Dispatches From NAM

As I'm in Munich on a collaborative visit at the moment I haven't made it to the National Astronomy Meeting this year. As well as meaning Durham were unable to retain the 5-a-side football trophy (as if I would have changed that) it means I have missed out on actually being in the room when some really interesting talks are given. Fortunately some people are live blogging the event here, its a good way to keep up with the goings on and to find pretty pictures like this one to steal:



Most of this picture has been around for a few years. It shows data from the SDSS which essentially shows the density of stars across a particular patch of sky, what is interesting is the number of coherent streams of stars visible. Many of these streams have been traced and found to be associated with dwarf satellites or globular clusters of our galaxy which are currently being torn apart by the gravity of the Milky Way. Whats new about this picture is that a team of astronmers (not sure who exactly, though the talk describing the result was given by Dan Zucker of the Institute of Astronomy) have used the original map to discover several new Milky Way satellite galaxies.

This is interesting in particular because its been known for a considerable amount of time that models of galaxy formation predict that a galaxy the size of the Milky Way should have many more dwarf galaxies than are actually observed. The discovery of more dwarf galaxies is helping to fix this discrepancy, the observation that many dwarfs are currently being destroyed by the MW also tends to lend support to the idea that originally there were many more, they have mostly been stripped and subsumed into the halo of the Galaxy. An additional bonus of the work presented at NAM is the observation that the motions of stars in the dwarf galaxies is much too fast to be explained without the dwarf galaxies being heavily dominated by dark matter, another prediction of current generations of galaxy formation models.

Score one complete (predicting the excess DM) and one partial victory (getting closer to the right number of satellites) for current theory then, there is however a final twist in the tale.
The shapes of the dwarf galaxies is apparently irregular, something that doesn't make that much sense if they are embedded in a larger dark matter halo, this should act to damp out external pertubations (say due to the Milky Ways gravity) and to keep the stars in a more regular shape. Whack one mole, another pops up, such is a scientists lot.

Friday Galaxy - 2 - NGC 720

This is a real hot off the press Friday Galaxy, the data for this was only taken last night, in Chile, by those very helpful people at the Gemini-South telescope. I'm using the 12 images they took (4 each of g',r' and i', that's blue, green and red to you and me) to pick out Globular Clusters for spectroscopic follow up.

The image below shows the image produced, there are a couple of odd things about this image. The first is that the galaxy itself is very blue, for an elliptical galaxy this is odd, these are usually known as being red and dead, because they don't form stars. At first I thought I had mixed up the blue and red channels, however in the top left corner you can see a very pretty background edge on spiral and this appears to be just the right colour for a spiral, hmm.

If we assume that the colours are correct and that we are seeing a blue elliptical galaxy, then their are two possibilities: Either some fraction of the galaxy is made up of hot young blue stars, which can't have been formed more than a few Gyrs ago (not that common for ellipticals), or else the galaxy must be very old and lacking in metals. This is one of the major drawbacks of using the colours of astronomical objects like galaxies to tell you about them, there is a degeneracy between the age of stellar populations and the amount of elements heavier than Helium that they contain (their metallicity). Basically things can appear blue for one of two reasons, they are either young, or they have a low metallicity (and are old).



To solve this conundrum will require spectroscopy, which hopefully we will be getting in the next few months. One other interesting thing that appears in this image can be seen in the top left, when you look at the spiral galaxy (shown enlarged below) you can just about make out what appears to be a stream of material trailing to the bottom right. This trail, if real, could be a trail of stars produced by a minor merger event, if I get the chance and have the space when I make up the mask for the spectroscopy I may well try and get a sly spectrum of this just to see whats going on.


That just shows you one of the cool things about astronomy, serendipity means you can find all sorts of interesting things in the unlikliest of places. There are loads of interesting things in the background of deep images like this one, if anyone finds anything interesting in the large version of the image, let me know, you never know I may try and get a spectrum of anything you find that looks interesting enough.

Friday Galaxy - 1 - NGC 524

I've decided to institute a new tradition of posting images of a favourite galaxy on a friday. For the first example I have decided to choose NGC 524, this galaxy is an S0 galaxy that I am working on at the moment.

The images I'm going to show are from archival HST images taken using WFPC2 (PI Brodie project 6554), I have produced a colour image of the galaxy, though I have cheated somewhat, as I only had access to two filters the F555W and the F814W, which I am going to treat as blue and red respectively, I'm then going to use an average of the two as the green channel. The downside is you're pretty much guaranteed to get something that looks red or blue, still this is interesting in itself, as blue galaxies tend to be young and red ones old. So here is the image.



You can see the centre of the galaxy is located towards the top left of the image, the diffuse glow around this is the halo of NGC 524, many foreground stars and background galaxies are also obvious. In this image the galaxy looks fairly boring, a very smooth looking ellipical galaxy, however I had seen some hints of something odd going on in the inner regions in some data I had from the Gemini telescopes and decided to investigate it. What I did was to average the images from the blue and red exposures, as this tends to pick out structures and dust in galaxies, this is because dust tends to absorb different amounts of the two wavebands. What I found was this:


First of all you can see that many objects disappear, this is just because they have similar amounts of flux in the blue and red, the centre of the galaxy however doesn't. You can see that some very pretty spiral structure emerges, so you can see that on closer inspection NGC 524 is being observed face-on, the Milky Way would probably look very similar if you stopped forming stars and then looked at it from above the disc after a few Billion years.

