Main meetings/events from Sept 2016 until Nov 2016
Members of the SKA Pulsar Science Working Group (SKA-PSWG) have had various opportunities for meetings and discussions during the trimester starting from September 2016. These include the following:
1) GRavitational-wave Astronomy Meeting in PAris (GRAMPA)
Paris, August 29-September 2, 2016
The workshop focussed on the physics and astrophysics of gravitational-wave sources for existing and future terrestrial interferometers, pulsar timing arrays, as well as future space-borne missions. It also explored the synergies of these experiments amongst themselves and with traditional electromagnetic astrophysics.
2) EPTA meeting on Sardinia.
Cagliari, October 3-5, 2016
The members of the European Pulsar Timing Array (EPTA), most of whom are also members of the SKA-PSWG, met in Cagliari to examine the progress of the ongoing projects and to plan future research on the way to SKA
3) 626. WE-Heraeus-Seminar: Neutron Stars: A Cosmic Laboratory for Matter under Extreme Conditions
Bad Honnef, October 26-29, 2016
The conference focussed on key questions in modern neutron star physics both from a theoretical as well as from an observational perspective. It provided a forum for scientific exchange between the two communities with focus on state-of-the-art results and future opportunities.
4) The First Pietro Baracchi Conference: Italo-Australian Radio Astronomy in the Era of the SKA
ARRC Building, Perth, Western Australia, 1-4 Nov 2016
This conference was designed to bring together Italian and Australian researchers in radio astronomy, to discuss and explore existing and potential future areas of mutual interest. The meeting was open to all areas of interest in radio astronomy (science, engineering, and computing), with an emphasis on those areas playing a key role in the era of the SKA, a project in which both Italy and Australia are founding members. In particular, perspectives for Italian-Australian collaborations in pulsar science were widely discussed.
Publications related to the PSWG from Sept 2016 to Nov 2016
During the 3 months from September to November 2016, about 150 papers related to the subjects of interest for the SKA-PSWG have been published, accepted and/or submitted to international refereed journals by the members of the PSWG and their collaborators. In the following, we report a selection of some of the announced works.
a) Liu, K., Bassa, C. G., Janssen, G. H., Karuppusamy, R., McKee, J., Kramer, M., Lee, K. J., Perrodin, D., Purver, M., Sanidas, S., Smits, R., Stappers, B. W., Weltevrede, P., & Zhu, W. W. 2016, Monthly Notices of the Royal Astronomical Society, http://adsabs.harvard.edu/abs/2016MNRAS.463.3239L Variability, polarimetry, and timing properties of single pulses from PSR J1713+0747 using the Large European Array for Pulsars. This paper reports on the single pulses from PSR J1713+0747 with data collected by the Large European Array for Pulsars (LEAP). Understanding the variability of the single pulses is essential for estimating the fundamental limit on the achievable pulsar timing precision, an important quantities for properly planning the timing observations with SKA.
b) Ridolfi, A., Freire, P. C. C., Torne, P., Heinke, C. O., van den Berg, M., Jordan, C., Kramer, M., Bassa, C. G., Sarkissian, J., D’Amico, N., Lorimer, D., Camilo, F., Manchester, R. N., & Lyne, A. 2016, Monthly Notices of the Royal Astronomical Society, http://adsabs.harvard.edu/abs/2016MNRAS.462.2918R Long-term observations of the pulsars in 47 Tucanae – I. A study of four elusive binary systems. Pulsars in globular clusters are very precious targets for a variety of physical and astrophysical studies, even more when a cluster hosts many of them, like 47 Tucanae. This work deals with the results of the timing for 4 additional binary pulsars in 47 Tucanae. This southern globular cluster is one of the primary targets for the first phase of SKA1 pulsar searches.
c) Clark, C. J., Pletsch, H. J., Wu, J., Guillemot, L., Camilo, F., Johnson, T. J., Kerr, M., Allen, B., Aulbert, C., Beer, C., Bock, O., Cullar, A., Eggenstein, H. B., Fehrmann, H., Kramer, M., Machenschalk, B., & Nieder, L. 2016, The Astrophysical Journal, http://cdsads.u-strasbg.fr/abs/2016ApJ…832L..15C The Braking Index of a Radio-quiet Gamma-ray Pulsar. The papers report on the discovery and timing of a radio-quiet gamma-ray pulsars in the list of pulsar-like unidentified Fermi-LAT sources. The latter list will also represent a target for future much deeper search of radio pulsations with SKA and its precursors.
