_version_ 1866911190128525312
author Fiscella, Sofia V. Sosa
Lam, Michael T.
Agazie, Gabriella
Anumarlapudi, Akash
Archibald, Anne M.
Arzoumanian, Zaven
Baker, Paul T.
Brook, Paul R.
Cromartie, H. Thankful
Crowter, Kathryn
De Biasi, Maria Silvina
DeCesar, Megan E.
Demorest, Paul B.
Dolch, Timothy
Ferrara, Elizabeth C.
Fiore, William
Fonseca, Emmanuel
Freedman, Gabriel E.
Garver-Daniels, Nate
Gentile, Peter A.
Glaser, Joseph
Good, Deborah C.
Hazboun, Jeffrey S.
Jennings, Ross J.
Jones, Megan L.
Kaplan, David L.
Kerr, Matthew
Lorimer, Duncan R.
Luo, Jing
Lynch, Ryan S.
McEwen, Alexander
McLaughlin, Maura A.
McMann, Natasha
Meyers, Bradley W.
Ng, Cherry
Nice, David J.
Pennucci, Timothy T.
Perera, Benetge B. P.
Pol, Nihan S.
Radovan, Henri A.
Ransom, Scott M.
Ray, Paul S.
Schmiedekamp, Ann
Schmiedekamp, Carl
Shapiro-Albert, Brent J.
Stairs, Ingrid H.
Stovall, Kevin
Susobhanan, Abhimanyu
Swiggum, Joseph K.
Wahl, Haley M.
author_facet Fiscella, Sofia V. Sosa
Lam, Michael T.
Agazie, Gabriella
Anumarlapudi, Akash
Archibald, Anne M.
Arzoumanian, Zaven
Baker, Paul T.
Brook, Paul R.
Cromartie, H. Thankful
Crowter, Kathryn
De Biasi, Maria Silvina
DeCesar, Megan E.
Demorest, Paul B.
Dolch, Timothy
Ferrara, Elizabeth C.
Fiore, William
Fonseca, Emmanuel
Freedman, Gabriel E.
Garver-Daniels, Nate
Gentile, Peter A.
Glaser, Joseph
Good, Deborah C.
Hazboun, Jeffrey S.
Jennings, Ross J.
Jones, Megan L.
Kaplan, David L.
Kerr, Matthew
Lorimer, Duncan R.
Luo, Jing
Lynch, Ryan S.
McEwen, Alexander
McLaughlin, Maura A.
McMann, Natasha
Meyers, Bradley W.
Ng, Cherry
Nice, David J.
Pennucci, Timothy T.
Perera, Benetge B. P.
Pol, Nihan S.
Radovan, Henri A.
Ransom, Scott M.
Ray, Paul S.
Schmiedekamp, Ann
Schmiedekamp, Carl
Shapiro-Albert, Brent J.
Stairs, Ingrid H.
Stovall, Kevin
Susobhanan, Abhimanyu
Swiggum, Joseph K.
Wahl, Haley M.
contents Accurate pulsar astrometric estimates play an essential role in almost all high-precision pulsar timing experiments. Traditional pulsar timing techniques refine these estimates by including them as free parameters when fitting a model to observed pulse time-of-arrival measurements. However, reliable sub-milliarcsecond astrometric estimations require years of observations and, even then, power from red noise can be inadvertently absorbed into astrometric parameter fits, biasing the resulting estimations and reducing our sensitivity to red noise processes, including gravitational waves (GWs). In this work, we seek to mitigate these shortcomings by using pulsar astrometric estimates derived from Very Long Baseline Interferometry (VLBI) as priors for the timing fit. First, we calibrated a frame tie to account for the offsets between the reference frames used in VLBI and timing. Then, we used the VLBI-informed priors and timing-based likelihoods of several astrometric solutions consistent with both techniques to obtain a maximum-posterior astrometric solution. We found offsets between our results and the timing-based astrometric solutions, which, if real, would lead to absorption of spectral power at frequencies of interest for single-source GW searches. However, we do not find significant power absorption due to astrometric fitting at the low-frequency domain of the GW background.
format Preprint
id arxiv_https___arxiv_org_abs_2509_21203
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The NANOGrav 15-Year Data Set: Improved Timing Precision With VLBI Astrometric Priors
Fiscella, Sofia V. Sosa
Lam, Michael T.
Agazie, Gabriella
Anumarlapudi, Akash
Archibald, Anne M.
Arzoumanian, Zaven
Baker, Paul T.
Brook, Paul R.
Cromartie, H. Thankful
Crowter, Kathryn
De Biasi, Maria Silvina
DeCesar, Megan E.
Demorest, Paul B.
Dolch, Timothy
Ferrara, Elizabeth C.
Fiore, William
Fonseca, Emmanuel
Freedman, Gabriel E.
Garver-Daniels, Nate
Gentile, Peter A.
Glaser, Joseph
Good, Deborah C.
Hazboun, Jeffrey S.
Jennings, Ross J.
Jones, Megan L.
Kaplan, David L.
Kerr, Matthew
Lorimer, Duncan R.
Luo, Jing
Lynch, Ryan S.
McEwen, Alexander
McLaughlin, Maura A.
McMann, Natasha
Meyers, Bradley W.
Ng, Cherry
Nice, David J.
Pennucci, Timothy T.
Perera, Benetge B. P.
Pol, Nihan S.
Radovan, Henri A.
Ransom, Scott M.
Ray, Paul S.
Schmiedekamp, Ann
Schmiedekamp, Carl
Shapiro-Albert, Brent J.
Stairs, Ingrid H.
Stovall, Kevin
Susobhanan, Abhimanyu
Swiggum, Joseph K.
Wahl, Haley M.
High Energy Astrophysical Phenomena
Instrumentation and Methods for Astrophysics
Accurate pulsar astrometric estimates play an essential role in almost all high-precision pulsar timing experiments. Traditional pulsar timing techniques refine these estimates by including them as free parameters when fitting a model to observed pulse time-of-arrival measurements. However, reliable sub-milliarcsecond astrometric estimations require years of observations and, even then, power from red noise can be inadvertently absorbed into astrometric parameter fits, biasing the resulting estimations and reducing our sensitivity to red noise processes, including gravitational waves (GWs). In this work, we seek to mitigate these shortcomings by using pulsar astrometric estimates derived from Very Long Baseline Interferometry (VLBI) as priors for the timing fit. First, we calibrated a frame tie to account for the offsets between the reference frames used in VLBI and timing. Then, we used the VLBI-informed priors and timing-based likelihoods of several astrometric solutions consistent with both techniques to obtain a maximum-posterior astrometric solution. We found offsets between our results and the timing-based astrometric solutions, which, if real, would lead to absorption of spectral power at frequencies of interest for single-source GW searches. However, we do not find significant power absorption due to astrometric fitting at the low-frequency domain of the GW background.
title The NANOGrav 15-Year Data Set: Improved Timing Precision With VLBI Astrometric Priors
topic High Energy Astrophysical Phenomena
Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2509.21203