relativity, cosmology, astronomy, special relativity, general relativity, astrophysics, Einstein’s relativity, spacetime, cosmos

BICEP2 and the detection of Gravitational Waves

The most significant news of late is the BICEP2 results – if you are unfamiliar with the result, let me first summarize the results and then offer feedback and alternative viewpoints.

BICEP2 was the second generation BICEP (Background Imaging of Cosmic Extragalactic Polarization) instrument for astronomy located at Earth’s south pole. Possessing a greatly improved focal plane transition edge sensor (TES) bolometer array of 512 sensors (256 pixels) operating at 150 GHz, this 26 cm aperture telescope replaced the BICEP1 instrument, and observed from 2010 to 2012. In March of 2014 a paper emerged suggesting that BICEP2 had detected B-modes from gravitational waves in the early universe. An announcement was made on 17 March 2014 from the Harvard–Smithsonian Center for Astrophysics.

B-mode polarization is a polarization signal in the cosmic microwave background radiation (CBR), in reference to the magnetic component of electromagnetic light in the CBR. The pattern of polarization in the cosmic microwave background can be broken into two components. One, a curl-free, gradient-only component, the E-mode (named in analogy to electrostatic fields), was first seen in 2002 by the Degree Angular Scale Interferometer (DASI). The second component is divergence-free, curl only, and is known as the B-mode.

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BICEP2 researchers say that they have found the first evidence of B-mode polarization in the cosmic microwave background. (Courtesy: National Science Foundation)

Cosmologists predict two types of B-modes, the first generated during cosmic inflation shortly after the big bang, and the second generated by gravitational lensing at later times. Its believed that when the universe was very young ~ 10–35 s after the Big Bang – it underwent a period of extremely rapid expansion, ‘inflation’, when its volume increased by a factor of up to 1080 in a tiny fraction of a second. About 380,000 years after the Big Bang, the CMB – the thermal remnant of the Big Bang – was produced on the last surface of scattering, when the universe became transparent to photons. Over the years, the CMB has been measured with great accuracy, but these observations brought some problems: the CMB showed that the entire observable universe seemed to be homogeneous, flat and isotropic, while the physics of the Big Bang suggests that it should be highly curved and heterogeneous.

Further its believed that rather extreme gravitational conditions prevailed during the universe’s infancy. Gargantuan primordial gravitational waves are thought to have propagated through the universe during the first moments of inflation and this would have produced a so-called cosmic gravitational-wave background (CGB). This gravitational-wave background would, in turn, have left its own imprint on the polarization of the CMB – a sort of “curl” component or rotation that is known as the primordial B-mode polarization.

Scientists cannot distinguish between the polarization caused by gravitational waves, which has a tensor component, and that caused by density waves, which have a scalar component, by looking at the temperature variations of the CMB. It’s believed that the primordial B-mode polarization is thought to be much weaker than the E-mode, making it even more difficult to detect. However, certain measurements on the polarization angles that can be detected at each point on the sky provide extra information and allow scientists to differentiate between the tensor and scalar components, providing a “tensor-to-scalar” ratio. This ratio has been measured by BICEP2 to be 0.20 with a statistical significance of about 3σ [3 Sigma]. The possibility that the ratio is zero is ruled out with a statistical certainty of 7σ [7 Sigma]. Read the results here.

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A value of 0.20 is considered to be significantly larger than that expected from previous analyses of data from the Planck and WMAP telescopes. If it’s confirmed, it is the first direct evidence not only for inflation, but of a quantum behaviour of space and time. The image of polarization is a relic imprint of roughly a single quanta of graviton action. According to the BICEP2 collaboration, its results suggest that “the long search for tensor B-modes is apparently over, and a new era of B-mode cosmology has begun”.

Sounds pretty exciting but there are some who say, maybe this is not what the BICEP team think it is:

Perimeter Institute director Neil Turok, who worked on an inflationary model of his own with Stephen Hawking in the 1990s, urges caution and says that extensive experimental confirmation is necessary before BICEP2′s results can be considered as evidence for inflation. Paul Steinhardt and Neil Turok were the two loudest critics of cosmic inflation.

