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4 results on '"Lam, M. T."'

1. A pulsar-based time-scale from the International Pulsar Timing Array

Author

Hobbs, G, Guo, L, Caballero, R, Coles, W, Lee, K, Manchester, R, Reardon, D, Matsakis, D, Tong, M, Arzoumanian, Z, Bailes, M, Bassa, C, Bhat, N, Brazier, A, Burke-Spolaor, S, Champion, D, Chatterjee, S, Cognard, I, Dai, S, Desvignes, G, Dolch, T, Ferdman, R, Graikou, E, Guillemot, L, Janssen, G, Keith, M, Kerr, M, Kramer, M, Lam, M, Liu, K, Lyne, A, Lazio, T, Lynch, R, Mckee, J, Mclaughlin, M, Mingarelli, C, Nice, D, Osłowski, S, Pennucci, T, Perera, B, Perrodin, D, Possenti, A, Russell, C, Sanidas, S, Sesana, A, Shaifullah, G, Shannon, R, Simon, J, Spiewak, R, Stairs, I, Stappers, B, Swiggum, J, Taylor, S, Theureau, G, Toomey, L, van Haasteren, R, Wang, J, Wang, Y, Zhu, X, Hobbs, G., Guo, L., Caballero, R. N., Coles, W., Lee, K. J., Manchester, R. N., Reardon, D. J., Matsakis, D., Tong, M. L., Arzoumanian, Z., Bailes, M., Bassa, C. G., Bhat, N. D. R., Brazier, A., Burke-Spolaor, S., Champion, D. J., Chatterjee, S., Cognard, I., Dai, S., Desvignes, G., Dolch, T., Ferdman, R. D., Graikou, E., Guillemot, L., Janssen, G. H., Keith, M. J., Kerr, M., Kramer, M., Lam, M. T., Liu, K., Lyne, A., Lazio, T. J. W., Lynch, R., McKee, J. W., McLaughlin, M. A., Mingarelli, C. M. F., Nice, D. J., Osłowski, S., Pennucci, T. T., Perera, B. B. P., Perrodin, D., Possenti, A., Russell, C. J., Sanidas, S., Sesana, A., Shaifullah, G., Shannon, R. M., Simon, J., Spiewak, R., Stairs, I. H., Stappers, B. W., Swiggum, J. K., Taylor, S. R., Theureau, G., Toomey, L., van Haasteren, R., Wang, J. B., Wang, Y., Zhu, X. J., Hobbs, G, Guo, L, Caballero, R, Coles, W, Lee, K, Manchester, R, Reardon, D, Matsakis, D, Tong, M, Arzoumanian, Z, Bailes, M, Bassa, C, Bhat, N, Brazier, A, Burke-Spolaor, S, Champion, D, Chatterjee, S, Cognard, I, Dai, S, Desvignes, G, Dolch, T, Ferdman, R, Graikou, E, Guillemot, L, Janssen, G, Keith, M, Kerr, M, Kramer, M, Lam, M, Liu, K, Lyne, A, Lazio, T, Lynch, R, Mckee, J, Mclaughlin, M, Mingarelli, C, Nice, D, Osłowski, S, Pennucci, T, Perera, B, Perrodin, D, Possenti, A, Russell, C, Sanidas, S, Sesana, A, Shaifullah, G, Shannon, R, Simon, J, Spiewak, R, Stairs, I, Stappers, B, Swiggum, J, Taylor, S, Theureau, G, Toomey, L, van Haasteren, R, Wang, J, Wang, Y, Zhu, X, Hobbs, G., Guo, L., Caballero, R. N., Coles, W., Lee, K. J., Manchester, R. N., Reardon, D. J., Matsakis, D., Tong, M. L., Arzoumanian, Z., Bailes, M., Bassa, C. G., Bhat, N. D. R., Brazier, A., Burke-Spolaor, S., Champion, D. J., Chatterjee, S., Cognard, I., Dai, S., Desvignes, G., Dolch, T., Ferdman, R. D., Graikou, E., Guillemot, L., Janssen, G. H., Keith, M. J., Kerr, M., Kramer, M., Lam, M. T., Liu, K., Lyne, A., Lazio, T. J. W., Lynch, R., McKee, J. W., McLaughlin, M. A., Mingarelli, C. M. F., Nice, D. J., Osłowski, S., Pennucci, T. T., Perera, B. B. P., Perrodin, D., Possenti, A., Russell, C. J., Sanidas, S., Sesana, A., Shaifullah, G., Shannon, R. M., Simon, J., Spiewak, R., Stairs, I. H., Stappers, B. W., Swiggum, J. K., Taylor, S. R., Theureau, G., Toomey, L., van Haasteren, R., Wang, J. B., Wang, Y., and Zhu, X. J.

