Subject: ASGRG Newsletter #13 ****************************************************************************** AUSTRALASIAN SOCIETY FOR GENERAL RELATIVITY AND GRAVITATION Electronic Newsletter -- #13, Autumn 2004 ****************************************************************************** Items for this newsletter should be emailed to the editor: asgrg *AT* hotmail *DOT* com The deadline for the next issue is 31 October, 2004. ****************************************************************************** CONTENTS: * KERR FEST, University of Canterbury, Christchurch, 26-28 August, 2004 * REPORT ON ACGRG4, Melbourne, 7-9 January, 2004 * MINUTES OF BIENNIAL GENERAL MEETING, Melbourne, 8 January, 2004 * LIFE IN BRUNEI * GRAVITY PROBE B * MEMBERSHIP DETAILS ONLINE at http://www.physics.adelaide.edu.au/ASGRG/members.html * SUBSCRIPTIONS * FORTHCOMING MEETINGS * MEMBERS' ABSTRACTS at gr-qc, December 2003 - May 2004 * ABSTRACTS FROM THE LIGO SCIENTIFIC COLLABORATION at gr-qc, June 2003 - May 2004 ****************************************************************************** NOTE: This item is a resend of the first announcement of Kerr Fest, which all ASGRG members should have received on May 6. ------------------------------------------------------------------ KERR FEST Black Holes in Astrophysics, General Relativity & Quantum Gravity ------------------------------------------------------------------ *A celebration in the year of Roy Kerr's 70th birthday* University of Canterbury, Christchurch, New Zealand Thurs 26 - Sat 28, August, 2004 ------------------------------------------------------------------ http://www.phys.canterbury.ac.nz/kerrfest/ ------------------------------------------------------------------ Speakers will include * Steve Carlip (UC Davis) * Brandon Carter (Observatoire de Paris, Meudon) * Andy Fabian (U Cambridge) * Josh Goldberg (Syracuse U) * Gary Horowitz (UC Santa Barbara) * Zoltan Perjes (KFKI Budapest) * Maurice van Putten (MIT) * David Robinson (Kings College, London) * Remo Ruffini (ICRA, U Rome) * Peter Szekeres (U Adelaide) * Matt Visser (VUW) Online registration for the Symposium to mark Roy Kerr's 70th birthday has NOW OPENED. Please visit the website for further details. For those of you coming from Australia - we realise it is in term time: however, we had to make it fit in our own mid-semester break to get accommodation in student halls, a lecture theatre etc. It should be possible to juggle your teaching, we hope, to take a couple of days off to come to this unique event. The welcome function will be held on Thursday, so as so make the programme as compact as possible for those of you coming from Australia. NOTE: there are very reasonably priced trans-Tasman airfares (around A$180-$200 including taxes one way from Melbourne/Sydney to Christchurch) now that Pacific Blue is operating, and other operators have also lowered their fares. The fares can be booked on the Internet and there are travel links on the conference web site. In addition to the scientific programme there will be a Welcome Reception, Public Lecture and Conference Banquet which are **all included** in the registration fee. Early bird registration (at NZ$250) is **due by 16 July, 2004 **. PROGRAM: We expect talks will begin first thing on Thursday, 26 August and finish around midday on Saturday 28 August, so most people will plan to stay for at least the 3 nights of 25th, 26th and 27th August. The welcome event and public will be on the evening of Thursday 26th, and the banquet on Friday 27th August. CONTRIBUTED TALKS: Contributed talks on the theme of black holes and Roy's scientific contributions are welcome. While we may take a slightly liberal interpretation of this, we will vet the contributions to make sure that there is some point of contact with Roy's work. Please get in early with your abstracts if possible - this can be done in advance of registering. In any event, abstracts of any proposed talks should be emailed by 16 July 2004 at the latest: d.wiltshire@phys.canterbury.ac.nz also by 16 July, 2004. POST CONFERENCE TOURS: We are not planning any ourselves, but a number of useful links are given under "Tours" on the webpage. ****************************************************************************** REPORT ON ACGRG4, Monash University, Melbourne, January 7-9 2004 The 4th Australasian Conference on General Relativity and Gravitation (ACGRG4) was held at Monash University in Melbourne, Australia from 7 to 9 January 2004. ACGRG4 was the fourth in a series of approximately biennial conferences on general relativity and gravitation organised by the ASGRG. At total of 36 presentations were given over the three days of ACGRG4, including plenary talks from David McClelland ("Gravitational wave detection"), Peter Veitch ("Development of high power lasers for gravitational wave interferometry"), Mike Ashley ("A heterodyne method for determining the stability of calibration lines in an interferometer"), Matthew Bailes ("Gravitational wave astrophysics with radio pulsars"), David Wiltshire ("Stable gravastars - An alternative to black holes"), Susan Scott ("Curvature singularities and abstract boundary singularity theorems for space-time"), Joey Medved ("Quasinormal modes and 'dirty' black holes"), Robin Tucker ("Relativistic balance laws for Cosserat media in general spacetimes"), and Michael Hall ("Exact uncertainty approach to quantum mechanics and quantum gravity"). In addition, David Blair aired a multi-media presentation on the new Gravity Discovery Centre at Gingin, and Antony Searle demonstrated the ANU's relativity video. The more specialised talks were divided into 10 parallel sessions which covered gravitational wave detection technology, brane world models, relativistic strings, relativistic cosmology, numerical relativity and an assortment of problems in mathematical relativity. The conference dinner was held at the Monash University Staff Club on the evening of January 8, and was enjoyed by all. Particular thanks should go to the local organisers (Leo Brewin, Tony Lun, Elizabeth Stark and Raymond Burston) for making ACGRG4 such a great success. ****************************************************************************** MINUTES OF THE 4TH BIENNIAL GENERAL MEETING OF THE ASGRG held at Monash University, Melbourne, 8 January, 2004 The meeting opened at 4.15 p.m. [14 ASGRG members were present. At the time of the BGM less than 56 of the members were financial, so the meeting was quorate.] Apologies: David Blair 1. The minutes of the 3rd Biennial General Meeting, held at the University of Western Australia, 11 July 2001, were presented to the meeting. Susan Scott moved that the minutes be accepted, and Antony Searle seconded. The motion was approved. 