The Dark Sector Revisited

Over at threesigmaresult.com I have started a revised and expanded version of my dark sector series of posts first seen here.

Galaxies, Lenses, Globulars, What More Do You Want?

Welcome to my first post for threesigmaresult! I've chosen to redo a post that previously appeared on my other blog, theobservershunch, I've done this because it was one of my favourites, partly because it has a very pretty pictures but mostly because it describes some research done by some of my colleagues. Enjoy.

Click for VERY Big.

The picture above which was released by the Hubble Heritage Project shows a cluster of galaxies called Abell S0740, the data used to make the picture was collected by a team of astronomers including two of my collaborators/friends at Durham, John Lucey and Russell Smith. There are two versions of the image, one without annotations and one showing zoomed regions of interest. See them both here.

Milky Way Behaving Badly

Head over to Space.comfor a story about the dark side of our well behaved galaxy's nature, its being throwing its weight around and generally being a bad neighbour. The story is all about the streams of stars that are being found trailing around the Milky Way, these trails are thought to be the shredded remains of dwarf galaxies or globular clusters that wandered too close to the MW. Below you can see some of the streams uncovered by the Sloan Digital Sky Survey. The streams are detected by looking at the colours and positions of a huge number of stars over as large an area as possible, doing this it is possible to pick out groups of stars with the same sort of colour, implying that they probably formed at the same time from the same material.


Some of the streams have been associated with known GCs or dwarf galaxies, basically these objects lie right in the middle of the stream, in the pictorial representation at the top you can see the original dwarf with its tails of stars which spread out both in front and behind it in its orbit of the MW. Over time the streams will stretch further and further, getting progressively thinner and more tangled, until they form a diffuse halo of stars around the MW.

This kind of research is interesting because the current theories for the formation of galaxies predict that there should be many more dwarf galaxies around the MW than we see at present, one solution is that many of them have simply been torn apart by the MW and their stars spread into the halo of the galaxy. If enough of these streams are found this could help solve this so called "missing satellite problem".

Astronomy In The News

The washingtonpost.com has a nice little article about the state of astronomy at the moment. Its fairly timely to me as I have just kicked off a few posts about the history and future of astronomy. Its well written and also happily pretty accurate, you can find it here (free registration may be required).

It briefly covers some of the larger discoveries of the last month or so, new exo-planets, the largest supernovae ever seen and the behaviour of Eta Carinae to name but a few. It also gives some interesting insights to the average reader about the replacement for the HST, the James Webb Space Telescope and also happily explains that astronomy is not just about the visible part of the spectrum.

The star Eta Carinae, a large mass star in the Milky Way which could go supernovae at any time.

The author of the piece, Joel Achenbach makes the point that we are in a golden age of astronomy, which it certainly seems to the average non professional astronomer, what with the almost constant announcements of amazing new discoveries. In my series of posts I will argue that we haven't quite reached the golden age, or at least we haven't reached the peak yet, the era of the 30-50m class telescopes and a working JWST would certainly open up whole new areas of research. All of which means that we can look forward to at least as many major discoveries in the next 30 years as we have had in the previous.

Maps Of The Universe

I've just come across a nice little site that gives an impression of the scales involved in astronomy. Its starts by showing the position of all the stars located within 12.5 light years of the Milky Way.

Progressive images increase the scale by a factor of roughly ten, until you reach the final one which shows the large scale structure of essentially the entire observable Universe. My personal favourite is the penultimate image which shows the structure located within about 1Glyr of the MW, the large superclusters of galaxies are readily apparent as are the filaments that stretch between the clusters.

There are also several nice pages which describe the Big Bang theory and General Relativity. Go check it out.

The History Of Astronomy - Part 1

Science nowadays is all about the big, the biggest this, the largest that, all discovered using some humongous new instrument. Astronomy is and always has been a leader in this respect, many of the largest scientific instruments ever built have been telescopes of one sort or another, from the stone circles like Stonehenge, which probably acted as primitive astronomical observatories, through the Uraniborg, built by Tycho Brahe the last of the great naked eye astronomers, to the first truly huge telescope the 72" leviathan of Parsonstown and on up to the modern age of optical telescopes of around 10m in diameter (Keck, Gemini, the VLT etc). Of course for large astronomical equipment you only have to look at the enormous radio telescopes available today, such as the VLA or Arecibo.

The primary mirror of the Gemini North telescope, and yes that is a person in the middle.

The question is what next? The consensus in the US and Europe seems to be to continue a triple pronged approach of larger space based instruments across a wide range of the electromagnetic spectrum (especially those regions blocked by the atmosphere), even larger ground based optical telescopes and vastly larger arrays of radio telescopes. The question tax payers are interested in is unsurprisingly, why? These things cost a lot of money, why do we really need them?

A possible next step in optical astronomy: the European Extremely large telescope, with diameter 42m. Car and two people for scale to the bottom left.

Well lets just ignore the philosophical reasoning of whether most of us are interested in exploring the origins of the Universe, and finding our place within it, we'll assume that everyone is sufficiently interested to want to do astronomy. Why do we need to build such large telescopes? This question was raised to me by a student at a school I was giving a talk at and it got me thinking and I think provides a nice way of explaining how the science of astronomy has developed hand in hand with the advances in technology, in fact often driving many of them. In this short series of posts I hope to explain the development of optical astronomy (the bit I'm familiar with), though I should point out that this is not meant to be an exhaustive description I hope it will cover the basics as I see them.

