Spinning Black Holes Are a Drag

When you release a lot of black hole results to the public, you can sometimes forget how weird these objects are. We focus on the significance and the novelty of the result, rather than the exotic features that are common to many black holes. A recent paper reminded me about the latter and highlighted one of the curiosities of General Relativity, concerning the distortion of spacetime near these extreme objects. This post discusses some of the physics of spinning black holes.

In late February, NASA released a new result where the authors "measure definitively, for the first time, the spin rate of a black hole with a mass 2 million times that of our sun." In their press release, written by Whitney Clavin and her JPL colleagues, they say that the supermassive black hole is "spinning almost as fast as Einstein's theory of gravity will allow". These are results from NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), the new X-ray kid on the space block, and the European Space Agency's XMM-Newton. The 1st author of the paper is Guido Risaliti from the Harvard-Smithsonian Center for Astrophysics (my home institution) in Cambridge, Mass., and the Italian National Institute for Astrophysics. The supermassive black hole is located in the middle of a beautiful galaxy called NGC 1365.

Guided by the press release, a NASA press conference, the science paper and a News and View article in Nature, science writers tackled the story. There are details about how the data enabled the authors to reach their conclusions, but I will focus on the basic result, the rapid spin of the black hole and how it was described. I'll also give some thoughts on how it should be described, given the luxury of time.

This artist's concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. (Smaller black holes also exist throughout galaxies.) In this illustration, the supermassive black hole at the center is surrounded by matter flowing onto the black hole in what is termed an accretion disk. This disk forms as the dust and gas in the galaxy falls onto the hole, attracted by its gravity. Also shown is an outflowing jet of energetic particles, believed to be powered by the black hole's spin. The regions near black holes contain compact sources of high energy X-ray radiation thought, in some scenarios, to originate from the base of these jets. This high energy X-radiation lights up the disk, which reflects it, making the disk a source of X-rays. The reflected light enables astronomers to see how fast matter is swirling in the inner region of the disk, and ultimately to measure the black hole's spin rate. [Caption reproduced from this NASA site] Credit: NASA/JPL-Caltech

The Bad Astronomer, Phil Plait, wrote at his Slate blog about the author's observations of the black hole and how they "were surprised to find out it's spinning so fast that the outer edge is moving at very nearly the speed of light!"

An LA Times article by Amina Khan has a headline of "X-rays show galactic black hole spinning near speed of light" and says the black hole "is spinning at 84% of the maximum possible rate" following the paper and the News and Views article. It also says:

"If you were standing near the event horizon of this particular black hole, you would have to turn around because your space-time is twisting," NuSTAR lead scientist Fiona Harrison, a Caltech astrophysicist, said at a news conference. "You would be turning around once every four minutes just to stand still."

An article in Physics World by Hamish Johnston says:

"The study confirms that the SMBH is spinning at a rate close to the limit defined by the general theory of relativity. While the rotational properties of a spinning gravitational singularity are difficult to describe in a simple way, Risaliti explains that the rotational energy of the SMBH at the heart of NGC1365 is about the same as the energy that is given off by a billion stars burning for a billion years."

That's three different stories giving different ways to describe the spin. I think Johnston explains the challenge well. How do you describe the properties of a spinning singularity in a simple way? To answer this question well I think it's useful to explain what is doing the spinning. Plait discusses the "very edge of the black hole" and he's presumably talking about the event horizon, the region surrounding the black hole that light cannot escape beyond. The event horizon is an important boundary, but it isn't a physical object, like a wall (unless some recent speculation about black hole firewalls is correct, as explained in this article by Jennifer Ouellette). If material makes it to the event horizon, as must occur regularly for some supermassive black holes, including the one in NGC 1365, it won't last there for long.

I looked back at how we have previously described black hole spin with Chandra results. We did a press release for Cygnus X-1, a black hole in our galaxy that is about 15 times as massive as the Sun, and a different press release for a group of nine supermassive black holes.

For Cygnus X-1 we said:

"the black hole is spinning at very close to its maximum rate. Its event horizon -- the point of no return for material falling towards a black hole -- is spinning around more than 800 times a second." 

That's a very impressive number and it's accurate, but it doesn't explain what is spinning.

On the left, an optical image from the Digitized Sky Survey shows Cygnus X-1, outlined in a red box. Cygnus X-1 is located near large active regions of star formation in the Milky Way, as seen in this image that spans some 700 light years across. An artist's illustration on the right depicts what astronomers think is happening within the Cygnus X-1 system. Cygnus X-1 is a so-called stellar-mass black hole, a class of black holes that comes from the collapse of a massive star. The black hole pulls material from a massive, blue companion star toward it. This material forms a disk (shown in red and orange) that rotates around the black hole before falling into it or being redirected away from the black hole in the form of powerful jets. [Caption reproduced from this Chandra website] Credit: Optical: DSS; Illustration: NASA/CXC/M.Weiss

For the sample of nine black holes we include a quote from astrophysicist Rodrigo Nemmen:

"We think these monster black holes are spinning close to the limit set by Einstein's theory of relativity, which means that they can drag material around them at close to the speed of light".

That's very close to the best answer. It's spacetime itself that is rotating at almost the speed of light in one of these black holes, and this is what drags material around with it at the same speed. (The technical term for this is "frame-dragging", as Matthew Francis explains in his Ars Technica article in more detail.) I checked with Robert Penna, a local expert on General Relativity and black holes, who confirmed this explanation. Here's the description he gave:

"A good mental picture is to think of the spacetime around a spinning black hole as a whirlpool. Objects are dragged around by spacetime as they fall towards the hole. At the horizon they are forced to rotate at the angular velocity of the whirlpool."

A subset of a sample of nine large galaxies is seen on the left of this graphic. These Chandra images show pairs of bubbles created in the gaseous atmospheres of the galaxies that were created by jets produced by giant central black holes. These data were used to help determine that the supermassive black holes are likely to be spinning very rapidly. The artist’s illustration (right) depicts how material very near the black hole falls inward and joins a rapidly spinning disk of matter. Most of this material is swallowed by the black hole, but some of it is swept outward in jets (colored blue) by quickly spinning magnetic fields close to the black hole. [Caption reproduced from this Chandra website] Credit: NASA/CXC/UFRGS/R.Nemmen et al.; Illustration: NASA/CXC/M.Weiss

Other explanations are useful, but they're not as clear. For example, the one by Risaliti gives a good explanation of the energy a spinning supermassive black hole has, but this is more useful for stories explaining the black hole's effect on their host galaxy. It also doesn't explain how fast the spin is or what is spinning. The answer by Harrison explains how fast the event horizon is spinning but it does not mention that an infinitely powerful rocket would be required to stand still near the event horizon of a spinning black hole, both to prevent infall and rapid spin.

