An analysis of the timing irregularities for 366 pulsars

View previous topic View next topic Go down

An analysis of the timing irregularities for 366 pulsars

Post by Borislav on 24th December 2009, 4:12 am

http://arxiv.org/abs/0912.4537
on 16 pages
PSR B1540−06: A significant periodicity is observed with a period of 4.38 yr. It is possible that the periodic signal is caused by the orbital motion of an unmodelled Earth-mass planetary companion. Including such a companion in the timing fit indicates an orbital period of Pb = 1530(3) days, a projected semi-major axis of a sin i = 0.00393(7) and an epoch of periastron of T0 = 48992(5). The rms timing residual decreases from 7.0ms without subtracting a cubic term or binary companion, 3.0ms after subtracting the cubic term alone and 1.1ms after subtracting the cubic and binary parameters. However, significant structure remains in the timing residuals after the removal of these terms and we do not consider this as compelling evidence for a planetary companion. In the top-left panel of Figure 15 we show one oscillation of the timing residuals. For this pulsar the radii of curvature (and hence the magnitude of the local value of ˙ ) at the maxima and minima are similar.

on 18 pages
For completeness we note that it has often been proposed that PSR B0329+59 has planetary companions. Demia´nski & Pr´oszy´nski (1979) and Bailes, Lyne & Shemar (1993) found a three-year periodicity in the timing residuals. However, Shabanova (1995) found no clear evidence for a three-year period, but did present the possibility of a 16.8 yr periodicity. Konacki et al. (1999) argued that there is no evidence for planetary companions. Our data set, which spans 36.5 yr, also shows no evidence for either a 3 yr nor a 16.8 yr periodicity and we believe that the timing noise for PSR B0329+59 has a similar form to the other pulsars in our sample.

Borislav
Jovian
Jovian

Number of posts : 556
Registration date : 2008-11-12

View user profile

Back to top Go down

Re: An analysis of the timing irregularities for 366 pulsars

Post by Stalker on 24th December 2009, 5:59 am

How many planets there found? 0?
avatar
Stalker
Jovian
Jovian

Number of posts : 526
Age : 26
Location : Paris, France
Registration date : 2008-06-16

View user profile http://exoplanetes.wetpaint.com/

Back to top Go down

Re: An analysis of the timing irregularities for 366 pulsars

Post by Borislav on 24th December 2009, 6:22 am

In article write only about suspicions beside PSR B1540-06. But in general millisecond pulsar in sample little (the majority since period about seconds), where sensitivity for the Earth-mass planets maximum. In article note that their sample pulsar very big.


Timing noise analyses with large samples of pulsars have been limited by the relatively short data spans studied. Long data-spans have been analysed in a few papers, but for only a small number of pulsars. For instance, Baykal et al. (1999) analysed four pulsars timed for 14 yr. Shabanova (1995) observed PSR B0329+54 for 16 yr, Stairs, Lyne & Shemar (2000) reported on 13 yr of PSR B1828
11 observations and Shabanova, Lyne & Urama (2001) analysed PSR B164203 over a 30 yr data span. More recently, the millisecond pulsar PSR J1713+0747 was observed for 12 yr (Splaver et al. 2005) and the young pulsar PSR B150958 for 21 yr (Livingstone et al. 2005). Most of the analysis has concentrated on obtaining high quality spectral estimates of the timing residuals or fitting a simple model to the timing residuals of a single pulsar. We note that our sample is 20 times larger than the previous large study of pulsar timing noise (D’Alessandro et al. 1995) in terms of the number of years of rotational history studied.


The Jodrell Bank data archive of pulsar observations contains over 6000 years of pulsar rotational history.

At the average 6000/366=17 measurements of the period of one pulsar of the sample.


Last edited by Borislav on 24th December 2009, 8:26 am; edited 1 time in total

Borislav
Jovian
Jovian

Number of posts : 556
Registration date : 2008-11-12

View user profile

Back to top Go down

Re: An analysis of the timing irregularities for 366 pulsars

Post by Borislav on 24th December 2009, 6:43 am

Can be concluded from the article that the planets (not only gas giants, but also Earth-mass) are very rare in pulsars?

Borislav
Jovian
Jovian

Number of posts : 556
Registration date : 2008-11-12

View user profile

Back to top Go down

Re: An analysis of the timing irregularities for 366 pulsars

Post by Sirius_Alpha on 24th December 2009, 8:44 am

It would seem that way.
Perhaps planets do not often survive the post main sequence evolution of their stars.

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3443
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: An analysis of the timing irregularities for 366 pulsars

Post by Lazarus on 24th December 2009, 10:21 am

Pulsar planets aren't really indications of planets surviving post-main sequence evolution though: mass loss associated with a supernova explosion would tend to unbind the planetary system, sending the planets off into interstellar space (you might save one or two planets if the supernova explosion is asymmetric and the resultant pulsar is kicked in a convenient direction, but the resulting system would be highly elliptical). Instead we're probably dealing with objects that formed after the supernova explosion, either from fallback discs, or tidally-disrupted companion stars.
avatar
Lazarus
dG star
dG star

Number of posts : 2805
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: An analysis of the timing irregularities for 366 pulsars

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum