المؤلفون: Deneva, J. S., McLaughlin, M., Olszanski, T. E. E., Lewis, E. F., Pang, D., Freire, P. C. C., Bagchi, M., Stovall, K.

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics

الوصف: The AO327 drift survey for radio pulsars and transients used the Arecibo telescope from 2010 until its collapse in 2020. AO327 collected ~3100 hours of data at 327 MHz with a time resolution of 82 us and frequency resolution of 24 kHz. While the main motivation for such surveys is the discovery of new pulsars and new, even unforeseen, types of radio transients, they also serendipitously collect a wealth of data on known pulsars. We present an electronic catalog of data and data products on 206 pulsars whose periodic emission was detected by AO327 and are listed in the ATNF catalog of all published pulsars. The AO327 data products include dedispersed time series at full time resolution, average ("folded") pulse profiles, Gaussian pulse profile templates, and an absolute phase reference that allows phase-aligning the AO327 pulse profiles in a physically meaningful manner with profiles from data taken with other instruments. We also provide machine-readable tables with uncalibrated flux measurements at 327 MHz and pulse widths at 50% and 10% of the pulse peak determined from the fitted Gaussian profile templates. The AO327 catalog data set can be used in applications like population analysis of radio pulsars, pulse profile evolution studies in time and frequency, cone and core emission of the pulsar beam, scintillation, pulse intensity distributions, and others. It also constitutes a ready-made resource for teaching signal processing and pulsar astronomy techniques.
Comment: Accepted for publication in the Astrophysical Journal

الوصول الحر: http://arxiv.org/abs/2401.01947Test

المؤلفون: Crawford, F., Lazio, T. J. W., McEwen, A., Deneva, J. S., Cordes, J. M., Spitler, L., Trainor, R. F.

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena

الوصف: We report two low-frequency measurements of the power-law index for the amplitudes of giant radio pulses from the Crab pulsar. The two observations were taken with the Arecibo and Green Bank radio telescopes at center frequencies of 327 MHz and 350 MHz, respectively. We find best-fit values for the differential power-law index $\beta$ (where $dN/dS \propto S^\beta$ and $S$ is pulse amplitude) of $-2.63 \pm 0.05$ and $-3.6 \pm 0.5$ from the Arecibo and Green Bank data sets, respectively. Both values are broadly consistent with other values previously measured for the Crab pulsar at low radio frequencies. These reported values may be useful in future giant pulse studies of the Crab pulsar.
Comment: 7 pages with 1 table and 1 figure. Accepted by The Astrophysical Journal

الوصول الحر: http://arxiv.org/abs/2304.02589Test

المؤلفون: Parent, E., Sewalls, H., Freire, P. C. C., Matheny, T., Lyne, A. G., Perera, B. B. P., Cardoso, F., McLaughlin, M. A., Allen, B., Brazier, A., Camilo, F., Chatterjee, S., Cordes, J. M., Crawford, F., Deneva, J. S., Dong, F. A., Ferdman, R. D., Fonseca, E., Hessels, J. W. T., Kaspi, V. M., Knispel, B., van Leeuwen, J., Lynch, R. S., Meyers, B. M., McKee, J. W., Mickaliger, M. B., Patel, C., Ransom, S. M., Rochon, A., Scholz, P., Stairs, I. H., Stappers, B. W., Tan, C. M., Zhu, W. W.

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics

الوصف: We present new discoveries and results from long-term timing of 72 pulsars discovered in the Arecibo PALFA survey, including precise determination of astrometric and spin parameters, and flux density and scatter broadening measurements at 1.4 GHz. Notable discoveries include two young pulsars (characteristic ages $\sim$30 kyr) with no apparent supernova remnant associations, three mode changing, 12 nulling and two intermittent pulsars. We detected eight glitches in five pulsars. Among them is PSR J1939+2609, an apparently old pulsar (characteristic age $\sim$1 Gy), and PSR J1954+2529, which likely belongs to a newly-emerging class of binary pulsars. The latter is the only pulsar among the 72 that is clearly not isolated: a non-recycled neutron star with a 931-ms spin period in an eccentric ($e\,=\,0.114$) wide ($P_b\,=\,82.7\,$d) orbit with a companion of undetermined nature having a minimum mass of $\sim0.6\,M_{\odot}$. Since operations at Arecibo ceased in 2020 August, we give a final tally of PALFA sky coverage, and compare its 207 pulsar discoveries to the known population. On average, they are 50% more distant than other Galactic plane radio pulsars; PALFA millisecond pulsars (MSP) have twice the dispersion measure per unit spin period than the known population of MSP in the Plane. The four intermittent pulsars discovered by PALFA more than double the population of such objects, which should help to improve our understanding of pulsar magnetosphere physics. The statistics for these, RRATS, and nulling pulsars suggest that there are many more of these objects in the Galaxy than was previously thought.
Comment: 39 pages, 18 figures, 9 tables. Accepted for publication in ApJ

الوصول الحر: http://arxiv.org/abs/2108.02320Test

المؤلفون: Hyman, S. D., Frail, D. A., Deneva, J. S., Kassim, N. E., Giacintucci, S., Kooi, J. E., Lazio, T. J. W., Joyner, I., Peters, W. M., Gajjar, V., Siemion, A. P. V.

