Spotted! The signature of our inflationary Universe?


Image: BICEP2 collaboration

It’s a good thing we got that Higgs Nobel prize out of the way last year, as we’ve got a big new contender lined up. After a few days of rumours, the team behind South Pole telescope BICEP2 today announced their detection of the signature of inflation in the polarization of the cosmic microwave background (CMB). In case the big words coming to you from the BBC, the Guardian, Nature, the New York Times, Peter Coles, Sean Carroll, roughly 500 twittering astronomers and Andrei Linde himself have not yet convinced you, let me add to those: if (if!) it stands, this is a Very Big Deal.

The distinctive wiggles found in the CMB polarization map are the imprints of the gravitational waves that accompanied inflation, the faster-than-light expansion the Universe underwent less than one-trillionth of a second after the Big Bang (13.8 billion years ago). This expansion explains why the Universe looks so smooth and uniform in all directions, despite its vastness.

If we leave aside the awesomeness of being able to detect any signals from anything that happened at this esoteric time, let alone offer a sensible interpretation, this is a major discovery for a number of reasons. It is very strong evidence that inflation actually happened as it was thought out by the early theoreticians who pioneered the theory. This in itself is a big missing piece of the puzzle of our Universe. In addition, the observed signal lends support to the notion that gravity was unified with the other fundamental forces in the hot early Universe. Finally, this is the first direct detection – or one the first, depending on how you define “direct” – of the highly elusive gravitational waves that astronomers have hunted for decades.

This stuff is too far from my own field for me to understand the details of the data or their interpretation, but the general consensus amongst social-media-connected astronomers is that the data look good and the analysis extremely rigorous. Teasing such a faint signal out of observational data is invariably a very tough task, with lots of systematics in the measurements to account for. Some scientists seem pretty skeptical, and that is a good thing. The data and accompanying papers will still need immense scrutiny and very thorough peer review before being officially accepted as Real and True. Whatever the outcome, this has clearly been a huge effort by the BICEP2 team, and they deserve a big congratulations for these results.

If you want to learn more about the physics of the very young Universe, I can highly recommend Alan Guth’s own book on his journey developing the theory of inflation, The Inflationary Universe, which is one of my all-time favourite popular science books. More generally on gravity and general relativity, fellow Oxfordian Pedro Ferreira just published a book entitled The Perfect Theory, which I’m enjoying at the moment.

A number of cosmologists have given their (more technical) opinions and interpretations online: Peter Coles at Sussex, Phil Bull in Oslo, and I’ll add a few more as I find them. 18/03: this from Renée Hlozek at Princeton,  more from Peter Coles,

The official papers and data are publicly available here.


Sunshine and Big Mirrors

Blue skies and citrus

Tucson in January: Blue skies and citrus

Last week I got back from a great work-pleasure jaunt to the United States. I started off in Tucson, Arizona, where I met with the MIRI test and calibration team to further our plans for space domination instrument testing, calibration and software development for our instrument, which will be launched on board the James Webb Space Telescope in 2018. I’ve been involved in testing MIRI for my entire postdoc career now and it’s always a pleasure to meet with the team, and see how far we’ve come in the project.

Many people ask me what there is left or us to do, now that MIRI is in the hands of NASA in the US. The answer to that is “LOTS”. Even though the immediate task of assembling and testing the actual instrument hardware is completed, we now have to work with our NASA colleagues to integrate MIRI further with the rest of the spacecraft and test over and over again that everything is still in working order. In addition, we have to define calibration procedures and the data and algorithms that are required for that, and develop software. There’s an awful lot of work still happening!

Aside from the productive meeting I was really pleased to get a tour of the Steward Mirror Lab, which I’d heard lots about. Several of the world’s largest astronomical mirrors were cast and polished in giant spinning ovens, deep in the bowels of the University of Arizona’s football stadium . In these ovens, heat melts the glass until it’s molten, and the rotation shapes it into a nice parabolic shape while it’s in that state. The temperature is then lowered very slowly in a controlled way to stop stresses and bubbles forming in the glass. The mirror is shaped around a honeycomb structure that is later removed, producing a nice lightweight mirror.