There is a subtlety regarding the 84% number quoted above. This refers to the quantity a* used by astronomers that is a measure of the angular momentum of the black hole, which itself depends on its mass and speed. This quantity a* is defined so that its maximum value is 1.0 for a black hole with an event horizon rotating at the fastest speed allowed, the speed of light. For no spin a*=0. For the black hole in NGC 1365, a* was estimated to be at least 0.84. However, this does not mean that the black hole's speed is at least 84% of the speed of light. The speed is given by this formula:

speed = (a*/(1+sqrt(1-a*^2))) c

provided by Robert Penna, where "c" is the speed of light. So, when a*=0.84 the speed is 0.54c, or just over half the speed of light.

This point is more pedantic than interesting, but it helps set up a related issue. Let's return to the stellar-mass black hole Cygnus X-1. The rate of spin given above for this black hole comes from a spin frequency estimate. The spin frequency of a black hole measured at the event horizon depends only on a* and the black hole's mass. For Cygnus X-1, if a*=1 then the spin frequency is 1091 Hz, that is spacetime at the event horizon would spin around 1091 times a second. That's mind-bogglingly fast, but it isn't the interesting numerical point that I want to make.

What happens when you double-check that the speed of the event horizon - in this extreme case of a*=1 - is the speed of light? The radius of the event horizon for Cygnux X-1 is 21.9 km. So, the speed of the horizon should be the circumference of the event horizon multiplied by the spin frequency, ie 2*pi*21.9*1091 km/s. But this only equals ~150,000 km/s, which is half the speed of light. What's going on here?

The answer is that our assumption about the geometry was wrong. Near a black hole the normal geometry that we learned in school doesn't apply and the circumference of a circle is less than 2*pi times the radius, because of the severe distortion of spacetime. When you use the correct geometry you find that that the speed of the event horizon for a black hole with a*=1 is the speed of light, as expected (I was assured that this is the case but I didn't do the calculation myself, since my General Relativity skills are a little rusty).

For some explanations and more details about how geometry is distorted near a black hole, you can check the illustrations and descriptions in "Black Holes and Time Warps: Einstein's Outrageous Legacy" by Kip Thorne given here and in "The Physical Universe: An Introduction to Astronomy" by Frank Shu given here.

General Relativity and black hole expert Robert Penna. Credit: Robert Penna.

I asked Penna what happens to the velocity of spacetime inside the black hole's event horizon, but we don't even have a useful definition of velocity in this region. In Penna's words:

"The velocity makes sense outside the horizon because there is a standard observer, the fixed observer at infinity [someone who is a very long distance away where the gravitational effects of the black hole are negligible]. This observer is not available inside the horizon, because an observer at infinity can't see across the horizon. And an observer inside the horizon can't be at rest: the severe gravity causes everything inside the horizon to fall towards the singularity. Different observers will measure different velocities, so there isn't a standard velocity inside the horizon."

With black holes you have objects where normal geometry and physics do not apply and where material can be pulled along at almost the speed of light just before it disappears from the observable universe for ever. These points about geometry and physics are well established but can sometimes be neglected by astronomers and science communicators. Black holes should not be taken for granted just because a lot of papers are published on them.


End-note: I would like to thank Robert Penna for his thoughtful comments and also black hole expert Jeff McClintock, from Harvard Smithsonian Center for Astrophysics, who directed my questions to Robert.

The Remarkable Properties of Neutron Stars

The collapse of a massive star in a supernova explosion is an epic event. In less than a second a neutron star (or in some cases a black hole) is formed and the implosion is reversed, releasing prodigious amounts of light that can outshine billions of Suns. That is a spectacular way to be born. Here, I'll explain that the properties of neutron stars are no less spectacular, even though they are not as famous as their collapsed cousins, black holes.

Because of the incredible pressures involved in core collapse, the density of neutron stars is astounding: all of humanity could be squashed down to a sugar cube-sized piece of neutron star. The escape velocity from their surface is over half the speed of light but an approaching rocket ship would be stretched, then crushed and assimilated into the surface of the star in a moment. Resistance would be futile.

If this cricket ball were made of neutron star material it would weigh about 20 trillion kg, or about 40 times the estimated weight of the entire human population.

Another remarkable property is that neutron stars generate the most extreme magnetic fields known in the universe, up to a quadrillion times the strength of Earth's magnetic field. If one of these ultra-magnetic neutron stars, called a magnetar, flew past Earth within 100,000 miles, its magnetic field would destroy the data on every credit card on Earth. Luckily for our economy none are that close, but the distant ones can put on spectacular shows. In 2004 a magnetar underwent an extraordinary outburst and become one of the brightest objects ever observed in the sky, causing a disturbance in the Earth's ionosphere that was recorded around the globe, as described in this paper by astrophysicist Bryan Gaensler (@SciBry on Twitter) from the University of Sydney (my alma mater). That's impressive for an object about the size of a city that is located around 50 thousand light years away.

An artist's conception of the spectacular outburst from the magnetar SGR 1806-20, including magnetic field lines. After the initial flash, smaller pulsations in the data suggest hot spots on the rotating magnetar’s surface.  This animation contains no audio, because "in space no-one can hear you scream".  Credit: NASA

Neutron star behavior can be so odd and distinctive that their discovery was initially greeted as the possible discovery of extraterrestrial intelligence. The real explanation is that a pulsar, a rotating neutron star, was discovered. Pulsars have become such an important tool for physics research that two different Nobel Prizes have been awarded in their name, the first for their discovery by Antony Hewish. Many people - including myself - have argued that Jocelyn Bell Burnell should have been awarded part of the Nobel prize with Hewish, since she made the discovery, but in an expression of modesty or Imposter Syndrome, Bell Burnell later commented that she did not deserve the award. However, this does not diminish the significance of her discovery, and of the outstanding research that it enabled.

Jocelyn Bell Burnell with the radio telescope she used to discover pulsars. Credit: Jocelyn Bell Burnell.

