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Showing posts from 2014

Scientists Have Figured Out What Colour The Universe Is

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What's old is new again?

Over at Business Insider Australia we are told (with some lovely language) that Scientists have figured out what colour the Universe is. You've got to love a new and interesting astronomy story, but alas, the result is rather, well, beige (I refuse to say latte).
But that's not the point of this post. Now, I am not a young man any more, and my memory is not what it was, but I know I had heard this story before, somewhere in the past.

The story doesn't name any scientists or cite an original article, and so I turned to google. Hmmm - virtually the same story appeared in the UK Telegraph in 2009! Unsurprisingly, the Daily Mail carry very similar stories.

So this "news" is at least 5 years old! But now we have some names! Karl Glazebrook and Ivan Baldry!

A little more detective work leads to New Scientist article entitled The Universe is not turquoise – it's beige. This story from 2002!!!!!!!! corrects and earlier story in which the…

The Redshift Drift

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Things are crazily busy, with me finishing teaching this week. Some of you may know, that I am writing a book, which is progressing, but more slowly than I hoped. Up to just over 60,000 words, with a goal of about 80 to 90 thousand, so more than half way through.

I know that I have to catch up with papers, and I have another article in The Conversation brewing, but I thought I would write about something interesting. The problem is that my limited brain has been occupied by so many other things that my clear thinking time has been reduced to snippets here and there.

But one thing that has been on my mind is tests of cosmology. Nothing I post here will be new, but you might not know about it. But here goes.

So, the universe is expanding. But how do we know? I've written a little about this previously, but we know that almost 100 years ago, Edwin Hubble discovered his "law", that galaxies are moving away from us, and the further away they are, the faster they are moving. …

Catching the Conversation

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Wow!!! Where has time gone! I must apologise for the sluggishness of posts on this blog. I promise you that it is not dead, I have been consumed with a number of other things and not all of it fun. I will get back to interesting posts as soon as possible.

So, here's a couple of articles I've written in the meantime, appearing in The Conversation

One on some of my own research: Dark matter and the Milky Way: more little than large



And the other on proof (or lack of it) in science: Where’s the proof in science? There is none



There's more to come :)

Sailing under the Magellanic Clouds: A DECam View of the Carina Dwarf

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Where did that month go? Winter is almost over and spring will be breaking, and my backlog of papers to comment on is getting longer and longer.
So a quick post this morning on a recent cool paper by PhD student, Brendan McMonigal, called "Sailing under the Magellanic Clouds: A DECAm View of the Carina Dwarf". The title tells a lot of the story, but it all starts with a telescope with a big camera.
The camera is DECam, the Dark Energy Camera located on the 4m CTIO telescope in Chile. This is what it looks like; It's not one CCD, but loads of them butted together allowing us to image a large chunk of sky. Over the next few years, this amazing camera will allow the Dark Energy Survey which will hopefully reveal what is going on in the dark sector of the Universe, a place where Australia will play a key-role through OzDES.
But one of the cool things is that we can use this superb facility to look at other things, and this is precisely what Bendan did. And the target was th…

A cosmic two-step: the universal dance of the dwarf galaxies

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We had a paper in Nature this week, and I think this paper is exciting and important. I've written an article for The Conversation which you can read it here.

Enjoy!


Resolving the mass--anisotropy degeneracy of the spherically symmetric Jeans equation

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I am exhausted after a month of travel, but am now back in a sunny, but cool, Sydney. It's feels especially chilly as part of my trip included Death Valley, where the temperatures were pushing 50 degrees C.

I face a couple of weeks of catch-up, especially with regards to some blog posts on my recent papers. Here, I am going to cheat and present two papers at once. Both papers are by soon-to-be-newly-minted Doctor, Foivos Diakogiannis. I hope you won't mind, as these papers are Part I and II of the same piece of work.

The fact that this work is spread over two papers tells you that it's a long and winding saga, but it's cool stuff as it does something that can really advance science - take an idea from one area and use it somewhere else.

The question the paper looks at sounds, on the face of it, rather simple. Imagine you you have a ball of stars, something like this, a globular cluster:
You can see where the stars are. Imagine that you can also measure the speeds of t…

Should academia be like Logan's Run? All out at 40?

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A quick post, as I am still on the road.
One of my favourite movies of all time is Logan's Run (partly because of the wonderful Jenny Agutter, who was also in another fav of mine, An American Werewolf in London). The premise of the movie is that in a futuristic society, to maintain populations, children are manufactured to order and when you get to thirty years of age, you go to carousel where you float up in to the air and explode.

 Should academia be like this? Not killing everyone at 30, but how about requiring everyone to leave at 40?

Now, before you start screaming about "academic freedom" and "tenure", hear me out. I quite like the idea. Let's start with what (I think) we can all agree on.

Basically, there are not enough academic jobs, and academic pipe leaks at all stages, with talented people having to leave due to the lack of positions at the next level.

Additionally, prising academics out of their jobs is notoriously hard, with many working until…

The Nature and Origin of Substructure in the Outskirts of M31 -- II. Detailed Star Formation Histories

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I am still playing catch up on papers, and I've just woken up early here in San Francisco and have a small amount of time before I have to prepare for my talk today. So, this will be quick.

The topic again is our nearest largest companion, the Andromeda Galaxy, especially working out the history of how stars have formed in the (relatively) inner regions of the galaxy. It might seem a little strange that we can work that out, because all we can see is stars, but with the magic of science, it is possible. That's the topic of this new paper by postdoctoral researcher, Edouard Bernard.

This beautiful science is done with the Hubble Space Telescope. The first thing you need to do is decide where to look. So, here's the fields we looked at
One of the sad things is that the area Hubble can image (its field of view) is tiny compared to the extent of Andromeda, and so we are doing key-hole surgery in select areas on interesting bits of Andromeda, especially prominent bits of subst…

The outer halo globular cluster system of M31 - II. Kinematics

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Well, I don't know where that month vanished, but I now find myself sitting in the very nice Swan's Hotel in Victoria, Canada, after doing some nice new work with Alan McConnachie at the Herzberg Institute of Astrophysics. The week has gone fast, and I've given two talks, and have four more to give in California next week.

But I realised that I have neglected the blog, and there has been quite a few papers of mine put on the arxiv I should talk about. I have quite a bit of catching up to do, so here's a first post, and I will try and post some more over the next couple of weeks.

A few weeks ago, I posted an article about the fact that we now have the final catalog of the globular clusters found in the PAndAS survey. This has been a major undertaking, seeing out these balls of a few million stars in the outer reaches of Andromeda. But it's been very successful, and we can now start to ask the question "what have we learnt?" This is the topic of this post,…

Misconceptions About the Universe

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Over on youtube, Veritasium has a nice discussion of Misconceptions about the Universe. I  like it, especially as I was the consultant cosmologist :)

A little look down the comments tho, and we see several claims that what Derek says is not correct. Here's a little excerpt
Well, as a cosmologist, I was surprised to read that the Hubble Sphere is an "outdated concept" having seen it used in a professional meeting last week. But let's take a look at the other claims that are made by "fullyawakened" - I must admit they have the lead on me as I am partiallyjetlagged at the moment. As ever, I am going to steal Tamara Davis's standard cosmological picture in a few different sets of coordinates to do this. I've explained these before, but the top one has distance as we know it along the x-axis, and time as we experience it up the y-axis.

"Our observable Universe is getting smaller" is simply wrong. Let's look at the bottom figure, which is i…