scholarly journals Gaia pulsars and where to find them

2020 ◽  
Vol 501 (1) ◽  
pp. 1116-1126
Author(s):  
John Antoniadis
Keyword(s):  
Massive Stars ◽  
Selection Effects ◽  
Millisecond Pulsar ◽  
Current Sensitivity ◽  
Empirical Relations ◽  
Supernova Explosions ◽  
Merger Rate ◽  
Kinematic Properties ◽  
Better Than ◽  
Rule Out

ABSTRACT While the majority of massive stars have a stellar companion, most pulsars appear to be isolated. Taken at face value, this suggests that most massive binaries break apart due to strong natal kicks received in supernova explosions. However, the observed binary fraction can still be subject to strong selection effects, as monitoring of newly discovered pulsars is rarely carried out for long enough to conclusively rule out multiplicity. Here, we use the second Gaia data release to search for companions to 1534 rotation-powered pulsars with positions known to better than 0.5 arcsec. We find 22 matches to known pulsars, including 1 not reported elsewhere, and 8 new possible companions to young pulsars. We examine the photometric and kinematic properties of these systems and provide empirical relations for identifying Gaia sources with potential millisecond pulsar companions. Our results confirm that the observed multiplicity fraction is small. However, we show that the number of binaries below the sensitivity of Gaia and radio timing in our sample could still be significantly higher. We constrain the binary fraction of young pulsars to be $f_{\rm young}^{\rm true}\le 5.3(8.3){{\ \rm per\ cent}}$ under realistic (conservative) assumptions for the binary properties and current sensitivity thresholds. For massive stars (≥10 M⊙) in particular, we find $f_{\rm OB}^{\rm true}\le 3.7{{\ \rm per\ cent}}$, which sets a firm independent upper limit on the Galactic neutron star merger rate, ≤7.2 × 10−4 yr−1. Ongoing and future projects, such as the CHIME/pulsar program, MeerTime, HIRAX, and ultimately the SKA, will significantly improve these constraints in the future.

scholarly journals 2D kinematics of massive stars near the Galactic Centre

2020 ◽  
Vol 500 (3) ◽  
pp. 3213-3239
Author(s):  
Mattia Libralato ◽  
Daniel J Lennon ◽  
Andrea Bellini ◽  
Roeland van der Marel ◽  
Simon J Clark ◽  
...  
Keyword(s):  
Moving Objects ◽  
Hubble Space Telescope ◽  
Massive Stars ◽  
Line Of Sight ◽  
Galactic Centre ◽  
Harsh Environment ◽  
Proper Motions ◽  
Sgr A ◽  
Better Than ◽  
Rule Out

ABSTRACT The presence of massive stars (MSs) in the region close to the Galactic Centre (GC) poses several questions about their origin. The harsh environment of the GC favours specific formation scenarios, each of which should imprint characteristic kinematic features on the MSs. We present a 2D kinematic analysis of MSs in a GC region surrounding Sgr A* based on high-precision proper motions obtained with the Hubble Space Telescope. Thanks to a careful data reduction, well-measured bright stars in our proper-motion catalogues have errors better than 0.5 mas yr−1. We discuss the absolute motion of the MSs in the field and their motion relative to Sgr A*, the Arches, and the Quintuplet. For the majority of the MSs, we rule out any distance further than 3–4 kpc from Sgr A* using only kinematic arguments. If their membership to the GC is confirmed, most of the isolated MSs are likely not associated with either the Arches or Quintuplet clusters or Sgr A*. Only a few MSs have proper motions, suggesting that they are likely members of the Arches cluster, in agreement with previous spectroscopic results. Line-of-sight radial velocities and distances are required to shed further light on the origin of most of these massive objects. We also present an analysis of other fast-moving objects in the GC region, finding no clear excess of high-velocity escaping stars. We make our astro-photometric catalogues publicly available.

