SDSS数据使用页面找到如何下载数据的相关信息
  • 如果你是一名教师并且希望利用一些活动帮助学生探索宇宙,那么你可以查看SDSS教育网站,这里面有很多相关资源可以帮助课堂教学。

 

 

Este fin de semana, Sloan Digital Sky Survey (SDSS) está celebrando su décimo tercera liberación de datos públicos o ¡afortunado DR13!

La liberación de datos es una parte importante de SDSS. Todos los datos que son observados por el Telescopio Sloan para los distintos estudios que forman parte de SDSS, son reducidos y procesados, y eventualmente puestos a disposición del público. Esto significa que cualquier persona con acceso a Internet puede bajar los datos, usarlos para su investigación, para enseñar o simplemente para ver las imágenes y los espectros que están disponibles. Sólo tienes que ir al sitio web de SDSS y ¡ya puedes comenzar a explorar los datos por ti mismo!

¿Qué tiene DR13 para ti? Además de incluir todos los datos que ya han sido hechos públicos anteriormente, también hay una gran cantidad de nuevos datos:

  • ¡DR13 es la primera liberación de datos para MaNGA! MaNGA es el acrónimo en inglés para Mapeo de Galaxias Cercanas desde el Observatorio de Apache Point, y estudia galaxias con espectroscopia de campo integral. Esto nos permite estudiar los elementos químicos y el movimiento del gas y la estrellas no solo en el centro de las galaxias, sino que también en sus partes externas. MaNGA está liberando sus espectros en cubos de datos para 1351 galaxias individuales, ¡convirtiéndolo en el estudio de campo integral más grande disponible en línea!
  • APOGEE, o experimento de Evolución Galáctica en el APO de sus siglas en inglés, está tomando espectros infrarrojos para cientos de miles de estrellas en la Vía Láctea. Para esta liberación de datos, se ha mejorado el análisis de todos los espectros publicados previamente y medido la abundancia de varios elementos químicos de las estrellas. Esto nos ayudará a entender cómo se ha formado la Vía Láctea en el tiempo.
  • eBOSS, acrónimo en inglés para Muestra Espectroscópica Extendida de la Oscilación Bariónica, está haciendo un mapa de la estructura del Universo, tomando espectros de más de un millón de galaxias y quásares. Su objetivo es medir la tasa de expansión del universo y la naturaleza de la misteriosa Energía Oscura que acelera su expansión. eBOSS está liberando análisis mejorados de sus espectros anteriores, así como también varios catálogos con información para las galaxias con líneas de emisión y quásares variables.

¿Quieres darle un vistazo a todos estos datos? Aquí hay algunos lugares para comenzar:

  • El SDSS SkyServer tiene varias herramientas para explorar los datos. Tu puedes por ejemplo:
    • Encontrar estrellas y galaxias con la herramienta Navigate.
    • Ver las imágenes y espectros de estrellas y galaxias con la herramienta QuickLook
    • Buscar un grupo particular de estrellas y galaxias con SQL.
  • Si eres un profesor y estás interesado en actividades que puedan ayudar a tus estudiantes a explorar el Universo, puedes mirar nuestra página de educación del SDSS donde hay muchos recursos para realizar en las clases.

 

 

 

Esse final de semana, o Sloan Digital Sky Survey (SDSS) celebra seu décimo terceiro lançamento de dados ao público, ou um sortudo DR13!

Os Lançamentos de Dados são uma parte importante do SDSS. Todos os dados que são observados pelo telescópio Sloan, para os vários levantamentos que são parte do SDSS, são reduzidos e processados, e em algum momento são disponibilizados para o público. Isso significa que qualquer pessoa com acesso à internet pode baixar esses dados, usar para sua pesquisa ou ensino, ou simplesmente olhar as imagens e espectros disponíveis. Basta ir à página do SDSS e começar a explorar!