The Scale Of Things

Wow, check out this composite picture of the moon partially occulting Saturn. Even as an Astronomer my mental image just didn't have Saturn appearing that big relative to the moon, click for the big version.

Here is the description from LPOD:

In England on March 2nd, 2007 the Moon slowly moved past Saturn. From Pete’s observing site in Selsey the Moon just barely nicked the planet itself but pleasingly covered about 40% of the rings. Here are Pete’s words on how he captured this event: The difference in brightness of the Moon compared to Saturn was huge at the time and in order to get both objects imaged simultaneously, one must suffer. In this case I exposed correctly for Saturn which meant that the Moon’s limb was burnt out. A number of shots were taken at 30s intervals (10s movie captures at 60fps, fixed on Saturn) which gave me the positional information I needed to build the composite you see here. The RGB image of Saturn was captured just before the occultation and the lunar limb just after (this is a three frame mosaic). The interval positions shown are separated by 90s in time. South is up in the image and the Moon would be moving towards the upper right.

Friday Lunchtime Talks - MOdified Gravity

On Friday we had the latest of the Durham Astronomy groups Friday Lunchtime Talks, these usually consist of two members of the group (which consists of over 50 members including students) giving a half hour talk, either about their own work or a paper that has appeared recently in which they have some interest. Last Fridays was something different however, it was an hour long talk by Professor Emeritus John Moffat of the Perimeter Institute on the subject of his own version of modified gravity, MOG.

I always have a lot of respect to someone that comes to Durham to talk about modified gravity, it really can be like entering the Lions den. Tinkering with gravity is usually done in an attempt to explain astrophysical phenomena without the need to demand that most of the mass in the Universe is invisible and can only be detected through its gravitational influence (the so called Dark Matter). Durham is world renowned as a centre of research into Dark Matter, as such some members of the group could be expected to be particularly partisan on the issue. I think its a great credit to the people involved that things never seem to get too heated, in fact in this Fridays talk, most of the difficult questions were directed from the one Professor in the group who has never been too happy with the current Cosmological Paradigm. He's generally good value for entertainment, and important in keeping everything honest.

Anyway, onto the talk itself. John Moffat has been working on modifying the gravitational laws for many years and has produced several different models. These models differ from most of the work on MOND (MOdified Netwonian Dynamics) in that from the beginning they were specifically chosen to be relativistic, that is that they are modifications to Einsteins General Relativity and not Newtons law of gravity. Essentially in MOdified Gravity (or if you prefer, MOffat Gravity, MOG) the gravitational constant G (also called Newtons Constant) is not in fact a constant, but can vary both in time and in space, so that the G that relates the force between two masses separated by one distance R1 is not the same G that relates the force between the same masses if they are separated by distance R2, similarly for time T1 and T2. These changes in G have to be negligible for objects within the solar system otherwise we should be able to detect deviations from the GR predictions which so far have not been observed, but they can become significant over galactic scales.

The speaker showed several examples of where his proposed changes would allow us to fit astronomical observations without the need to invoke Dark Matter. In particular he mentioned fitting the rotation curves of dwarf galaxies, spiral galaxies and clusters of galaxies (for clusters its technically not a rotation curve but the principle is the same). This in particular interested me as rotation curves are something I have personal experience with, both in my MSci project and the first paper I have published. Below is an example of a spiral galaxy rotation curve, it simply measures the speed at which stars at different radii in the disk orbit the galaxy, the data is the black circles (with error bars) the various dashed lines show the amount of velocity provided by the mass of various components of the galaxy including a DM halo. MOG allows you to explain the observed rotation of the galaxy without this DM component, by assuming the influence of the other two components is stronger than you would naively expect using Newtonian (or GR) gravity.

For me the first and largest problem that appeared during the talk appeared when JM was talking about these fits to the rotation curves. It seems it is possible using his model to fit all spiral galaxies using the same values for two parameters, as far as I could tell these parameters deal with the scale over which G begins to diverge from a constant value and some sort of normalisation of the size of the divergence. The problem was that when he fit the rotation curves of dwarf galaxies, or of clusters of galaxies the values of these two free parameters were different, all dwarfs had the same values, all clusters had the same values but different from the dwarfs or the spirals. This would appear to mean that there has to be yet another effect going on, meaning we need more free parameters to explain everything in terms of one unified gravitational theory. If this is true it would seem to be a problem. I have to go and look at the actual papers and see if in fact this is the case, or if I simply misunderstood something, it could be that the values he was quoting were actually telling you something about the scales involved, i.e that dwarf galaxies are smaller than spirals which are smaller than clusters.

The second major part of the talk dealt with JM's attempts to explain the results from the Bullet Cluster without the need for Dark Matter. This cluster is so far unique and very exiting. Its unique because it is actually two clusters, one of which has passed through the other, during this interaction the hot gas that resides in the clusters hit each other and slowed down, the gas from the smaller cluster having shocked and formed a bullet like shape as seen as the red triangle on the right of the image below. In the image below you can see the hot intracluster gas as the red regions. This is interesting because the hot intracluster gas has been separated from the galaxies of the clusters (seen in the blue regions), normally there is around 10x as much mass in this hot gas as there is in the galaxies of a cluster. By crashing through each other the two clusters have managed to separate the collisional material (the gas) from the collision less material (the galaxies and any Dark Matter).