Instrumental Distortions of Raman Lines

1982 ◽  
Vol 36 (4) ◽  
pp. 424-427 ◽  
Author(s):  
A. K. Arora ◽  
V. Umadevi
Keyword(s):  
Low Temperatures ◽  
Full Width ◽  
Line Shapes ◽  
Peak Intensity ◽  
Empirical Relations ◽  
Extended Range ◽  
Main Component ◽  
Lorentzian Spectrum ◽  
True Peak ◽  
Better Than

The effect of spectrometer resolution on the peak intensity and the full width at half maximum (FWHM) of a Lorentzian spectrum is obtained by evaluating the convoluted line shapes. Spectrometer resolution functions (SRF) having Gaussian and triangular profiles are considered separately. Empirical relations to estimate the true peak intensity and the FWHM from the observed parameters are suggested. These relations are valid over an extended range of parameters with an accuracy better than that of other methods suggested earlier. As an application, the true FWHM's and peak intensities of the main component of the Raman active Ag mode of sulphate ion in potash alum at low temperatures are evaluated.

scholarly journals A hot and fast ultra-stripped supernova that likely formed a compact neutron star binary

Science ◽  
2018 ◽  
Vol 362 (6411) ◽  
pp. 201-206 ◽  
Author(s):  
K. De ◽  
M. M. Kasliwal ◽  
E. O. Ofek ◽  
T. J. Moriya ◽  
J. Burke ◽  
...  
Keyword(s):  
Neutron Star ◽  
Kinetic Energy ◽  
Light Curve ◽  
Stellar Evolution ◽  
Binary Systems ◽  
Massive Stars ◽  
Compact Binary ◽  
Compact Binary Systems ◽  
Supernova Explosions ◽  
Star Binary

Compact neutron star binary systems are produced from binary massive stars through stellar evolution involving up to two supernova explosions. The final stages in the formation of these systems have not been directly observed. We report the discovery of iPTF 14gqr (SN 2014ft), a type Ic supernova with a fast-evolving light curve indicating an extremely low ejecta mass (≈0.2 solar masses) and low kinetic energy (≈2 × 1050ergs). Early photometry and spectroscopy reveal evidence of shock cooling of an extended helium-rich envelope, likely ejected in an intense pre-explosion mass-loss episode of the progenitor. Taken together, we interpret iPTF 14gqr as evidence for ultra-stripped supernovae that form neutron stars in compact binary systems.

60Fe and 244Pu deposited on Earth constrain the r-process yields of recent nearby supernovae

Science ◽  
2021 ◽  
Vol 372 (6543) ◽  
pp. 742-745
Author(s):  
A. Wallner ◽  
M. B. Froehlich ◽  
M. A. C. Hotchkis ◽  
N. Kinoshita ◽  
M. Paul ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Neutron Stars ◽  
Neutron Capture ◽  
Half Life ◽  
Massive Stars ◽  
Chemical Elements ◽  
Capture Process ◽  
Isotopic Signatures ◽  
Supernova Explosions ◽  
R Process

Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust—iron-60 (60Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and plutonium-244 (244Pu) (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of 60Fe to Earth in the last 10 million years and accompanying lower quantities of 244Pu. The 244Pu/60Fe influx ratios are similar for both events. The 244Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.

A Comparison of Architectures of Parallel Mechanisms for Workspace and Kinematic Properties

1995 ◽  
Author(s):  
Clement M. Gosselin ◽  
Rémi Ricard ◽  
Meyer A. Nahon
Keyword(s):  
Parallel Manipulators ◽  
Parallel Architectures ◽  
Parallel Mechanisms ◽  
Design And Optimization ◽  
Stiffness Properties ◽  
Structural Differences ◽  
Six Degree Of Freedom ◽  
Kinematic Properties ◽  
Better Than ◽  
Normalization Factors

Abstract This paper presents a study of the workspace and kinematic properties of four different architectures of six-degree-of-freedom parallel mechanisms. For each architecture, the volume of the Cartesian workspace is computed at different orientations of the moving platform. The distribution of the workspace is also found by computing the 2D sections of the 3D workspace. The rotational workspace is then determined at the reference position of the platform. Finally, the stiffness properties of the architectures are obtained. Normalization factors are then defined to account for the structural differences between the architectures of mechanisms. The comparison of the different architectures of parallel mechanisms has been performed using SIMPA, a specialized CAD tool developed for the kinematic analysis and optimization of parallel manipulators. The results thus obtained illustrate the range of performance which can be expected from different parallel architectures. Although none of the architectures proves to be better than all the others in all respects, particular architectures do excel in particular performance measures. The approach proposed would therefore be useful in further studies relating to the design and optimization of parallel manipulators and mechanisms.