With this technology Steward produced the mirrors for the 3.5-m mirrors for the ARC at Apache Point, New Mexico, and the WIYN at Kitt Peak, AZ; the 6.5-m’s for Magellan in Chile and for MMT at Mt. Hopkins, AZ; and the twin 8.4-m mirrors for the Large Binocular Telescope at Mt. Graham, also in Arizona.

Excitingly, several large mirrors are currently in production there at the moment. The first two 8-m segments for the Giant Magellan Telescope have been produced, and a third is under way. The primary mirror for the Large Synoptic Survey Telescope (LSST) was being polished while I was there. This mirror is pretty amazing, as it contains both the blanks for the primary and the tertiary mirror, so two different profiles are being polished into it. I’ve included some pictures below [feel free to use them but please credit to me when you do!].


Steward Mirror Lab

Steward Mirror Lab

Arizona stadium

Arizona stadium

Arizona stadium, home of the Steward Mirror Lab.

Arizona stadium, home of the Steward Mirror Lab.

The LSST primary and tertiary mirrors, being polished.

The LSST primary and tertiary mirrors, being polished.

The polishing tool working its way around

The polishing tool working its way around

Preparing for another GMT mirror segment

Preparing for another GMT mirror segment

Explosion in the Sky

The supernova in M 82 Credit: UCL/University of London Observatory/Steve Fossey/Ben Cooke/Guy Pollack/Matthew Wilde/Thomas Wright

The supernova in M 82
Credit: UCL/University of London Observatory/Steve Fossey/Ben Cooke/Guy Pollack/Matthew Wilde/Thomas Wright

The Universe is so vast, it’s not unreasonable to assume that at any given time, something, somewhere, is going bang. We know of many kinds of objects that produce cataclysmic explosions, and some explosions remain unexplained. But to discover such an event in our own cosmic backyard is pretty rare. That’s what happened yesterday, when a supernova was spotted in nearby galaxy M82. First observations suggest that this is a type Ia supernova, thought to occur when a white dwarf accreting material from a companion star reaches a critical mass, collapses and explodes.

Astronomers round the world will have a lot of fun studying this new nearby supernova in the months and years to come. Indeed the new supernova is probably still some days or even weeks away from its peak brightness. Another similar recent supernova, SN1987A, located in the Large Magellanic Cloud, has virtually spawned its own research field.

A very cool aspect of the discovery is that the first reports were made on 21 Jan by students and a lecturer, Dr Steve Fossey, at University College London‘s observatory in Mill Hill, ULO, where I spent much time myself as an undergraduate and PhD student. They were taking images of the galaxy as part of their training to use the instruments on the observatory’s telescopes. Steve Fossey was in charge of many of the observing activities in my student days too, everyone liked working with him, and I remember enjoying the time I spent there. And really, what is 15 years in cosmic time?! Fun to think that this could have been me.

It’s a wonderful experience for the students who were taking the images, and who knows, maybe even a great start to their careers in astronomy! A good reminder too that even small telescopes in urban areas can do lots of science: catch exploding stars, spot exoplanet transits, track variable objects, and much much more.

Stargazing Live Portsmouth

For a few years now the BBC have run a big live astronomy event in January, called Stargazing Live. In previous years I’ve always followed online, jealously from across the Channel, sans television. So I’m pretty excited this year that I’m able to go along to one of the big events and take part. I’m part of a small group of Oxford astronomers going to Portsmouth to join our colleagues there to have some sciencey fun with lots and lots of amateur astronomers and enthusiasts in the Portsmouth Historic Dockyard.

As well as my first Stargazing event it’s also my first ever visit to Portsmouth, so that is quite exciting too. I’m not sure what to expect but I hope to report back on all the fun and excitement of the evening.

The main event takes place at Jodrell Bank, and BBC2 will be broadcasting from 8 pm this evening from there and the other events taking place around the country. Fellow Oxford astros and good friends Chris Lintott and Rob Simpson will be at Jodrell, together with TV regulars Brian Cox and Dara O Briain, and as I understand it the Zooniverse projects will be featured on the show.