The second Nobel prize was for Russell Hulse and Joseph Taylor, who discovered the first known binary pulsar, PSR1913+16, which has become extremely valuable for testing Einstein's Theory of General Relativity (GR). Since then other important objects have been discovered, including a double pulsar system known as PSR J0737-3039A/B that is one of the best objects available for testing GR and alternative theories of gravity, as explained in this paper by Michael Kramer from the University of Manchester.

Looking ahead in pulsar work, there is an exciting and ingenious project called the North American Nanohertz Observatory (NANOGrav) that is attempting a direct detection of gravitational waves, ripples in the fabric of space-time, using pulsars. Like several of the topics covered here this project deserves a dedicated blog post, but for now I'll just say that exotic objects like black hole binaries are expected to produce gravitational waves. Two of the pulsar experts leading this project are Scott Ransom from NRAO, whose enthusiasm for pulsars is well explained by the papers he writes, like this one: "Pulsars are cool. Seriously" and Victoria Kaspi, from McGill University, seen here speculating about some possible applications of pulsar research.

So far I've emphasized spectacular features of neutron stars and some famous results. These stories capture a lot of attention and do an excellent job at promoting astrophysics, but most research occurs in the gaps between catchy headlines and Nobel prizes. These gaps contain plenty of room for excellent research, much of it about understanding the nature of neutron stars, rather than testing fundamental physics with them.

Some of the most important open questions about neutron stars concern their size and structure. How large are they? What makes up their atmosphere? What is their core like?

One key advantage that neutron stars have over black holes is that their surface is visible to us, enabling much to be be learned about their atmospheres and interior structure. For example, in 2009, Wynn Ho from the University of Southampton and Craig Heinke from the University of Alberta, found evidence for a carbon atmosphere on the neutron star in the Cassiopeia A supernova remnant, using NASA's Chandra X-ray Observatory (note: I work at the Chandra X-ray Center in the Education and Public Outreach Group). This resolved a mystery about the nature of the neutron star, as the press release and Nature paper explain. An interesting side-note: the researchers calculate that the carbon atmosphere is only about 4 inches thick, as shown in the figure, because it has been compressed by a surface gravity that is 100 billion times stronger than on Earth. We're used to talking about massive scales and distances in astronomy, not small ones.

The properties of the carbon atmosphere on the neutron star in the Cassiopeia A supernova remnant are remarkable. It is only about four inches thick, has a density similar to diamond and a pressure more than ten times that found at the center of the Earth. As with the Earth's atmosphere, the extent of an atmosphere on a neutron star is proportional to the atmospheric temperature and inversely proportional to the surface gravity. The temperature is estimated to be almost two million degrees, much hotter than the Earth's atmosphere. However, the surface gravity on Cas A is 100 billion times stronger than on Earth, resulting in an incredibly thin atmosphere. Caption taken from Chandra web-site. Credit: NASA/CXC/M.Weiss

Heinke and Ho followed up this work with an even more interesting result, the first direct evidence for a superfluid, a bizarre, friction-free state of matter, at the center of a neutron star. First, a 4% drop in the temperature of the Cas A neutron star over 10 years was observed with Chandra and reported by Heinke et al. Then, two different papers, one in Physics Review Letters led by Dany Page from the National Autonomous University in Mexico and another in Monthly Notices of the Royal Astronomical Society led by Peter Shternin from the Ioffe Institute in St Petersburg, Russia independently came up with the same explanation. When the temperature of the neutron star fell below a critical level, a superfluid formed in the core of the star, forming neutrinos which travel outwards, taking energy with them. This causes the star to cool rapidly as observed with Chandra.

This image shows a composite of X-rays from Chandra (red, green, and blue) and optical data from the Hubble Space telescope (gold) of Cassiopeia A, the remains of a massive star that exploded in a supernova. The artist’s illustration in the inset shows a cutout of the interior of the neutron star where densities increase from the crust (orange) to the core (red) and finally to the part of the core where evidence for a superfluid has been found (inner red ball). The blue rays emanating from the center of the star represent the copious numbers of neutrinos -- nearly massless, weakly interacting particles -- that are created as the core temperature falls below a critical level and a neutron superfluid is formed, a process that began about 100 years ago as observed from Earth. These neutrinos escape from the star, taking energy with them and causing the star to cool much more rapidly. Credit: X-ray: NASA/CXC/UNAM/Ioffe/D.Page,P.Shternin et al; Optical: NASA/STScI; Illustration: NASA/CXC/M.Weiss

Other important information about the structure of neutron stars comes from studying the relationship between their size and mass. For a given mass, the size of a neutron star will depend on how stiff or soft the structure is. These are all relative terms, since by Earthly standards, nothing about neutron stars is soft.

Old neutron stars are typically faint objects, but when they pull material away from companion stars they can become much brighter, allowing good studies of their atmospheres. Observations of the amount of X-rays at different wavelengths, combined with theoretical models for their atmospheres, can allow the relationship between the radius and mass of the neutron star to be estimated. This work has been performed by Heinke, by Natalie Webb and Didier Barret (both from the Institut de Recherche en Astrophysique et Planétologie) as explained in this paper, and by Sebastien Guillot (Seb_Guillot on Twitter) from McGill University, in this paper. All of these observations were of neutron star binaries in globular clusters.

Neutron stars pulling material away from companions have also been observed to undergo bursts of X-rays, caused by thermonuclear explosions on their surfaces. These explosion can cause the atmosphere of the neutron star to expand. If observers catch one of these bursts they can follow as the star cools and calculate its surface area. When this area is combined with independent estimates of the distance to the neutron star, the relationship between the mass and radius of this object can be estimated. Two researchers who have applied this technique with great success are Feryal Ozel from the University of Arizona and Tolga Guver from Sabanci University, as described in this set of papers here, here, here, and here.

Each of the papers quoted in the previous two paragraphs provide information about the mass and radius of the neutron star and about their structure. However, there may be problems with relying too much on a single technique or a single object. A very good new paper by Andrew Steiner, from the University of Washington, avoids this problem by combining all of the papers mentioned above: 4 neutron stars in globular clusters quietly pulling material from a companion and 4 undergoing X-ray bursts.

A Chandra X-ray Observatory image of 47 Tucanae, my favorite globular cluster. One of the neutron star binaries from Steiner et al. (2013), called X7, is labeled. Credit: NASA/CXC/Michigan State/A.Steiner et al.

