scholarly journals Prospects for Detecting Exoplanets around Double White Dwarfs with LISA and Taiji

2021 ◽  
Vol 162 (6) ◽  
pp. 247
Author(s):  
Yacheng Kang ◽  
Chang Liu ◽  
Lijing Shao
Keyword(s):  
White Dwarfs ◽  
Laser Interferometer ◽  
Outer Edge ◽  
Occurrence Rate ◽  
High Signal ◽  
Low Frequencies ◽  
Detection Rates ◽  
Common Envelope ◽  
Laser Interferometer Space Antenna ◽  
The Common

Abstract Recently, Tamanini & Danielski discussed the possibility of detecting circumbinary exoplanets (CBPs) orbiting double white dwarfs (DWDs) with the Laser Interferometer Space Antenna (LISA). Extending their methods and criteria, we discuss the prospects for detecting exoplanets around DWDs not only by LISA, but also by Taiji, a Chinese space-borne gravitational-wave (GW) mission that has slightly better sensitivity at low frequencies. We first explore how different binary masses and mass ratios affect the abilities of LISA and Taiji to detect CBPs. Second, for certain known detached DWDs with high signal-to-noise ratios, we quantify the possibility of CBP detections around them. Third, based on the DWD population obtained from the Mock LISA Data Challenge, we present basic assessments of the CBP detections in our Galaxy during a 4 yr mission time for LISA and Taiji. We discuss the constraints on the detectable zone of each system, as well as the distributions of the inner/outer edge of the detectable zone. With the DWD population, we further inject two different planet distributions with an occurrence rate of 50% and constrain the total detection rates. We briefly discuss the prospects for detecting habitable CBPs around DWDs with a simplified model. These results can provide helpful inputs for upcoming exoplanetary projects and help analyze planetary systems after the common envelope phase.

scholarly journals On the detectability of transiting planets orbiting white dwarfs using LSST

2019 ◽  
Vol 488 (2) ◽  
pp. 1695-1703 ◽  
Author(s):  
Jorge Cortés ◽  
David Kipping
Keyword(s):  
White Dwarfs ◽  
Occurrence Rate ◽  
Apparent Magnitude ◽  
Short Time Scale ◽  
Habitable Zone ◽  
Detection Rates ◽  
Transiting Planets ◽  
Photometric Observations ◽  
Sky Survey ◽  
Short Time

ABSTRACT White dwarfs are one of the few types of stellar object for which we have yet to confirm the existence of companion planets. Recent evidence for metal contaminated atmospheres, circumstellar debris discs, and transiting planetary debris all indicates that planets may be likely. However, white dwarf transit surveys are challenging due to the intrinsic faintness of such objects, the short time-scale of the transits, and the low transit probabilities due to their compact radii. The Large Synoptic Survey Telescope (LSST) offers a remedy to these problems as a deep, half-sky survey with fast exposures encompassing approximately 10 million white dwarfs with r < 24.5 apparent magnitude (mr). We simulate LSST photometric observations of 3.5 million white dwarfs over a 10 yr period and calculate the detectability of companion planets with P < 10 d via transits. We find typical detection rates in the range of 5 × 10−6 to 4 × 10−4 for Ceres-sized bodies to Earth-sized worlds, yielding ∼50–$4000$ detections for a 100 per cent occurrence rate of each. For terrestrial planets in the continuously habitable zone, we find detection rates of ∼10−3 indicating that LSST would reveal hundreds of such worlds for occurrence rates in the range of 1–10 per cent.

scholarly journals Circumbinary exoplanets and brown dwarfs with the Laser Interferometer Space Antenna

2019 ◽  
Vol 632 ◽  
pp. A113 ◽  
Author(s):  
C. Danielski ◽  
V. Korol ◽  
N. Tamanini ◽  
E. M. Rossi
Keyword(s):  
Laser Interferometer ◽  
Signal To Noise Ratio ◽  
Brown Dwarfs ◽  
Major Axis ◽  
Matrix Analysis ◽  
Occurrence Rate ◽  
Space Antenna ◽  
Semi Major Axis ◽  
Laser Interferometer Space Antenna ◽  
Three Body

