Archivi tag: High redshift galaxies

Gas and stars in galaxies: A multi-wavelength 3D perspective

In 2008 ESO hosted the first conference on extragalactic 3D multi-wavelength astronomy. This very successful workshop attracted more than 150 astronomers with expertise ranging from the radio to the optical wavelengths. In the intervening five-year period, 3D spectroscopic techniques have greatly extended our understanding of the key subjects addressed in this workshop. The kinematics, mass assembly and evolution of galaxies has been explored in large samples in the optical and near-infrared by programs such as the SAURON/ATLAS3D and CALIFA surveys of nearby galaxies and the SINS and MASSIV surveys at z~1-2. 3D spectroscopy at these wavelengths has become a standard technique to such an extent that on 8-m telescopes survey style instruments have been developed. Meanwhile, for the next generation of extremely large telescopes IFU spectrographs are selected among the first instruments to be commissioned. At the longer end of the wavelength range, the JVLA has now come online and new radio facilities are producing commissioning results. Over the last few years millimeter interferometers have produced spectacular 3D maps of carbon monoxide and various other atomic and molecular lines of galaxies out to redshifts of z=6, as well as very detailed cubes of nearby galaxies. Against this background, it is an excellent moment to hold a second workshop in this series. The 2nd generation VLT instruments KMOS and MUSE are taking up science operations in 2013/14. ALMA is conducting Cycle 1 observations and is preparing for new observing modes and increased sensitivity and angular resolution in future Cycles. The timing is perfect to evaluate the scientific progress made since 2008 and to make the community aware of the expanding science capabilities of ESO’s 3D instrumentation suite.

Scientific topics covered at the conference will include:

  • Nearby Galaxy Dynamics
  • Starbursts and interacting galaxies
  • Supermassive black holes and AGN
  • High redshift galaxies
  • Cosmology and deep fields
By adapting a multi-wavelength approach to these scientific questions the stellar, hot and cold gas dynamics can be combined to provide an unprecedented opportunity to study many processes involved in galaxy formation such as infall, outflows, star-formation, mergers and AGN-related phenomena. Like in 2008, we envisage a highly interactive meeting with a focus on the presentation of scientific results based on current technology, but also an investigation into the exciting possibilities of future technologies. A secondary goal of this workshop is for the different communities to learn about the tools used to analyze and visualize 3-dimensional data, and to understand how they can be combined in optimal ways.

In support of this goal of the workshop, a concise description of the capabilities of these three new facilities is presented in this flyer.

New hints on the dust content in the early Universe

Secondo uno studio recente, guidato da David Fisher della Swinburne University of Technology, la polvere cosmica distribuita nelle galassie appartenenti all’Universo primordiale potrebbe essere un ingrediente molto più raro di quanto ipotizzato in precedenza. Infatti, gli astronomi hanno misurato il più basso contenuto di polvere in una galassia denominata IZw 18.

It’s not just that the dust mass is low. We found that the dust mass is 100 times smaller than would be expected based on commonly assumed theories“, Fisher said. The galaxy, I Zw 18, is nearby, which makes it easier to study, but has properties that are very similar to galaxies of the high redshift Univese. “It’s an extreme galaxy in the local Universe, but it tells us a lot about a stage that almost all galaxies have gone through, so it gives us a picture of what the first galaxies look like“.

Fisher said the results imply that galaxies of the early Universe may have less dust than has been expected.

This means, firstly, that they will look different than we expect and make different populations of stars than we expect. And secondly, that they will be much more difficult to observe, even with state-of-the-art facilities being built now such as the Atacama Large Millimeter/sub-millimeter Array (ALMA) of radio telescopes in northern Chile. IZw 18 is typical of very high redshift galaxies because it is very actively forming stars, and has a chemistry that is more like galaxies of the very early Universe with a very low abundance of metals and a lot of gas in the form of hydrogen“, he said. “Our result implies that current theories to describe the formation of stars when the Universe was very young are incomplete, and are built on invalid assumptions“. According to Fisher, the amount of dust is very important for the formation of stars. “What we think is going on, is that the harsh environment inside the galaxy we examined is adversely affecting the amount of dust in it. The radiation field measured inside I Zw 18 was roughly 200 times stronger than what we experience here in the Milky Way“. Fisher said that based on the findings, theories should be amended to account for environment in making stars.

Swinburne University of Technology: Early Universe less dusty than thought

arXiv: Dust May Be More Rare Than Expected in Metal Poor Galaxies

Exploring Into Darkness

WISH is a space science mission project whose primary goal is to reveal the first-generation galaxies in the early young universe. We launch a 1.5m-aperture telescope equipped with 0.5-degree-diameter wide-field NIR camera by 2020 in order to conduct ultra-deep and wide-area sky survey with the depth that cannot have been achieved by previous ground-based telescopes. WISH will be a very powerful and unique facility not only to search for the first-generation objects, but also to probe dark energy through type-Ia SNe as well as strong/weak-lensing phenomena and to study the galaxy evolution across the Hubble time. Its capability is of course not limited to extragalactic science. The Galactic structure and solar system bodies are also within the scope of the mission.

Foundation of the WISH working-group has been approved by the JAXA/ISAS Space Science Committee in Sept. 2008. WISH team so far developed the basic scientific goals, specifications of telescope, camera and satellite, and we are executing research, development and tests on essential technical components in order to prepare for the JAXA/ISAS AO for future program that is expected in near future. Meanwhile, international interest for WISH is growing. In 2012, two proposals for Missions of Opportunities were submitted to NASA in the US and CNES in France.

At this stage, we would like to have an opportunity to discuss the central mission science cases, namely the “Galaxies beyond Cosmic Reionization” and “Cosmic Expansion Histories and Dark Energy” as well as the new insight in many other fields of astronomy achieved by the WISH survey strategy and by the campaign programs for auxiliary science. The meeting is opened to the international colleagues, current and potential partners. The program will consist of talks and discussions exploring WISH science cases, survey strategy, and instruments including the optional spectrograph.