Steiner et al. take these results and apply the latest neutron star models to estimate that the radius of a neutron star with a mass that is 1.4 times the mass of the Sun - a typical value - is between 10.4 and 12.9 km (6.5 to 8.0 miles), as we reported recently in a Chandra image release. They also estimate that the density at the center of a neutron star is almost ten times that of nuclear matter found in Earth-like conditions. This is equivalent to a pressure that is over ten trillion trillion times the pressure required for diamonds to form inside the Earth.

Using their results, Steiner et al. are able to compare their results with values derived from nuclear physics experiments performed on Earth, such as the distance between protons and neutrons in atomic nuclei. A larger neutron star radius implies that, on average, neutrons and protons in a heavy nucleus like Uranium are farther apart.

What is the core of a neutron star made of? It could be neutrons or it could be free quarks, the fundamental particles that combine to form protons and neutrons but which are not usually found in isolation. The paper by Steiner et al. cannot distinguish between these two possibilities, but there is potential to do so with future neutron star work.

There are many other interesting and important results about neutron stars. Regarding their structure, there are the very strong constraints that have come from pulsar work, such as the mass measurement of (1.97+/-0.04) solar masses by Demorest et al. (2010), with Scott Ransom as a co-author, that has already accumulated over 400 citations! An even larger neutron star mass might have been found by Romani et al. (2012). Then there are the astonishing spin rates that these incredibly massive, city-sized objects can reach, such as PSR J1748-2446ad which spins around 716 times a second, as reported by Hessels et al. (2006), with Ransom and Victoria Kaspi as co-authors.

I will continue to follow developments in neutron star research closely, as part of my job with Chandra but also because of my excellent location at Harvard-Smithsonian Center for Astrophysics (CfA), which has a regular stream of visitors covering a wide range of astrophysics. For example, Bryan Gaensler is giving the CfA colloquium next week, on a topic that is yet to be announced, and Scott Ransom is giving a talk in early April about NANOGrav.

In the meantime, I may write a blog post or two on black holes, which are rumored to be interesting objects.

What Does a Progressive Scientific Society Look Like?

In principle, scientific societies can play an important role in helping scientists perform, discuss and publicize their research. If they are progressive and open-minded, rather than old-fashioned and elitist, these societies can be very effective at enabling science and science communication.

The question I'll address in this blog post is how progressive and open-minded is my scientific society, the American Astronomical Society (AAS)?

The AAS is over 110 years old and was once dominated by people who looked like this:

Some astronomers at the AAS meeting in 1910. Credit: University of Chicago Photographic Archive, [apf digital item number, e.g., apf12345], Special Collections Research Center, University of Chicago Library.

and this:

The AAS meeting in 1910. Credit: University of Chicago Photographic Archive, [apf digital item number, e.g., apf12345], Special Collections Research Center, University of Chicago Library.

[As an aside, when I look at pictures like the ones shown above I imagine someone whispering "carpe", which gives me an excuse to show a clip from one of my favorite movies, Dead Poets Society:

]

Enough with the movie-watching digression. Here's a recent movie from real life showing what AAS members look like now:

based on a party held recently at the 221st meeting of the AAS, in Long Beach, California.

The people attending the AAS have changed a lot in appearance, but how well has the AAS kept up with these changes? How representative is the AAS membership of the general population and where are the disparities? What is the AAS doing right and where is there room for improvement?

Diversity

Those early photos show that AAS meetings were once male-dominated. That's not a huge surprise. This domination began with the leadership, as the AAS presidents were all men from 1899 until Margaret Burbidge took on the role between 1976 and 1978. Another lull followed until Andrea Dupree became president between 1996 and 1998. Since then three women have been president, not including Meg Urry (@UrryM on Twitter), from Yale University, who was recently announced as the latest AAS member to take on this role, beginning next year. This is a great development because Urry has made exceptional efforts to enhance the participation of women in astronomy, and received an award last year from the AAS for this service.

Of the 16 plenary, or keynote, sessions held during the day at the recent AAS meeting, 5 were given by women. That's not terrible, but it could be better. For the press briefings the number was lower: only 4 out of 45 speakers. So, there's definitely room for improvement there. [I decided to check back over our own publicity with Chandra X-ray Observatory to see how we're doing with including women and our numbers aren't very different. We also have room for improvement.]

What about broader statistics for women in astronomy and the AAS? An article by Joan Schmelz, chair of the AAS Committee on the Status of Women, pointed out that women make up only about 15% of the tenured faculty members of PhD astronomy departments in the US. This is higher than the 7% figure that applied in 2001 but it's still pathetic, as pointed out by Ann Finkbeiner in an interesting blog post at the excellent blog The Last Word on Nothing.

I tweeted about these statistics and the AAS quickly gave a response on their Facebook page:

"A tweet today by @peterdedmonds, points out that only about 15% of tenured astronomy faculty are women. This graph helps explain why. The demography of the American Astronomical Society is not uniform with age. 

The oldest astronomers have roughly a 15 to 20 percent fraction of women (or less), while the youngest age brackets are nearly at parity. This has not always been the case. In the 1970s, the Society had roughly 15% women in all age categories. 

Progress is being made, but it takes time, policy changes that welcome women into our field and support them during their career as well as engaged women interested in pursuing a career in astronomy. 

We don't know if women are being disadvantaged in other ways from our data, but are working on a longitudinal survey with the help of the American Institute of Physics to find out."

Here's the graph mentioned by the AAS correspondent on Facebook:

Blue bars are the fraction of women in that age group, and yellow is the fraction of men. Credit: AAS.

Similar graphs were produced for 1995 and 2003. A good discussion followed on the AAS Facebook page about whether a disproportionately high percentage of women drop out of the AAS as they get older. The Facebook correspondent from the AAS stated that this wasn't occurring. Michael Merrifield attempted a quick test of this claim by taking the 1995 data, then moving it forward 15 years and overplotting it on the 2010 graph (astronomers like playing with numbers). The resulting figure gives a hint of systematic drop-outs in the youngest of the age bins where a comparison is possible. However, it's unclear whether these differences are significant because the raw numbers are not given and error bars cannot be estimated. The youngest and oldest age bins contain relatively few members, as mentioned by the AAS in the Facebook discussion, so the errors bars could be large.