Bom, mas o que é que o DR13 tem? Além dos dados de todos os lançamentos anteriores, um montão de novidades foram incluídas:

  • DR13 é o primeiro a conter dados do levantamento MaNGA! MaNGA significa Mapeamento de Galáxias Próximas no Observatório de Apache Point (em inglês, Mapping Nearby Galaxies at Apache Point Observatory), e estuda galáxias usando espectroscopia de campo integral. Isso nos permite estudar os elementos químicos e o movimento das estrelas e do gás não apenas no centro de galáxias, mas também em sua periferia. MaNGA está liberando seus espectros em cubos de dados para 1.351 galáxias, fazendo dele o maior levantamento disponível online de galáxias observadas com campo integral até hoje.
  • APOGEE, ou o Experimento de Evolução da Galáxia no APO (em inglês, APO Galaxy Evolution Experiment) está observando espectros no infravermelho para centenas de milhares de estrelas na Via-Láctea. Nesse lançamento de dados eles melhoraram a análise de todos os espectros liberados anteriormente, medindo a abundância de vários elementos químicos nas estrelas. Isso vai nos ajudar a entender como a Via-Láctea se formou e evoluiu ao longo do tempo.
  • eBOSS, abreviação de extended Baryon Oscillation Spectroscopic Survey, está mapeando a estrutura do Universo, observando espectros de mais de um milhão de galáxias e quasares. Seu objetivo é medir a taxa de expansão do Universo, e a natureza da misteriosa Energia Escura que acelera essa expansão. eBOSS está disponibilizando análises melhoradas de espectros liberados anteriormente, além de vários catálogos com informação sobre galáxias com linhas de emissão e variabilidade de quasares.

Você quer dar uma olhada em todo esse conjunto de dados? Por onde começar:

  • O SkyServer do SDSS tem várias ferramentas para explorar os dados. Você pode, por exemplo:
    • encontrar estrelas e galáxias usando o Navigate
    • olhar imagens e espectros com o QuickLook
    • procurar por uma amostra de galáxias ou estrelas em particular usando SQL
  • Se você está interessado em analisar os dados você mesmo, você pode encontrar mais informações de como baixar os dados na página SDSS data access
  • Se você for um professor e está interessado em atividades que possam ajudar seus estudantes a explorar o Universo, dê uma olhada em nossa página educativa, com vários recursos para a sala de aula.

 

 

It takes a large team of people to put together a data release: from collecting the data at the telescopes, to processing the data, analyzing the data, and documenting the data. The SDSS DR13 website, that describes all the various datasets now available in DR13, was mostly written at DocuFeest, by a dedicated group of SDSS scientists. Image credit: Jennifer Johnson.  数据释放要经过很多环节:从望远镜收集数据、处理数据、分析数据、以及准备相关文档,这是我们大团队共同努力的结晶。SDSS DR13网站描述了DR13中包含的所有数据,这个网站大部分都是由一批SDSS科学家在DocuFeest上完成的。照片由Jennifer Johnson提供 Se debe reunir un grupo grande de personas para generar los datos públicos: desde recolectar los datos en los telescopios, luego procesar y analizar los datos, hasta finalmente documentarlos. El sitio para el DR13, que describe todos los conjuntos de datos ahora disponibles, fue escrito en su mayor parte en el DocuFeest por un grupo dedicado de científicos de SDSS.  Concluir um lançamento de dados requer um grande time de pessoas: da coleta de dados nos telescópios, ao seu processamento, análise, e documentação. A página do DR13 do SDSS, que descreve todos os distintos conjuntos de dados agora disponíveis no DR13, foi quase toda escrita por um dedicado grupo de cientistas do SDSS numa reunião batizada de DocuFeest (Feest é festa em holandês, origem de uma das organizadoras do evento de documentação). Crédito da imagem: Jennifer Johnson.

 

Caption: all the SDSS data are stored at the servers of the Center for High Performance Computing (CHPC[https://chpc.utah.edu/]), at the University of Utah. This particular server holds all the SDSS data releases, including DR13. The total data volume is about 267 TeraBytes (TB = 1000 Gigabyte = 1012 bytes): that is more than 58,000 DVDs worth of data! Image credit: Adam Bolton.