Abstract

We have constructed a new time-scale, TT(IPTA16), based on observations of radio pulsars presented in the first data release from the International Pulsar Timing Array (IPTA). We used two analysis techniques with independent estimates of the noise models for the pulsar observations and different algorithms for obtaining the pulsar time-scale. The two analyses agree within the estimated uncertainties and both agree with TT(BIPM17), a post-corrected time-scale produced by the Bureau International des Poids et Mesures (BIPM). We show that both methods could detect significant errors in TT(BIPM17) if they were present. We estimate the stability of the atomic clocks from which TT(BIPM17) is derived using observations of four rubidium fountain clocks at the US Naval Observatory. Comparing the power spectrum of TT(IPTA16) with that of these fountain clocks suggests that pulsar-based time-scales are unlikely to contribute to the stability of the best time-scales over the next decade, but they will remain a valuable independent check on atomic time-scales. We also find that the stability of the pulsar-based time-scale is likely to be limited by our knowledge of solar-system dynamics, and that errors in TT(BIPM17) will not be a limiting factor for the primary goal of the IPTA, which is to search for the signatures of nano-Hertz gravitational waves.

Published
2020

2. The International Pulsar Timing Array: second data release

Author

Perera, B, Decesar, M, Demorest, P, Kerr, M, Lentati, L, Nice, D, Osłowski, S, Ransom, S, Keith, M, Arzoumanian, Z, Bailes, M, Baker, P, Bassa, C, Bhat, N, Brazier, A, Burgay, M, Burke-Spolaor, S, Caballero, R, Champion, D, Chatterjee, S, Chen, S, Cognard, I, Cordes, J, Crowter, K, Dai, S, Desvignes, G, Dolch, T, Ferdman, R, Ferrara, E, Fonseca, E, Goldstein, J, Graikou, E, Guillemot, L, Hazboun, J, Hobbs, G, Hu, H, Islo, K, Janssen, G, Karuppusamy, R, Kramer, M, Lam, M, Lee, K, Liu, K, Luo, J, Lyne, A, Manchester, R, Mckee, J, Mclaughlin, M, Mingarelli, C, Parthasarathy, A, Pennucci, T, Perrodin, D, Possenti, A, Reardon, D, Russell, C, Sanidas, S, Sesana, A, Shaifullah, G, Shannon, R, Siemens, X, Simon, J, Spiewak, R, Stairs, I, Stappers, B, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Vallisneri, M, Vecchio, A, Wang, J, Zhang, S, Zhang, L, Zhu, W, Zhu, X, Perera, B. B. P., DeCesar, M. E., Demorest, P. B., Kerr, M., Lentati, L., Nice, D. J., Osłowski, S., Ransom, S. M., Keith, M. J., Arzoumanian, Z., Bailes, M., Baker, P. T., Bassa, C. G., Bhat, N. D. R., Brazier, A., Burgay, M., Burke-Spolaor, S., Caballero, R. N., Champion, D. J., Chatterjee, S., Chen, S., Cognard, I., Cordes, J. M., Crowter, K., Dai, S., Desvignes, G., Dolch, T., Ferdman, R. D., Ferrara, E. C., Fonseca, E., Goldstein, J. M., Graikou, E., Guillemot, L., Hazboun, J. S., Hobbs, G., Hu, H., Islo, K., Janssen, G. H., Karuppusamy, R., Kramer, M., Lam, M. T., Lee, K. J., Liu, K., Luo, J., Lyne, A. G., Manchester, R. N., McKee, J. W., McLaughlin, M. A., Mingarelli, C. M. F., Parthasarathy, A. P., Pennucci, T. T., Perrodin, D., Possenti, A., Reardon, D. J., Russell, C. J., Sanidas, S. A., Sesana, A., Shaifullah, G., Shannon, R. M., Siemens, X., Simon, J., Spiewak, R., Stairs, I. H., Stappers, B. W., Swiggum, J. K., Taylor, S. R., Theureau, G., Tiburzi, C., Vallisneri, M., Vecchio, A., Wang, J. B., Zhang, S. B., Zhang, L., Zhu, W. W., Zhu, X. J., Perera, B, Decesar, M, Demorest, P, Kerr, M, Lentati, L, Nice, D, Osłowski, S, Ransom, S, Keith, M, Arzoumanian, Z, Bailes, M, Baker, P, Bassa, C, Bhat, N, Brazier, A, Burgay, M, Burke-Spolaor, S, Caballero, R, Champion, D, Chatterjee, S, Chen, S, Cognard, I, Cordes, J, Crowter, K, Dai, S, Desvignes, G, Dolch, T, Ferdman, R, Ferrara, E, Fonseca, E, Goldstein, J, Graikou, E, Guillemot, L, Hazboun, J, Hobbs, G, Hu, H, Islo, K, Janssen, G, Karuppusamy, R, Kramer, M, Lam, M, Lee, K, Liu, K, Luo, J, Lyne, A, Manchester, R, Mckee, J, Mclaughlin, M, Mingarelli, C, Parthasarathy, A, Pennucci, T, Perrodin, D, Possenti, A, Reardon, D, Russell, C, Sanidas, S, Sesana, A, Shaifullah, G, Shannon, R, Siemens, X, Simon, J, Spiewak, R, Stairs, I, Stappers, B, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Vallisneri, M, Vecchio, A, Wang, J, Zhang, S, Zhang, L, Zhu, W, Zhu, X, Perera, B. B. P., DeCesar, M. E., Demorest, P. B., Kerr, M., Lentati, L., Nice, D. J., Osłowski, S., Ransom, S. M., Keith, M. J., Arzoumanian, Z., Bailes, M., Baker, P. T., Bassa, C. G., Bhat, N. D. R., Brazier, A., Burgay, M., Burke-Spolaor, S., Caballero, R. N., Champion, D. J., Chatterjee, S., Chen, S., Cognard, I., Cordes, J. M., Crowter, K., Dai, S., Desvignes, G., Dolch, T., Ferdman, R. D., Ferrara, E. C., Fonseca, E., Goldstein, J. M., Graikou, E., Guillemot, L., Hazboun, J. S., Hobbs, G., Hu, H., Islo, K., Janssen, G. H., Karuppusamy, R., Kramer, M., Lam, M. T., Lee, K. J., Liu, K., Luo, J., Lyne, A. G., Manchester, R. N., McKee, J. W., McLaughlin, M. A., Mingarelli, C. M. F., Parthasarathy, A. P., Pennucci, T. T., Perrodin, D., Possenti, A., Reardon, D. J., Russell, C. J., Sanidas, S. A., Sesana, A., Shaifullah, G., Shannon, R. M., Siemens, X., Simon, J., Spiewak, R., Stairs, I. H., Stappers, B. W., Swiggum, J. K., Taylor, S. R., Theureau, G., Tiburzi, C., Vallisneri, M., Vecchio, A., Wang, J. B., Zhang, S. B., Zhang, L., Zhu, W. W., and Zhu, X. J.

