Small galaxy, Massive black hole

Tomorrow’s edition of Nature contains an interesting astrophysics paper that I must blog about for the sake of domestic peace and harmony. It’s commonly accepted that all galaxies contain a massive black hole at their centre. Measuring the masses of these black holes is tough, but those we’ve been able to make that measurement for show a strong correlation between the black hole mass and that of the total mass of stars in the galaxy. This suggests that somehow the evolution of a galaxy and that of its central black hole are intricately linked, and this is now a key given in our understanding of galaxy evolution.

This new paper, by Remco van den Bosch here at MPIA and a number of collaborators, now convincingly challenges this assumption. In a large survey of very massive nearby galaxies with the Texan Hobby Eberly Telescope, they discovered a number of galaxies that appear to contain black holes whose mass dominates their total stellar mass. For one of these, the team obtained much additional data to rule out any problems with their original data or the methods used to derive the black hole mass. This galaxy, NGC 1277, is the subject of the paper.

NGC 1277 is definitely an interesting galaxy, but on its own cannot change these long-held assumptions. After all, every population has its outliers. What’s particularly exciting is that there appear to be others like it.

I’ve watched this paper in the making over the last few months, years even, and while it’s not my work, I’m quite proud to see it in print and receiving attention in so many places. Congrats to the authors and well done for the hard work.

van den Bosch et al, An over-massive black hole in the compact lenticular galaxy NGC 1277, Nature 2012 (paywalled) – or astro-ph. [links added, 29/11/12]


RB Editor’s Selections: Planck Appetisers, CSI-style Imaging, Maths Education and Risk, and Hungry Black Holes

Sarah Kendrew Sarah Kendrew selects interesting and notable posts in the physical sciences, chemistry, engineering, computer science, geosciences and mathematics. She blogs about astronomy at One Small Step.

[cross-posted from News]

Exciting new science has a habit of getting published when I’m on holiday – so it was no surprise to come back from a refreshing week in the mountains to some awesome new stuff in the journals and on ResearchBlogging. Here are some picks from the physical sciences categories.

  • First Planck results: The Sunyaev-Zeldovich Effect. Scientist working on data from European cosmic microwave background mission Planck published 25 new papers to the Arxiv last Wednesday with a first batch of results from the satellite. It’s a lot to digest, and thankfully some of the papers are being discussed online to provide us with digested reads and comment. On The Eternal Universe, Joseph Smidt talks about Planck’s observations of galaxy clusters using the Sunyaev-Zeldovich effect; I agree that these results bode extremely well for the bulk of the science we can expect from Planck in 2013.
  • Computer-enhanced imaging with almost perfect resolution. We astronomers spend a lot of time figuring out how to extract information from noisy images, and I’m always curious about the clever methods scientists in other fields develop for this purpose. In All That Matters, Joerg Heber describes an interesting technique developed by Israeli optical scientists to reconstruct images to the sub-wavelength resolution level from imperfect images.
  • Does mathematical training increase our risk tolerance? The critical assessment of risk is one of the most important skills we can learn from our maths lessons at school. It’s a little counter-intuitive then to learn, via Evolving Economics, that maths education appears to change our innate perception of numbers, potentially leading to a higher tolerance to risk.
  • Black holes are not fed by colliding galaxies after all. The co-evolution of galaxies and their black holes throughout the history of the Universe is one of the hottest topics in astrophysics at the moment. On Basic Space, Kelly Oakes discusses newly published research challenging a popular theory behind the triggering of black hole activity. This paper has received quite a bit of attention on blogs, see also the discussion on Science and Reason.

I’ll be back next week with more selections. Thanks for the great posts!

Black hole-iday


Astronomer (m)e(e/a)ts Powder

As I alluded to in my previous post, last week I spent a rather fabulous week in the Rocky Mountain resort of Aspen. The Aspen Center for Physics hosted a conference, organised by Andrea Ghez, Vicky Kalogera, Fred Rasio, and Steinn Sigurdsson (of the Dynamics of Cats blog), on the Formation and Evolution of Black Holes. I don’t work on black holes myself* but am lucky enough that my significant other does, and the prospect of a week in Aspen just sounded too good to turn down.

I was planning to attend some talks and maybe blog about the meeting, but in the end the lure of the white stuff proved too strong and I spent all my time skiing. Luckily Daniel Holz, blogger at Cosmic Variance, was also in attendance and he will be writing about the meeting on CV.

The one conference activity I attended, apart from eating and drinking, was the customary mid-week public lecture in teh Aspen Opera House, which was given by the ever-enthusiastic Andrea Ghez of UCLA on her work on the supermassive black hole in the Galactic Centre. As well as being an excellent scientist, Andrea is a fun speaker and a great advocate for astronomy. You can watch the lecture online at

Aspen is a pricey ski resort but the infrastructure and facilities are truly fantastic, if you enjoy the snow I recommend you try to go there sometime (on someone else’s grant). Through the Aspen Center for Physics, conference participants get incredibly generous discounts on lift passes, ski rentals, classes, and even food on the mountains – and these discounts extend to hangers-on like me. A really big thanks for that!

* Yet! That may change in 2011. Sort of.

Shape matters in black hole growth

Fig. 1 (from Schawinski et al., 2010)

Active galaxies have gone by many names: active galactic nuclei, quasars, QSOs, Seyfert galaxies, radio galaxies. Astronomers used to think these were all distinct types of objects, unified by the observation of large amounts of energy emerging from a compact region at the centre of the galaxy. These days, despite a great variety in observational characteristics, active galaxies’ engines are generally thought to be driven by a single mechanism, the accretion of material onto a supermassive central black hole.

In a paper published to the Arxiv last week, Kevin Schawinski and collaborators have used Galaxy Zoo classifications of local Universe galaxies to show that active elliptical galaxies are markedly different from those with a more disk-like or spiral shapes, adding morphology as an additional factor to consider in our model of active galaxies.

[Read more...]