All the SDSS data are stored at the servers of the Center for High Performance Computing (CHPC), at the University of Utah. This particular server holds all the SDSS data releases, including DR13. The total data volume is about 267 TeraBytes (TB = 1000 Gigabyte = 1012 bytes): that is more than 58,000 DVDs worth of data! Image credit: Adam Bolton.  所有的SDSS数据都存储在美国犹他大学高性能计算中心(CHPC)的服务器上。这台服务器存储着所有SDSS释放过的数据,包括DR13。整个数据容量大约是267T (1T=1000G=1012 bytes):这比58000张DVD包含的数据都要多!照片由Adam Bolton提供 Todos los datos de SDSS están almacenados en los servidores del Centro de Computación de Alto Rendimiento de la Universidad de Utah. Este servidor contiene todos los datos públicos, incluyendo DR13. El volumen total de datos es de alrededor de 267 TB, ¡esto es más de 58.000 DVDs!  Todos os dados estão armazenados em servidores no Center for High Performance Computing (CHPC), na University of Utah. Esses servidores em particular contem todos os lançamentos de dados do SDSS, incluindo o DR13. O volume total de dados é de cerca de 267 Terabytes (TB = 1000 Gigabyte = 1012 bytes): isso é mais que 58.000 DVDs cheios de dados! Crédito da imagem: Adam Bolton.

 

montage_1st_gal_plate

The very first 17 galaxies observed by MaNGA, one plate full! These galaxies are all included in DR13. Some galaxies have been off-set from the centre of the IFU to allow inclusion of foreground stars, to test our measurement precisions (this was only done for this first commissioning plate). Image credit: Kevin Bundy.  这17个星系来自MaNGA的首次观测,是在同一个光纤插板上的所有星系!这些星系都包含在DR13里面。有些星系偏离了IFU的中心,这是因为我们要同时拍摄一些前景恒星用来检测测量精度 (不过这种情况只发生在这第一个光纤插板上)。照片由Kevin Bundy提供 ¡Las primeras 17 galaxias observadas por MaNGA en una sola placa! Todas estas galaxias están incluidas en el DR13. Algunas galaxias han sido desalineadas del centro del IFU para incluir estrellas en el fondo, las cuales permiten probar la precisión de las mediciones (esto fue hecho sólo para esta primera placa).  As 17 primeiríssimas galáxias observadas pelo MaNGA, são um verdadeiro gol de placa! Essas galáxias foram todas incluídas no DR13. Algumas galáxias foram deslocadas do centro do IFU para incluir estrelas, a fim de testar a precisão de nossas medidas (isso foi feito apenas para essa placa inaugural de comissionamento do instrumento). Crédito da imagem: Kevin Bundy.

Red Geysers in MaNGA: New Evidence for AGN Maintenance Mode Feedback

(This is a guest post by Edmond Cheung at the Kavli IPMU)

While there have been many recent studies addressing how galaxies shut off, or quench, their star formation, an equally interesting yet relatively unstudied question is how these quenched galaxies remain quenched. This is interesting because these quiescent galaxies often contain gas (from stellar mass loss or mergers) that—if left unimpeded—should cool and form stars. But since we know that quiescent galaxies have not formed a significant amount of stars since they’ve been quenched, there must be something that prevents this gas from cooling.

In the new study by Cheung et al. 2016, Nature, 533, 504, this ‘something’ has been found. Using the ongoing SDSS IV MaNGA survey, which takes resolved spectroscopy for 10,000 nearby galaxies, Cheung et al. discovered a new class of quiescent galaxies—dubbed “red geysers”—that hosts outflowing winds powerful enough to heat ambient gas and suppress future star formation. These winds are manifested in bisymmetric emission features (in H-alpha, [OII], and other strong lines) and are likely powered by their weakly-accreting supermassive black holes.

To highlight the key characteristics of this class, Cheung et al. focus on a prototypical red geyser, which they nicknamed “Akira”—a reference to the critically-acclaimed manga comic of the same name, and in homage to the MaNGA survey and the lead author’s current institute in Japan (Kavli IPMU). Akira is undergoing a minor interaction with another galaxy, which they’ve nicknamed “Tetsuo”—another character in the same manga comic as Akira; the SDSS image of the interaction is shown in panel a of the figure below, which is reproduced from the Cheung et al. 2016. According to merger simulations, Tetsuo is depositing cool gas into Akira, which is detected in redshifted Na D absorption (panels d and e). The expected star-formation from this cool gas, however, is absent: Cheung et al. find that the measured star-formation rate of Akira is much lower than what is expected given the amount of cold gas present. Thus something is prohibiting star formation in Akira—what is it?