Abstract

In this paper, we describe the International Pulsar Timing Array second data release, which includes recent pulsar timing data obtained by three regional consortia: the European Pulsar Timing Array, the North American Nanohertz Observatory for Gravitational Waves, and the Parkes Pulsar Timing Array. We analyse and where possible combine high-precision timing data for 65 millisecond pulsars which are regularly observed by these groups. A basic noise analysis, including the processes which are both correlated and uncorrelated in time, provides noise models and timing ephemerides for the pulsars. We find that the timing precisions of pulsars are generally improved compared to the previous data release, mainly due to the addition of new data in the combination. The main purpose of this work is to create the most up-to-date IPTA data release. These data are publicly available for searches for low-frequency gravitational waves and other pulsar science.

Published
2019

3. Studying the Solar system with the International Pulsar Timing Array

Author

Caballero, R, Guo, Y, Lee, K, Lazarus, P, Champion, D, Desvignes, G, Kramer, M, Plant, K, Arzoumanian, Z, Bailes, M, Bassa, C, Bhat, N, Brazier, A, Burgay, M, Burke-Spolaor, S, Chamberlin, S, Chatterjee, S, Cognard, I, Cordes, J, Dai, S, Demorest, P, Dolch, T, Ferdman, R, Fonseca, E, Gair, J, Garver-Daniels, N, Gentile, P, Gonzalez, M, Graikou, E, Guillemot, L, Hobbs, G, Janssen, G, Karuppusamy, R, Keith, M, Kerr, M, Lam, M, Lasky, P, Lazio, T, Levin, L, Liu, K, Lommen, A, Lorimer, D, Lynch, R, Madison, D, Manchester, R, Mckee, J, Mclaughlin, M, Mcwilliams, S, Mingarelli, C, Nice, D, Osłowski, S, Palliyaguru, N, Pennucci, T, Perera, B, Perrodin, D, Possenti, A, Ransom, S, Reardon, D, Sanidas, S, Sesana, A, Shaifullah, G, Shannon, R, Siemens, X, Simon, J, Spiewak, R, Stairs, I, Stappers, B, Stinebring, D, Stovall, K, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Toomey, L, van Haasteren, R, van Straten, W, Verbiest, J, Wang, J, Zhu, X, Zhu, W, Caballero, R. N., Guo, Y. J., Lee, K. J., Lazarus, P., Champion, D. J., Desvignes, G., Kramer, M., Plant, K., Arzoumanian, Z., Bailes, M., Bassa, C. G., Bhat, N. D. R., Brazier, A., Burgay, M., Burke-Spolaor, S., Chamberlin, S. J., Chatterjee, S., Cognard, I., Cordes, J. M., Dai, S., Demorest, P., Dolch, T., Ferdman, R. D., Fonseca, E., Gair, J. R., Garver-Daniels, N., Gentile, P., Gonzalez, M. E., Graikou, E., Guillemot, L., Hobbs, G., Janssen, G. H., Karuppusamy, R., Keith, M. J., Kerr, M., Lam, M. T., Lasky, P. D., Lazio, T. J. W., Levin, L., Liu, K., Lommen, A. N., Lorimer, D. R., Lynch, R. S., Madison, D. R., Manchester, R. N., McKee, J. W., McLaughlin, M. A., McWilliams, S. T., Mingarelli, C. M. F., Nice, D. J., Osłowski, S., Palliyaguru, N. T., Pennucci, T. T., Perera, B. B. P., Perrodin, D., Possenti, A., Ransom, S. M., Reardon, D. J., Sanidas, S. A., Sesana, A., Shaifullah, G., Shannon, R. M., Siemens, X., Simon, J., Spiewak, R., Stairs, I., Stappers, B., Stinebring, D. R., Stovall, K., Swiggum, J. K., Taylor, S. R., Theureau, G., Tiburzi, C., Toomey, L., van Haasteren, R., van Straten, W., Verbiest, J. P. W., Wang, J. B., Zhu, X. J., Zhu, W. W., Caballero, R, Guo, Y, Lee, K, Lazarus, P, Champion, D, Desvignes, G, Kramer, M, Plant, K, Arzoumanian, Z, Bailes, M, Bassa, C, Bhat, N, Brazier, A, Burgay, M, Burke-Spolaor, S, Chamberlin, S, Chatterjee, S, Cognard, I, Cordes, J, Dai, S, Demorest, P, Dolch, T, Ferdman, R, Fonseca, E, Gair, J, Garver-Daniels, N, Gentile, P, Gonzalez, M, Graikou, E, Guillemot, L, Hobbs, G, Janssen, G, Karuppusamy, R, Keith, M, Kerr, M, Lam, M, Lasky, P, Lazio, T, Levin, L, Liu, K, Lommen, A, Lorimer, D, Lynch, R, Madison, D, Manchester, R, Mckee, J, Mclaughlin, M, Mcwilliams, S, Mingarelli, C, Nice, D, Osłowski, S, Palliyaguru, N, Pennucci, T, Perera, B, Perrodin, D, Possenti, A, Ransom, S, Reardon, D, Sanidas, S, Sesana, A, Shaifullah, G, Shannon, R, Siemens, X, Simon, J, Spiewak, R, Stairs, I, Stappers, B, Stinebring, D, Stovall, K, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Toomey, L, van Haasteren, R, van Straten, W, Verbiest, J, Wang, J, Zhu, X, Zhu, W, Caballero, R. N., Guo, Y. J., Lee, K. J., Lazarus, P., Champion, D. J., Desvignes, G., Kramer, M., Plant, K., Arzoumanian, Z., Bailes, M., Bassa, C. G., Bhat, N. D. R., Brazier, A., Burgay, M., Burke-Spolaor, S., Chamberlin, S. J., Chatterjee, S., Cognard, I., Cordes, J. M., Dai, S., Demorest, P., Dolch, T., Ferdman, R. D., Fonseca, E., Gair, J. R., Garver-Daniels, N., Gentile, P., Gonzalez, M. E., Graikou, E., Guillemot, L., Hobbs, G., Janssen, G. H., Karuppusamy, R., Keith, M. J., Kerr, M., Lam, M. T., Lasky, P. D., Lazio, T. J. W., Levin, L., Liu, K., Lommen, A. N., Lorimer, D. R., Lynch, R. S., Madison, D. R., Manchester, R. N., McKee, J. W., McLaughlin, M. A., McWilliams, S. T., Mingarelli, C. M. F., Nice, D. J., Osłowski, S., Palliyaguru, N. T., Pennucci, T. T., Perera, B. B. P., Perrodin, D., Possenti, A., Ransom, S. M., Reardon, D. J., Sanidas, S. A., Sesana, A., Shaifullah, G., Shannon, R. M., Siemens, X., Simon, J., Spiewak, R., Stairs, I., Stappers, B., Stinebring, D. R., Stovall, K., Swiggum, J. K., Taylor, S. R., Theureau, G., Tiburzi, C., Toomey, L., van Haasteren, R., van Straten, W., Verbiest, J. P. W., Wang, J. B., Zhu, X. J., and Zhu, W. W.