A comparison between the gender balance of the 2010 AAS and the 1995 AAS shifted by 15 years. Credit: AAS and Michael Merrifield. 

Although the data presented here are inconclusive, it's certainly plausible that a higher fraction of women than men drop out of astronomy as they get older. A recent article in the Guardian noted that the fraction of women in biomedical science drops off as one goes to higher professional levels. One possible explanation given for these trends is that women are treated less fairly than men, as suggested by a paper led by Corinne Moss-Racusin from Yale University. Astrophysicist John Johnson has written about this very interesting study and the effects of unconscious bias, and Meg Urry also wrote about the Moss-Racusin paper for CNN.

Another considerable challenge involves work-life balance. As pointed out by Mary Mason from Berkeley in a longitudinal study:

"family formation—most importantly marriage and childbirth—accounts for the largest leaks in the pipeline between Ph.D. receipt and the acquisition of tenure for women in the sciences."

A related issue is unreasonable travel workloads for Principal Investigators, as explained by astrophysicist Sara Seager from MIT.

These problems are difficult to counter. The Moss-Racusin paper and the Mason study both present some suggestions and I encourage you to read them. Regarding work-like balance, astrophysicist David Charbonneau from Harvard University has argued that improved access to childcare should be provided. I expect that the AAS Committee on the Status of Women is working on some possible solutions. With Meg Urry as president elect and with responsive AAS officers and councilors, I'm hopeful that real progress can be made.

I'm encouraged by the AAS's attempts to be inclusive with members of the lesbian, gay, bisexual, transgender, intersex, and questioning (LGBTIQ) communities. There is a AAS Working Group on LGBTIQ equality (WGLE) and at the recent AAS meeting there was a workshop on "How to Be a Better Professor or Teaching Assistant for your LGBT Students". There was also a reception held by WGLE and a LGBTIQ networking dinner. I haven't seen reports about the effectiveness of these workshops and networking opportunities, but it's good to see that attempts are being made to be inclusive.

I'm less encouraged by the possibility that the number of African Americans in astronomy will rise significantly above the current number, which is very small. Kevin Marvel, Executive Officer of the AAS, admits this is a considerable challenge. There are limits to the influence that a scientific society can have. We're lucky to have one of the most famous scientists in the world in our ranks - Neil Tyson - but strong role models can only help so much. Also, Tyson is still relatively young for a renowned scientist, so many children inspired by him will not have graduated yet from school or university. This important topic is appropriate for a separate discussion, preferably led by astrophysicists like Neil Tyson and John Johnson.

Meeting Etiquette

The winter and summer meetings held by the AAS are the "largest and most logistically complex astronomy meetings in the world". To help with this complexity, the AAS included a "Guide to AAS Meeting Etiquette"in the handbook for the recent meeting. A cynic might argue that his guide is just common-sense advice for nerds with poor social skills. But, I think it's more than that, as it includes discussion of several important and subtle issues. It also acts as compensation for the lack of professional development that many scientists experience, beyond standard research skills.

The guide begins with a general statement that

"It is AAS policy that all participants in Society activities will enjoy an environment free from all forms of discrimination, harassment, and retaliation."

It provides a link to the anti-harassment policy of the AAS and a few pages later gives the text for this policy, following a letter from the current AAS president, David Helfand, titled "Harassment Will Not be Tolerated at AAS Meetings". Helfand's letter ends with:

"We must all work together to ensure an environment free of harassment so that our scholarly and collegial interactions are focused on our common mission: to enhance and share humanity’s scientific understanding of the Universe. We can only accomplish this mission fully when we respect each other as professionals, and I call on each of you to help us in this regard."

The guide later gives some tips about asking questions during meetings:

"When asking questions of speakers, please be professional, courteous, and polite. This is especially important when questioning students presenting their dissertation research."

I think this is useful advice, especially for any older astronomers who were "broken-in" as students by aggressive questioning at talks, and who might think behavior like this is professional. Of course, it's up to the session chair to control and, if necessary, stop this sort of behavior.

The issue of "astronomical bullying" has been discussed in at least two different venues by Joan Schmelz, including a previous AAS meeting, as reported in this blog post and a talk at my institution, the Harvard-Smithsonian Center for Astrophysics. A pdf of the presentation is included here. I'm sure various forms of academic bullying occur in other scientific disciplines, and it's important for them to be addressed.

Journalists & Embargoes

The next section in the conference handbook is about journalists and embargoes. Because it isn't very long and it overlaps with my professional interests, I'll include the complete text from this section:

"If your presentation covers results that have been, or will be, submitted to Nature or Science or any other journal with a strict embargo policy, be sure you understand how that policy applies to scientific meetings. No journal wishes to hinder communication between scientists. For example, both Science and Nature state explicitly that conference presentations do not violate their embargo policies. 

But both journals also state that if your presentation covers work that has been, or will be, submitted to them, you should limit your interaction with reporters to clarifying the specifics of your presentation. As Science puts it, "We ask that you do not expand beyond the content of your talk or give copies of the paper, data, overheads, or slides to reporters." That does not mean you should be rude if a reporter asks you for such materials or poses a questions that you do not want to answer - just explain that your results are under embargo at Science or Nature, and the reporter will understand why you cannot be more forthcoming."

This is good advice, which isn't surprising considering that the AAS press officer Rick Fienberg managed to get onto Ivan Oransky's Embargo Watch honor roll, and to maintain this status by smart handling of an embargo break.

I've noticed there is sometimes confusion about Nature and Science embargoes among astronomers, and presumably other scientists as well. Some astronomers are surprised to hear they can talk about their Nature or Science papers at conferences, and post their papers to the arXiv before publication.

Blogging & Tweeting

Another section of the etiquette guide concerns blogging and tweeting, and again I'll include their text because it isn't very long and because it overlaps with my interests:

"If you blog, tweet, or otherwise post near-real-time material from the meeting online, you must follow the guidelines above concerning the use of computers, tablets, mobile phones, and AAS wireless bandwidth. 

Please do not publicly report private conversations — only scheduled presentations and public comments are fair game for blogging, tweeting, etc. 

Remember that many presentations at AAS meetings concern work that has not yet been peer-reviewed. So think twice before posting a blog entry or tweet that is critical of such work. It is helpful to receive constructive criticism during the Q&A after your talk or while standing next to your poster, but it is hurtful to be raked over the coals online before your session is even over and with no easy way to respond.

