scholarly journals FAST early pulsar discoveries: Effelsberg follow-up

2021 ◽  
Author(s):  
M Cruces ◽  
D J Champion ◽  
D Li ◽  
M Kramer ◽  
W W Zhu ◽  
...  
Keyword(s):  
Electron Density ◽  
Radio Telescope ◽  
White Dwarf ◽  
Wide Band ◽  
Mass Function ◽  
Ultra Wide Band ◽  
Linearly Polarized ◽  
Drift Scan ◽  
L Band

Abstract We report the follow-up of 10 pulsars discovered by the Five-hundred-meter Aperture Spherical radio-Telescope (FAST) during its commissioning. The pulsars were discovered at a frequency of 500-MHz using the ultra-wide-band (UWB) receiver in drift-scan mode, as part of the Commensal Radio Astronomy FAST Survey (CRAFTS). We carried out the timing campaign with the 100-m Effelsberg radio-telescope at L-band around 1.36 GHz. Along with 11 FAST pulsars previously reported, FAST seems to be uncovering a population of older pulsars, bordering and/or even across the pulsar death-lines. We report here two sources with notable characteristics. PSR J1951+4724 is a young and energetic pulsar with nearly 100 per cent of linearly polarized flux density and visible up to an observing frequency of 8 GHz. PSR J2338+4818, a mildly recycled pulsar in a 95.2-d orbit with a Carbon-Oxygen white dwarf (WD) companion of $\gtrsim 1\, \rm {M}_{\odot }$, based on estimates from the mass function. This system is the widest WD binary with the most massive companion known to-date. Conspicuous discrepancy was found between estimations based on NE2001 and YMW16 electron density models, which can be attributed to under-representation of pulsars in the sky region between Galactic longitudes 70○ < l < 100○. This work represents one of the early CRAFTS results, which start to show potential to substantially enrich the pulsar sample and refine the Galactic electron density model.

scholarly journals The NIBLES bivariate luminosity–H I mass distribution function revised using Arecibo follow-up observations

2020 ◽  
Vol 642 ◽  
pp. A175
Author(s):  
Z. Butcher ◽  
W. van Driel ◽  
S. Schneider
Keyword(s):  
Mass Distribution ◽  
Radio Telescope ◽  
Luminosity Function ◽  
Mass Function ◽  
Bivariate Analysis ◽  
Dimensional Distribution ◽  
Low Mass ◽  
The One ◽  
Mass Distribution Function

We present a modified optical luminosity–H I mass bivariate luminosity function based on H I line observations from the Nançay Interstellar Baryons Legacy Extragalactic Survey (NIBLES), including data from our new, four times more sensitive follow-up H I line observations obtained with the Arecibo radio telescope. The follow-up observations were designed to probe the underlying H I mass distribution of the NIBLES galaxies that were undetected or marginally detected in H I at the Nançay Radio Telescope. Our total follow-up sample consists of 234 galaxies, and it spans the entire luminosity and color range of the parent NIBLES sample of 2600 nearby (900 <  cz <  12 000 km s−1) SDSS galaxies. We incorporated the follow-up data into the bivariate analysis by scaling the NIBLES undetected fraction by an Arecibo-only distribution. We find the resulting increase in low H I mass-to-light ratio densities to be about 10% for the bins −1.0 ≤ log(MHI/M⊙/Lr/L⊙) ≤ −0.5, which produces an increased H I mass function (HIMF) low mass slope of α = −1.14 ± 0.07, being slightly shallower than the values of −1.35 ± 0.05 obtained by recent blind H I surveys. Applying the same correction to the optically corrected bivariate luminosity function from our previous paper produces a larger density increase of about 0.5 to 1 dex in the lowest H I mass-to-light ratio bins for a given luminosity while having a minimal effect on the resulting HIMF low mass slope, which still agrees with blind survey HIMFs. This indicates that while low H I-mass-to-light ratio galaxies do not contribute much to the one-dimensional HIMF, their inclusion has a significant impact on the densities in the two-dimensional distribution.

scholarly journals An in-depth investigation of 11 pulsars discovered by FAST

2020 ◽  
Vol 495 (3) ◽  
pp. 3515-3530 ◽  
Author(s):  
A D Cameron ◽  
D Li ◽  
G Hobbs ◽  
L Zhang ◽  
C C Miao ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Radio Astronomy ◽  
Lessons Learned ◽  
Polarization Angle ◽  
Next Generation ◽  
Highly Sensitive ◽  
Linearly Polarized ◽  
Drift Scan ◽  
One Year ◽  
The Way

ABSTRACT We present timing solutions and analyses of 11 pulsars discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). These pulsars were discovered using an ultrawide bandwidth receiver in drift-scan observations made during the commissioning phase of FAST, and were then confirmed and timed using the 64-m Parkes Radio Telescope. Each pulsar has been observed over a span of at least one year. Highlighted discoveries include PSR J0344−0901, which displays mode-changing behaviour and may belong to the class of so-called swooshing pulsars (alongside PSRs B0919+06 and B1859+07); PSR J0803−0942, whose emission is almost completely linearly polarized; and PSRs J1900−0134 and J1945+1211, whose well-defined polarization angle curves place stringent constraints on their emission geometry. We further discuss the detectability of these pulsars by earlier surveys, and highlight lessons learned from our work in carrying out confirmation and monitoring observations of pulsars discovered by a highly sensitive telescope, many of which may be applicable to next-generation pulsar surveys. This paper marks one of the first major releases of FAST-discovered pulsars, and paves the way for future discoveries anticipated from the Commensal Radio Astronomy FAST Survey.