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena

الوصف: From an on-going survey of the Galactic bulge, we have discovered a number of compact, steep spectrum radio sources. In this present study we have carried out more detailed observations for two of these sources, located 43 arcmin and 12.7 deg from the Galactic Center. Both sources have a very steep spectrum (alpha ~ -3) and are compact, with upper limits on the angular size of 1-2 arcsec. Their flux densities appear to be relatively steady on timescales of years, months, and hours, with no indications of rapid variability or transient behavior. We detect significant circularly polarized emission from both sources, but only weak or upper limits on linear polarization. Neither source has a counterpart at other wavelengths and deep, high-frequency searches fail to find pulsations. We compare their source properties with other known compact, non-thermal source populations in the bulge (e.g. X-ray binaries, magnetars, the Burper, cataclysmic variables). Our existing data support the hypothesis that they are scatter broadened millisecond or recycled pulsars, either at the bulge or along the line of sight. We also consider the possibility that they may be a new population of Galactic radio sources which share similar properties as pulsars but lack pulsations; a hypothesis that can be tested by future large-scale synoptic surveys.
Comment: 12 pages, 4 figures. Submitted to MNRAS

الوصول الحر: http://arxiv.org/abs/2105.03282Test

المؤلفون: Roshi, D. Anish, Aponte, N., Araya, E., Arce, H., Baker, L. A., Baan, W., Becker, T. M., Breakall, J. K., Brown, R. G., Brum, C. G. M., Busch, M., Campbell, D. B., Cohen, T., Cordova, F., Deneva, J. S., Devogele, M., Dolch, T., Fernandez-Rodriguez, F. O., Ghosh, T., Goldsmith, P. F., Gurvits, L. I., Haynes, M., Heiles, C., Hessel, J. W. T., Hickson, D., Isham, B., Kerr, R. B., Kelly, J., Kiriazes, J. J., Lautenbach, J., Lebron, M., Lewandowska, N., Magnani, L., Manoharan, P. K., Margot, J. L., Marshall, S. E., McGilvray, A. K., Mendez, A., Minchin, R., Negron, V., Nolan, M. C., Olmi, L., Paganelli, F., Palliyaguru, N. T., Pantoja, C. A., Paragi, Z., Parshley, S. C., Peek, J. E. G., Perera, B. B. P., Perillat, P., Pinilla-Alonso, N., Quintero, L., Radovan, H., Raizada, S., Robishaw, T., Route, M., Salter, C. J., Santoni, A., Santos, P., Sau, S., Selvaraj, D., Smith, A. J., Sulzer, M., Vaddi, S., Vargas, F., Venditti, F. C. F., Venkataraman, A., Verkouter, H., Virkki, A. K., Vishwas, A., Weinreb, S., Werthimer, D., Wolszczan, A., Zambrano-Marin, L. F.

مصطلحات موضوعية: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Solar and Stellar Astrophysics, Physics - Atmospheric and Oceanic Physics, Physics - Instrumentation and Detectors

الوصف: The Arecibo Observatory (AO) is a multidisciplinary research and education facility that is recognized worldwide as a leading facility in astronomy, planetary, and atmospheric and space sciences. AO's cornerstone research instrument was the 305-m William E. Gordon telescope. On December 1, 2020, the 305-m telescope collapsed and was irreparably damaged. In the three weeks following the collapse, AO's scientific and engineering staff and the AO users community initiated extensive discussions on the future of the observatory. The community is in overwhelming agreement that there is a need to build an enhanced, next-generation radar-radio telescope at the AO site. From these discussions, we established the set of science requirements the new facility should enable. These requirements can be summarized briefly as: 5 MW of continuous wave transmitter power at 2 - 6 GHz, 10 MW of peak transmitter power at 430 MHz (also at 220MHz under consideration), zenith angle coverage 0 to 48 deg, frequency coverage 0.2 to 30 GHz and increased Field-of-View. These requirements determine the unique specifications of the proposed new instrument. The telescope design concept we suggest consists of a compact array of fixed dishes on a tiltable, plate-like structure with a collecting area equivalent to a 300m dish. This concept, referred to as the Next Generation Arecibo Telescope (NGAT), meets all of the desired specifications and provides significant new science capabilities to all three research groups at AO. This whitepaper presents a sample of the wide variety of the science that can be achieved with the NGAT, the details of the telescope design concept and the need for the new telescope to be located at the AO site. We also discuss other AO science activities that interlock with the NGAT in the white paper.
Comment: 82 pages (executive summary 10 pages), 21 figures, Arecibo observatory white paper (Updated with the complete author list and minor edits)

