Transcripts of 10874_Suzaku_Sim_Press_Conf_H264_1280x720_30

[00:00:12.28] Lynn Chandler: Okay. Good morning
[00:00:16.37] and welcome to the NASA press conference on the latest scientific
[00:00:20.49] discoveries from the Suzaku mission. I am Lynn Chandler and I am the
[00:00:24.58] press officer for the Suzaku mission and today we have with us
[00:00:28.65] Dr. Kim Weaver, Astrophysicist
[00:00:32.76] and Dr. Koji Mukai,
[00:00:36.81] Suzaku Guest Observer Facility Lead.
[00:00:40.93] And at this time
[00:00:44.96] time I would like to turn it over to our scientists for their presentations.
[00:00:49.07] Dr. Kim Weaver: Thanks Lynn. We're discussing a new result from the Suzaku
[00:00:53.20] X-ray satellite. For the first time, individual
[00:00:57.29] clouds of gas have been caught in the act orbiting a giant black hole
[00:01:01.34] at the center of a galaxy, this galaxy is named NGC 1365.
[00:01:05.35] The movements and shapes of such clouds have long
[00:01:09.45] been a mystery to astronomers. Remarkably these clouds have
[00:01:13.52] a shape similar to the comets that we see in our solar system.
[00:01:17.55] These clouds can also tell us a great deal about the extreme environments near
[00:01:21.65] black holes. The science technique used to study these clouds
[00:01:25.97] is called occultation or the blocking of x-ray light by the
[00:01:30.04] clouds themselves. An occultation is when an apparently larger body
[00:01:34.07] passes in front of a apparently smaller one. This happens for example
[00:01:38.22] when we see the moon pass in front of a star as it orbits the
[00:01:42.32] Earth. With Suzaku we have an occultation of a black hole
[00:01:46.37] by orbiting clouds of gas. This is only the second
[00:01:50.39] time an occultation in x-rays has been tracked so closely as to
[00:01:54.48] capture movements so near to a black hole but it's the first time
[00:01:58.54] such unique dimming of x-ray light has been seen that contains enough
[00:02:02.57] information to actually determine the shapes of the clouds themselves that make up
[00:02:06.68] the x-ray curtain in a galaxy. Koji will now tell us about
[00:02:10.83] Suzaku and its importance for this science, Koji. Dr. Koji Mukai: Thanks Kim.
[00:02:14.88] Suzaku is an x-ray astronomy satellite built by a
[00:02:18.89] collaboration between Japan and the U.S. and launched in July of 2005.
[00:02:22.93] You may not have heard of Suzaku before.
[00:02:27.03] If you heard about one x-ray astronomy mission, it's likely to be Chandra,
[00:02:31.12] which is justifiably famous for the exquisite x-ray images
[00:02:35.17] that it can capture, but there are other x-ray astronomy satellites
[00:02:39.18] satellites in orbit today. So why do we need more than one x-ray
[00:02:43.27] astronomy satellite? This is because it takes a lot of resources
[00:02:47.38] to build one satellite that can do everything that
[00:02:51.43] an x-ray astronomer would ever want to do. It makes sense
[00:02:55.58] for each project to focus on different aspects of
[00:02:59.68] x-ray astronomy and build a satellite that can do that
[00:03:03.73] aspect very well. In the case of Chandra it was the
[00:03:07.76] fine imaging ability, in the case of Suzaku,
[00:03:11.86] the team decided to focus on spectroscopy.
[00:03:15.94] Spectroscopy is the study of intensity of electromagnetic
[00:03:19.97] radiation, visible light, x-rays and so on, as a function
[00:03:24.11] of its wavelength or the energies of individual x-ray photons.
[00:03:28.23] One particular way that Suzaku excels is
[00:03:32.30] that it covers a wide range of x-ray energies. Suzaku
[00:03:36.31] has one type of instrument that can detect x-rays
[00:03:40.39] of the same energies that Chandra can study, but
[00:03:44.45] Suzaku carries another instrument which studies higher energy x-rays.
[00:03:48.48] So it's like seeing all the colors of the rainbow
[00:03:52.57] with Suzaku instead of just seeing oranges and reds.
[00:03:56.64] It also happens that higher-energy x-rays
[00:04:00.67] --bluer photons, so to speak--penetrate deeper
[00:04:04.69] into gas clouds and lower energy x-rays
[00:04:08.74] tend to get more absorbed. You can say that
[00:04:12.79] Suzaku and the supermassive black hole to x-ray
[00:04:16.82] the gas cloud orbiting around the NGC 1365, much like
[00:04:20.93] doctors do with your bones, which is actually quite rare
[00:04:24.95] in x-ray astronomy. This needed the
[00:04:28.98] Suzaku's ability to study x-rays,
[00:04:31.93] wide range of x-ray energies.
[00:04:36.04] Another reason why Suzaku was essential for this study, was that,
[00:04:40.12] we tend to stare at one object for a long time to
[00:04:44.17] build up the x-ray spectra because you need to
[00:04:48.28] collect enough photons at each energy to have a good spectrum.