New York Times editor Bill Keller said it well. When it comes to meetings among colleagues, he explained, "We need a zone of trust, where people can say what's on their minds without fear of having an unscripted remark or a partially baked idea zapped into cyberspace. Think of it as common courtesy." "

I think their advice here is well-intentioned, even if it might give the impression to uninitiated readers that Twitter and blogs are dominated by critical and hasty commentary. I'm interested to hear if other scientific societies have guidelines for blogging and tweeting.

Conclusion

My conclusion is that the AAS is progressive and open-minded and is serving its members well. Feel free to add comments if I've missed some key problem areas or if you have suggestions for improvements. I am happy to pass these comments along to the AAS.

For scientists who aren't astronomers, how is your scientific society doing? For non-scientists, I hope you've enjoyed this small window into the thinking of a modern scientific society.

ScienceOnline in Three Words

Performance, feedback, revision. Those three words will be immediately familiar to fans of Baba Brinkman, including people who attended his talk and performance at the ScienceOnline2013 meeting held recently. Not only was Brinkman brilliant, but I think his words capture the spirit and motivation behind the best conference I've ever attended. (The words will also be familiar to people who read Kelly Oakes' excellent blog post about the same meeting and words. Most of my post was already written before I saw Kelly's post and we have different viewpoints, so I decided to finish this post.)

Science-lovers online and offline at the ScienceOnline meeting at North Carolina State University. Conference maestro Karyn Traphagen can be seen chatting in the background on the left. Credit: Russ Creech.

There were many outstanding aspects to the ScienceOnline meeting, the 7th one held. The organization was superb, with close attention given to minimizing typical conference distractions, like "where shall we eat", and maximizing chances for interactions between people. The "converge" sessions, similar to key-note talks, were stimulating and entertaining, and the smaller discussion sessions covered a lot of interesting material. To accommodate the many people unable to attend the meeting, the converge sessions and some of the discussion sessions were streamed live, and watch parties were organized around the world.

The food was excellent and the coffee was apparently very good. There was a quiet room where people could gather their thoughts by escaping the intense post-session discussions. New science books were curated and there were skills workshops. There were field trips before the meeting started, so the newcomers could get to know each other, and people were kept informed about late-breaking news on Twitter. For example, that's how I discovered that a spot opened up on the tour of the Duke Lemur Center, a few days before the meeting. I could go on.

Surely an important reason for this excellence is that the organizers, Karyn Traphagen, Bora Zivkovic and Anton Zuiker have listened carefully to feedback given at previous conferences and revised the details many times. It's the process that Baba Brinkman uses in improving his rap performances, as explained in this video, and highlighted by blogger Joe Hanson.

Baba Brinkman performing at the converge session at ScienceOnline. Credit: Russ Creech.

I was skeptical when I first heard about an evolution rapper performing at the conference party on Thursday night, but Brinkman quickly won me over during his talk and performance at the Converge session the next morning. One highlight was "I'm a African", a rapping guide to evolution where he explains that we all came from Africa originally. He also enjoyed mocking our natural inclination to say "I'm an African" as he coached us to sing the title words properly. I won't give any more details, but I strongly encourage you to watch the video from the converge session if you weren't there, or to watch it again if you were. You can also watch him on YouTube:

The first step, of performing rap or science communication - or both, in the case of Brinkman - is important. However, I would argue that the second step, of listening to feedback and criticism, is even more important. Even though it can be difficult to hear critical comments, for science communicators and science writers it's a key part of their job.

The session Nadia Drake and I led at the meeting was driven by the desire for feedback. It was titled: "Working towards better press releases: What do writers want?" and was aimed at seeking advice from science writers. Thanks to some popular competing sessions - see below - and useful information from the meeting app, we knew that few writers were likely to attend our session, so I sent questions to science writers by email and received some excellent, detailed responses. These will be included in a future blog post. We also wrote two blog posts before the session, an introduction by me and an entertaining reply by Nadia. So, this was a more personal case of feedback and revision.

My two major concerns about the session were that I would mumble incoherently, without the crutch of powerpoint slides, and that this would result in a lack of discussion. So, I was happy and relieved that the discussion ended up being energetic and stimulating. It was mostly attended by PIOs and people who produce, rather than consume, press releases, but there were some very useful comments from writers Peter Aldhous, David Harris, and, of course, Nadia. Thanks to everyone who came and joined in.

Nadia Drake at the end of our session on press releases.

Perhaps the most outstanding feature of this meeting was the friendly and unpretentious attitude of the people who attended. There were many talented writers, scientists, educators and communicators at the meeting, some with substantial fan-bases, yet everybody was very welcoming to me, as a newcomer. This attitude was openly encouraged by the organisers and reinforced by details such as the lack of institutions or titles on the name badges.

At the reception to open the meeting, I met the well-known author and science writer Maryn McKenna and I mentioned that a session she was co-moderating was going to occur at the same time as my session on press releases with Nadia. I then mentioned that I hadn't met her co-moderator David Dobbs.
So, she ran off looking for him so she could introduce us. How welcoming is that? She was unable to find him, and I didn't get a chance to meet Dobbs later, but I appreciated her effort.

Readers may have seen an excellent interview that Matt Shipman did with Dobbs recently, where they discussed a number of topics about writing, including Dobb's reaction to feedback:

"CB [Shipman]: What sort of feedback have you gotten from the science community about your work? 

DD [Dobbs]: Mostly good, but I’m well aware that may be because most people like to be nice, or at least to avoid conflict, and so are more likely to say nice things than ugly things. I’m pleased, though, truly, when a scientist presses me a bit or lodges an objection or correction or difference of view or opinion. I know I’m not getting everything (anything?) as right as I’d like to, so appreciate all the critical feedback I can get. 

I’m writing about behavioral genetics right now, so count myself lucky that geneticists tend to be especially frank about their field. Alas, it’s a field that’s ludicrously complicated and in extreme turmoil, so that makes it almost impossible anyway. That’s why the book is taking a bit longer than I’d hoped."

This attitude is extremely refreshing. If people are openly receptive to feedback then they're much more likely to receive it, and then improve. For example, I feel sheepish about complaining when I see press stories that contain errors because I wonder whether writers - whom I mostly don't know very well - might be turned off by receiving criticism. We like writers to write about our stories with the Chandra X-ray Observatory, not avoid them because they don't want to hear complaints.