It is possible to use gravitational lensing of background galaxies by the clusters of galaxies to work out the mass that must be contained within the galaxy clusters. This cluster is so important because it can be convincingly shown that even though the vast majority of the visible mass (the intracluster gas) has been removed the effect of gravity is still very strong, considerably stronger than can possibly be explained by the visible mass contained in the galaxies in the cluster. The traditional explanation is therefore that there must be some invisible mass (DM), which from this cluster we can see must be collision less, otherwise it would have piled up where the intracluster gas is. In MOG the explanation for the extra lensing, above what is predicted by GR for just the normal mass is that the gravity from the galaxies is stronger at larger distances, and also I believe that there is some lensing caused by the gravity from the intracluster gas.

If this is the case then there is happily a way to test which approach is correct, MOG or DM, the intracluster gas is much more massive than the mass contained in the luminous matter of the galaxies, but it is also located on one side of the cluster. Therefore it would seem that if MOG is correct there should be an increase in lensing on the side of the cluster nearest to the gas, of course the size of the effect would depend on many factors, but may in principle be measurable. If MOG is incorrect and DM is really at work, then the lensing should be more symmetric around the cluster, both because the DM is by far the largest mass contribution but also because the gravity of the gas is much less at larger distances than predicted by MOG.

Whatever the result of work such as this, we are really going to learn something fundamental about the Universe. Either most of the mass of the Universe is in some really exotic form, or else the force of gravity is even stranger than we have ever dreamt.

Unfortunately time caught up with us and we didn't get to find out much on the implications of this modified gravity on Cosmology, for example whether it could explain the mysterious Dark Energy at the same time that does away with Dark Matter. Many other interesting questions were raised however, it appears that MOG doesn't allow for singularities, so no black holes, though objects observationally indistinguishable from them probably can exist. This led one prominent member of the group to spend the time to see if the Metric for MOG is compatible with these condensed objects having a "last stable orbit", apparently it doesn't seem like it can, and as these are thought to be observed around BHs this is probably a problem for the theory.

All in all a very interesting talk, a perfect example of the kind of research that is ongoing in Astronomy. I don't think anyone is going to be packing in the DM work anytime soon, but if the DM particles continue to remain so illusive, its good to see that there are concrete alternatives being formulated.

South Pole Telescope

High time for some real science I think, the South Pole Telescope has just seen first light.

This telescope, located as the name suggests at the south pole is designed to look for small changes in the Cosmic Microwave Background (CMB) caused by the influence of clusters of galaxies. The south pole was chosen to site the telescope because the cold, dry (little moisture in the air) conditions are perfect for astronomy at the sub-millimeter wavelengths being used by this telescope.

The telescope will make use of an effect known as the Sunyaev-Zel'dovich effect to search for large clusters of galaxies. The SZ effect occurs when photons from the CMB interact with energetic electrons found in clusters of galaxies, some of the CMB photons are boosted in energy by the electrons through the Compton effect. By accurately measuring the CMB you can see regions where the CMB appears to be slightly hotter than it should be, these regions generally correlate with the position of clusters of galaxies. It should be noted that the CMB (see pic below) naturally has fluctuations in its temperature, these were the "seeds" that led to the formation of structure in the Universe after the Big Bang, so to determine which fluctuations in temperature are due to SZ and which are due to inherent fluctuations is actually slightly tricky. There are also other effects that need to be taken into account but you get the picture, its pretty hard.


By mapping the distribution of clusters it is possible to learn something about the elusive Dark Energy, particularly it may be possible to determine between the two competing explanations of Dark Energy, the Cosmological Constant and Quintessence.

Best Paying Jobs!

CNN has an interesting article on the best paying professions in the US, well its interesting if you're in my line of work, here is the rundown:

1. Surgeons: $177,690
2. Anesthesiologist: $174,240
3. Obstetricians and Gynecologists: $171,810
4. Orthodontists: $163,410
5. Oral and Maxillofacial Surgeons: $160,660
6. Internists, General: $156,550
7. Psychiatrists: $146,150
8. Prosthodontists: $146,080
9. Family and General Practitioners: $140,370
10. Chief Executives: $139,810
11. Pediatricians, General: $139,230
12. Airline Pilots, Copilots, and Flight Engineers: $135,040
13. Dentists, General: $133,680
14. Podiatrists: $111,250
15. Lawyers: $110,520
16. Air Traffic Controllers: $105,820
17. Engineering Managers: $105,470
18. Computer and Information Systems Managers: $102,360
19. Marketing Managers: $101,990
20. Astronomers: $101,360
21 Natural Sciences Managers: $99,140
22. Sales Managers: $98,510
23. Petroleum Engineers: $97,350
24. Financial Managers: $96,620
25. Law Teachers, Postsecondary: $95,570
26. Optometrists: $95,500
27. General and Operations Managers: $95,470
28. Computer and Information Scientists, Research: $94,030
29. Judges, Magistrate Judges, and Magistrates: $91,500
30. Physicists: $91,480
31. Actuaries: $90,760
32. Nuclear Engineers: $90,690
33. Industrial-Organizational Psychologists: $89,980
34. Human Resources Managers: $89,950
35. Pharmacist: $88,650
36. Securities, Commodities, and Financial Services Sales Agents: $87,990
37. Health Diagnosing and Treating Practitioners: $87,630
38. Computer Hardware Engineers: $87,170
39. Public Relations Managers: $85,820
40. Aerospace Engineers: $85,450
41. Political Scientists: $84,820
42. Physical Scientists: $84,380
43. Computer Software Engineers, Systems Software: $84,310
44. Personal Financial Advisors: $82,970
45. Health Specialties Teachers, Postsecondary: $82,450
46. Chiropractors: $82,060
47. Industrial Production Managers: $81,960
48. Construction Managers: $81,760
49. Purchasing Managers: $81,440
50. Advertising and Promotions Managers: $81,250

All I can say is yes! Boo to all the snooty "proper" physicists, you can keep your hard work and real science, I'm buying a Ferrari. No doubt things are not as rosy this side of the pond, however I am prepared to travel.