scholarly journals Supernova Abundance Generation

1991 ◽  
Vol 145 ◽  
pp. 21-38
Author(s):  
K. Nomoto ◽  
T. Shigeyama ◽  
T. Tsujimoto
Keyword(s):  
Heavy Element ◽  
Massive Stars ◽  
Theoretical Models ◽  
Light Curves ◽  
Maximum Brightness ◽  
Sn 1987A ◽  
New Models ◽  
Decline Rate ◽  
Type Ia ◽  
Supernova Explosions

Theoretical models of supernova explosions of various types are reviewed to obtain heavy element yields from supernovae. We focus on new models for SN 1987A, and Type Ia, Ib, and Ic supernovae. Maximum brightness and decline rate of their light curves suggest that 12–18 M⊙ stars produce larger amount of 56Ni than more massive stars. We discuss relative roles of various types of supernovae in the chemical evolution of galaxies.

scholarly journals Dark matter gravity waves at LIGO and LISA

2019 ◽  
Vol 34 (16) ◽  
pp. 1950124
Author(s):  
Paul H. Frampton
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Gravitational Wave ◽  
Gravity Waves ◽  
Gravitational Radiation ◽  
Massive Stars ◽  
Strain Sensitivity ◽  
Intermediate Mass ◽  
To Come ◽  
Merger Rate

We study the merger rate of dark matter PIMBHs (Primordial Intermediate Mass Black Holes). We conclude that the black holes observed by LIGO in GW150914 and later events were probably not dark matter PIMBHs but rather the result of gravitational collapse of very massive stars. To study the PIMBHs by gravitational radiation will require a detector sensitive to frequencies below 10 Hz and otherwise more sensitive than LIGO. The LISA detector, expected to come online in 2034, will be useful at frequencies below 1 Hz but further gravitational wave detectors beyond LISA, sensitive up to 10 Hz, and higher strain sensitivity will be necessary to fully study dark matter.

scholarly journals 60Fe deposition during the late Pleistocene and the Holocene echoes past supernova activity

2020 ◽  
Vol 117 (36) ◽  
pp. 21873-21879
Author(s):  
A. Wallner ◽  
J. Feige ◽  
L. K. Fifield ◽  
M. B. Froehlich ◽  
R. Golser ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Massive Stars ◽  
Particle Density ◽  
Time Profile ◽  
Single Atom ◽  
Dust Particles ◽  
Deep Sea Sediment ◽  
Interstellar Clouds ◽  
The Past ◽  
Supernova Explosions

Nuclides synthesized in massive stars are ejected into space via stellar winds and supernova explosions. The solar system (SS) moves through the interstellar medium and collects these nucleosynthesis products. One such product is60Fe, a radionuclide with a half-life of 2.6 My that is predominantly produced in massive stars and ejected in supernova explosions. Extraterrestrial60Fe has been found on Earth, suggesting close-by supernova explosions ∼2 to 3 and ∼6 Ma. Here, we report on the detection of a continuous interstellar60Fe influx on Earth over the past ∼33,000 y. This time period coincides with passage of our SS through such interstellar clouds, which have a significantly larger particle density compared to the local average interstellar medium embedding our SS for the past few million years. The interstellar60Fe was extracted from five deep-sea sediment samples and accelerator mass spectrometry was used for single-atom counting. The low number of 19 detected atoms indicates a continued but low influx of interstellar60Fe. The measured60Fe time profile over the 33 ky, obtained with a time resolution of about ±9 ky, does not seem to reflect any large changes in the interstellar particle density during Earth’s passage through local interstellar clouds, which could be expected if the local cloud represented an isolated remnant of the most recent supernova ejecta that traversed the Earth ∼2 to 3 Ma. The identified60Fe influx may signal a late echo of some million-year-old supernovae with the60Fe-bearing dust particles still permeating the interstellar medium.

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