Day: March 25, 2019

Shedding New Light on Dark Matter

By Dr Mireia Montes

Using the Hubble Space telescope’s past observations, astronomer Dr Mireia Montes’ group demonstrated that intracluster light—the diffuse glow between galaxies in a cluster—traces the path of dark matter, illuminating its distribution more accurately than existing methods.

Like humans, galaxies don’t like to live alone
Image Credit: NASA, ESA, Jennifer Lotz and the HFF Team

Galaxies are collections of millions of stars, gas and dust hold together by gravity. They also contain the mysterious, dark matter. Although dark matter makes up most of the mass of the Universe, we can only see dark matter through its effect on normal (baryonic) matter. UNSW Women Science champion Mireia Montes and her collaborator Ignacio Trujillo however have found a new way to see the location where the dark matter should be using intracluster light–a byproduct of interactions between galaxies in clusters.

Like humans, galaxies don’t like to live alone and tend to gather in groups (containing tens of galaxies) or clusters (hundreds to thousands of galaxies). As you travel away from the centre of a cluster of galaxies, it is increasingly dominated by dark matter. Interestingly this is also where you find the intracluster light. Dr Montes and Trujillo showed that by mapping intracluster light, this very faint glow could indicate how dark matter is distributed as it has the exact the same gravitational potential.

“Annoying” intracluster light could actually help us understand on one of astronomy’s great mysteries: the nature of dark matter.
Image credit: NASA, ESA and M. Montes

To test this, they used the images of the Hubble Frontier Fields. The Hubble Frontier Fields program was a deep imaging initiative designed to use the natural magnifying glass of galaxy clusters’ gravity to see the extremely distant galaxies beyond them, and thereby gain insight into the early (distant) universe and the evolution of galaxies since that time. Interestingly, at the time, intracluster light was considered an annoyance for these kind of studies as it made it more difficult to identify the distant galaxies beyond. Dr Montes and Trujillo however have shown that this “annoying” faint glow  could actually shed significant light on one of astronomy’s great mysteries: the nature of dark matter.

When asked what is next, Dr Montes said “Now it is time to extend this project to more clusters, further away from the centre of the cluster and see if in other objects, groups of galaxies or even galaxies, this result is still true.”

Read more about the MNRAS journal article: ‘Intracluster light: a luminous tracer for dark matter in clusters of galaxies’.

Follow Mireia on Twitter

(Based on the UNSW press release from Ivy Shih)

 

ASPIRE Holiday Program–Reaching Out to Regional NSW

By Kristina Fidanovski

ASPIRE Team (in red) with the boys and girls of Coolah (purple) and student helpers (blue).

“It works!” The girl’s disgruntled face suddenly clears and lights up the same way her circuit just has. I don’t get to admire her enthusiasm for long though–I’m drawn away to make sure the group aerial testing their light-up helicopter creations don’t wind up with concussions to take home as well. I’m in a small rural town in New South Wales running science workshops for APSIRE’s holiday program. ASPIRE aims to empower disadvantaged kids and make university education a real and attainable option for them. Part of that mission is exposing kids to what a university education means and the broad range of fields that they could pursue. Across the school there are workshops going on in drama, programming, sport, art, and engineering for girls and boys across Years 4 to 8. We’re building simple paper helicopters with finicky light up circuits for the science workshop. Neither Ngozi, my co-pilot, nor I know particularly much about circuits. It’s been a while since my undergraduate in Physics and these days I can be more reliably found pouring something toxic into something flammable and hoping a polymer comes out the other end. Ngozi’s optometry work in assessing habitual impacts on the ocular surface of children isn’t helping her much either. We’re doing admirably well, though; I think. Most people seem impressed with my improvised diagnostic tools as we try and get the little lights to turn on. A more challenging prospect than you might expect, but in my defence the wires are conductive tape that little fingers have mangled, not the standard insulated fair of science kits everywhere. Even the most irreverent and stubbornly cool preteens among the group–who will remain nameless–can’t help being pleased when their circuits work.

Ngozi showcases a new optometry program designed at UNSW to help researchers study eye-hand coordination in children.

“Why does the plus side of the battery have to be connected to the plus side of the light?” The girl asking is the loudest among a group of girls determined to convince anyone listening that they have no interest at all in anything that could be mistaken for school. I’m onto them though; all their circuits work. Also, they have good questions.

I freeze and cast my mind back to sitting in a lecture 5 years ago while a stereotypically old, white gentleman explained the principles of diodes to a hall full of young men. I was sitting two seats away from one of a handful of young women in our 60+ cohort. We hadn’t spoken before and I was planning ways to start a conversation that wasn’t just: “We should be friends because we’re the only two girls currently in this room.”

Ngozi troubleshoots a helicopter.

Fortunately, I remember enough of the lecture to explain it to the satisfaction of a 12 year old (which is actually harder than if I could have just regurgitated the technical details to a colleague familiar with the function of an electron). It does remind me though, why I’m out in regional Australia in the first place. Every lecturer I had at university, in both Chemistry and Physics, was old, white and male (except for the notable exception of our third-year lecturer on general relativity who was a breath of feminine-fresh air). In fact, even my high school teachers adhered to the stereotypes. Despite the reassurances of my family that I could, and indeed should, go into science, and the famous examples of female scientists they doggedly told me about, my face-to-face experiences with science had never been with someone who looked like me. Neither as a child, nor as an adult. I won’t pretend that I’m hoping a few hours spent in the company of two young PhD candidates waxing lyrical about research and science will be enough to turn that same stereotype around in the minds of the young girls and boys we encountered. I am hoping that it will spark something for them though. Our visit alone won’t be enough. But maybe when they log on to Facebook tonight they’ll see a lady scientist doing a demonstration video. Or they’ll catch the tail end of an interview with a lady scientist on the news. And maybe next year when ASPIRE comes past again with another bright-eyed PhD student with no idea how to explain diodes to a 12 year old, that’ll be enough to get them to think: “I can do it too.”

Learn more about ASPIRE at their website. We visited two schools–in Gilgandra and the even tinier town of Coolah–in the week we spent putting on workshops and science stalls, but ASPIRE visits schools across the region and they do incredible work.

I explain non-Newtonian fluids (a.k.a. make slime) while we wait for the sun to set and the moonlight cinema to begin. (Yes, my scarf is perfectly in character – it’s the exact one I wear underneath my lab coat when it gets chilly at work.)

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