d) Shaifullah, G., Verbiest, J. P. W., Freire, P. C. C., Tauris, T. M., Wex, , Oslowski, S., Stappers, B. W., Bassa, C. G., Caballero, R. N., Champion, D. J., Cognard, I., Desvignes, G., Graikou, E., Guillemot, L., Janssen, G. H., Jessner, A., Jordan, C., Karuppusamy, R., Kramer, M., Lazaridis, K., Lazarus, P., Lyne, A. G., McKee, J. W., Perrodin, D., Possenti, A., & Tiburzi, C. 2016, Monthly Notices of the Royal Astronomical Society, http://adsabs.harvard.edu/abs/2016MNRAS.462.1029S 21 year timing of the black-widow pulsar J2051-0827. The black widow pulsars are outstanding targets for studying the final phases of the binary evolution leading to the formation of the so-called recycled pulsars. A deep investigation of these targets is very important in preparation for SKA1, the much higher sensitivity of which will provide the opportunity to monitor their long-term and short-time variations with unprecedented detail.
e) McKee, J. W., Janssen, G. H., Stappers, B. W., Lyne, A. G., Caballero, R. N., Lentati, L., Desvignes, G., Jessner, A., Jordan, C. A., Karuppusamy, R., Kramer, M., Cognard, I., Champion, D. J., Graikou, E., Lazarus, P., Oslowski, S., Perrodin, D., Shaifullah, G., Tiburzi, C., Verbiest, J. P. W. 2016, Monthly Notices of the Royal Astronomical Society, http://adsabs.harvard.edu/abs/2016MNRAS.461.2809M A glitch in the millisecond pulsar J0613-0200. The paper is based on data belonging to the first data release of the European Pulsar Timing Array (EPTA) project. A very small glitch is shown to have occurred in a millisecond pulsar. It is found that accurately modelling the glitch does not impact the timing precision for pulsar timing array applications; this is an important indication in the perspective of using SKA1 as a gravitational wave detector.
f) Mereghetti, S., Kuiper, L., Tiengo, A., Hessels, J., Hermsen, W., Stovall, , Possenti, A., Rankin, J., Esposito, P., Turolla, R., Mitra, D., Wright, G., Stappers, B., Horneffer, A., Oslowski, S., Serylak, M., Grieszligmeier, J.-M., 2016, The Astrophysical Journal, http://cdsads.u-strasbg.fr/abs/2016ApJ…831…21M A Deep Campaign to Characterize the Synchronous Radio/X-Ray Mode Switching of PSR B0943+10 . The paper focuses on a “moding” pulsar and confirms the synchronous X-ray/radio switching between a radio-bright (B) mode and a radio-quiet (Q) mode, in which the X-ray flux is about a factor 2.4 higher than in the B-mode. X-ray pulsations during the B-mode have been also discovered. The moding pulsars are primary targets for fully exploiting the synergies of SKA1 with other future world-class instruments operating in the X-ray band.
g) Lam, M. T., Cordes, J. M., Chatterjee, S., Arzoumanian, Z., Crowter, K., Demorest, P. B., Dolch, T., Ellis, J. A., Ferdman, R. D., Fonseca, E., Gonzalez, M. E., Jones, G., Jones, M. L., Levin, L., Madison, D. R., McLaughlin, M. A., Nice, D. J., Pennucci, T. T., Ransom, S. M., Shannon, R. , Siemens, X., Stairs, I. H., Stovall, K., Swiggum, J. K., Zhu, W. W., 2016, ArXiv e-prints, http://cdsads.u-strasbg.fr/abs/2016arXiv161001731L , The NANOGrav Nine-Year Data Set: Excess Noise in Millisecond Pulsar Arrival Times. This work shows that the noise in timing residuals exceeds that predicted for the pulse arrival time estimation for millisecond pulsars observed by the North American Nanohertz Observatory for Gravitational Waves (NanoGrav) and characterize the excess noise using variance and structure function analyses. These results are discussed in terms of detection of gravitational waves at nanohertz frequencies, one of the major aims of SKA1.