[00:04:52.39] With short observations we would have missed
[00:04:56.46] some of the important moments of this occultation event,
[00:05:00.48] so that was another reason why Suzaku was
[00:05:04.59] important. I hope I've made it clear why Suzaku was
[00:05:08.67] a great tool for this research. I will now turn it back to Kim
[00:05:12.71] who will explain the significance of this scientific discovery. Dr. Kim Weaver: Thanks Koji.
[00:05:16.72] The black hole we are talking about is about two million times the mass
[00:05:20.82] of our sun. As material comes close to the black hole it heats
[00:05:24.87] up to about millions of degrees and gives off x-rays.
[00:05:28.89] Obscuration of x-rays by dense gas is seen in many galaxies
[00:05:32.99] but actual occultation by clouds themselves are rarely caught.
[00:05:37.06] One reason is that a galaxy must be observed for a long time,
[00:05:41.10] uninterrupted. It can be very hard to schedule such a long block of
[00:05:45.22] time on our telescopes but it does happen. This particular observation
[00:05:49.31] was three and a half days long, quite long. The graphic
[00:05:53.36] currently being shown, shows the intensity of x-ray
[00:05:57.56] light with time that was measured from this galaxy, and you
[00:06:01.62] can see a lot of variability in the x-ray light. Suzaku
[00:06:05.67] saw two distinct eclipsing events marked by the green lines.
[00:06:09.70] As you can see for each eclipse there is a sudden dimming in x-rays
[00:06:13.79] due to the transit of a dense cloud covering about sixty five percent of the x-ray
[00:06:17.86] source. The specific variability of x-ray light
[00:06:21.94] in NGC 1365 was fairly easy to find due to the
[00:06:25.96] way in which the galaxy is actually tilted with respect to how we see it.
[00:06:30.14] The tilt, this pretty high tilt, gives us a high chance of seeing through many clouds.
[00:06:34.26] Other galaxies could be tilted differently so it could be very hard
[00:06:38.31] to catch views of their clouds. It's possible that the events like
[00:06:42.43] this are simply very rare for astronomers to witness.
[00:06:46.51] The next graphic shows side-by-side pictures of an artist concept of the
[00:06:50.58] comet-like cloud passing in front of the black hole. A fast
[00:06:54.61] fade out of light, like we saw in the light curve before, means that the dense
[00:06:58.70] cold cloud has to have a sharp leading edge as we see here.
[00:07:02.75] On the left hand side you can see the dense cloud blocking the black
[00:07:06.79] hole itself. Slower dimming of the x-ray light over longer
[00:07:10.88] time indicates less dense gas streaming out behind the dense
[00:07:14.95] cloud like the tail of a comet, and you can see on the right hand side of the graphic
[00:07:18.98] now the comet part of the cloud is passing in front of it.
[00:07:23.13] The cloud geometry can be roughly sketched out. Scientists can
[00:07:27.19] only reconstruct the shape of the tail projected on to the plane of the
[00:07:31.26] sky; they can't actually determine the shape of the cloud along
[00:07:35.29] our direction. The next graphic shows the comet
[00:07:39.40] cloud in relation to our solar system, in relation to the sun-Earth
[00:07:43.42] distance. The length of the cloud's tail covers a distance
[00:07:47.45] at about the same as that between the earth and the sun and as you can see here in this
[00:07:51.44] artist's concept. As these clouds orbit the black hole they
[00:07:55.50] constantly loose mass and the expected lifetime
[00:07:59.54] of an individual cloud is only two months. Where
[00:08:03.56] does the gas go that is lost? It's probably not accreted
[00:08:07.65] or eaten by the black hole. It either heats up to ten million degrees
[00:08:11.71] and becomes part of a hot haze of gas that the clouds have to pass
[00:08:15.73] through, or the gas loss is caused by radiation pressure for the black hole
[00:08:19.83] and the gas becomes part of an out-flowing wind. About a
[00:08:23.90] tenth of a solar mass per year, which is many clouds' worth, could be lost
[00:08:27.94] this way. What are the clouds? This is unclear.
[00:08:32.05] Atmospheres of stars can produce mass loss that resembles tails
[00:08:36.14] but there are not nearly enough stars here to account for the number of clouds that are
[00:08:40.19] seen. The dense clouds are probably moving supersonically
[00:08:44.21] through a less dense haze. This would set up a system of shocks, like
[00:08:48.30] bow shocks. As the dense clouds plow through the regions of hot gas,
[00:08:52.36] the clouds erode, and the erosion creates the tails.
[00:08:56.40] Is a comet shape common for such clouds? Well that's not known.
[00:09:00.52] We need more observations of occulting events like this to understand these
[00:09:04.60] and other questions. Lynn Chandler: Thank you Kim and Koji.
[00:09:08.69] And that concludes our presentation portion of the press briefing today,
[00:09:12.75] and at this time we're going to take questions. We do have some callers
[00:09:16.77] on the phone and I ask that you specify which scientist you would like to
[00:09:20.87] answer your question. And our first caller is from Jeffrey
[00:09:24.94] a student in California. Jeffrey: This is for doctor Mukai.
