Dark stuff that matters

here's a new story, maybe a teeny bit longer than usual, about the dark 'nests' where the most frenzied galaxies in cosmic history are born...

Herschel quantifies the dark matter threshold for starburst galaxies
How much dark matter is needed to trigger a starburst in the cosmic cribs where galaxies are born? A new study, based on data from ESA's Herschel Space Observatory, has revealed that dark matter halos with a mass larger than 300 billion times the Sun's are particularly efficient at igniting massive starbursts, as they house the most active star-forming galaxies in the Universe. Astronomers have discovered this key threshold by measuring small fluctuations in the Cosmic Infrared Background, the integrated diffuse emission produced by the dust from every galaxy that ever existed. These fluctuations trace the distribution of otherwise mostly unresolved star-forming galaxies and of the dark matter halos that enshroud them. More...

Image credits: The Virgo Consortium/Alexandre Amblard/ESA

lenses in the sky – without diamonds

and finally a new story about cosmology and a good old friend of yours truly, i.e. gravitational lensing... yay!

New method reveals gravitationally lensed galaxies in Herschel-ATLAS first survey

Astronomers using early data from one of the largest projects to be undertaken with the ESA Herschel Space Observatory have demonstrated that virtually all bright sub-millimetre galaxies in the distant Universe are subject to gravitational lensing, which amplifies their flux thus easing their detection and characterisation. Analysis of less than three per cent of the entire Herschel-ATLAS survey, which probes the distant and hidden Universe, yielded a first sample of five lensed galaxies and paves the way for the compilation, in the near future, of a rich catalogue of distant, star-forming and dust-obscured galaxies. More...

Image credits: ESA/NASA/JPL-Caltech/Keck/SMA

Job Hunting in the Galaxy Zoo

Massive help from citizen scientists opens new paths for full time astronomers

We are all under the same sky. Sooner or later, we all raise our eyes to gaze at the stars in the celestial vault and wonder about the mysteries of the Universe. As humankind is tied to the skies, it is natural to expect a large participation in citizen science projects inspired by astronomy. However, the massive success of “Galaxy Zoo” exceeded expectations and lead the venture to the next phase, even opening up brand-new academic positions.

Citizen scientists are members of the public that contribute to genuine scientific research. They might count birds, fish or stars, play with proteins on their computers or look for oddities in images of the cosmos, and then send their results back to professional scientists. A long-established tradition for researchers, resorting to the so-called power of the crowds yields myriad benefits to both groups.

The “Galaxy Zoo” project has been running for almost three years. The organisers, a group of astronomers based in the UK and US, had the ambitious goal of asking the public to classify the shapes of a million galaxies. The zoo analogy is striking, as galaxies in the Universe have a plethora of different morphological features; when it comes to their overall shape, however, astronomers have basically two choices: spiral or elliptical.


Understanding the shape of a galaxy goes well beyond a simple catalogue compilation, as it identifies its formation and dynamical history: stars in a spiral galaxy rotate around the centre in an ordered fashion, whereas in an elliptical galaxy they move in a much more chaotic way. Beautiful images of nearby galaxies are usually straightforward to interpret, their stunning spiral arms or roundish appearance leaving astronomers with little doubt. Far away galaxies, instead, look more like small, undefined blobs and sorting them into these two classes is an extremely delicate task.

In the past decades, countless graduate students have devoted years to the classification of galaxy shapes, which is mostly performed via visual inspection. Even though modern astronomy is a highly computer-dominated discipline, it is not trivial to teach a machine how to recognise shapes, and the human brain is still the most powerful tool in this context. Given these premises, the potential of a scheme to involve citizen scientists in galaxy classification was huge, and the “Galaxy Zoo” team has fully exploited it.

Only a few days after the launch of the project’s website, 35 000 enthusiasts had completed the same amount of work that a graduate student could have performed devoting months to this sole task. Employing the public in these operations does not demote professional astronomers; instead, it enables them to perform research with plenty of new, fresh data, without having to perform the “dirty” job themselves. Using the “Galaxy Zoo” samples, astronomers have learned new, exciting details regarding the evolution and the distribution of different galaxies, and even discovered some unexpected and never-before-seen features. More than a dozen papers have already been published in international journals, and many others are in progress, thanks to the devotion of this immense community that self-styled themselves as “Zooites”.

After the first successful results, the project has already moved to the next level: a new online sample of galaxies is ready to be characterised in much greater detail than the previous one; members of the public can also look for additional features, such as mergers between neighbouring galaxies. And there’s more, as the project’s next step involves citizen and professional scientists alike.

In order to turn the massive amount of data analysed by the community into proper results, one or more astronomers have to devote their entire energies to the “Galaxy Zoo” cause. On March 1st, a postdoctoral researcher will start working full time on this project at the University of Oxford, where it all began; soon another post-doc position will be filled at the University of Nottingham, and the Adler Planetarium, an astronomy museum with an active research group in Chicago, is recruiting scientists and software developers to join the “Galaxy Zoo” team.

This and other projects have provided innumerable members of the public with a chance to share the excitement of scientific discovery and to get a glimpse of how research works. In turn, the citizen scientists have contributed, over the years, to close the circle, dutifully delivering data and occasionally leading to scientific breakthroughs. Now, with citizen scientists literally employing professional astronomers, new research perspectives open: the circle has evolved into a spiral.

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This story is also an exercise i wrote just over a month ago...
For more info about the project: www.galaxyzoo.org

Image credits: Galaxy Zoo and the Sloan Digital Sky Survey

Physics: the Nobel seizes the light

The prize goes to Willard Boyle and George Smith, fathers of digital photography

On Tuesday, October 6th, the Nobel Prize in Physics 2009 has been awarded to Willard S. Boyle and George E. Smith, the fathers of digital photography. In 1969, the two scientists from Bell Laboratories, in New Jersey, USA, invented a device able to capture light without using photographic film — the so-called CCD (Charge-Coupled Device).

The technology behind the CCD exploits the photoelectric effect, through which light is transformed into an electric signal. The explanation of the photoelectric effect won Albert Einstein the Nobel Prize in 1921. Boyle and Smith faced the challenge of converting this effect into a practical application, and designed a sensor able to catch light at several different points (called pixels) and to transform it, over an extremely short time lapse, into electric signals to then be transported and reproduced on a monitor or stored in a file.


The CCD has revolutionised photography and our approach to it for ever, as it is the very heart of tens of millions digital cameras produced in the world, including those integrated into many mobile phones and other gadgets. However, digital photography meant an even more remarkable revolution for science, and for astronomy in particular, a field which literally lives off the images of the sky.

All current professional telescopes are in fact equipped with digital sensors, vastly more sensitive than the old photographic plates astronomers made use of until only a few decades ago. Furthermore, CCDs can be used again many times and their output signal, being already in digital form, is ready to be stored and analysed by computers. In fact, without this new technology, it wouldn’t have been possible even to conceive the massive catalogues containing detailed information about hundred of millions of far-away galaxies, which allowed astronomers to understand the properties of the Universe better and better.

Boyle and Smith shared the most prestigious of all scientific awards with physicist Charles K. Kao, for his work concerning the transmission of light signals through optical fibres. Optical fibres, just like the CCD, also contributed to the digital revolution, making the sharing of data and information possible over increasingly short time intervals. Without them, the internet as we know it could not exist.

It is interesting to note how, during the International Year of Astronomy 2009, the Nobel Prize in Physics has been awarded to three scientist whose research focussed on light and has contributed to the production of vital tools for astronomers, professionals and amateurs alike.

Image credit: NASA

Translated from Il Denaro, 08.10.2009