2. President's Report: David McClelland gave an upbeat assessment of the recent fortunes of the general relativity community in Australasia. There had been some funded ARC support, and the spin-offs from this should help the ASGRG to attract new members. There had been some new faculty appointments, and experimental relativity in particular was growing nicely in Australia. Similarly, with the appointment of David Wiltshire at the University of Canterbury and Matt Visser at Victoria University in Wellington, general relativity was flourishing in New Zealand. One less positive feature was the dearth of international participation at ACGRG4, particular from North America, but this was possibly due to the timing of the conference. David briefly mentioned the most recent activity of the Society, namely the Relativity Minisymposium attached to the 6th Australia-New Zealand Mathematics Convention in Sydney in July 2003. Prior to that, the ASGRG supported the attendance of Barry Barish as a plenary invited speaker at AIP 2002 (also in Sydney). The next important event on the Society's calendar was the 2005 AIP Congress, which was to be held in Canberra in February 2005. The suggestion raised by David at the last BGM that the ASGRG should become a member of FASTS had not been pursued, and David was happy for it to lapse. Similarly, no action had yet been taken on assigning a separate ARC Category Code to general relativity, gravitation and cosmology. There are no ARC theory grants in gravity at present, and David believed that the incoming ASGRG President should pursue this matter more aggressively. Laurie Cram, the ARC programme manager for gravity-related areas, was about to step down, and we didn't know who his replacement would be 3. Treasurer's Report: Susan Scott reported that immediately before the start of ACGRG4 the Society had a total of 70 members, of which 24 were life members, 24 were ordinary members, 3 were retired, 4 were unwaged, and 15 were student members. Five of the 70 members were female, and 17 were from outside Australia. The Society's funds had increased slightly from $11,393 in June 2001 to $12,206 in November 2003. Much of the increase was due to the AIP meeting in Sydney in July 2002, which returned a profit of $1500 to the Society. Another, minor, source of revenue for the Society were the processing fees for the sale of the ANU's relativity video, which contributed $50 per video. Susan reported that many of the ordinary members were in arrears, and that the Treasurer's job was complicated by the fact that she had no access to the membership details on the Adelaide University website. Malcolm Anderson moved that the Treasurer be given access to the membership details, and Matt Visser seconded. The motion was approved. A further problem for the Treasurer was the fact that the Society's Commonwealth Bank credit card facility had been cancelled because of low transaction volume. It would cost a minimum of $12 a month to have it reactivated, and even then it would available through mail-order only, not EFTPOS. The incoming ASGRG Treasurer was asked to investigate the facilities offered by other financial institutions. Antony Searle moved that the incoming Treasurer be requested to do a quick web search and bring prospective members to the attention of the ASGRG Committee. Mike Ashley seconded. The motion was approved. 4. Auditor's Report: The Auditor, John Schuz, stated that he was satisfied with the Society's accounts and had signed a letter to that effect. Matt Visser moved that the ASGRG offer a vote of thanks to John for his work as Auditor, and John Steele seconded. The motion was approved. 5. Appointment of Auditor for the next session: John Schutz agreed to remain the Auditor of the Society's accounts. 6. Date and venue for ACGRG5: The meeting decided (tentatively) that ACGRG5 would be held at the University of Canterbury, Christchurch, in September 2006. In view of this, the meeting moved to co-opt Matt Visser as an extraordinary member of the ASGRG Committee. 7. Election of officers: The following people were elected officers of the ASGRG Committee by acclamation (the mover and seconder are shown in brackets): President: Susan Scott (McClelland, Searle) Treasurer: Antony Searle (McClelland, Scott) Secretary: Malcolm Anderson (Wiltshire, Visser) Officer: David Wiltshire (Charlton, Sandeman) Officer: Peter Veitch (McClelland, Wiltshire) 8. Bid for GR18 in 2007: The meeting voted to bid for GR18 in Sydney in July 2007. A professional conference organiser would be appointed, if we won. The Society should also seek legal advice as to whether it should be incorporated as a non-profit association. Bronwyn Palmer of the Sydney Convention and Visitors Bureau gave an outline of the possible bid. The location would be Darling Harbour (the Sydney Convention and Exhibition Centre), which has 3500 and 1000 seat auditoria. Accommodation would range from $46 a night (2-star) to $170 a night (5-star). More detailed (and confidential) budget information was also given. 9. Proceedings of ACGRG4: David McClelland and Susan Scott were made responsible for co-ordinating the publication of the proceedings of ACGRG4, which would appear in General Relativity and Gravitation. The deadline for manuscripts was nominated as May 31, 2004. Only article per talk could be submitted, but there were no page limits. 