MICROARCSECOND VLBI PULSAR ASTROMETRY WITH PSRπ. I. TWO BINARY MILLISECOND PULSARS WITH WHITE DWARF COMPANIONS

Model-independent distance constraints to binary millisecond pulsars (MSPs) are of great value to both the timing observations of the radio pulsars, and multiwavelength observations of their companion stars. Very Long Baseline Interferometry (VLBI) astrometry can be employed to provide these model-independent distances with very high precision via the detection of annual geometric parallax. Using the Very Long Baseline Array, we have observed two binary millisecond pulsars, PSR J1022+1001 and J2145-0750, over a two-year period and measured their distances to be 700 +14 -10 pc and 613 +16 -14 pc respectively. We use the well-calibrated distance in conjunction with revised analysis of optical photometry to tightly constrain the nature of their massive (M ~ 0.85 Msun) white dwarf companions. Finally, we show that several measurements of their parallax and proper motion of PSR J1022+1001 and PSR J2145-0750 obtained by pulsar timing array projects are incorrect, differing from the more precise VLBI values by up to 5 sigma. We investigate possible causes for the discrepancy, and find that imperfect modeling of the solar wind is a likely candidate for the timing model errors given the low ecliptic latitude of these two pulsars.

[1]  A. Deller,et al.  A PARALLAX DISTANCE AND MASS ESTIMATE FOR THE TRANSITIONAL MILLISECOND PULSAR SYSTEM J1023+0038 , 2012, 1207.5670.

[2]  D. Lorimer,et al.  ON PULSAR DISTANCE MEASUREMENTS AND THEIR UNCERTAINTIES , 2012, 1206.0428.

[3]  P. Bergeron,et al.  AN IMPROVED SPECTROSCOPIC ANALYSIS OF DA WHITE DWARFS FROM THE SLOAN DIGITAL SKY SURVEY DATA RELEASE 4 , 2011, 1102.0056.

[4]  Dimitrios Psaltis,et al.  ON THE MASS DISTRIBUTION AND BIRTH MASSES OF NEUTRON STARS , 2012, 1201.1006.

[5]  W. M. Goss,et al.  Very Long Baseline Array Measurement of Nine Pulsar Parallaxes , 2002 .

[6]  Andre Heck,et al.  Information Handling in Astronomy - Historical Vistas , 2002 .

[7]  Daniel Foreman-Mackey,et al.  emcee: The MCMC Hammer , 2012, 1202.3665.

[8]  Tao An,et al.  Very Long Baseline Interferometry with the SKA , 2014, 1412.5971.

[9]  R. Karuppusamy,et al.  High-precision timing of 42 millisecond pulsars with the European Pulsar Timing Array , 2016, 1602.08511.

[10]  Revised bolometric corrections and interstellar extinction coefficients for the ACS and WFPC2 photometric systems , 2008, 0804.0498.

[11]  M. J. Reid,et al.  Microarcsecond Radio Astrometry , 2013, 1312.2871.

[12]  A. Deller,et al.  Extremely High Precision VLBI Astrometry of PSR J0437–4715 and Implications for Theories of Gravity , 2008, 0808.1594.

[13]  W. Brisken,et al.  PRECISION SOUTHERN HEMISPHERE PULSAR VLBI ASTROMETRY: TECHNIQUES AND RESULTS FOR PSR J1559–4438 , 2008, 0808.1598.

[14]  D. A. García-Hernández,et al.  THE TENTH DATA RELEASE OF THE SLOAN DIGITAL SKY SURVEY: FIRST SPECTROSCOPIC DATA FROM THE SDSS-III APACHE POINT OBSERVATORY GALACTIC EVOLUTION EXPERIMENT , 2013, 1307.7735.

[15]  James M. Cordes,et al.  Pulsar distances and the galactic distribution of free electrons , 1993 .

[16]  The parallax, mass and age of the PSR J2145-0750 binary system , 2004, astro-ph/0406634.

[17]  W. Alef,et al.  DiFX-2: A More Flexible, Efficient, Robust, and Powerful Software Correlator , 2011, 1101.0885.

[18]  Sergei M. Kopeikin.  Proper Motion of Binary Pulsars as a Source of Secular Variations of Orbital Parameters , 1996 .

[19]  J. Cordes,et al.  THE BENEFITS OF VLBI ASTROMETRY TO PULSAR TIMING ARRAY SEARCHES FOR GRAVITATIONAL RADIATION , 2012, 1210.2469.

[20]  Andrew E. Dolphin,et al.  WFPC2 Stellar Photometry with HSTphot , 2000, astro-ph/0006217.

[21]  D. Stinebring,et al.  THE NANOGRAV NINE-YEAR DATA SET: OBSERVATIONS, ARRIVAL TIME MEASUREMENTS, AND ANALYSIS OF 37 MILLISECOND PULSARS , 2015, 1505.07540.