[00:09:28.97] What information does the Suzaku mission seek to discover? And what are the most
[00:09:33.08] important purposes of this probe? Dr. Koji Mukai: Well one
[00:09:37.17] answer to this question is that Suzaku is a facility for the entire
[00:09:41.21] astronomical community. So the community decide what questions to
[00:09:45.32] to tackle and what objects to observe and so on. But
[00:09:49.42] we did have some overarching goals for the mission, when we built the
[00:09:53.48] mission. One is we'd like to study how
[00:09:57.51] various chemical elements are formed in the universe, and how they're dispersed.
[00:10:01.61] Another focus area is the study of matter and the
[00:10:05.68] extreme conditions such as these clouds right near a black hole.
[00:10:09.72] Lynn Chandler: Okay. And our second caller, Lauren
[00:10:13.74] is a student from Texas. Lauren: This is for Dr. Weaver. How large
[00:10:17.83] is a supersize black hole? What would a normal size black hole be like?
[00:10:21.86] Dr. Kim Weaver: A normal black hole we be the most common type that we see
[00:10:25.97] which are stellar mass black holes. A black hole that has the
[00:10:30.05] mass of about the mass of our sun would be about three miles across, so
[00:10:34.10] it would be very small, very tiny. A supersize
[00:10:38.12] black hole can be much, much larger and range from with sizes
[00:10:42.21] anywhere from a tenth of a distance between the earth and the sun to as
[00:10:46.27] large as our entire solar system put together.
[00:10:49.95] Lynn Chandler: Okay. And our next question comes from Bailey in Michigan.
[00:10:54.02] Bailey: This is for Dr. Weaver. Approximately how big is the black holes
[00:10:58.07] diameter, and are there black holes bigger than this one?
[00:11:02.09] Dr. Kim Weaver: Yes. There are black holes bigger than this one. There are many
[00:11:06.18] in fact, you can a have black holes with masses that are up to a billion
[00:11:10.23] times the mass of the sun, so one hundred times more
[00:11:14.25] massive than this black hole. And a black hole like that would be about
[00:11:18.34] one hundred times larger, and again that would be roughly the size of our
[00:11:22.40] solar system. Lynn Chandler: Okay. And our next question comes
[00:11:26.36] from Brittney in New York. Brittney: For Dr. Mukai.
[00:11:30.41] Why is Suzaku called the red bird of the south?
[00:11:33.36] Dr. Koji Mukai: That's a very interesting question. The first x-ray
[00:11:37.47] astronomy satellite launched by our Japanese colleagues was called Hakucho,
[00:11:41.53] which is the Japanese name for the constellation Cygnus or swan.
[00:11:45.57] So that started the tradition of naming the x-ray astronomy satellites
[00:11:49.68] after flying creatures. The fourth one was called ASCA,
[00:11:53.76] which was an acronym but also meant a flying bird
[00:11:57.81] and it also was the name of an ancient
[00:12:01.82] Japanese era. So for
[00:12:05.92] their fifth x-ray astronomy satellite they picked Suzaku, which
[00:12:09.99] not only means "the red bird of the south", but it's also a name
[00:12:14.02] of another era in Japanese history. Lynn Chandler: Okay. And our next
[00:12:18.13] question come from Madeline, a student from Louisiana.
[00:12:22.21] Madeline: This is for Dr. Weaver. In what ways are clouds detected around the black
[00:12:26.26] hole comparable to those observed in our own solar system?
[00:12:30.28] Dr. Kim Weaver: Well clouds in our solar system are like the clouds that we see in our--
[00:12:34.38] Earth's--atmosphere. So the way in which their similar; when you look up
[00:12:38.44] in the sky and it's a cloudy day, the clouds are blocking the sun's light
[00:12:42.47] from us to see, these clouds are similar in that they are blocking
[00:12:46.57] the x-ray light in the galaxy. Lynn Chandler: And our last question today
[00:12:50.69] comes from Andrew in Virginia. Andrew: This one is for Dr. Weaver.
[00:12:54.77] What's the importance of this finding for astronomy?
[00:12:58.82] Dr. Kim Weaver: Well Koji mentioned one importance and that's understanding the extreme environments
[00:13:02.87] around black holes, but another thing that's really interesting about this is that
[00:13:06.88] black holes generally are thought of as gobbling up material that comes
[00:13:10.96] near them, and eating stuff that flies by,
[00:13:15.03] never to be seen again. But in this case we're actually understanding material
[00:13:19.06] that's going to be going away from the black hole, being pushed away from the
[00:13:23.17] black hole in an out-flowing wind. So we're using this
[00:13:27.24] experiment to understand things that move away
[00:13:31.28] from the black hole and thus are a part of the entire system of
[00:13:35.39] the black hole galaxy environment.
[00:13:39.41] Lynn Chandler: Okay. Thank you for joining us today and this concludes
[00:13:43.50] our NASA press briefing on the Suzaku mission.