The Hunt For Dark Matter And Energy Gets A New Weapon

John P. Millis, PhD for redOrbit.com – Your Universe Online

The search for dark matter – and the even more mysterious dark energy – has both captivated and frustrated the minds of cosmologists and astronomers. There are the obvious reasons: by definition these phenomenon are difficult, if not impossible, to observe directly, and their effects can often be so subtle that making precise enough measurements proves a technical challenge.

To overcome these difficulties, a team from the Subaru Telescope developed the new Hyper-Suprime Cam (HSC) – replacing the previous Suprime-Cam – to take the highest resolution, wide field of view images of galaxies ever. These images will allow researchers to better map and image dark matter regions. In addition, with the precise velocity measurements that will be possible, astronomers will be able to refine measurements of dark energy’s distribution in our Universe.

Earlier this month the HSC team released the first image using the new camera: a detailed rendering of M31, more commonly known as the Andromeda Galaxy, Our closest major galactic neighbor. (There are closer dwarf galaxies, but M31 is the nearest object of similar size and structure to our Milky Way.) The giant spiral has been studied for more than 1,000 years and, despite lurking at some 2.5 million light-years from us, is one of the few extra-galactic entities that is visible to the naked eye.

Dr. Masahiro Takada (Kavli IPMU), the chair of the HSC science working-group, shared how the release of the M31 image signals a great advancement in research because of the HSC: “This first image from HSC is truly exciting. We can now start the long-awaited, largest-ever galaxy survey for understanding the evolutionary history and fate of the expanding universe.”

“A ‘cosmic census,’ i.e. a large-scale imaging survey of every galaxy over a wide solid angle in the sky and in sufficient depth to probe the distant universe, will include the detailed measurement of hundreds of millions of galaxy shapes and assessment of the effects of gravitational lensing. Such data will allow scientists to map the distribution of dark matter, constrain the nature of dark energy, and search for baby galaxies that were just born in the early universe.”

Dr. Hitoshi Murayama, Director of Kavli IPMU and the Principal Investigator of the Subaru Measurements of Images and Redshifts (SuMIRe) Project, also noted, “HSC is a tremendously exciting project. We at Kavli IPMU have been involved in the project to our full extent. We contributed about a half of the project cost, and put more than 20 people working on it.”

“We are also developing and building a multi-object spectrograph called PFS to follow up on the HSC imaging data to determine the distance, motion, and chemical composition of galaxies. The combination of HSC and PFS would allow us to conduct an unprecedented ‘cosmic census.’ We are very much looking forward to the coming survey data!”

With such a wide field of view – some 1.5 degrees across – the HSC allows researchers to study a significant part of the sky all at once, while at the same time collecting very high resolution data. This is one of the significant milestones of the HSC, as astronomers have traditionally had to sacrifice one (either field of view or resolution) in favor of the other.

While closure on the source of dark matter and dark energy are still a long way off, the new data being released by the HSC has the potential to significantly advance the search for answers.

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