The image and diagnostic diagrams of  "Akira", a prototypical red geyser.

The images and diagnostic diagrams of “Akira”, a prototypical red geyser. 

Inspecting the ionized gas properties of Akira, Cheung et al. find an interesting bisymmetric emission pattern in H-alpha and other strong emission lines (panel c). These emission patterns roughly align with the ionized gas velocity gradient (panel h), suggestive of an outflow. To prove that the ionized gas is in an outflowing wind instead of in a rotating disk, Cheung et al. had to disprove the latter case. Using the stellar dynamics of Akira (panels f and g), they obtain a tight constraint on its gravitational potential, from which they are able to predict the ionized gas kinematics in the case of a regularly rotating disk. They find that the observed ionized gas kinematics are significantly higher than the predicted ionized gas kinematics (panel j), indicating that the ionized gas is not under the influence of gravity alone.

Ruling out the disk interpretation, Cheung et al. developed a qualitative wind model that reproduces many of the features of the data, including the ionized gas velocity field and the ionized gas velocity dispersion field. They theorize that this outflowing wind is likely powered by the weakly-accreting supermassive black hole at the center of Akira, which is detected as a central radio point source in the FIRST survey and in followup Jansky VLA observations. They calculate that the energetic output from this low-luminosity active galactic nuclei (AGN) is sufficient to power this outflowing wind, which in turn, has enough energy to counterbalance the cooling of both the warm and cool gas within Akira, and thereby suppress star formation.

While Akira is an ideal case-study, perhaps the most exciting aspect of this study is the fact that there are many more red geysers. Red geysers make up about 10% of quiescent galaxies at moderate stellar masses (2×1010 solar masses), which could have important implications on the duty cycle of this kind of supermassive black hole feedback. Moreover, because they are relatively common, red geysers may exemplify how typical quiescent galaxies maintain their quiescence.

An artist view of the universe 艺术家眼里的宇宙

Recently, a Chinese artist, Jian Yang, organized his personal exhibition in Beijing, China. The exhibition is called “the beginning of infinity” and one of his art pieces showed in this exhibition has a component made of an SDSS plate.

最近中国的一位艺术家杨健在北京进行了一次个人艺术展。这次展出的名字叫 “无穷的开始”,而其中的一件艺术品是利用了SDSS的一块光纤插板做成的。

The room holding the exhibition was designed as a maze. The art piece with the SDSS plate was placed at the center of a maze. It is named “The Universe” and the idea came from an old fairy tale: The earth is a big whale and the sky is a huge elephant. If you could find a leg of the elephant and climb up along the leg, then you could grab the stars. In the artist’s view, the SDSS telescope is trying to capture and analyze the starlight. So he combined science and the fairy tale by putting the SDSS plate at the bottom of the flying elephant’s leg, which means the plate could help us climb up and reach the stars.

展览的场地被别出心裁的设计成了迷宫的模式。而这件包含SDSS光纤插板的艺术品就被放置在迷宫的正中央。作品的灵感来源于艺术家小时候听到的神话故事:说大地是一只鲸鱼,宇宙是一只巨大的大象,如果你能找到大象的腿,往上爬就能抓到星星。对于艺术家来说,SDSS项目就是在做捕获分析星光的工作。杨健把SDSS光纤插板当作一只升腾起来的大象的脚底板,通过这种形象的建构来联合中国与国际,神话和科学。

 

The room holding the exhibition was designed as a maze.

The room holding the exhibition was designed as a maze. 整个展览场地被设计成一个迷宫的形式。

 

The art piece with an SDSS plate (plate# 3939).