Cranks Emails - 3 - Or William C. Mitchell Knows Nothing About Cosmology/Astronomy

Yesterday I asked for some more examples of crank emails, this morning I found about 15 in my inbox, a big shout out to CMB for sending his collection. In particular one stood out, it is an author attempting to hawk his Anti Big Bang book called - Bye Bye Big Bang - Hello Reality, or as I would have called it Bye Bye Scholarly Study - Hello Page After Page Of Embarrasingly Poor Arguments. NOTE: I haven't changed anything except to tidy up the lines a bit, all those strange symbols were in the original email. Oh and I removed the links to the book at Amazon because they don't fit on the page, the spelling mistakes are all the original authors. If this is a Google search then welcome, let's just have a quick look at how little William C. Mitchell knows about Cosmology, and research, and writing legibly.

Subject: COSMOLOGY

If you aren't interested in cosmology, please don't read any further. I
don't want to annoy anyone.

BIG BANG FRAUD © 2004 William C. Mitchell
The following is a review of some of the many items that are part of an
elaborate fraud that is perpetrated by the Big Bang cosmology establishment.

Some Necessary Background Information.
The solutions to Einstein's Special Relativity equations, as solved by Alexander Friedmann, provided for three possible cosmological ”cases” on which Big Bang Theory (BBT) is based. Those cases are: a “closed“ universe having positively curved space that would eventually collapse; a “flat” universe having uncurved Euclidean space that would expand forever; or an “open” universe having negatively curved space that also would expand forever, but at a slowly increasing rate. (Before Friedmann's work, I don’t believe that Einstein had ever given any consideration to negatively curved space.)

The Velocity of Matter in Space.
The velocity of matter departing from us in space, that is calculated by an equation [V/c = (Z+1)2 -1)/(Z+1)2 +1)], that is derived from the Einstein-Lorentz transformations, results in a rate of expansion that reaches c for large redshifts. However, that is incompatible with the Friedmann closed, flat or open universe cases mentioned above; and it is also incompatible with a universe of relatively slowly increasing expansion that has recently gained considerable acceptance. Regardless of those incompatibilities, that equation continues to be used to determine the velocity of matter in space as a function of redshift.

Lets look at this claim, that cosmologists use the above equation to "determine the velocity of matter in space as a function of redshift", this is of course rubbish, we don't need to know the velocities of objects, we can measure it using spectroscopy. We use the measured velocities to determine the physical distance to the object, using Hubble's Law.

The second claim appears to be claiming that it is impossible for objects to appear to recede at greater than the speed of light, this is down to Mitchell's utter lack of understanding of the expansion of the Universe. It is entirely possible for space to appear to expand faster than the speed of light, individual regions of space expand at a fixed rate, so that if you look over a long enough distance the individual expansions add up to produce an expansion that is faster than light. There is absolutely no problem with reconciling faster than light expansion of space with General Relativity.

The third claim is either a misstatement or a flat out lie, he is essentially claiming that when working out distances to objects in the distant Universe cosmologists neglect the effect of the extra expansion due to Dark Energy. This very easily disproven, many people use Ned Wrights handy Cosmology calculator to convert between things like redshift, physical distance, comoving distance etc, this program can be found here. Try it out, you input the value of the Hubble Constant, the fraction of the energy of the Universe that is in matter (both luminous and dark), the redshift to the object you want to know the distance to, and, drum roll, the fraction of the energy of the Universe that is due to Dark Energy. Try changing the value of the DE while leaving everything else the same, what happens? that's right all of the calculated numbers change. So there you have it cosmologists do include the effect of Dark Energy.

Some More Background Information.
Hubble time, which is the time that the BB would have occurred if the universe had a fixed rate of expansion at the Hubble rate (the Hubble constant) ever since the BB. The consensus of working astronomers seems to be that rate should be about 65 km/sec/MPc, but, because it appears to make the BB universe older, BBers prefer a value of about 50 km/sec/MPc (equal to about 15 km/sec/MLYs) putting the Hubble Time at about 20 billion years,

This book is now quite out of date so I will forgive most of this, even though it is all wrong now, the currently accepted value of the Hubble Constant is around 72 km/s /Mpc, on its own this would infer an age of the Universe that was too short, when compared to the ages of stars. Clearly you can't have stars older than the Universe. However when you include the effects of Dark Energy and Dark Matter, and do the full calculation you get and age of the Universe that is between 13 and 14 Billion Years (Gyr), more than old enough to accommodate even the oldest objects in the Universe.

The Age of the Universe.
The age of the BB universe is based on the “flat” universe case that became important as a result of Inflation Theory. According to that theory, the age of that flat universe is equal to 2/3 of the Hubble time, or about 13.3 billion years. Lately, that approximate age is most often presented as the true BB universe age.
A very much “open” universe of accelerating expansion, has recently become the favored new theory of many BBer. However, the age of the universe that is presented in the media is still based on the flat universe case of inflation theory; that is, at 2/3 of the 20 billion year Hubble time.