Abstract

Pulsar-timing analyses are sensitive to errors in the Solar-system ephemerides (SSEs) that timing models utilize to estimate the location of the Solar-system barycentre, the quasi-inertial reference frame to which all recorded pulse times-of-arrival are referred. Any error in the SSE will affect all pulsars, therefore pulsar timing arrays (PTAs) are a suitable tool to search for such errors and impose independent constraints on relevant physical parameters. We employ the first data release of the International Pulsar Timing Array to constrain the masses of the planet-moons systems and to search for possible unmodelled objects (UMOs) in the Solar system. We employ 10 SSEs from two independent research groups, derive and compare mass constraints of planetary systems, and derive the first PTA mass constraints on asteroidbelt objects. Constraints on planetary-system masses have been improved by factors of up to 20 from the previous relevant study using the same assumptions, with the mass of the Jovian system measured at 9.5479189(3) × 10-4M⊙. The mass of the dwarf planet Ceres is measured at 4.7(4) × 10-10M⊙. We also present the first sensitivity curves using real data that place generic limits on the masses of UMOs, which can also be used as upper limits on the mass of putative exotic objects. For example, upper limits on dark-matter clumps are comparable to published limits using independent methods.While the constraints on planetary masses derived with all employed SSEs are consistent, we note and discuss differences in the associated timing residuals and UMO sensitivity curves.