Another astrophysicist Peter Coles, who is based at the University of Sussex in the UK, is also cautious about the BICEP2 data interpretations.

Theoretical physicists and cosmologists James Dent, Lawrence Krauss, and Harsh Mathur have submitted a brief paper (arXiv:1403.5166 [astro-ph.CO]) stating that, while ground breaking, the BICEP2 Collaboration findings have yet to rule out all possible non-inflation sources of the observed B-mode polarization patterns and the “surprisingly large value of r, the ratio of power in tensor modes to scalar density perturbations.”

Sir Roger Penrose even goes as far as to suggest that the gravitational waves detected were produced pre-big bang in a previous universe and denies the existence of inflation entirely.

Whatever position you take the results are topical, but still in my mind they need further investigation as to other possible explanations. My biggest concern is that in order to suggest that the Gravitational Waves were produced by inflation, why not asked could have they been produced in the primordial universe without inflation.

Lastly, and more importantly – regardless of inflation – the detection of Gravitational Waves is additional evidence confirming Einstein’s General Theory of Relativity and that to me is the most significant result.

Cosmologist claims Universe may not be expanding

Christof Wetterich, a theoretical physicist at the University of Heidelberg in Germany, posted a paper on the arXiv preprint server, that offers a different cosmology in which the Universe is not expanding but the mass of everything has been increasing over time. Although the paper has yet to be peer-reviewed, none of the experts contacted by Nature dismissed it as obviously wrong, and some of them found the idea worth pursuing. “I think it’s fascinating to explore this alternative representation,” says Hongsheng Zhao, a cosmologist at the University of St Andrews, UK. “His treatment seems rigorous enough to be entertained.”

Wetterich points out, the characteristic light emitted by atoms is also governed by the masses of the atoms’ elementary particles, and in particular of their electrons. If an atom were to grow in mass, the photons it emits would become more energetic. Because higher energies correspond to higher frequencies, the emission and absorption frequencies would move towards the blue part of the spectrum. Conversely, if the particles were to become lighter, the frequencies would become redshifted. In other words, in the early universe red shifted light would have been emitted as all the mass was smaller and thus the energy of the emitted light was also smaller, and then increasing over time.

Its an interesting idea – go to Nature to read the full article, and there is a link to the paper at the bottom.

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Image Credit: Nature & Take 27 LTD/SPL

 

The most distance object: MACS0647-JD

In November 2012, a new distance record breaker has been weighed in with a photometric redshift of  z ~ 10.8 which is roughtly 420 million years after the big bang. This is pretty significant.

The Cluster Lensing and Supernova survey with Hubble (CLASH), and the Spitzer/IRAC has measured the photometric redshift and with the help of Gravitational Lensing has been able to see the object by it’s increased visability and determined its distance.

The paper on the object, together with 2 other distance candidates, can be viewed (in full if you have access) on ApJ: http://iopscience.iop.org/0004-637X/762/1/32 or you can get a pre-print on ArXiv which is almost the same as the ApJ paper: http://arxiv.org/pdf/1211.3663v1.pdf

MACS0647-JD is the one of the three with the largest redshift, and a Lyman Break Galaxy. The light from the relic galaxy, at the time of transmission, was so small and may have been in the first stages of forming a larger galaxy.

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Comet PANSTARRS

Comet PANSTARRS

Comet PANSTARRS

* Comet PANSTARRS (C/2011 L4) in Cetus * Photo By Humayun Qureshi. Taken from Canberra.

Astronomers discovered Comet PANSTARRS (C/2011 L4) on June 7, 2011. In early February, the comet reached its southernmost point, but by the end of May it will lie near Polaris (Alpha [α] Ursae Minoris).