The art piece with an SDSS plate (plate# 3939). The plate (编号3939) is placed at the bottom of an elephant’s leg. 用SDSS光纤插板做成的艺术品. SDSS的板子被当做大象的脚底板。

 

The art piece viewed from the bottom.

The art piece viewed from the bottom. 从下面看这件艺术品。

Astronomers studying galaxy mergers using MaNGA data

(The following is a guest post by Lihwai Lin, an assistant research fellow at Academia Sinica, Institute of Astronomy and Astrophysics. She is curretnly chairing the MaNGA merger working group and organized the MaNGA merger mini-workshop described in the article below.)
Galaxies are not isolated. During the lifetime of galaxies, they may encounter another galaxy and merge together to become a larger one. Mergers can induce gas to flow toward the inner parts of galaxies through tidal forces, triggering starbursts or even “switching on” a galaxy’s central black hole (the result is called an “active galactic nucleus,” or AGN). As a result of rapid gas consumption during mergers, a galaxy may lose the majority of its gas and end up as a “dead” system with little on-going star formation. This kind of merger event is rare, but is suggested to be an important process that transforms star-forming galaxies into the quiescent population. One of the key sciences that MaNGA is attempting to address concerns the role of galaxy interactions and mergers in shaping the properties of galaxies. With just one year of the MaNGA survey, we have obtained Integral Field Unit (IFU) observations for ~150 paired galaxies, ranging from early encounters to post-mergers.
Examples of galaxy pairs selected from the SDSS. The magenta hexagons represent the IFU coverage of MaNGA. (Credit: SDSS)

Examples of galaxy pairs selected from the SDSS. The magenta hexagons represent the IFU coverage of MaNGA. (Credit: SDSS)

In early November of 2015, experts studying galaxy mergers gathered together in Taipei for the “SDSS-IV/MaNGA mini-workshop on galaxy mergers”. This 3-day workshop consists of 6 invited talks, 5 contributed talks, plus 2 discussion sessions devoted to theoretical and observational efforts, chaired by Jennifer Lotz (STScI) and Sara Ellison (University of Victoria) respectively.

Participants for the MaNGA mini-workshop on galaxy mergers, held at Academia Sinica, Institute of Astronomy and Astrophysics (ASIAA), Taipei, on Nov. 4-6, 2015.

Participants for the MaNGA mini-workshop on galaxy mergers, held at Academia Sinica, Institute of Astronomy and Astrophysics (ASIAA), Taipei, on Nov. 4-6, 2015.

With MaNGA’s spatially resolved observations for merging galaxies, we can study not only where and when the star formation is triggered and shut down during the process of  galaxy interactions, but also how the massive black holes in the center of galaxies can be fueled and grow through galaxy mergers. The observational results from MaNGA will also be compared in great detail with theoretical predictions from state-of-art simulations. Stay tuned for more exciting science that will come from MaNGA!

Letter from the New Editor in Chief

Dear Readers of the SDSS Blog,

I am Zheng Zheng, a SDSS-IV postdoctoral research fellow at the National Astronomical Observatories, Chinese Academy of Sciences (NAOC). I will be your new Editor in Chief for the SDSS Blog for the next 6 months and I will try my best to work with other bloggers to make the blog posts more interesting and smooth.

I got my PhD at Johns Hopkins University and now I am a postdoctoral researcher working at the NAOC and partially at the Institute of Cosmology and Gravity (ICG) at the University of Portsmouth in the U.K. I am currently studying extra-galactic galaxies using the SDSS-IV MaNGA data. I am also interested/involved in MaNGA stellar library, APOGEE and eBOSS projects.

As you may have known, the SDSS is an internationally collaborated survey project and the member institutes come from all over the world. In the future, we will introduce more interesting SDSS related sciences/events from all over the world, including the U.S., Europe, East Asia, and South America. We are aiming to a post frequency of about 1 ‘long’ post (like the ones introducing science projects) per 1-2 weeks. We will also have ‘short’ posts reporting SDSS related events and/or short news.

Please do not hesitate to make comments and let us know your ideas about the blog posts. Your feedback is highly appreciated and we will try our best to post more articles according to your interests.

Sincerely,

Zheng Zheng

 

Zheng observing at Palomar