الوصول الحر: http://arxiv.org/abs/2103.01367Test

المؤلفون: Deneva, J. S., Ray, P. S., Camilo, F., Freire, P. C. C., Cromartie, H. T., Ransom, S. M., Ferrara, E., Kerr, M., Burnett, T. H., Parkinson, P. M. Saz

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena

الوصف: We present timing solutions for eight binary millisecond pulsars (MSPs) discovered by searching unidentified Fermi-LAT source positions with the 327 MHz receiver of the Arecibo 305-m radio telescope. Five of the pulsars are "spiders" with orbital periods shorter than 8.1 h. Three of these are in "black widow" systems (with degenerate companions of 0.02-0.03 solar masses), one is in a "redback" system (with a non-degenerate companion of $\gtrsim 0.3$ solar masses), and one (J1908+2105) is an apparent middle-ground case between the two observational classes. The remaining three pulsars have white dwarf companions and longer orbital periods. With the initially derived radio timing solutions, we detected gamma-ray pulsations from all MSPs and extended the timing solutions using photons from the full Fermi mission, thus confirming the identification of these MSPs with the Fermi-LAT sources. The radio emission of the redback is eclipsed during 50% of its orbital period, which is typical for this kind of system. Two of the black widows exhibit radio eclipses lasting for 10-20% of the orbit, while J1908+2105 eclipses for 40% of the orbit. We investigate an apparent link between gamma-ray emission and a short orbital period among known binary MSPs in the Galactic disk, and conclude that selection effects cannot be ruled out as the cause. Based on this analysis we outline how the likelihood of new MSP discoveries can be improved in ongoing and future pulsar searches.
Comment: 23 pages, 8 figures; accepted for publication in the Astrophysical Journal

الوصول الحر: http://arxiv.org/abs/2012.15185Test

المؤلفون: Guillot, S., Kerr, M., Ray, P. S., Bogdanov, S., Ransom, S., Deneva, J. S., Arzoumanian, Z., Bult, P., Chakrabarty, D., Gendreau, K. C., Ho, W. C. G., Jaisawal, G. K., Malacaria, C., Miller, M. C., Strohmayer, T. E., Wolff, M. T., Wood, K. S., Webb, N. A., Guillemot, L., Cognard, I., Theureau, G.

المصدر: ApJL, 887, L27 (2019)

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena

الوصف: NICER observed several rotation-powered millisecond pulsars to search for or confirm the presence of X-ray pulsations. When broad and sine-like, these pulsations may indicate thermal emission from hot polar caps at the magnetic poles on the neutron star surface. We report confident detections ($\ge4.7\sigma$ after background filtering) of X-ray pulsations for five of the seven pulsars in our target sample: PSR J0614-3329, PSR J0636+5129, PSR J0751+1807, PSR J1012+5307, and PSR J2241-5236, while PSR J1552+5437 and PSR J1744-1134 remain undetected. Of those, only PSR J0751+1807 and PSR J1012+5307 had pulsations previously detected at the 1.7$\sigma$ and almost 3$\sigma$ confidence levels, respectively, in XMM-Newton data. All detected sources exhibit broad sine-like pulses, which are indicative of surface thermal radiation. As such, these MSPs are promising targets for future X-ray observations aimed at constraining the neutron star mass-radius relation and the dense matter equation of state using detailed pulse profile modeling. Furthermore, we find that three of the detected millisecond pulsars exhibit a significant phase offset between their X-ray and radio pulses.
Comment: 25 pages, 11 tables, 4 figures. In press in The Astrophysical Journal Letters

الوصول الحر: http://arxiv.org/abs/1912.05708Test

المؤلفون: Zharikov, S., Kirichenko, A., Zyuzin, D., Shibanov, Yu., Deneva, J. S.