Comet watchers should target February 21 through March 27, when the Comet PANSTARRS should shine more brightly than a 2nd-magnitude star (like Polaris). On March 5, the 1st-magnitude comet lies closest to Earth. Search for it after sunset 17° southeast of the Sun. Use binoculars or a rich-field telescope.

Hubble Finds the Oldest Star (as of March 2013)

This is a Digitized Sky Survey image of the oldest star with a well-determined age in our galaxy. The aging star, cataloged as HD 140283, lies 190.1 light-years away. The Anglo-Australian Observatory (AAO) UK Schmidt telescope photographed the star in blue light. Credit: Digitized Sky Survey (DSS), STScI/AURA, Palomar/Caltech, and UKSTU/AAO

A team of astronomers using NASA’s Hubble Space Telescope has taken an important step closer to finding the birth certificate of a star that’s been around for a very long time.

“We have found that this is the oldest known star with a well-determined age,” said Howard Bond of Pennsylvania State University in University Park, Pa., and the Space Telescope Science Institute in Baltimore, Md.

The star could be as old as 14.5 billion years (plus or minus 0.8 billion years), which at first glance would make it older than the universe’s calculated age of about 13.8 billion years, an obvious dilemma. This is going to be a strom in the cosmology world, as most believe that the univsere 13.7 gigayears (billion years) old – admittedly its only an estimate, but one that will be pushed back.

But earlier estimates from observations dating back to 2000 placed the star as old as 16 billion years. And this age range presented a potential dilemma for cosmologists. “Maybe the cosmology is wrong, stellar physics is wrong, or the star’s distance is wrong,” Bond said. “So we set out to refine the distance.”

The new Hubble age estimates reduce the range of measurement uncertainty, so that the star’s age overlaps with the universe’s age — as independently determined by the rate of expansion of space, an analysis of the microwave background from the big bang, and measurements of radioactive decay.

http://www.nasa.gov/mission_pages/hubble/science/hd140283.html

Cairns total eclipse 2012

A small group of us went to Cairns for the total eclipse. I wanted to see and photograph the event – the experience was quite something special but alas it was plagued with bad weather. I managed to photograph before totality and after, but during totality the cloud completely covered the wondrous sight. None the less it has made me more determined to photograph totality properly in the next full solar eclipse!

You can see a couple photos here before and after totality – note the cloud cover:

Totality was not visible at all – as you can view totality without the need for solar filters, all filters were removed but nothing but a black cloudy sky was visible. Only towards the end of the eclipse was I starting to get OK photos.

The above photos are before totality overlooking the Cairns waterway –  and the view during totality. The eclipse darkness was quite spectacular!

Before the eclipse has begun it was darker than usual - similar to a partial. Being so very dark, with light in the distance around you was quite something – and an event that everyone should experience, at least once.

The LHC found a boson – but was the Tevatron was there first?

It was a race to find the Higgs Boson – a scientific quest that has been years in the making.

July 2 2012: The Tevatron:

The scientists at the U.S. Department of Energy’s Tevatron collider revealed their latest results on July 2nd, two days before the highly anticipated announcement of the latest Higgs results from CERN and the Large Hadron Collider in Europe. The Tevatron scientists spent 10 years gathering and analyzing data from the CDF and DZero collaborations have and announced that they’d found their strongest indication to date for the much sought after, Higgs boson particle. The team collated the last bit of information out of 500 trillion collisions produced by the Tevatron since March 2001, yet the final analysis of the data did not categorically answer the question of whether the Higgs boson exists, but it stood on the scientific precipice with a fuzzy haze of a result lying in the misty fog of data.

“We achieved a critical step in the search for the Higgs boson,” said Dmitri Denisov, DZero cospokesperson and physicist at Fermilab. “While 5-sigma significance is required for a discovery, it seems unlikely that the Tevatron collisions mimicked a Higgs signal. Nobody expected the Tevatron to get this far when it was built in the 1980s.”

The Tevatron was the world’s second largest proton-antiproton collider. Residing at Fermilab, the Tevatron accelerated and stored beams of protons and antiprotons traveling in opposite directions around an underground ring four miles in circumference at almost the speed of light before colliding them at the centre of two detectors. However, due to funding costs in the US it was shut down on Sept. 29, 2011. And so all data was produced prior to that shut down.

The Tevatron data indicated that the Higgs boson, if exists, should possess a mass between 115 and 135 GeV/c2 ~ 130 times the mass of the proton.

July 4 2012: The LHC:

A few reports were leaked by CERN employees, anomalously of course, states that a discovery announcement was imminent. Then on the 4th July 2012 physicists announced that they have seen a clear signal of a Higgs boson — a key part of the mechanism that gives all particles their masses.

Two independent experiments reported their results, showing convincing evidence of a new boson particle weighing around 125 gGeV/c2, which so far is the best fit for the predictions of the Higgs previously made by theoretical physicists.

Direct at CERN, Rolf Heuer, was reported saying, “we have a discovery,” of a new subatomic particle, a boson, that is “consistent with a Higgs boson.”

The ATLAS experiment has seen a new type of boson decaying into four electrons – a good indicator that it is a Higgs particle.

Boson to be sure but is it the Higgs:

Clearly the result is a boson but the energy-mass level is different than initially predicted – so it’s possible it may be something more exotic – maybe even Dark Matter. In any case it is a huge break through and a great change in about to come to world of particle physics.

SKA Split decision – the best solution!

The selection of the best site for the Square Kilometre Array (SKA), which was between South Africa and a joint Australian/New Zealand bid, surprised most people. But it makes real sense to utilize the preliminary facilities that both nations have started to contribute.

In an earlier article on RelativeCosmos.com I suggested Australia would be best but in light of the split decision, it is a welcome selection!

Australia will launch phase 1 of the plan and get started sooner and South Africa will come in a little later with phase 2. It really is a workable solution and it is coup for both countries’ astronomy communities – many details are yet to be finalised but it’s one of those great times where a turning point makes for great history.

To quote Nature, “But splitting the site does have potential benefits. For one thing, the redundancy created by international collaboration can come in handy. The ISS, for example, continues to be serviced by a slew of vehicles from its different partners, even though the US space shuttle no longer flies there. There is also a perverse financial advantage — multiple partners are less likely to cancel an over-budget project than is a single government. But the greatest benefit is human: a more complex project draws in more people from more places and gives them an opportunity to participate.”

Read more on:  Nature  485, 548 (31 May 2012) doi:10.1038/485548a

Square Kilometre Array (SKA) may go to South Africa but is it really the best site?

By Estelle Asmodelle

SKA Image courtesy: Paul Bourke and Jonathan Knispel and supported by WASP (UWA), iVEC, ICRAR, and CSIRO

Recent reports on the selection of the site for the Square Kilometre Array (SKA) have suggested that South Africa offers the best site and a panel of advisors recommended the SA site over Australia. The argument was put that the SA site was cheaper for construction, yet Australia had lower insurance fees, and primarily that the SA site was at a higher altitude.

The issue of altitude is really irrelevant here for at higher frequencies water vapour, or Scintillation (the distortion of waves moving through varying densities) can become a problem, but not so much for long radio waves, the bigger problem there is  radio frequency interference. Australia would be the best place for SKA, especially in WA which is ‘radio quite,’ not so in South Africa. Most long wave radio dishes are low lying. Altitude is more important for millimetre or sub-millimetre arrays.

I think this is really a political issue, South Africa really needs help financially and the SKA would boost their economy. I just hope that Australia is chosen, for South Africa’s site is not as remote and within 10 years, of completion, the site could suffer considerable radio interference problems, which would seriously degrade its operational status.