Published
2018

4. From spin noise to systematics: Stochastic processes in the first International Pulsar Timing Array data release

Author

Lentati, L, Shannon, R, Coles, W, Verbiest, J, van Haasteren, R, Ellis, J, Caballero, R, Manchester, R, Arzoumanian, Z, Babak, S, Bassa, C, Bhat, N, Brem, P, Burgay, M, Burke-Spolaor, S, Champion, D, Chatterjee, S, Cognard, I, Cordes, J, Dai, S, Demorest, P, Desvignes, G, Dolch, T, Ferdman, R, Fonseca, E, Gair, J, Gonzalez, M, Graikou, E, Guillemot, L, Hessels, J, Hobbs, G, Janssen, G, Jones, G, Karuppusamy, R, Keith, M, Kerr, M, Kramer, M, Lam, M, Lasky, P, Lassus, A, Lazarus, P, Lazio, T, Lee, K, Levin, L, Liu, K, Lynch, R, Madison, D, Mckee, J, Mclaughlin, M, Mcwilliams, S, Mingarelli, C, Nice, D, Osłowski, S, Pennucci, T, Perera, B, Perrodin, D, Petiteau, A, Possenti, A, Ransom, S, Reardon, D, Rosado, P, Sanidas, S, Sesana, A, Shaifullah, G, Siemens, X, Smits, R, Stairs, I, Stappers, B, Stinebring, D, Stovall, K, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Toomey, L, Vallisneri, M, van Straten, W, Vecchio, A, Wang, J, Wang, Y, You, X, Zhu, W, Zhu, X, Lentati, L., Shannon, R. M., Coles, W. A., Verbiest, J. P. W., van Haasteren, R., Ellis, J. A., Caballero, R. N., Manchester, R. N., Arzoumanian, Z., Babak, S., Bassa, C. G., Bhat, N. D. R., Brem, P., Burgay, M., Burke-Spolaor, S., Champion, D., Chatterjee, S., Cognard, I., Cordes, J. M., Dai, S., Demorest, P., Desvignes, G., Dolch, T., Ferdman, R. D., Fonseca, E., Gair, J. R., Gonzalez, M. E., Graikou, E., Guillemot, L., Hessels, J. W. T., Hobbs, G., Janssen, G. H., Jones, G., Karuppusamy, R., Keith, M., Kerr, M., Kramer, M., Lam, M. T., Lasky, P. D., Lassus, A., Lazarus, P., Lazio, T. J. W., Lee, K. J., Levin, L., Liu, K., Lynch, R. S., Madison, D. R., McKee, J., McLaughlin, M., McWilliams, S. T., Mingarelli, C. M. F., Nice, D. J., Osłowski, S., Pennucci, T. T., Perera, B. B. P., Perrodin, D., Petiteau, A., Possenti, A., Ransom, S. M., Reardon, D., Rosado, P. A., Sanidas, S. A., Sesana, A., Shaifullah, G., Siemens, X., Smits, R., Stairs, I., Stappers, B., Stinebring, D. R., Stovall, K., Swiggum, J., Taylor, S. R., Theureau, G., Tiburzi, C., Toomey, L., Vallisneri, M., van Straten, W., Vecchio, A., Wang, J. -B., Wang, Y., You, X. P., Zhu, W. W., Zhu, X. -J., Lentati, L, Shannon, R, Coles, W, Verbiest, J, van Haasteren, R, Ellis, J, Caballero, R, Manchester, R, Arzoumanian, Z, Babak, S, Bassa, C, Bhat, N, Brem, P, Burgay, M, Burke-Spolaor, S, Champion, D, Chatterjee, S, Cognard, I, Cordes, J, Dai, S, Demorest, P, Desvignes, G, Dolch, T, Ferdman, R, Fonseca, E, Gair, J, Gonzalez, M, Graikou, E, Guillemot, L, Hessels, J, Hobbs, G, Janssen, G, Jones, G, Karuppusamy, R, Keith, M, Kerr, M, Kramer, M, Lam, M, Lasky, P, Lassus, A, Lazarus, P, Lazio, T, Lee, K, Levin, L, Liu, K, Lynch, R, Madison, D, Mckee, J, Mclaughlin, M, Mcwilliams, S, Mingarelli, C, Nice, D, Osłowski, S, Pennucci, T, Perera, B, Perrodin, D, Petiteau, A, Possenti, A, Ransom, S, Reardon, D, Rosado, P, Sanidas, S, Sesana, A, Shaifullah, G, Siemens, X, Smits, R, Stairs, I, Stappers, B, Stinebring, D, Stovall, K, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Toomey, L, Vallisneri, M, van Straten, W, Vecchio, A, Wang, J, Wang, Y, You, X, Zhu, W, Zhu, X, Lentati, L., Shannon, R. M., Coles, W. A., Verbiest, J. P. W., van Haasteren, R., Ellis, J. A., Caballero, R. N., Manchester, R. N., Arzoumanian, Z., Babak, S., Bassa, C. G., Bhat, N. D. R., Brem, P., Burgay, M., Burke-Spolaor, S., Champion, D., Chatterjee, S., Cognard, I., Cordes, J. M., Dai, S., Demorest, P., Desvignes, G., Dolch, T., Ferdman, R. D., Fonseca, E., Gair, J. R., Gonzalez, M. E., Graikou, E., Guillemot, L., Hessels, J. W. T., Hobbs, G., Janssen, G. H., Jones, G., Karuppusamy, R., Keith, M., Kerr, M., Kramer, M., Lam, M. T., Lasky, P. D., Lassus, A., Lazarus, P., Lazio, T. J. W., Lee, K. J., Levin, L., Liu, K., Lynch, R. S., Madison, D. R., McKee, J., McLaughlin, M., McWilliams, S. T., Mingarelli, C. M. F., Nice, D. J., Osłowski, S., Pennucci, T. T., Perera, B. B. P., Perrodin, D., Petiteau, A., Possenti, A., Ransom, S. M., Reardon, D., Rosado, P. A., Sanidas, S. A., Sesana, A., Shaifullah, G., Siemens, X., Smits, R., Stairs, I., Stappers, B., Stinebring, D. R., Stovall, K., Swiggum, J., Taylor, S. R., Theureau, G., Tiburzi, C., Toomey, L., Vallisneri, M., van Straten, W., Vecchio, A., Wang, J. -B., Wang, Y., You, X. P., Zhu, W. W., and Zhu, X. -J.

