J/ApJ/814/128 Timing noise & astrometry of Fermi-LAT pulsars (Kerr+, 2015)
Timing gamma-ray pulsars with the Fermi Large Area Telescope: timing noise and
astrometry.
Kerr M., Ray P.S., Johnston S., Shannon R.M., Camilo F.
<Astrophys. J., 814, 128 (2015)>
=2015ApJ...814..128K 2015ApJ...814..128K (SIMBAD/NED BibCode)
ADC_Keywords: Pulsars ; Gamma rays ; Radio sources
Keywords: pulsars: general
Abstract:
We have constructed timing solutions for 81 γ-ray pulsars
covering more than five years of Fermi data. The sample includes 37
radio-quiet or radio-faint pulsars which cannot be timed with other
telescopes. These timing solutions and the corresponding pulse times
of arrival are prerequisites for further study, e.g., phase-resolved
spectroscopy or searches for mode switches. Many γ-ray pulsars
are strongly affected by timing noise (TN), and we present a new
method for characterizing the noise process and mitigating its effects
on other facets of the timing model. We present an analysis of TN over
the population using a new metric for characterizing its strength and
spectral shape, namely, its time-domain correlation. The dependence of
the strength on ν and {dot}ν is in good agreement with previous
studies. We find that noise process power spectra S(f) for unrecycled
pulsars are steep, with strong correlations over our entire data set
and spectral indices s(f)∝f-α of α∼5-9. One
possible explanation for these results is the occurrence of unmodeled,
episodic "microglitches". Finally, we show that our treatment of TN
results in robust parameter estimation, and in particular we measure a
precise timing position for each pulsar. We extensively validate our
results with multi-wavelength astrometry, and using our updated
position, we firmly identify the X-ray counterpart of PSR J1418-6058.
Description:
We analyze 5.2 years of Source-class Pass 7 Fermi-LAT data acquired
between 2008 August 4 (MET239557418) and 2013 October 21 (MET404063018).
For a subset of our pulsars, we have obtained high-quality timing data
from radio telescopes. Most data come from the Parkes campaign
(Weltevrede et al. 2010, J/other/PASA/27.64).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 106 61 Positions from Fermi timing and from multi-wavelength
(MWL) observations for normal ("unrecycled") pulsars
table2.dat 104 19 Positions from Fermi timing and from multi-wavelength
(MWL) observations for millisecond ("recycled") pulsars
refs.dat 56 31 References
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See also:
J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)
J/ApJS/208/17 : 2nd Fermi LAT cat. of gamma-ray pulsars (2PC) (Abdo+, 2013)
J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)
J/MNRAS/414/1679 : 315 glitches in 102 pulsar rotations (Espinoza+, 2011)
J/other/PASA/27.64 : Parkes Radio Telescope pulsar timing (Weltevrede+, 2010)
J/A+A/492/923 : Pulsar Timing for Fermi Gamma-ray Telescope (Smith+, 2008)
J/MNRAS/372/777 : Parkes Multibeam Pulsar Survey. VI. (Lorimer+, 2006)
J/MNRAS/353/1311 : Long-term timing observations of 374 pulsars (Hobbs+, 2004)
J/AZh/79/501 : Normal+millisecond pulsars radio luminosities (Kuz'min, 2002)
J/MNRAS/328/855 : Pulsar timing at UAO (Wang+, 2001)
http://fermi.gsfc.nasa.gov/ssc/data/access/lat/ephems/ : Pulsars ephemerides
http://www.slac.stanford.edu/~kerrm/fermi_pulsar_timing/ : Fermi PSR pipeline
overview
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- PSR PSR name (JHHMM+DDMM)
12- 13 I2 d Cad [7/58] Time of arrival (TOA) cadence
15- 17 A3 --- TN Best-fit timing noise (TN) model (1)
19- 20 I2 h RAh Hour of right ascension (J2000) (2)
22- 23 I2 min RAm Minute of right ascension (J2000)
25- 31 F7.4 s RAs Second of right ascension (J2000)
33- 38 F6.4 s e_RAs [0/2.4] RAs uncertainty
40 A1 --- DE- sign of declination (J2000) (2)
41- 42 I2 deg DEd Degree of declination (J2000) (2)
44- 45 I2 arcmin DEm Arcminute of declination (J2000)
47- 52 F6.3 arcsec DEs Arcsecond of declination (J2000)
54- 59 F6.3 arcsec e_DEs [0.001/25] DEs uncertainty
61- 62 I2 h RAMh ? MWL hour of right ascension (J2000) (2)
64- 65 I2 min RAMm ? Minute of right ascension (J2000)
67- 73 F7.4 s RAMs ? Second of right ascension (J2000)
75 A1 --- l_RAMs Limit flag on e_RAMs
76- 81 F6.4 s e_RAMs [0/2.4]? RAMs uncertainty
83 A1 --- DEM- MWL sign of declination (J2000) (2)
84- 85 I2 deg DEMd ? MWL degree of declination (J2000) (2)
87- 88 I2 arcmin DEMm ? Arcminute of declination (J2000)
90- 95 F6.3 arcsec DEMs ? Arcsecond of declination (J2000)
97 A1 --- l_DEMs Limit flag on DEMs
98-102 F5.3 arcsec e_DEMs [0/25]? DEMs uncertainty
104-106 A3 --- Ref MWL astrometry reference(s)
(see refs.dat file)
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Note (1): Models as follows:
NTN = no timing noise: A=0 in Equation (2) below
FPL = pure power law with fixed spectral index: A>0, α=3, fc≪1/T
PL = pure power law with free spectral index: A>0, α>0, fc≪1/T
BPL = broken power law with low frequency cutoff: A>0, α>0, fc>0
Equation (2): S(f)=A2[1+(f/fc)2]-α/2,
with the "corner frequency" fc providing a low-frequency saturation,
α the spectral index, and A the amplitude; T is the length of
the data set. See sections 3.1 and 3.2.
Note (2): All positions are computed at the epoch MJD 55555 (2010 December 25),
and positions reported in the literature are advanced to this epoch,
with propagation of error, when proper motions are available.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1 A1 --- Ref Reference code
3- 21 A19 --- BibCode Bibcode
23- 39 A17 --- Aut First author's name
42- 56 A15 --- Comm Comment
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 03-Mar-2016