And also South Africa has many other issues, such as social unrest which could affect the operation of the telescope, or the employees. The argument that SA would be best as they have already started building the array, but it’s also true of Australia, who under the project name ASKAP, or the Australian Square Kilometre Array Pathfinder have already deployed some of the planned 36 dishes which will be complete in 2013, and can be integrated into the SKA if Australia is chosen, some dishes have already seen first light. See the site:

ASKAP, or the Australian Square Kilometre Array Pathfinder

http://www.atnf.csiro.au/projects/askap/index.html

See the status of the ASKAP site here in real time – updated often:

http://www.atnf.csiro.au/projects/askap/askap-live/

Don’t take my word for it – see Brian Boyle’s burb on the advantages Australia offers for the SKA:

http://www.ska.gov.au/Pages/BrianBoyle’s2012SKAUpdate.aspx

Some say that people who are astronomers, or students like me who will be looking for placement soon, are just feathering their nest – not true, for most of the people who will work on these sites will be from all over the world, the very cream of the crop, and probably not be Australian to a large extent.

So in fact we are further along than SA. So why the support for SA – word is, as I’ve eluded too, it’s really about politics not science – see this article:

http://www.gizmodo.com.au/2012/02/ska-bid-should-come-down-to-science-not-politics/

The last thing to bear in mind – Australia will soon have the NBN rolled out all over the country – this will assist the data handling to a very large extent – certainly by the time the SKA is complete we will have one of the best broadband networks in the world!

Interestingly the last big astronomy project SA was involved in had endless imaging problems (Although an optical site), and still does to an extent, and even more recently, poor broadband and operating problems:

http://www.salt.ac.za/

And read more here:

http://www.southafrica.info/about/science/salt-telescope.htm

All in all the remote WA site is best suited for such an astronomical site for several reasons but most importantly the size of our site  - see the map for details:

Potential SKA array station placement in Australia and New Zealand overlaid on a population density map. Major broadband network links (existing and planned) are also shown. Credit: CSIRO

 

 

 

 

 

 

 

THE TRANSIT OF VENUS and also the TOTAL SOLAR ECLIPSE.

By Estelle Asmodelle

The transit of Venus is happening 5th-6th June 2012.

There are plenty of Astronomical Societies who are holding ‘transit parties,’ including two that I do presentations to: The first one, here is a page from the Newcastle Astronomical Society with their ‘transit party’ and they had ABC radio there as well:

http://www.nas.org.au/HTML%20Pages/venus_transit_event_2004.htm

I understand they will be doing the same thing this year… and I will be going as well.

The second is the Sutherland Astronomical Society (largest such group in Sydney) – they have their own observatory, and it’s a good one too. They too are going to have a ‘transit party’

http://www.sasi.net.au/index.php

Incidentally, I am giving  a presentation to this group (in response to an invite from them after reading some of my articles in Cosmos) entitled: “Cosmology and the role of the General Theory of Relativity.” Which will be 2 nights after the transit – this will be the first time that I’ve given a presentation to this group, and I feel a bit intimidated by it as it’s a 90 minute presentation and they usually get university lecturers to do such presentations – fingers crossed that I have my ducks all in a row…

I didn’t see the 2004 transit as I was overseas at the time but I won’t miss this one! Here is an Australian site dedicated to the transit that you may find interesting as well:

http://www.transitofvenus.com.au/HOME.html

Incidentally, Jeremiah Horrocks was the first person to successfully predict and observe the transit of Venus in 1639.

But the BIG news is really the total solar eclipse in Cairns, which is at the top of Queensland, that is the big news. Cairns is 3 hour flight and 2 hour drive from my home but we have our flight booked and our hotel booked ready – I am taking my two nephews as well, one is at Uni and the other is very interested in astronomy as well. Here in Australia its big news for many people and most of Cairns is booked out – I will taking my telescope and HD video camera, together with a suitable filter, to film the event – so it’s really exciting – it’s my first total eclipse. I have seen a couple of partials but never a total! Here is an Australian website with some more details:

http://www.eclipsecairns.com/

By November it should be dry, also Cairns gets tropical rain and as the eclipse is just after sunrise it will 95% be dry, I just hope it’s clear skies!