At ScienceOnline2013 I enjoyed meeting people who I'd interacted with on Twitter throughout the last year, including my talented co-moderator Nadia Drake, and others like Matthew Francis, Emily Willingham, Matt Shipman, and Ivan Oransky. All of these writers and scientists have different backgrounds and interests, but they share a devotion to receiving and responding to feedback. It's a lesson that many people at ScienceOnline, especially the organizers and Baba Brinkman, are great at passing onto others. I was excited and proud to be a small part of it.

A Slightly Curmudgeonly Take on the Press Release

[P.Edmonds comment: It's a pleasure to welcome Nadia Drake for a guest blog post. She provides episode two of our blog mini-series about improving science press releases, leading up to our ScienceOnline2013 session next week. Episode one, titled "Science Press Releases: Good, Bad or Zombies?" appeared last week. Over to Nadia...]

Q: Press Releases: What Do Journalists Want?

A: <fantasy> An exclusive, you-get-first-dibs press release that points toward a story that just can’t be ignored…about newly discovered robot laser sharks in space.

With video.

I realize I’m asking for a lot here. But in the absence of video (let’s be realistic, how many telescopes shoot such a thing?), I’d settle for a high-res artist’s conception of celestial Selachimorphs. And even though it might not be necessary, a little bit of background to put the discovery in context.

“Color me stupid, did you see that thing?!” asked the stunned graduate student whose dissertation just wrote itself.

On the off-chance that the laser-wielding astrosharks stayed a secret until formally described in a publication, I’d love a copy of the study. Or at least a link to a site where one is available. And some contact information for relevant astromarinebiologists, as well as the appropriate press contact.

Then, 

End.

#####

</fantasy>

The continuing search for robot laser sharks. Credit: Evil Cheese Scientist/Flickr

Really, journalists just want press releases that make our jobs easier. Sounds simple, but it’s not. We fill different roles at publications looking for different types of stories – it’s nearly impossible for press releases to be one-size-fits-all. Writing a release that will simultaneously work for a) a website that re-runs releases verbatim, b) a publication that hesitates to even re-run quotes, and c) the middle ground? Probably can’t be done efficiently.

As a result, I’m more than curious to peer behind the scenes as Peter describes how the press release process works (P.E.: episode three of our series, coming soon).

Until then, I can share what I like to see in a press release.

First, I always appreciate knowing right up top what the news is – preferably in the subject line of an email. If it’s about a paper, please tell me where and when a study appeared, and link to it.

[I realize this might be a me-thing, but I won’t write about a study unless I’ve had a chance to read it. Even if I’m just writing a brief.]

Instead of padding the text, consider using footnotes to provide additional background information, reference previous papers, or define terms (the European Southern Observatory does this really well).

Researcher contact info – preferably several – is key, though I’d be surprised if that detail is often omitted.

And… art. Never underestimate the selling power of a great visual. Scrambling around looking for photos or video makes me crabby – and sometimes, a sweet visual will earn at least a newsbrief treatment, if not more.

Things not to do?

Leave mistakes uncorrected. One of the questions Peter and I are considering is how best to correct errors after a release has gone out. It’s sometimes possible to find out which reporters relied on which press release by tracing the mistakes that appear in stories (SMH). I’ve very curious to find out during Karl Leif Bates and Charles Choi’s session how often errors creep into releases, and why …

Also, promoting a study or event that’s past its expiration date is disappointing (Great study, great pic – wait, it was published in August? Dang).

I’m undecided on a few points, but the one that nags at me the most is the issue of whether a release should suggest outside commenters. Reporter-on-a-deadline Nads says, “Yeah, good idea. Sweet!” Control freak reporter says, “No way. Make us actually do some reporting and I want to find my own people. Because stubborn.” (Though ultimately, even if an outside commenter is suggested, it’s still up to me to decide what to do with them.)

Things I don’t care as much about as other people do: Hyping (though, as Peter mentioned, there are some egregious and unacceptable instances of this: arsenic life, super-intelligent space dinosaurs...) I know this might score me some negative points, but journalists: Isn’t part of our job figuring out what’s newsworthy, and what’s over-hyped? There are checks and balances at work here. Send me enough crap and it’ll go straight to the can.

Lastly, you know what totally scores points? Finding out which areas I cover and sending relevant stuff before I ask. Thanks, press officers who are paying attention!

Here are some examples of the good and the bad. Agree? Disagree? Come talk about it during our session at Science Online!

Good: Even Brown Dwarfs May Grow Rocky Planets, from ESO. [News up top, art, just enough background, footnotes, great contact info, *link to paper*]

Asteroid’s Troughs Suggest Stunted Planet, from AGU. [This one has everything – links, news, images -- even a slightly dissenting outside comment!]

Most things by JPL’s DC Agle. For example, this release: NASA Says Comet Elenin Gone and Should be Forgotten. [Features interplanetary bogeymen and Monty Python. I always, always, always appreciate good writing!]

Dismal: Ancient Eurasian archaic humans featured a bi-level nasal floor as seen in Neandertals [Just, wow. WTF? No.]

Science Press Releases: Good, Bad or Zombies?

At the ScienceOnline2013 meeting, less than two weeks away, Nadia Drake and I will be moderating a session about science press releases: "Working towards better press releases: What do writers want?" Nadia is a science writer for wired.com, and I work in publicity for the Chandra X-ray Observatory, a NASA mission.

Press releases have been implicated in some infamous examples of science communication, where problems with the publicity have received as much attention as the science itself. Examples include arseniclife, a cunning kraken, and super-intelligent space dinosaurs. Our ScienceOnline2013 session will discuss how press releases should be improved, focusing on the needs and wishes of science writers. It's important for writers and scientists to debunk and dismantle the weak or shoddy claims made in some press releases, and I'm planning to attend a ScienceOnline2013 session about this, titled "“They said what?!”: Fighting bullshit in the scicomm ecosystem", led by Carl Zimmer and Brian Switek. However, our session offers writers a chance to suggest guidelines for improving source material before it goes public. These improvements won't prevent all cases of communication crap, but they should limit the flow.