10. Other business: ASGRG members were encouraged to send items of interest in to the Society newsletter. David Wiltshire remained in charge of the Society's website. The meeting closed with a vote of thanks for the outgoing Committee. ****************************************************************************** LIFE IN BRUNEI Malcolm Anderson, ASGRG Secretary ASGRG members often ask me what it's like to live and work in Brunei. Most people living outside South-East Asia, I have found, are not even certain where Brunei is. They know perhaps that the Sultan of Brunei was once reputed to be the world's richest man, and that the country's wealth rests on oil, and assume naturally that it must be somewhere in the Middle East. In fact, Brunei is a tiny enclave on the north coast of the island of Borneo, which is otherwise divided between Indonesia and Malaysia. Brunei lies on the same line of longitude as Perth, and is about 5 degrees north of the equator. With an area of only 5765 square kilometres, Brunei is less than one tenth the size of Tasmania. Its population is similar to Canberra's (some 330,000) and is about 67% Malay and 15% Chinese. There are about 50,000 expatriate workers, the majority of them Indian. Up until the 19th century Brunei was an independent Malay sultanate, and controlled most of north Borneo. The British established a protectorate over it in 1888, and if it were not for the discovery of off-shore oil in 1929 Brunei would now most probably be just one of the many states of Malaysia. Oil is of course the mainstay of Brunei's economy. It should be stressed that Brunei is not actually a major oil producer. It pumps about 180,000 barrels a day, which is less than a quarter of Australia's oil production. But in view of Brunei's tiny population, and the fact that much of the oil revenue is used to support what is by Asian standards a generous welfare system, the country has the highest standard of living in South-East Asia outside Singapore. It is difficult to overstate the pervasive (and corrosive) effects that the government and the oil money have on the economy and society of Brunei. Almost all adult Malays have jobs for life in the Bruneian public service (although job levels were frozen in the wake of the 1997 currency crisis, and youth unemployment is now becoming a matter of concern). And a "job for life" includes subsidised housing, interest-free car loans and a generous pension on retirement at age 55. The housing market is also completely distorted by government subsidies. For example, the flat I am living in costs $5000 a month (!) to rent. (The Brunei dollar has roughly the same value as the Australian dollar.) This is more than my monthly salary, but the university very kindly pays for all but $130 of it. The net effect is a simple transfer of oil money from the government to my landlady, who just happens to be the Sultan's ex-wife. On a more personal level, life in Brunei is generally very relaxed. Although Brunei is a Muslim state and there are a number of seemingly draconian laws on the statute books, these laws are rarely enforced. Malay women are supposed to wear Muslim headgear and "modest" clothing, but most women dress no differently from Westerners. The purchase and public consumption of alcohol is illegal, but it is easily imported from Malaysia, most restaurants will allow you to bring your own, and most hotels will happily sell it (although at black market prices). The University of Brunei Darussalam, where I work, has about 200 staff and 4000 students (mostly student teachers). I teach two courses a semester (in calculus, geometry and mechanics), to classes that range in size from 50 to 150. I also supervise on average two honours project students a year. All lectures in the Science Faculty are in English, and more than half of the students are female. Unfortunately the local students are in general very weak, and have little interest in any mathematics beyond A-level, as most of them intend to become high- school maths teachers. The semesters are 14 weeks long, lasting from August to December, then January to May. The working week has a "split weekend", as Friday is a holiday in place of Saturday. I found this arrangement difficult to adjust to at first, but eventually got used to it. The campus is only about 10 years old, and boasts some attractive buildings modelled on traditional Malay architecture, but unfortunately the typical Bruneian disdain for maintenance means that much of it is already falling apart. In fact, the sorry state of the infrastructure is probably the only difficult feature of life in Brunei. The food is cheap, the roads are ultra-modern, the weather is great, and the wildlife is extraordinarily varied. Most radio and TV stations are in English, as are most of the movies in the cinemas. Computer software and video and audio CDs are all pirated and ridiculously cheap. Singapore, the local centre of fashion and culture, is only a two-hour flight away. But if you attempt to make an international phone call, or connect to the internet, or rely on the water, electricity or air conditioning at home or work, you often end up frustrated. And it's best to avoid the government bureaucracy whenever possible - my travel refund when I first arrived was delayed by 9 months because someone sent my file to "Pensions" instead of "Passage", and it was only retrieved because I found it myself... ****************************************************************************** GRAVITY PROBE B Gravity Probe B has finally been launched after being "in the pipeline" for decades. For more, read on. ----------------------------------------------------------------------------- "In Search of Gravitomagnetism", by Tony Phillips, for Science@NASA Gravity Probe B has left Earth to measure a subtle yet long-sought force of Nature. April 20, 