The skies are a pristine blue outside my office window right now (mocking me, after the drenching I received on my morning run) so perhaps there could even be some actual live stargazing later in the day. Here’s hoping!


Milky Way Project: We’re Back!


I’ve been a happy member of the science team for the Zooniverse‘s Milky Way Project for a few years now, and since joining Oxford earlier this year I’ve had the opportunity to work a bit more closely with friend & fellow postdoc  Rob Simpson, who leads the project. A huge amount of data has been classified over the years, we’ve published a few neat science papers within the team, and have had the project and our data acknowledged by numerous other scientists working on star formation in our Galaxy, which is very nice. I’ve listed our papers, and a few related ones from the past year, below in case you’re interested. And I know for a fact that more follow-up work is in progress and I’m looking forward to seeing that come out in the new year.

The original dataset, that covering the inner plane of the Milky Way Galaxy, has been completely classified by our many users, which is fab. But the fun isn’t over. A couple of weeks ago the Milky Way Project was relaunched with a new look and some great new data. The designers and Rob have done a great job with the redesign and personally I’m loving the new interface. So what’s changed?

The images we’re showing now are still from the Spitzer Space Telescope, but covering different parts of the Galaxy than the original images from the GLIMPSE and MIPSGAL surveys. Rob’s blog post on the MWP blog tells all on the new surveys, from which we’ve taken around 40,000 images to classify. The colours show slightly different wavelengths from our previous data as well: we’re no longer covering the 24 µm of the MIPSGAL survey, showing instead three shorter wavelength bands, at 3.6, 4.5 and 8.0 µm.

Part of the new look of the site is also the classification interface, which reflects the lessons we learnt from the first stage of the project. The designers have included a cool new tutorial introducing you to the new features and the objects to look for. For bubbles, the classification tool is now a single ellipse rather than an annulus, and for other types of objects we have a simple circular shape to draw with.We’re also giving some different types of objects to classify that we think are more scientifically interesting.


One of those types are the Extended Green Objects, or EGOs – sometimes also called Green Fuzzies in the literature. These are distinctive green smudgey objects, often found near bubbles, that may (but not always) mark a very young massive star in the process of forming. The green stuff in this case is emission from molecular hydrogen excited by powerful outflows from the massive protostar. This very early stage of a massive star’s life is hard to study as massive stars are rare and they spend a long period of time deeply embedded inside cold dense clouds of gas. EGOs are therefore super interesting targets for further study. In fact my most recent paper, which you should all read immediately, showed infrared and millimeter follow-up data for one, also identified in Spitzer data, located very near to the centre of our Galaxy in Sgr C.

Following the MWP relaunch we’ve had a ton of renewed interest and classifications, and we’re looking forward to having some new data, and new catalogues, to play with very soon!

Recap: MWP papers for your Christmas reading

Simpson, Povich, Kendrew et al, The Milky Way Project First Data Release: a bubblier Galactic disc, MNRAS 424 (4), pp. 2442-2460 (2012) Our first paper + data catalogue!

Kendrew, Simpson, Bressert et al, The Milky Way Project: A Statistical Study of Massive Star Formation Associated with Infrared Bubbles, ApJ 755(1), id. 71 (2012) My follow-up on correlations between bubbles and massive young stars. Everyone knows this one by now (right? right?).

Some MWP-related reading from the past year, for Boxing Day and beyond

Tackenberg, Beuther, Plume et al, Triggered/sequential star formation? A multi-phase ISM study around the prominent IRDC G18.93-0.03, A&A 550, id. A116 (2013)

Alexander, Kobulnicky, Kerton & Arvidsson, The Interstellar Bubbles of G38.9-0.4 and the Impact of Stellar Feedback on Star Formation, ApJ 770(1), id. 1 (2013)

Walch, Whitworth, Bisbas, Wünsch & Hubber, Clumps and triggered star formation in ionized molecular clouds, MNRAS 435(2), 917-927 (2013)

Hou & Gao, A statistical study of gaseous environment of Spitzer bubbles, Arxiv 1311.4943 (2013)

Morales, Wyrowski, Schuller & Menten, Stellar clusters in the Inner Galaxy and their correlation with cold dust emission, A&A 560, id. A76 (2013)