scholarly journals Ultra-Wide Band and Multifunctional Polarization Converter Based on Dielectric Metamaterial

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3857 ◽  
Author(s):  
Ju Gao ◽  
Yiming Zhang ◽  
Yang Sun ◽  
Qiang Wu
Keyword(s):  
Communication Systems ◽  
Wide Band ◽  
Ultra Wide Band ◽  
Transformation Theory ◽  
Polarization Converter ◽  
Frequency Bands ◽  
Polarization Control ◽  
Narrow Bandwidth ◽  
Linearly Polarized ◽  
Low Permittivity

Polarization has always been an important issue in modern communication systems, especially in sensitive measurements. Conventional polarization converters show limited applications due to their large size and narrow bandwidth. In this paper, we demonstrate an ultra-wide band, multifunctional, and highly efficient metamaterial-based polarization converter that is capable of converting a linearly polarized wave into its cross-polarized wave and circularly polarized wave over different frequency bands. The design principle is based on the field transformation theory and the anisotropic plate is made with high/low permittivity strip metamaterials. The simulation results show that the metamaterial-based polarization converter is able to achieve linear-to-linear conversion over 11.5–12.6 GHz, and linear-to-circular conversion over two frequency bands, 3.0–11.5 GHz and 12.6–17.0 GHz, with an average polarization conversion efficiency over 90%. The polarization converter proposed in this paper provides an important stepping stone for future communication systems’ polarization control and can also be extended to higher frequency bands.

scholarly journals Simultaneous multi-telescope observations of FRB 121102

2020 ◽  
Vol 496 (4) ◽  
pp. 4565-4573 ◽  
Author(s):  
M Caleb ◽  
B W Stappers ◽  
T D Abbott ◽  
E D Barr ◽  
M C Bezuidenhout ◽  
...  
Keyword(s):  
Radio Telescope ◽  
Single Pulse ◽  
Wide Band ◽  
Complex Frequency ◽  
Frequency Range ◽  
Low Frequencies ◽  
Pulse Detection ◽  
Full Band ◽  
Continuous Band

ABSTRACT We present 11 detections of FRB 121102 in ∼3 h of observations during its ‘active’ period on the 10th of 2019 September. The detections were made using the newly deployed MeerTRAP system and single pulse detection pipeline at the MeerKAT radio telescope in South Africa. Fortuitously, the Nançay radio telescope observations on this day overlapped with the last hour of MeerKAT observations and resulted in four simultaneous detections. The observations with MeerKAT’s wide band receiver, which extends down to relatively low frequencies (900–1670 MHz usable L-band range), have allowed us to get a detailed look at the complex frequency structure, intensity variations, and frequency-dependent sub-pulse drifting. The drift rates we measure for the full-band and sub-banded data are consistent with those published between 600 and 6500 MHz with a slope of −0.147 ± 0.014 ms−1. Two of the detected bursts exhibit fainter ‘precursors’ separated from the brighter main pulse by ∼28 and ∼34 ms. A follow-up multi-telescope campaign on the 6th and 8th of 2019 October to better understand these frequency drifts and structures over a wide and continuous band was undertaken. No detections resulted, indicating that the source was ‘inactive’ over a broad frequency range during this time.

An Arecibo follow-up study of seven pulsars discovered by Five-hundred-meter Aperture Spherical radio Telescope (FAST)

2021 ◽  
Vol 21 (10) ◽  
pp. 251
Author(s):  
Shen Wang ◽  
Wei-Wei Zhu ◽  
Di Li ◽  
Zhi-Chen Pan ◽  
Pei Wang ◽  
...  
Keyword(s):  
Electron Density ◽  
Radio Telescope ◽  
Free Electron ◽  
Single Pulse ◽  
Dispersion Measure ◽  
Radiation Mechanism ◽  
Free Electron Density ◽  
Pulsar Radiation ◽  
Show Evidence

Abstract We present Arecibo 327 MHz confirmation and follow-up studies of seven new pulsars discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). These pulsars are discovered in a pilot program of the Commensal Radio Astronomy FAST Survey (CRAFTS) with the ultra-wide-bandwidth commissioning receiver. Five of them are normal pulsars and two are extreme nulling slow pulsars. PSR J2111+2132’s dispersion measure(DM: 78.5 pc cm−3) is above the upper limits of the two Galactic free electron density models, NE2001 and YMW16, and PSR J2057+2133’s position is out of the Scutum-Crux Arm, making them uniquely useful for improving the Galactic free electron density model in their directions. We present a detailed single pulse analysis for the slow nulling pulsars. We show evidence that PSR J2323+1214’s main pulse component follows a non-Poisson distribution and marginal evidence for a sub-pulse-drift or recurrent period of 32.3±0.4 rotations from PSR J0539+0013. We discuss the implication of our finding to the pulsar radiation mechanism.

Activity Recognition using Ultra Wide Band Range-Time Scan

2021 ◽  
Author(s):  
Arijit Chowdhury ◽  
Taniya Das ◽  
Smriti Rani ◽  
Anwesha Khasnobish ◽  
Tapas Chakravarty
Keyword(s):  
Activity Recognition ◽  
Wide Band ◽  
Ultra Wide Band ◽  
Time Scan
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