h) Jaodand, A., Archibald, A. M., Hessels, J. W. T., Bogdanov, S., D’Angelo, R., Patruno, A., Bassa, C., Deller, A. T., 2016, The Astrophysical Journal, http://cdsads.u-strasbg.fr/abs/2016ApJ…830..122J, Timing Observations of PSR J1023+0038 During a Low-mass X-Ray Binary State. Transitional millisecond pulsars (tMSPs) switch, on roughly multi-year timescales, between rotation-powered radio millisecond pulsar and accretion-powered low-mass X-ray binary (LMXB) states. As such, they represent unique test-bed for the models of formation of the radio millisecond pulsars and will be prime targets for SKA. This paper reports that the average spin-down rate of the neutron star in the LMXB phase is about 27% faster than the rate during the radio millisecond pulsar state, suggesting that the pulsar wind continues to operate at a largely unmodified level in both states.
i) Weisberg, J. M., Huang, Y., 2016, The Astrophysical Journal, http://cdsads.u-strasbg.fr/abs/2016ApJ…829…55W, Relativistic Measurements from Timing the Binary Pulsar PSR B1913+16, Highly relativistic binary pulsars, alike the one in the focus of this paper, are primary targets for SKA1. The paper reports on the first successfully measurement ever of two parameters characterising the Shapiro gravitational propagation delay in PSR B1913+16. The time derivative of the projected semi-major axis has been also marginally detected. This is very promising: in fact, with the enhanced capabilities of SKA1, this could lead to ultimately constrain the pulsar’s moment of inertia, and then, in turn, the equation of state of fundamental matter.
j) Shannon, R. M., Lentati, L. T., Kerr, M., Bailes, M., Bhat, N. D. R., Coles, W. A., Dai, S., Dempsey, J., Hobbs, G., Keith, M. J., Lasky, P. D., Levin, Y., Manchester, R. N., Oslowski, S., Ravi, V., Reardon, D. J., Rosado, P. A., Spiewak, R., van Straten, W., Toomey, L., Wang, J.-B., Wen, , You, X.-P., Zhu, X.-J., 2016, The Astrophysical Journal, http://cdsads.u-strasbg.fr/abs/2016ApJ…828L…1S, The Disturbance of a Millisecond Pulsar Magnetosphere Using data from the Parkes Pulsar Timing Array (PPTA), it is shown that a new component of emission appears in the pulse profile of a millisecond pulsar, decays over four months, and results in a permanently modified pulse shape. Similar profile variations could be the origin of timing noise observed in other millisecond pulsars. It is discussed how the sensitivity of pulsar-timing observations to gravitational wave emission (a major aim of SKA) could be increased by accounting for this variability.
k) Deller, A. T., Vigeland, S. J., Kaplan, D. L., Goss, W. M., Brisken, W. F., Chatterjee, S., Cordes, J. M., Janssen, G. H., Lazio, T. J. W., Petrov, L., Stappers, B. W., Lyne, A., 2016, The Astrophysical Journal, http://cdsads.u-strasbg.fr/abs/2016ApJ…828….8D, Microarcsecond VLBI Pulsar Astrometry with PSRp. I. Two Binary Millisecond Pulsars with White Dwarf Using the VLBI technique, parallax and proper motion of two binary millisecond pulsars have been measured. The authors show that the more precise VLBI values differ from those obtained by the pulsar timing array projects by up to 5s. An imperfect modelling of the solar wind – relevant for the low ecliptic latitude of the two examined pulsars – is indicated to be a likely candidate for the discrepancy. If confirmed by future observations, the consideration of this effect will be an important ingredient for optimally planning the pulsar timing observations with SKA.
l) Fonseca, E., Pennucci, T. T., Ellis, J. A., Stairs, I. H., Nice, D. J., Ransom, S. M., Demorest, P. B., Arzoumanian, Z., Crowter, K., Dolch, T., Ferdman, R. D., Gonzalez, M. E., Jones, G., Jones, M. L., Lam, M. T., Levin, L., McLaughlin, M. A., Stovall, K., Swiggum, J. K., Zhu, W., 2016, The Astrophysical Journal, in press, http://adsabs.harvard.edu/abs/2016arXiv160300545F,The NANOGrav Nine-year Data Set: Mass and Geometric Measurements of Binary Millisecond Pulsars. This paper presents mass measurements for 14 pulsars, including 4 new Shapiro delay detections and refinements of several previously known masses. This project relates to the SKA goal of determining the neutron-star equation of state.