A press release was behind these three infamous stories: arseniclife, the cunning Kraken and intelligent space dinosaurs. Credit: World News Network (upper left), Slate & Carl Zimmer (upper right), Nobu Tamura (lower left), Flickr user "anajonmary" (lower right) and prpretaporter.wordpress.com (background)

Different Views of Press Releases

For our outreach group at the Chandra X-ray Center, a press release is a useful way to tell science writers and the public about the most interesting science results and images that our observatory are involved with, using language that is easier to comprehend than what is used in journal papers. Over 400 papers involving Chandra data are published each year, and that's a lot for writers to wade through looking for interesting results, especially considering that many other observatories are also prolific.

Here's an SAT-like analogy, for US-educated audiences. One can say that the press release is to the science result, like an agent is to an actor. The aim is for the agent to help the actor - who is hopefully talented and interesting - get noticed. If the agent or the agent's work becomes the story, then something has likely gone wrong. Similarly, if the press release becomes an important part of the story, rather than the science result, then something bad has likely happened.

Based on my observations using Twitter, some people think nearly all press releases are terrible, but there's a big selection effect involved here. People hear about press releases when they're problematic and attract attention, but many solid results generate widespread attention and have solid press releases behind them. In that case the press releases don't get noticed by many people, but the science does.

For others, press releases are like zombies or zombies-in-the-making. I've spotted articles like "The Press Release Will be Dead in 36 Months" and "Die! Press release! Die! Die! Die!" These articles were from 2008 and 2006 respectively. Press releases are still around, so either these predictions and hopes were unfounded or zombie press releases are on the loose!

Are Press Releases Used?

Are press releases alive, but routinely ignored by writers? (By writers I mean good writers.) No, at least some are noticed, as explained in this excellent article by Liz Neeley who interviewed a group of accomplished science writers Alan Boyle, Bryn Nelson, Chris Joyce, Ed Yong, Erik Vance, Hillary Rosner, Mark Fischetti, and Susan Moran about press releases. (As an aside, Neeley, Boyle, Yong, Vance, and Rosner are all signed up for ScienceOnline2013.) One of the questions Neeley asked is: "Do you read press releases?" and the direct answers are "Yup", "I do", "I skim their headlines", "Absolutely", "Sometimes", "Yes, if they start with a headline", and "Yes, but not frequently". The "sometimes" answer comes from Hillary Rosner who says "I tend not to cover news", so that response comes with an asterisk.

Clearly press releases have some use for these writers, at least in providing tips about potential stories, and I know from experience that press releases lead to the majority of press coverage obtained for Chandra. Some of that involves churnalism and this is an important issue that I will mention briefly later in this post.

Improving Press Releases

There are two options for improving the science stories that are inspired or generated by press releases. Either the press releases should be improved or they should be phased out. I'll concentrate on the former option here. As stated earlier, an important goal of our ScienceOnline2013 session is to get advice from science writers on how to improve press releases. The writers interviewed by Liz Neeley give several suggestions, and I encourage you to read them.

Nadia and I have generated our own questions, including general ones: What are the minimum requirements for a good press release? How can we make press releases — which are generally one-size-fits-all — useful for news organizations with vastly different practices? Is there a way to make the process more efficient for both PIOs and reporters?

We also have a number of more detailed questions: Should attempts be made to explain the importance of a result, or is there too much potential for hype? How useful are quotes in press releases? How useful is it for PIOs to provide independent experts for comment and context? How much effort should be spent producing deeper context or background in case longer articles are being considered?

Serious suggestions have been made to phase out press releases, including the press release diet as proposed by Denise Graveline. In follow-up posts she gives more ammunition for this idea and gives options for alternatives to the press release. Graveline is not the only person thinking along these lines. Here is a list of 10 different alternatives to a press release.

There are other alternatives to the standard press release, including just posting a title, lede, and quotes, plus a link to the paper. We are interested to hear what people, especially writers, think about these possibilities.

Coming Up

In a future blog post I will give more details about how our Chandra outreach group searches for papers and how our press release packages are prepared. This future post will discuss our extensive review process, which is relevant to the ScienceOnline2013 session "Did anybody look at this !*%&#%@* press release?" led by Karl Leif Bates and Charles Choi, which I am also planning to attend. This session is a response to reports that scientists sometimes do not see the press release associated with their paper, and it may also discuss churnalism and the role of the public information officer. These are important issues.

As a further introduction to our session, co-moderator Nadia Drake is also planning a blog post to give her perspective on press releases, as a science writer, and I'm looking forward to seeing her thoughts.

We are encouraging feedback. How should press releases be improved? Should they be retained? What important questions or issues have we missed? We are interested in having a good discussion during our ScienceOnline2013 session, but we also welcome feedback and suggestions on this blog and on Twitter (use #betterpr). We recognize that attendance at this meeting is limited and there are also six other sessions being run in parallel with ours. These include some well-known names and discussions that I would have liked to attend myself!

Preliminary data suggests that the session "Spies, spacemen, seamstresses, and sailors: What science writers can learn from genre writing" is the most popular, with 27 people expressing an interest, at the time of writing. That's not surprising, given the talent and reputation of the moderators, Maryn McKenna and David Dobbs. All of the other sessions sound good, especially this one: "How to make sure you're being appropriately skeptical when covering scientific and medical studies" by Ivan Oransky and Tara Smith.

Below is the full list of sessions for February 1st at 10:30am. There are 9 other sessions with a similar format that are also packed full of interesting topics at this meeting, and there are other events scheduled too. I'm looking forward to these discussions and meeting a lot of different people. This will be my first ScienceOnline meeting, so I will finally get to see what I've been missing.

Session 5: Friday, February 1st, 10:30-11:30 am

Session	Title	Moderators	Room
Session 5A	Formal science education, informal science education and science writing	Marie-Claire Shanahan and Emily Finke	3
Session 5B	Spies, spacemen, seamstresses, and sailors: What science writers can learn from genre writing	Maryn McKenna and David Dobbs	4
Session 5C	Working towards better press releases: What do writers want?	Nadia Drake and Peter Edmonds	6
Session 5D	Thinking beyond text	Ben Lillie and Rose Eveleth	7a
Session 5E	How to make sure you're being appropriately skeptical when covering scientific and medical studies	Ivan Oransky and Tara Smith	7b
Session 5F	What’s news in citizen science? Perspectives, people, projects, and platforms (part I)	Darlene Cavalier and Caren Cooper	8
Session 5G	The world's largest explainer	Blake Stacey and Khadijah Britton	10