2004: NASA's Gravity Probe B spacecraft left Earth today in search of a force of nature, long suspected but never proven: gravitomagnetism. Gravitomagnetism is produced by stars and planets when they spin. "It's similar in form to the magnetic field produced by a spinning ball of charge," explains physicist Clifford Will of Washington University (St. Louis). Replace charge with mass, and magnetism becomes gravitomagnetism. We don't feel gravitomagnetism as we go about our everyday lives on Earth, but according to Einstein's theory of General Relativity it's real. When a planet (or a star or a black hole ... or anything massive) spins it pulls space and time around with it, an action known as "frame dragging." The fabric of spacetime twists like a vortex. Einstein tells us that all gravitational forces correspond to a bending of spacetime; the "twist" is gravitomagnetism. What does gravitomagnetism do? "It can make the orbits of satellites precess," says Will, "and it would cause a gyroscope placed in Earth orbit to wobble." Both effects are small and difficult to measure. Researchers led by physicist Ignazio Ciufolini have tried to detect the gravitomagnetic precession of satellite orbits. For their study, they used the Laser Geodynamic Satellites, LAGEOS & LAGEOS II, two 60 cm diameter balls studded with mirrors. Precise laser ranging of the pair allows their orbits to be monitored. The researchers did find a small amount of precession consistent (at the 20% level) with gravitomagnetism. But there's a problem: Earth's equatorial bulge pulls on the satellites, too, and causes a precession billions of times greater than gravitomagnetism. Did Ciufolini et al. subtract that huge pull with enough precision to detect gravitomagnetism? Many scientists accept their results, notes Will, while others are skeptical. Gravity Probe B, developed by scientists at Stanford University, NASA and Lockheed Martin, will do the experiment differently, using gyroscopes. The spacecraft circles Earth in a polar orbit 400 miles high. Onboard are four gyroscopes, each one a sphere, 1.5 inches in diameter, suspended in vacuum and spinning ten thousand times per minute. If Einstein's equations are correct and gravitomagnetism is real, the spinning gyroscopes should wobble as they orbit the earth. Their spin axes will shift, little by little, until a year from now they point 42 milli-arcseconds away from where they started. Gravity Probe B can measure this angle with a precision of 0.5 milli-arcseconds, or about 1%. ----------------------------------------------------------------------------- The full text of this article can be found at: http://science.nasa.gov/headlines/y2004/19apr_gravitomagnetism.htm?list726964 The Gravity Probe B mission homepage is at: http://einstein.stanford.edu/ ****************************************************************************** MEMBERSHIP DETAILS ONLINE: Due to requests from members, David Wiltshire has written some HTML scripts which generate membership details online from our records. If you click on http://www.physics.adelaide.edu.au/ASGRG/members.html you will find a members' list. Clicking on individual members gives their current contact details. By following a further link private details of the subscription status of any member will be sent to their registered email. This feature should enable us to update our records more frequently in response to members' input, and to allow members to keep track of their subscriptions. ****************************************************************************** SUBSCRIPTIONS: The membership script programs are intended to be run automatically once a year, at the end of July, to give members other than life members details of their current subscription status. The new version of the subscription form, at http://www2.phys.canterbury.ac.nz/ASGRG/subsform.html has been simplified so that it does not need to be updated each year. Given that our annual fee is modest, members are encouraged to pay for multiple years, and to fill in the years they are paying for. E.g., when the July 2004 - June 2005 subscriptions are requested, if you wish to pay for July 2005 - June 2006 at the same time, it may simplify matters. ****************************************************************************** FORTHCOMING MEETINGS June 2-5, 2004: 11th Hellenic Gravity Meeting University of the Aegean, Lesbos, Greece http://www.aegean.gr/marine/XI-NEB/main.htm June 7-18, 2004: Summer School in Gravitational Wave Astronomy Center for Gravitational Wave Astronomy Brownsville, Texas http://cgwa.phys.utb.edu/outreach/summerschool.php June 11-12, 2004: 17th Eastern Gravity Meeting Bowdoin College, Brunswick, Maine http://www.bowdoin.edu/conferences/egm7/ June 28 - July 3, 2004: 6th Alexander Friedmann International Seminar on Gravitation and Cosmology Cargese Institute, Corsica, France http://www.fisica.ufpb.br/~jfonseca/friedmann/ July 12-15, 2004: 5th LISA Symposium ESTEC, Noordwijk, The Netherlands http://www.congrex.nl/04a07/ July 18-23, 2004: 17th International Conference on General Relativity and Gravitation (GR17) RDS Convention Centre, Dublin, Ireland http://www.dcu.ie/~nolanb/gr17.htm July 25 - August 6, 2004: 11th Brazilian School of Cosmology and Gravitation Rio de Janeiro, Brazil http://www.cosmologia.cbpf.br August 1-7, 2004: "New Geometry of Nature: Mathematics, Physics, Geophysics and Astronomy" Kazan State University, Irkutsk, Russia http://www.ksu.ru/GeoN-Kazan-2003 August 9-16, 2004: "Number, Time and Relativity" Bauman Moscow State Technical University, Moscow, Russia http://www.hypercomplex.ru/index_eng.html August 26-28, 2004: Kerr Fest "Black Holes in Astrophysics, Relativity and Quantum Gravity" University of Canterbury, Christchurch, New Zealand http://www.phys.canterbury.ac.nz/kerrfest/ September 6-7, 2004: Current Themes in Quantum Gravity: A Two-day Conference in Honour of the 60th Birthday of Chris Isham Imperial College, London, United KIngdom http://theory.ic.ac.uk/ September 13-16, 2004: 16th Sigrav Conference on General Relativity and Gravitational Physics Vietri sul Mare, Salerno, Italy http://www.sa.infn.it/sigrav04/ September 17-21, 2004: International Workshop on Particle Physics and the Early Universe (COSMO-04) University of Toronto, Canada http://www.cita.utoronto.ca/%7Ecosmo04/index.shtml September 20-25, 2004: Summer School on "Structure and Dynamics of Compact Objects" Albert Einstein Institute, Potsdam, Germany http://sfb.aei.mpg.de/School04/ September 23-25, 2004: XXVII Spanish Relativity Meeting Miraflores de la Sierra, Madrid, Spain http://gesalerico.ft.uam.es/ere2004/ere2004.html October 15-16, 2004: 14th Midwest Relativity Meeting (MWRM-14) University of Wisconsin, Milwaukee http://www.lsc-group.phys.uwm.edu/mwrm14/ December 13-17, 2004: 22nd Texas Symposium Stanford University, California http://texasatstanford.slac.stanford.edu/ December 15-18, 2004: 9th Annual Gravitational Wave Data Analysis Workshop Annecy-le-Vieux Particle Physics Laboratory, Annecy, France http://lappc-in39.in2p3.fr/GWDAW9/ January 11-14, 2005: International Conference on Relativity (ICR-2005) Amravati, India March 29 - 2 April, 2005: "Spacetime in Action: One Hundred Years of Relativity" Pavia, Italy April 5-8, 2005: "Geometry and Physics After 100 Years of Einstein's Relativity: 10 Years of the Albert Einstein Institute" Albert Einstein Institute, Potsdam, Germany http://www.aei.mpg.de/ ****************************************************************************** MEMBERS' ABSTRACTS at gr-qc, December 2003 - May 2004 We list here all new abstracts that we are aware of that have been submitted by our members to gr-qc, or which are cross-linked at gr-qc. (We have not searched for abstracts on other Los Alamos archives which are not crosslinked to gr-qc.) If you do not send your papers to gr-qc but would like to have them noted in the newsletters, please send them to the Editor. ----------------------------------------------------------------------------- gr-qc/0404123 From: John McNabb Date: Thu, 29 Apr 2004 21:00:28 GMT (199kb) Overview of the BlockNormal Event Trigger Generator Authors: J W C McNabb, M Ashley, L S Finn, E Rotthoff, A Stuver, T Summerscales, P Sutton, M Tibbits, K Thorne, K Zaleski Comments: GWDAW-8 proceedings, 6 pages, 2 figures In the search for unmodeled gravitational wave bursts, there are a variety of methods that have been proposed to generate candidate events from time series data. Block Normal is a method of identifying candidate events by searching for places in the data stream where the characteristic statistics of the data change. These change-points divide the data into blocks in which the characteristics of the block are stationary. Blocks in which these characteristics are inconsistent with the long term characteristic statistics are marked as Event-Triggers which can then be investigated by a more computationally demanding multi-detector analysis. ----------------------------------------------------------------------------- gr-qc/0401068 From: Alan Barnes Date: Thu, 15 Jan 2004 21:51:42 GMT (7kb) Purely magnetic spacetimes Authors: Alan Barnes Comments: 6 pages, no figures, LaTeX. To appear in the Proceedings of the 27th Spanish Relativity Meeting (Encuentros Relativistas Espanoles), Alicante, Spain. September,2003 Spacetimes in which the electric part of the Weyl tensor vanishes (relative to some timelike unit vector field) are said to be purely magnetic. Examples of purely magnetic spacetimes are known and are relatively easy to construct, if no restrictions are placed on the energy-momentum tensor. However it has long been conjectured that purely magnetic vacuum spacetimes (with or without a cosmological constant) do not exist. The history of this conjecture is reviewedand some advances made in the last year are described briefly. A generalisationof this conjecture first suggested for type D vacuum spacetimes by Ferrando andSaez is stated and proved in a number of special cases. Finally an approach to a general proof of the conjecture is described using the Newman-Penrose formalism based on a canonical null tetrad of the Weyl tensor. ----------------------------------------------------------------------------- gr-qc/0402070 From: Robert Bartnik Date: Mon, 16 Feb 2004 00:51:38 GMT (37kb) Phase space for the Einstein equations Authors: Robert Bartnik Comments: 33 pages, 0 figures, LaTeX2e, submitted to Comm Analysis and Geometry A Hilbert manifold structure is described for the ADM phase space of asymptotically flat initial data $(g,\pi)$ with local $H^2\times H^1$ Sobolev regularity. Solutions of the constraint equations form a Hilbert submanifold. A regularized RT Hamiltonian is defined and smooth on the full phase space and generates the Einstein evolution for any lapse-shift asymptotic to a (time) translation at infinity. Critical points for the total (ADM) mass, considered as a function on the Hilbert manifold of constraint solutions, arise precisely at initial data generating stationary vacuum spacetimes. ----------------------------------------------------------------------------- gr-qc/0405092 From: Robert Bartnik Date: Mon, 17 May 2004 23:35:04 GMT (49kb) The Constraint Equations Authors: Robert Bartnik, Jim Isenberg Comments: 34 pages, LaTeX, to appear in the proceedings of the 2002 Cargese meeting "50 Years of the Cauchy Problem, in honour of Y. Choquet-Bruhat", editors P.T.Chru\'sciel and H. Friedrich We review the properties of the constraint equations, from their geometric origin in hypersurface geometry through to their roles in the Cauchy problem and the Hamiltonian formulation of the Einstein equations. We then review properties of the space of solutions and construction techniques, including the conformal and conformal thin sandwich methods, the thin sandwich method, quasi-spherical and generalized QS methods, gluing techniques and the Corvino-Schoen projection. ----------------------------------------------------------------------------- gr-qc/0404129 