As my two previous points have explained this is simply wrong, use the cosmology calculator you will see that changing the value of any of the parameters, including the Dark Energy gives a different age for the Universe, (its the part that says: "It is now XXX Gyr since the Big Bang.").

The Size of the Universe.
Using the above erroneously derived age of the universe, and based on no factual data, BBers have also erroneously assumed that the expansion of the outer edge of the universe has expanded at the speed of light. That allows them to determine its radius, in billions of light years, to be equal to its age in billions of years, or about 13.3 BLYs.
(A plot of the Friedmann's solutions to Einstein’s SR equations would show that, although the rate of expansion of a fixed rate universe would ever be at c, the initial rate of expansion of a flat rate BB universe would be higher, perhaps at about 2c; and the initial rate of expansion of a closed BB universe would be even higher, perhaps at about 3c or more; and the initial rate of expansion of the newly popular BB universe of accelerating expansion might be as low as 1/2c, or even lower.)

This whole statement is garbage, even the wikipedia article gets the facts right on this. The fact that space/time is curved and that the Universe is expanding means that the radius of the observable Universe is not simply just the speed of light divided by the age of the Universe. The actual observable Universe calculated using all of the parameters in the cosmology calculator is about 46 Billion Light years in radius, you can see this in the cosmology calculator if you put a very high redshift, say 2000, this corresponds to a time only 65 thousand years after the Big Bang, now look at the Comoving radial distance, this is how far light can have travelled from 65 thousand years after the Big Bang till now. Again Mitchell reveals he understands nothing about Cosmology, certainly not anything to do with the implications of an expanding Universe in General Relativity.

The Distance to Matter in Space.
Based on that erroneously derived present size of the universe, BBers have concluded that the distance to remote matter in space is proportional to its erroneously derived departing velocity.
Although many BBers still believe that, in accordance with inflation theory, the radius of the universe is many times larger than 13.3 BRYs, they continue to report the distance to high redshift matter in space in accordance with the above; and although many of them have recently accepted the very open universe of accelerating expansion, they continue to report the distance to matter in the same manner.
Thus the distance of matter in space and its velocity as determined by BBers are, not only erroneous, but inconsistent with any currently accepted variety of BB.

I'm not really sure what he means here, but as it is entirely based on his erroneous premises, it can clearly be seen to be nonsense.

Resulting Media Reports.
By the use of such fallacious logic, the distances and departing speeds of matter in the space of the universe, as determined and disseminated by the comological establishment, all that is read, seen or heard in the media, and accepted by all the world regarding those figures, is based on those compounded errors.

The only errors we have seen so far have been yours, to paraphrase a favourite film of mine, "you are a poor scientist Mr Mitchell".

More Background Information.
The so-called “Age Paradox” has plagued BBT since day one. Some stars are known by astronomers to be considerably older than the reputed age of the BB universe; and far worse than that, a number of astronomers have estimated that it might have taken more than 100 billion years for the formation of the giant galactic structures that are observed in space.
That is not a “paradox,” but a disastrous problem that BBers have struggled for decades to overcome, meanwhile attempting to hide it, or dismiss it as a trivial, soon to be solved problem.

There is no age paradox its all a load of bullshit, mostly spread by Creationists who think that if they can disprove BBT then more people will believe the world is 6000 years old. I will state this clearly so it can be understood by anyone, including hopefully the incompetent like Mr Mitchell. There are no known objects in the Universe that have measured ages greater than the age of the Universe within the errors of the measurement. I work on the study of Globular Cluster systems, cranks often claim that the ages of GCs are older than the Universe, they are wrong, correctly determining the ages of these systems is difficult and requires a lot of telescope time, usually you don't get enough to do it very accurately, so what you do is try to measure many at once, when you do this equal numbers appear to be younger or older than their actual ages, this makes some of the objects which are actually 10-12Gyr old appear to be 15 Gyr old. This is simply to do with signal-to-noise, statistics and fitting of templates to determine ages. Similarly with objects like white dwarfs, or certain low mass stars which we know could continue to shine for 100 Billion years, yet we never see any of them that are older than 13 Gyr, why is this? Because there are none older than 13Gyr.

The point he makes about galaxy structures would actually appear to be true if you don't actually think about the issues for a moment. Lets face it what crank actually wants to do some thinking and then some difficult maths? For one, the early Universe was much more dense than it is now, as gravity acts as an inverse square of the distance between mass this means that if the Universe was half the size the average force of gravity between clumps of matter would be 4 times larger. Clearly earlier in the Universe it was much easier for gravity to pull matter together to from stars/galaxies/clusters of galaxies. A second point is that the simulations he talks about do not include the effects of dark matter, which contains many times as much mass as luminous matter, adding this in means you can easily form large structures in as little as a few Gyr. If you don't believe me here is a picture of a simulation showing exactly that. Every dot in the image is a huge clump of dark matter (and stars).

Solutions to the Big Bang Age Problem.
A recent new scheme to help BBers solve their age-old age paradox is the invention of “dark energy” or “quintessence.” They have decided that those imaginary entities cause the rate of expansion of the universe to be accelerating. The universe would therefore have expanded more slowly in the past. It would therefore be older than previously thought, thus helping to solve their age problem. (Incidentally, some Bbers of long ago had proposed a universe of accelerating expansion, but their schemes failed to survive.)