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena

الوصف: We present optical time-resolved multi-band photometry of the black widow binary millisecond pulsar J2052+1219 using direct-imaging observations with the 2.1m telescope of Observatorio Astronomico Nacional San Pedro Martir, Mexico (OAN-SPM). The observations revealed a variable optical source whose position and periodicity P = 2.752h coincide with the pulsar coordinates and the orbital period obtained from radio timing. This allowed us to identify it with the binary companion of the pulsar. We reproduce light curves of the source modelling the companion heating by the pulsar and accounting for the system parameters obtained from the radio data. As a result, we independently estimate the distance to the system of 3.94(16) kpc, which agrees with the dispersion measure distance. The companion star size is 0.12-0.15 Rsun, close to filling its Roche lobe. It has a surface temperature difference of about 3000 K between the side facing the pulsar and the back side. We summarise characteristics of all black widow systems studied in the optical and compare them with the PSR J2052+1219 parameters derived from our observations.
Comment: Accepted for publication in MNRAS; 10 pages, 5 figures

الوصول الحر: http://arxiv.org/abs/1909.00483Test

المؤلفون: Parent, E., Kaspi, V. M., Ransom, S. M., Freire, P. C. C., Brazier, A., Camilo, F., Chatterjee, S., Cordes, J. M., Crawford, F., Deneva, J. S., Ferdman, R. D., Hessels, J. W. T., van Leeuwen, J., Lyne, A. G., Madsen, E. C., McLaughlin, M. A., Patel, C., Scholz, P., Stairs, I. H., Stappers, B. W., Zhu, W. W.

مصطلحات موضوعية: Astrophysics - High Energy Astrophysical Phenomena

الوصف: We report on eight millisecond pulsars (MSPs) in binary systems discovered with the Arecibo PALFA survey. Phase-coherent timing solutions derived from 2.5 to 5 years of observations carried out at Arecibo and Jodrell Bank observatories are provided. PSR J1921+1929 is a 2.65-ms pulsar in a 39.6-day orbit for which we detect $\gamma$-ray pulsations in archival Fermi data. PSR J1928+1245 is a very low-mass-function system with an orbital period of 3.3 hours that belongs to the non-eclipsing black widow population. We also present PSR J1932+1756, the longest-orbital-period (41.5 days) intermediate-mass binary pulsar known to date. In light of the numerous discoveries of binary MSPs over the past years, we characterize the Galactic distribution of known MSP binaries in terms of binary class. Our results support and strengthen previous claims that the scatter in the Galactic scale height distribution correlates inversely with the binary mass function. We provide evidence of observational biases against detecting the most recycled pulsars near the Galactic plane, which overestimates the scale height of lighter systems. A possible bimodality in the mass function of MSPs with massive white dwarfs is also reported.
Comment: Submitted to ApJ, 21 pages, 10 figures

الوصول الحر: http://arxiv.org/abs/1908.09926Test

المؤلفون: Zhu, W. W., Freire, P. C. C., Knispel, B., Allen, B., Stappers, B. W., Lyne, A. G., Chatterjee, S., Cordes, J. M., Crawford, F., Deneva, J. S., Ferdman, R. D., Hessels, J. W. T., Kaspi, V. M., Lazarus, P., Lynch, R., Ransom, S. M., Stovall, K., Donner, J. Y.

مصطلحات موضوعية: Astrophysics - Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena

الوصف: In this paper, we present the results of timing observations of PSRs J1949+3106 and J1950+2414, two binary millisecond pulsars discovered in data from the Arecibo ALFA pulsar survey (PALFA). The timing parameters include precise measurements of the proper motions of both pulsars, which show that PSR J1949+3106 has a transversal motion very similar to that of an object in the local standard of rest. The timing also includes measurements of the Shapiro delay and the rate of advance of periastron for both systems. Assuming general relativity, these allow estimates of the masses of the components of the two systems; for PSR J1949+3106, the pulsar mass is $M_p \, = \, 1.34^{+0.17}_{-0.15} \, M_{\odot}$ and the companion mass $M_c \, = \, 0.81^{+0.06}_{-0.05}\, M_{\odot}$; for PSR J1950+2414 $M_p \, = \, 1.496 \, \pm \, 0.023\, M_{\odot}$ and $M_c \, = \, 0.280^{+0.005}_{-0.004}\, M_{\odot}$ (all values 68.3 % confidence limits). We use these masses and proper motions to investigate the evolutionary history of both systems: PSR J1949+3106 is likely the product of a low-kick supernova; PSR J1950+2414 is a member of a new class of eccentric millisecond pulsar binaries with an unknown formation mechanism. We discuss the proposed hypotheses for the formations of these systems in light of our new mass measurements.
Comment: 12 pages, 5 figures, accepted for publication in the Astrophysical Journal

الوصول الحر: http://arxiv.org/abs/1907.05046Test