From: Jefferson Crowder Date (v1): Fri, 30 Apr 2004 18:01:21 GMT (31kb) Date (revised v2): Mon, 3 May 2004 21:34:54 GMT (31kb) LISA Source Confusion Authors: Jeff Crowder, Neil J. Cornish Comments: 8 pages, 14 figures The Laser Interferometer Space Antenna (LISA) will detect thousands of gravitational wave sources. Many of these sources will be overlapping in the sense that their signals will have a non-zero cross-correlation. Such overlaps lead to source confusion, which adversely affects how well we can extract information about the individual sources. Here we study how source confusion impacts parameter estimation for galactic compact binaries, with emphasis on the effects of the number of overlaping sources, the time of observation, the gravitational wave frequencies of the sources, and the degree of the signal correlations. Our main findings are that the parameter resolution decays exponentially with the number of overlapping sources, and super-exponentially with the degree of cross-correlation. We also find that an extended mission lifetime is key to disentangling the source confusion as the parameter resolution for overlapping sources improves much faster than the usual square root of the observation time. ----------------------------------------------------------------------------- gr-qc/0312042 From: Neil J. Cornish Date: Sun, 7 Dec 2003 21:59:19 GMT (14kb) Rapid LISA Astronomy Authors: Neil J. Cornish Comments: 4 Pages, 2 Figures, RevTex A simple method is presented for removing the amplitude, frequency and phase modulations from the Laser Interferometer Space Antenna (LISA) data stream for sources at any sky location. When combined with an excess power trigger or the fast chirp transform, the total demodulation procedure allows the majority of LISA sources to be identified without recourse to matched filtering. ----------------------------------------------------------------------------- gr-qc/0402042 From: Antony Searle Date: Tue, 10 Feb 2004 00:50:10 GMT (5kb) The ACIGA Data Analysis programme Authors: Susan M Scott, Antony C Searle, Benedict J Cusack, David E McClelland Comments: 10 pages, 0 figures, accepted, Classical and Quantum Gravity, (Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 2003) Journal-ref: Class.Quant.Grav. 21 (2004) S853-S856 The Data Analysis programme of the Australian Consortium for Interferometric Gravitational Astronomy (ACIGA) was set up in 1998 by the first author to complement the then existing ACIGA programmes working on suspension systems, lasers and optics, and detector configurations. The ACIGA Data Analysis programme continues to contribute significantly in the field; we present an overview of our activities. ----------------------------------------------------------------------------- gr-qc/0403031 From: John Steele Date: Sun, 7 Mar 2004 21:49:37 GMT (28kb) Calculating Symmetries in Newman-Tamburino metrics Authors: John D. Steele In this paper I show that the Newman-Tamburino spherical metrics always admit a Killing vector, correcting a claim by Collinson and French, (1967 J. Math. Phys. 8 701) and also admit a homothety. A similar calculation is given for the limit of the Newman-Tamburino cylindrical metric. ----------------------------------------------------------------------------- gr-qc/0402069 From: Matt Visser Date (v1): Sun, 15 Feb 2004 21:33:53 GMT (16kb) Date (revised v2): Sun, 22 Feb 2004 21:23:25 GMT (16kb) Dirty black holes: Spacetime geometry and near-horizon symmetries Authors: A J M Medved, Damien Martin, Matt Visser Comments: 23 pages, plain LaTeX. V2: Discussion regarding extremal horizons corrected. Two references addded. No other physics changes We consider the spacetime geometry of a static but otherwise generic black hole (that is, the horizon geometry and topology are not necessarily spherically symmetric). It is demonstrated, by purely geometrical techniques, that the curvature tensors, and the Einstein tensor in particular, exhibit a very high degree of symmetry as the horizon is approached. Consequently, the stress-energy tensor will be highly constrained near any static Killing horizon. More specifically, it is shown that -- at the horizon -- the stress-energy tensor block-diagonalizes into "transverse" and "parallel" blocks, the transverse components of this tensor are proportional to the transverse metric, and these properties remain invariant under static conformal deformations. Moreover, we speculate that this geometric symmetry underlies Carlip's notion of an asymptotic near-horizon conformal symmetry controlling the entropy of a black hole. ----------------------------------------------------------------------------- gr-qc/0403026 From: Matt Visser Date: Fri, 5 Mar 2004 05:52:52 GMT (16kb) Dirty black holes: Symmetries at stationary non-static horizons Authors: A J M Medved, Damien Martin, Matt Visser Comments: 21 pages; plain LaTeX We establish that the Einstein tensor takes on a highly symmetric form near the Killing horizon of any stationary but non-static (and non-extremal) black hole spacetime. [This follows up on a recent article by the current authors, gr-qc/0402069, which considered static black holes.] Specifically, at any such Killing horizon -- irrespective of the horizon geometry -- the Einstein tensor block-diagonalizes into "transverse" and "parallel" blocks, and its transverse components are proportional to the transverse metric. Our findings are supported by two independent procedures; one based on the regularity of the on-horizon geometry and another that directly utilizes the elegant nature of a bifurcate Killing horizon. It is then argued that geometrical symmetries will severely constrain the matter near any Killing horizon. We also speculate on how this may be relevant to certain calculations of the black hole entropy. ----------------------------------------------------------------------------- astro-ph/0403336 From: Matt Visser Date: Mon, 15 Mar 2004 04:50:43 GMT (10kb) Power-laws from critical gravitational collapse: The mass distribution of subsolar objects Authors: Matt Visser (Victoria University of Wellington) Nicolas Yunes (Pennsylvania State University) Comments: 12 pages: plain LaTeX Report-no: CGPG-03/10-6 Critical gravitational collapse and self similarity are used to probe the mass distribution of subsolar objects. We demonstrate that at very low mass the distribution is given by a power law, with an exponent opposite in sign to that observed at high-mass regime. We further show that the value of this low-mass exponent is in principle calculable via dynamical systems theory applied to gravitational collapse. Qualitative agreement between numerical experiments and observational data is good. ----------------------------------------------------------------------------- astro-ph/0404434 From: Matt Visser Date: Wed, 21 Apr 2004 22:21:49 GMT (14kb) Universality of the subsolar mass distribution from critical gravitational collapse Authors: Matt Visser (Victoria University of Wellington), Nicolas Yunes (Pennsylvania State University) Comments: 17 pages, uses aastex Self-similarity induced by critical gravitational collapse is used as a paradigm to probe the mass distribution of subsolar objects. At large mass (solar mass and above) there is widespread agreement as to both the form and parameter values arising in the mass distribution of stellar objects. At subsolar mass there is still considerable disagreement as to the qualitative form of the mass distribution, let alone the specific parameter values characterizing that distribution. For the first time, the paradigm of critical gravitational collapse is applied to several concrete astrophysical scenarios to derive robust qualitative features of the subsolar mass distribution. We further contrast these theoretically derived ideas with the observational situation. In particular, we demonstrate that at very low mass the distribution is given by a power law, with an exponent opposite in sign to that observed in the high-mass regime. The value of this low-mass exponent is in principle calculable via dynamical systems theory applied to gravitational collapse. Qualitative agreement between theory, numerical experiments, and observational data is good, though quantitative issues remain troublesome. ----------------------------------------------------------------------------- gr-qc/0405103 From: Sayan Kar Date: Wed, 19 May 2004 09:43:30 GMT (7kb) Quantifying energy condition violations in traversable wormholes Authors: Sayan Kar (IITKgp, India), Naresh Dadhich (IUCAA, India), Matt Visser (Victoria University of Wellington, New Zealand) Comments: 8 pages, no figures, to appear in Proceedings of ICGC04, Cochin, India (January 5-10,2004) The 'theoretical' existence of traversable Lorentzian wormholes in the classical, macroscopic world is plagued by the violation of the well-known energy conditions of General Relativity. In this brief article we show : (i) how the extent of violation can be quantified using certain volume integrals (ii) whether this 'amount of violation' can be minimised for some specific cut-and-paste geometric constructions. Examples and possibilities are also outlined. ----------------------------------------------------------------------------- gr-qc/0403093 From: Albert Lazzarini Date: Tue, 23 Mar 2004 01:49:47 GMT (373kb) Optimal combination of signals from co-located gravitational wave interferometers for use in searches for a stochastic background Authors: A. Lazzarini, S. Bose, P. Fritschel, M. McHugh, T. Regimbau, K. Reilly, J.D. Romano, J. T. Whelan, S. Whitcomb, B. F. Whiting Comments: 14 pages, 4 figures, submitted to Physical Review D This article derives an optimal (i.e., unbiased, minimum variance) estimator for the pseudo-detector strain for a pair of co-located gravitational wave interferometers (such as the pair of LIGO interferometers at its Hanford Observatory), allowing for possible instrumental correlations between the two detectors. The technique is robust and does not involve any assumptions or approximations regarding the relative strength of gravitational wave signals in the detector pair with respect to other sources of correlated instrumental or environmental noise. An expression is given for the effective power spectral density of the combined noise in the pseudo-detector. This can then be introduced into the standard optimal Wiener filter used to cross-correlate detector data streams in order to obtain an optimal estimate of the stochastic gravitational wave background. In addition, a dual to the optimal estimate of strain is derived. This dual is constructed to contain no gravitational wave signature and can thus be used as on "off-source" measurement to test algorithms used in the "on-source" observation. ----------------------------------------------------------------------------- gr-qc/0405138 From: Chengmin Zhang Date: Fri, 28 May 2004 14:22:08 GMT (64kb) Dirac Spin Precession in Kerr Spacetime by the parallelism description Authors: C.M. Zhang Comments: 6 pages In the framework of parallelism general relativity (PGR), the Dirac particle spin precession in the rotational gravitational field is studied. In terms of the equivalent tetrad of Kerr frame, we investigate the torsion axial-vector spin coupling in PGR. In the case of the weak field and slow rotation approximation, we obtain that the torsion axial-vector has the dipole-like structure, but different from the gravitomagnetic field, which indicates that the choice of the Kerr tetrad will influence on the physics interpretation of the axial-vector spin coupling. ****************************************************************************** ABSTRACTS FROM THE LIGO SCIENTIFIC COLLABORATION at gr-qc, June 2003 - May 2004 The LIGO Scientific Collaboration is a consortium of scientific institutions doing work on the Laser Interferometer Gravitational-Wave Observatory (LIGO), which consists of two laser interferometers 3030 km apart, one