Not much to say here, he provides no proof that the cosmological constant or quintessence is impossible, mostly because it is far beyond his intellect to grapple with the maths I'm sure.

The Two Biggest Frauds of All:
The Big Bang creation of the universe was “out of nothing.” Until Inflation theory came along in the early 1980s, BBers believed that, before the Big Bang, there was no matter, no energy, no time, no space.
An equally ridiculous solution to that fraud was the ”inflation” resulting from a “vacuum fluctuation” of the energy of empty space as the source of the Big Bang. Somehow the space and energy, that hadn’t perviously existed, was now said to have been there all the time, and it contained unimaginable amounts of energy.

This is a vacuous and also incorrect statement. The BBT makes no real claims about what happens before the BB in fact it makes no real claims at present about what happened in the very smallest fraction of a second after the BB, why? Because when the matter reaches the incredibly high energies found just after the BB the laws of physics break down, we cannot use the laws we have now to explain all the way back. We know that the laws of physics break down because gravity is not yet reconciled with quantum mechanics and until we have a quantum theory of gravity we can't know what happens earlier with any certainty. Does this matter? Not really, the theory as a whole does not depend on the mechanism, as long as some process can produce the initial expansion and then the inflationary phase everything is fine.

The above are just a few of the items of fraud that continue to be disseminated. However, leading BB cosmologists are well aware of those; and many more problems and inconsistencies of BBT. While attempting to appear unconcerned, minimize their importance, or avoid mention of them, they struggle to invent new schemes to circumvent them; while making big money as professors, lecturers, TV personalities, and authors of articles and books with intriguing new titles. However, most of the innovations they produce (like inflation and acceleration), that are intended to solve BBT problems, produce only new problems.
Meanwhile, those intelligent and educated establishment folks choose to ignore the problems of BBT, and to perpetrate the fraud that continues to be disseminated in the media.

I'd love to know who makes big money from being an astronomer, I certainly don't know of any rich astronomers. If I wanted to be rich the easiest way would be to take up televangelism, or to write a really poor book about how scientists are frauds and the BBT is wrong and then try and sell it to the wingnut creationists. I mean you wouldn't even need to do any hard work then right? No need to check facts, or test theories, you know those people will believe anything as long as it makes BBT or evolution look bad.

If you would like to gain a thorough understanding of Big Bang Theory and its many flaws; and then learn the truth about cosmology based, not on wild ideas and fantasies, but on vast amounts of astronomical data, true science, logic and common sense, you must read my book, BYE BYE BIG BANG - Hello Reality.
This inexpensive, 446 page, paperback - that includes a bibliography, 5 appendixes, and name and subject indexes - can be found in most large US city and large US university libraries; or order it from your book dealer (at $19.95 - available to them from THE DISTRIBUTORS*), or click on:

Best wishes,
William C. (Bill) Mitchell
Carson City, Nevada, USA

*Conact Patty Walsh at THE DISTRIBUTORS, 702 S. Michigan, South Bend, Indiana
46601, USA. Email: pwalsh01@ameritech.net, Telephone: 574-232-8500

In conclusion I can't help but feel terribly embarrassed for the poor guy, it really is that bad, he hasn't even checked the simplest of his arguments, I would expect better from a high school essay. There are plenty of problems with the BBT, none of which are major, if there weren't there wouldn't be anything left for Astronomers to do, but he has decided to attack problems that don't exist. Very sad. I think we can see from the short email that reading the book is probably going to be pointless. If he can fit that many distortions, lies, out of date data into just that few lines how many will the book have?

Hubble Heritage

Click for VERY Big.

Thanks to the BadAstronomer I have found out about a cool new HST image from the Hubble Heritage site, what's even better is that two of the people that worked on the project to get the data work along the corridor, hence I am actually better informed than the BadAstronomer for the first time. The picture released by Hubble Heritage shows a cluster of Galaxies called Abell S0740. There are two versions of the image one without annotations and one showing zoomed regions of interest. See them both here.

This data is of particular interest because of what was found in the inner regions of the large elliptical galaxy at the centre of the cluster, when examined carefully it was discovered (by Russell Smith, here's the paper to prove it) that there were 3 gravitational arcs within the galaxy, you can see them in the inset in the top right of the image above. These arcs are the result of the light from a background galaxy being bent by the gravity of the large foreground elliptical galaxy, this has the effect of making several images of the same galaxy which are brighter and larger than they would usually be, making it possible to see galaxies further away. The gravitational arcs in this galaxy are the closest known example of strong lensing by an individual galaxy, as opposed to lensing by a cluster of galaxies.

The reason these lenses are so interesting is that when the position and brightness of the lenses are combined with the distance to the actual background galaxy (which can be worked out from its redshift) it becomes possible to measure precisely the amount of mass in the lensing galaxy within the radius of the arcs, with little or no assumptions. By looking at the way brightness of the lensing galaxy it is then possible (assuming that brightness is related to the amount of stars) to work out fraction of the mass in the lensing galaxy that is from normal matter and the fraction from dark matter. But wait that's not all.

By using the mass determined with the observed brightness of the lensing galaxy and the measured motion of stars in the galaxy (measured from spectroscopy) it becomes possible to work out exactly how the stars in the galaxy move as well, allowing a determination of parameters that can be used to constrain models of how galaxies form. Essentially these lenses could allow determinations of all the physical parameters of the lensing galaxy at accuracies previously unheard of.

