Φανταστικό timing... Και ενώ σκεφτόμουν τα σχετικά με τον διπλό pulsar PSR J0737-3039A/B, ο οποίος αποτελεί ένα φανταστικό τεστ της γενικής σχετικότητας τόσο στην περιοχή του ασθενούς βαρυτικού πεδίο όσο και σε περιοχές που πλησιάζουν στο ισχυρό πεδίο, και μάζευα κάποια σχετικά links δεδομένου και του ότι σήμερα ανέβηκε στο arXiv και το άρθρο, The Double Pulsar System in its 8th anniversary, κοιτάζω τα e-mails μου και μόλις μου έχει έρθει ένα από την Ακαδημία όπου ανακοινώνεται το παρακάτω σεμινάριο:
The Research Center for Astronomy and Applied Mathematics of the Academy of Athens invites you to the Seminar:
Date: Tuesday 9 October 2012
Time: 12:00
Location: RCAAM Seminars Room (Soranou Efesiou 4, Athens; see map)
Speaker: Maxim Lyutikov (Purdue University & INAF Osservatorio Astrofisico di Arcetri)
Title: The Double Pulsar as a Probe of Fundamental Physics
Abstract:
The discovery of the double radio pulsar system, PSR J0737-3039A/B, surpassed most expectations, both theoretical and observational, as a tool to probe general relativity, stellar evolution and pulsar theories. I will describe rich observational properties of the system, like eclipses, orbital variations in magnetospheric activity, evidence for relativistic reconnection, trapped magnetospheric particles. The system allows a measurement of the relativistic spin precession and offers a new test of theories of gravity in strong regime. We can also pin-point the location and the shape of the region producing enigmatic coherent radio emission.
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Research Center for Astronomy and Applied Mathematics of the Academy of Athens
Soranou Efesiou 4, Athens, GR-11527
E-mail: keaem AT academyofathens.gr
Web: http://astro.academyofathens.gr/
Το φανταστικό της υπόθεσης είναι ότι θυμόμουν ότι είχε γίνει μια σχετική διάλεξη και στο Perimeter Institute πριν ένα χρόνο πάνω στον συγκεκριμένο διπλό pulsar την οποία είχα δει, οπότε μόλις είχα κοιτάξει για να βρω το παρακάτω link,
Διάλεξη στο Perimeter Institute:
The Double Pulsar: testing GR in strong regime
Speaker(s): Maxim Lyutikov
Abstract: The long awaited discovery of the double radio pulsar system, PSR J0737-3039A/B, surpassed most expectations, both theoretical and observational, as a tool to probe general relativity, stellar evolution and pulsar theories. The Double Pulsar provides a unique and the most complete and clean test of theories of gravity in a regime sensitive to possible strong-gravitational self-field effects. All six post-Keplerian parameters have been measured (including the measurement of the relativistic spin precession), some parameters to a precision of 10^{-4}.
Απίστευτο timing έτσι...
Τα παρατηρησιακά constraints στα οποία αναφέρεται το Abstract της διάλεξης απεικονίζονται στο παρακάτω σχήμα από την εργασία στο περιοδικό Science των Kramer et al., Science 314, 97 (2006),
Fig. 1. Graphical summary of tests of GR parameters. Constraints on the masses of the two stars (A and B) in the PSR J0737-3039A/B binary system are shown; the inset is an expanded view of the region of principal interest. Shaded regions are forbidden by the individual mass functions of A and B because sin i must be ≤1. Other constraining parameters are shown as pairs of lines, where the separation of the lines indicates the measurement uncertainty. For the diagonal pair of lines labeled as R, representing the mass ratio derived from the measured semimajor axes of the A and B orbits, the measurement precision is so good that the line separation becomes apparent only in the inset. The other constraints shown are based on the measured PK parameters interpreted within the framework of general relativity. The PK parameter describes the relativistic precession of the orbit, γ combines gravitational redshift and time dilation, and Ṗb represents the measured decrease in orbital period due to the emission of gravitational waves. The two PK parameters s and r reflect the observed Shapiro delay, describing a delay that is added to the pulse arrival times when propagating through the curved space-time near the companion. The intersection of all line pairs is consistent with a single point that corresponds to the masses of A and B. The current uncertainties in the observed parameters determine the size of this intersection area, which is marked in blue and reflects the achieved precision of this test of GR and the mass determination for A and B.
Συνιστώ σε όποιον ενδιαφέρεται να πάει να την παρακολουθήσει την ομιλία γιατί θα έχει πολύ ενδιαφέρον.
Και ένα review άρθρο πάνω στο θέμα γενικά: Testing General Relativity with Pulsar Timing