[22]  J. Liebert,et al.  A COMPREHENSIVE SPECTROSCOPIC ANALYSIS OF DB WHITE DWARFS , 2011, 1105.5433.

[23]  W. Goss,et al.  Submitted to the Astrophysical Journal Preprint typeset using L ATEX style emulateapj v. 2/19/04 PRECISION ASTROMETRY WITH THE VERY LONG BASELINE ARRAY: PARALLAXES AND PROPER MOTIONS FOR 14 PULSARS , 2022 .

[24]  Nrl,et al.  Getting Its Kicks: A VLBA Parallax for the Hyperfast Pulsar B1508+55 , 2005, astro-ph/0509031.

[25]  Eric W. Greisen,et al.  AIPS, the VLA, and the VLBA , 2003 .

[26]  W. M. Goss,et al.  VLBA Measurement of Nine Pulsar Parallaxes , 2002, astro-ph/0204105.

[27]  J. Cordes,et al.  SYSTEMATIC AND STOCHASTIC VARIATIONS IN PULSAR DISPERSION MEASURES , 2015, 1512.02203.

[28]  Patrick Charlot,et al.  The International Celestial Reference Frame as Realized by Very Long Baseline Interferometry , 1998 .

[29]  M. Bailes,et al.  Timing analysis for 20 millisecond pulsars in the Parkes Pulsar Timing Array , 2015, 1510.04434.

[30]  A. Deller,et al.  VLBI ASTROMETRY OF PSR J2222–0137: A PULSAR DISTANCE MEASURED TO 0.4% ACCURACY , 2013, 1305.4865.

[31]  T. Damour,et al.  On the orbital period change of the binary pulsar PSR 1913+16 , 1991 .

[32]  D. Stinebring,et al.  The International Pulsar Timing Array: First Data Release , 2016, 1602.03640.

[33]  C. Gwinn,et al.  Measurement of pulsar parallaxes by VLBI , 1986 .

[34]  Jean-Luc Starck,et al.  Astronomical Data Analysis , 2007 .

[35]  A. Deller,et al.  PRECISION SOUTHERN HEMISPHERE VLBI PULSAR ASTROMETRY. II. MEASUREMENT OF SEVEN PARALLAXES , 2009, 0906.3897.

[36]  A. S. Fruchter,et al.  Drizzle: A Method for the Linear Reconstruction of Undersampled Images , 1998 .

[37]  A. T. Deller,et al.  DiFX: A Software Correlator for Very Long Baseline Interferometry Using Multiprocessor Computing Environments , 2007, astro-ph/0702141.

[38]  A. Deller,et al.  mJIVE-20: A SURVEY FOR COMPACT mJy RADIO OBJECTS WITH THE VERY LONG BASELINE ARRAY , 2013, 1310.8191.

[39]  Z. Arzoumanian,et al.  THE NANOGRAV NINE-YEAR DATA SET: ASTROMETRIC MEASUREMENTS OF 37 MILLISECOND PULSARS , 2015, 1509.08982.

[40]  Douglas P. Finkbeiner,et al.  MEASURING REDDENING WITH SLOAN DIGITAL SKY SURVEY STELLAR SPECTRA AND RECALIBRATING SFD , 2010, 1012.4804.

[41]  Eugene Magnier,et al.  A THREE-DIMENSIONAL MAP OF MILKY WAY DUST , 2015, 1507.01005.

[42]  Andrew E. Dolphin,et al.  A Revised Characterization of the WFPC2 CTE Loss , 2009, 0906.3557.

[43]  O. Titov,et al.  ON THE CONNECTION OF THE APPARENT PROPER MOTION AND THE VLBI STRUCTURE OF COMPACT RADIO SOURCES , 2011, 1103.3963.

[44]  M. Kramer,et al.  Formation of millisecond pulsars with CO white dwarf companions – II. Accretion, spin-up, true ages and comparison to MSPs with He white dwarf companions , 2012, 1206.1862.

[45]  Jeff Wagg,et al.  Advancing Astrophysics with the Square Kilometre Array , 2015 .

[46]  Zaven Arzoumanian,et al.  THE NANOGRAV NINE-YEAR DATA SET: MASS AND GEOMETRIC MEASUREMENTS OF BINARY MILLISECOND PULSARS , 2016, 1603.00545.

[47]  Richard L. White,et al.  The FIRST Survey: Faint Images of the Radio Sky at twenty centimeters , 1995 .

[48]  B Efron,et al.  Statistical Data Analysis in the Computer Age , 1991, Science.

[49]  Mit,et al.  Discovery of Five Binary Radio Pulsars , 2000, astro-ph/0012154.