Great you say, lets do it, but this is where things get difficult, it turns out that the arcs are so narrow that with current technology is actually impossible to get enough signal from them to determine a redshift, bugger. Basically they are so narrow that you add much more lensing galaxy light then you do lensed galaxy light. If STIS on the HST is ever repaired it may be possible, but if not it could be 10 years before its feasible. Note: if you happen to be someone sitting on a TAC (telescope allocation committee) and I, R. Smith or J. Lucey have a proposal to do what I've just claimed is impossible, I was wrong, we can do it, please give us the time.

Another thing I like about this work is shown in the other inset, a whole bunch of globular clusters. I study globulars, and when observing them from the ground it becomes very difficult to observe them at distances probably around 30-50Mpc away, these ones are located at 142Mpc, makes me even more annoyed that ACS has broken down, there will be no more new data like this for at least two years.

Cool Sky Map

I came across this cool bit of astronomy software the other day. There seems to be two versions about sky-map.org and wikisky.org. They seem to be identical. They allow you to slide around the night sky with or without constellations and to search for your favourite night sky objects (like NGC galaxies), so far, so like any other planetarium software. The cool thing with this software is that it also has the SDSS imaging survey built in. So you can switch to SDSS mode and look at the actual images produced by the Sloan survey. Unfortunately the SDSS doesn't cover the whole sky so many of my favourites aren't in it.

This is really only the start, we have been talking about software like this at work for awhile now, the ultimate (wet) dream for astronomers would be software like this that started in planetarium view but over layed survey areas from the various surveys, or even little symbols to show where the HST had been pointed at an object (The first steps have been made to do this in the Astro Photo section, check it out). You would then be able to click on the little links to take you directly to the data, it would make life much simpler than searching dozens of archives to find out if what you would like to do has already been done, saving time and money for eveyone, plus it would make a great toy for everyone to enjoy.

Give it a go, there's probably plenty of weird things to be seen in the SDSS images.

The Universe, All Of It On Your Screen

Here is an image that the ICCmofos had on their door a while back, showing distances to objects stretching from the Core of the Earth to the edge of the observable Universe. Using a logarithmic scale it shows the distances to objects such as Earth orbiting satellites, the planets, nearby stars, galaxies, clusters of galaxies, SDSS galaxies and the Cosmic Microwave Background. It is very cool in a very nerdy way. Unfortunately I can't seem to track down who made it right now.

Of particular note are the SDSS galaxies shown at the top of the page as blue dots, the filamentary structure of the Universe on large scales is immediately obvious. I still think it is pretty amazing that we're smart enough as a species to measure such things and then are able to plot the distances to anything in the Universe on only 3-4 sheets of A4.

Disaster

This is what ACS looks like on the ground...

Disaster, the main instrument on the Hubble Space Telescope died on Saturday. The camera, the Advanced Camera for Surveys (ACS) is the most in demand instrument on the telescope. The last call for proposals which only closed on Friday had 747 proposals to use HST, 498 (one of which was mine dammit) of which were to use ACS, thats 67% to you stat lovers. It looks like its not going to be possible to repair the instrument, at least not before the next servicing mission sometime next year, and even then there probably isn't enough time to do much while they are there. This is going to prove to be a huge loss to the astronomical community as no other instrument is capable of the fine resolution over a relatively large field of view that ACS provided. The servicing mission will install a new camera WFPC3, but this just won't be as sensitive as ACS at certain wavelengths (like the ones I'm interested in).

... and this is what it could do when in space.

It looks like we can kiss goodbye to our HST proposal, unless we can come up with a clever way to use one of the other instruments. Hmm, back to work.

New Links.

I'm planning on periodically adding to the links section on the sidebar to the right, I'm not sure how often this will be, it all depends on how much work I have on. Anyway, here is the first set of new links, all to do with pictures of Science:

The Hubble Heritage site has a very good selection of some of the HST's greatest hits, many will be familiar but there are one or two new ones, and others that have changed slightly since they were first released. See them in all their glory here.

In a similar vein, but looking the other way, here is a link to the US Geological Survey's image gallery, check out the galleries called Earth As Art.

The Earth Science Picture of the Day, is set up along much the same lines as the Astro-Picture of the Day, in particular check out the archives for many spectacular pictures of the Earth and natural phenomena.

The National Geographic also has a picture of the day, the archive found here is again worth a look (its where the picture at the top comes from).

Hobbit Galaxies

According to this story from space.com the SDSS has found 8 more dwarf galaxies in the local group. Seven of which appear to be satellites of the Milky Way, these seven galaxies, all of which are very faint and diffuse appear to be essentially old. The one new galaxy which is not thought to be bound to the MW appears to still be forming stars and to have a significant reservoir of neutral hydrogen with which to form more stars.

This is all very interesting because it has implications for one of the big problems of modern cosmology, the so called "missing satellite" problem. This is the observation that cosmological simulations of structure formation in a dark-energy, dark matter dominated Universe seem to predict many more small satellite galaxies around larger galaxies like the MW than we see. If however these galaxies do exist and they are simply very faint and hard to see as the SDSS results imply, then there isn't any problem at all. Seeing as the SDSS only covers about an eighth of the sky, and doesn't see very faint things, it does imply that there should be many more of these galaxies left out there to be found. I think a cottage industry of trying to find these things is probably about to spring up.