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Lifting the Veil on the Early Universe

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The Creation of a Galactic Metropolis

An artist’s conception of a giant protocluster of galaxies forming in the early universe. The galaxies are busy forming new stars while at the same time interacting with each other. Courtesy: ESO/M. Kornmesser

From time to time astronomers give us a peek at the early universe and each time they do, they lift the veil on earlier and earlier time periods of our cosmic history. In recent years, they’ve shown us early “shreds” of galaxies and hints of the first stars to ever form. Galaxies began forming some 500 million years after the Big Bang occurred. As galaxies formed through collision and cannibalism, they also clumped together in clusters. One of the oldest clusters is called the Spiderweb Galaxy (or MTC1138-262) is at the heart of a galactic protocluster that began assembling more than 10 billion years ago.

Astronomers interested in star formation in infant galaxies during those early epochs of galaxy building took a closer look at this cluster using the APEX Telescope in Chile, part of the European Southern Observatory. This telescope is exquisitely sensitive to millimeter wavelengths of light (part of the infrared spectrum of light).  It opens a window on distant universe, allowing astronomers to look for faint glimmers of energy from the early universe. They used something called the LABOCA (which stands for Large Bolometer Camera) instrument to look at the cluster. This camera is essentially a sensitive thermometer that helps astronomers sense any kind of heat above absolute zero.  That means it can detect the glimmers of star formation from the early universe, even if they’re hidden by clouds of dust and gas.

Essentially, the APEX telescope and instruments revealed that there are many more sources of star formation in the region of the Spiderweb than astronomers suspected. Their ability to peek behind the veil of dust that hid parts of the cluster’s activity showed astronomers something of a surprise. Yes, star formation is happening there, growing in the interacting galaxies. But, it is  not where they expected it to be. It’s clustered in a relatively small region of the cluster, and not in filaments of gas and dust strung between the member galaxies, where such events usually occur as galaxies interact. Galaxy collisions regularly set off bursts of star formation, and you often see bluish starburst knots strung out between member galaxies like strings of fuzzy pearls.

So, why is star birth so constrained to a smallish, non-central area of the cluster? Good question. Finding the star formation is great news, but now astronomers need to figure out why it’s occurring in a region where they didn’t expect it to be. What processes are shaping the starbirth nurseries in this cluster? Do they tell us something about how clusters formed in the early universe?  Good questions, which astronomers hope to answer by focusing the massed ALMA array on the region when they get a chance. It should give them nicely resolved looks at the stellar creches in the Spiderweb Galaxy and its siblings in the cluster.

 

 

 

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Starbirth Visions

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Starbirth Art and Science

An image of Herbig-Haro object HH 46/47 is based on observations made at radio wavelengths by ALMA as well as visible-light observations made with the European Southern Observatory’s New Technology Telescope. The ALMA observations (orange and green, lower right) of the newborn star reveal a large energetic jet moving away from us, which in the visible is hidden by dust and gas. To the left (in pink and purple) the visible part of the jet is seen, streaming partly towards us. Courtesy: ESO/ALMA (ESO/NAOJ/NRAO)/H. Arce. Acknowledgements: Bo Reipurth

This image may look like an impressionistic painting of space, but it’s based on actual data taken by the Atacama Large Millimeter/Submillimeter Array (ALMA) and observations in visible light taken with the New Technology Telescope (ESO),  high in the Andes of South America. It a multi-wavelength view that is giving astronomers a whole new view of a starbirth region not far from Earth.

First of all, what is this object?  As the caption says, it’s an image made from data taken during observations of a Herbig-Haro object. These glowing clouds of gas and dust are named after two astronomers named George Herbig and Guillermo Haro, who studied the properties of light they give off. Their work revealed that Herbig-Haro objects occur in starbirth areas where material ejected at really high speeds from newborn stars creates shocks in the surrounding clouds.

It turns out that young stars are really active and can be quite violent as they “grow up”, almost more like rebellious teenagers. They eject material away from themselves at close to a million kilometers per hour (about 640,000 miles per hour) through massive jets. When those jets intersect the surrounding cloud of gas and dust, it heats and energizes the gas, and that causes it to glow.

This particular Herbig-Haro object is actually quite close to us in cosmic terms—only about 1,400 light-years away. In the newly released ALMA image, astronomers can make out two jets. One is headed toward Earth and the other points away from us.  In this image, the jets stream out to the upper left and lower right. The newborn star is at the center of the butterfly-shaped object. Interestingly, the birth cloud for the hot young star doesn’t seem to be symmetrical. You can tell because one jet seems to be slamming into thick areas of cloud while the other jet escapes almost to empty space. In addition, astronomers think there may be a third outflow from the young star, carving its way out from the birth nest.

Radio astronomy (which senses wavelengths of light or radio frequencies commonly known as radio, millimeter, submillimeter, and microwave) allows astronomers to look beyond clouds of gas and dust that can block visible light and hide things from our view. The ALMA installation is an array of multiple sensors that can take very high resolution (sharp) data of distant objects and show us more detail in them. ALMA is only just beginning its “career” as Earth’s latest radio telescope array designed to ferret out naturally occurring signals from active objects in the cosmos.