at Hanford, Washington State and the other at Livingston, Louisiana. The LIGO Scientific Collaboration includes ASGRG members David McClelland, Susan Scott and Antony Searle, who are all at the Australian National University. ----------------------------------------------------------------------------- gr-qc/0308043 From: David Shoemaker Date (v1): Thu, 14 Aug 2003 12:40:21 GMT (641kb) Date (revised v2): Fri, 15 Aug 2003 21:44:22 GMT (641kb) Date (revised v3): Wed, 17 Sep 2003 18:58:22 GMT (643kb) Detector Description and Performance for the First Coincidence Observations between LIGO and GEO Authors: The LIGO Scientific Collaboration: B. Abbott, et al Comments: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial changes Journal-ref: Nucl.Instrum.Meth. A517 (2004) 154-179 For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data. ----------------------------------------------------------------------------- gr-qc/0308050 From: M. Alessandra Papa Date: Thu, 14 Aug 2003 22:31:14 GMT (479kb) Setting upper limits on the strength of periodic gravitational waves using the first science data from the GEO600 and LIGO detectors Authors: The LIGO Scientific Collaboration: B.Abbott, et al Comments: 16 pages,8 figures Report-no: LIGO-P030008-E-Z Journal-ref: Phys.Rev. D69 (2004) 082004 Data collected by the GEO600 and LIGO interferometric gravitational wave detectors during their first observational science run were searched for continuous gravitational waves from the pulsar J1939+2134 at twice its rotation frequency. Two independent analysis methods were used and are demonstrated in this paper: a frequency domain method and a time domain method. Both achieve consistent null results, placing new upper limits on the strength of the pulsar's gravitational wave emission. A model emission mechanism is used to interpret the limits as a constraint on the pulsar's equatorial ellipticity. ----------------------------------------------------------------------------- gr-qc/0308069 From: Patrick Brady Date: Thu, 21 Aug 2003 13:58:21 GMT (460kb) Analysis of LIGO data for gravitational waves from binary neutron stars Authors: The LIGO Scientific Collaboration: B.Abbott, et al Comments: 17 pages, 9 figures We report on a search for gravitational waves from coalescing compact binary systems in the Milky Way and the Magellanic Clouds. The analysis uses data taken by two of the three LIGO interferometers during the first LIGO science run and illustrates a method of setting upper limits on inspiral event rates using interferometer data. The analysis pipeline is described with particular attention to data selection and coincidence between the two interferometers. We establish an observational upper limit of $\mathcal{R}<$1.7 \times 10^{2}$ per year per Milky Way Equivalent Galaxy (MWEG), with 90% confidence, on the coalescence rate of binary systems in which each component has a mass in the range 1-3 $M_\odot$. ----------------------------------------------------------------------------- gr-qc/0312056 From: Alan J. Weinstein Date (v1): Tue, 9 Dec 2003 19:19:30 GMT (139kb) Date (revised v2): Wed, 10 Dec 2003 03:56:48 GMT (139kb) Date (revised v3): Tue, 6 Jan 2004 18:15:35 GMT (139kb) Date (revised v4): Tue, 30 Mar 2004 17:59:20 GMT (140kb) First upper limits from LIGO on gravitational wave bursts Authors: LIGO Scientific Collaboration: B. Abbott, et al Comments: 21 pages, 15 figures, accepted by Phys Rev D. Fixed a few small typos and updated a few references Report-no: LIGO-P030011 Journal-ref: Phys.Rev.D (2004) We report on a search for gravitational wave bursts using data from the first science run of the LIGO detectors. Our search focuses on bursts with durations ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivityband of 150 to 3000 Hz. We bound the rate for such detected bursts at less than1.6 events per day at 90% confidence level. This result is interpreted in termsof the detection efficiency for ad hoc waveforms (Gaussians and sine-Gaussians)as a function of their root-sum-square strain h_{rss}; typical sensitivities lie in the range h_{rss} ~ 10^{-19} - 10^{-17} strain/rtHz, depending on waveform. We discuss improvements in the search method that will be applied to future science data from LIGO and other gravitational wave detectors. ----------------------------------------------------------------------------- gr-qc/0312088 From: Joseph Romano Date: Fri, 19 Dec 2003 18:00:01 GMT (723kb) Analysis of First LIGO Science Data for Stochastic Gravitational Waves Authors: LIGO Scientific Collaboration: B. Abbott, et al Comments: 26 pages, 17 figures We present the analysis of between 50 and 100 hrs of coincident interferometric strain data used to search for and establish an upper limit on a stochastic background of gravitational radiation. These data come from the first LIGO science run, during which all three LIGO interferometers were operated over a 2-week period spanning August and September of 2002. The method of cross-correlating the outputs of two interferometers is used for analysis. We describe in detail practical signal processing issues that arise when working with real data, and we establish an observational upper limit on a f^{-3} power spectrum of gravitational waves. Our 90% confidence limit is Omega_0 h_{100}^2 < 23 in the frequency band 40 to 314 Hz, where h_{100} is the Hubble constant in units of 100 km/sec/Mpc and Omega_0 is the gravitational wave energy density per logarithmic frequency interval in units of the closure density. This limit is approximately 10^4 times better than the previous, broadband direct limit using interferometric detectors, and nearly 3 times better than the best narrow-band bar detector limit. As LIGO and other worldwide detectors improve in sensitivity and attain their design goals, the analysis procedures described here should lead to stochastic background sensitivity levels of astrophysical interest. -----------------------------------------------------------------------------