Abstract

We analyse the stochastic properties of the 49 pulsars that comprise the first International Pulsar Timing Array (IPTA) data release. We use Bayesian methodology, performing model selection to determine the optimal description of the stochastic signals present in each pulsar. In addition to spin-noise and dispersion-measure (DM) variations, these models can include timing noise unique to a single observing system, or frequency band. We show the improved radio-frequency coverage and presence of overlapping data from different observing systems in the IPTA data set enables us to separate both system and band-dependent effects with much greater efficacy than in the individual pulsar timing array (PTA) data sets. For example, we show that PSR J1643-1224 has, in addition to DM variations, significant band-dependent noise that is coherent between PTAs which we interpret as coming from time-variable scattering or refraction in the ionized interstellar medium. Failing to model these different contributions appropriately can dramatically alter the astrophysical interpretation of the stochastic signals observed in the residuals. In some cases, the spectral exponent of the spin-noise signal can vary from 1.6 to 4 depending upon the model, which has direct implications for the long-term sensitivity of the pulsar to a stochastic gravitational-wave (GW) background. By using a more appropriate model, however, we can greatly improve a pulsar's sensitivity to GWs. For example, including system and band-dependent signals in the PSR J0437-4715 data set improves the upper limit on a fiducial GW background by ~60 per cent compared to a model that includes DM variations and spin-noise only.

Published
2016

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