Aims. We explore the prospects for the detection of giant circumbinary exoplanets and brown dwarfs (BDs) orbiting Galactic double white dwarfs (DWDs) binaries with the Laser Interferometer Space Antenna (LISA). Methods. By assuming an occurrence rate of 50%, motivated by white dwarf pollution observations, we built a Galactic synthetic population of P-type giant exoplanets and BDs orbiting DWDs. We carried this out by injecting different sub-stellar populations, with various mass and orbital separation characteristics, into the DWD population used in the LISA mission proposal. We then performed a Fisher matrix analysis to measure how many of these three-body systems show a periodic Doppler-shifted gravitational wave perturbation detectable by LISA. Results. We report the number of circumbinary planets (CBPs) and BDs that can be detected by LISA for various combinations of mass and semi-major axis distributions. We identify pessimistic and optimistic scenarios corresponding, respectively, to 3 and 83 (14 and 2218) detections of CBPs (BDs), observed during the length of the nominal LISA mission. These detections are distributed all over the Galaxy following the underlying DWD distribution, and they are biased towards DWDs with higher LISA signal-to-noise ratio and shorter orbital period. Finally, we show that if LISA were to be extended for four more years, the number of systems detected will be more than doubled in both the optimistic and pessimistic scenarios. Conclusions. Our results present promising prospects for the detection of post-main sequence exoplanets and BDs, showing that gravitational waves can prove the existence of these populations over the totality of the Milky Way. Detections by LISA will deepen our knowledge on the life of exoplanets subsequent to the most extreme evolution phases of their hosts, clarifying whether new phases of planetary formation take place later in the life of the stars. Such a method is strongly complementary to electromagnetic studies within the solar region and opens a window into the investigation of planets and BDs everywhere in the entire Galaxy, and possibly even in nearby galaxies in the Local Group.

scholarly journals Time-delay interferometry

2020 ◽  
Vol 24 (1) ◽  
Author(s):  
Massimo Tinto ◽  
Sanjeev V. Dhurandhar
Keyword(s):  
Time Delay ◽  
Laser Interferometer ◽  
Laser Light ◽  
Space Antenna ◽  
Phase Measurements ◽  
Laser Noise ◽  
Future Space ◽  
Laser Interferometer Space Antenna ◽  
Overall Performance ◽  
Mathematical Foundations

AbstractEqual-arm detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is differenced at the photo detector. In this situation, much lower level secondary noises then set the overall performance. If, however, the two arms have different lengths (as will necessarily be the case with space-borne interferometers), the laser noise experiences different delays in the two arms and will hence not directly cancel at the photo detector. To solve this problem, a technique involving heterodyne interferometry with unequal arm lengths and independent phase-difference readouts has been proposed. It relies on properly time-shifting and linearly combining independent Doppler measurements, and for this reason it has been called time-delay interferometry (TDI). This article provides an overview of the theory, mathematical foundations, and experimental aspects associated with the implementation of TDI. Although emphasis on the application of TDI to the Laser Interferometer Space Antenna mission appears throughout this article, TDI can be incorporated into the design of any future space-based mission aiming to search for gravitational waves via interferometric measurements. We have purposely left out all theoretical aspects that data analysts will need to account for when analyzing the TDI data combinations.

scholarly journals Predictors of Occult Paroxysmal Atrial Fibrillation in Cryptogenic Strokes Detected by Long-Term Noninvasive Cardiac Monitoring

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Archit Bhatt ◽  
Arshad Majid ◽  
Anmar Razak ◽  
Mounzer Kassab ◽  
Syed Hussain ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Paroxysmal Atrial Fibrillation ◽  
Cryptogenic Stroke ◽  
Cardiac Monitoring ◽  
High Signal ◽  
Detection Rates ◽  
Non Invasive ◽  
Patient Reported ◽  
Premature Beats

Background and Purpose. Paroxysmal Atrial fibrillation/Flutter (PAF) detection rates in cryptogenic strokes have been variable. We sought to determine the percentage of patients with cryptogenic stroke who had PAF on prolonged non-invasive cardiac monitoring.Methods and Results. Sixty-two consecutive patients with stroke and TIA in a single center with a mean age of 61 (+/− 14) years were analyzed. PAF was detected in 15 (24%) patients. Only one patient reported symptoms of shortness of breath during the episode of PAF while on monitoring, and 71 (97%) of these 73 episodes were asymptomatic. A regression analysis revealed that the presence of PVCs (ventricular premature beats) lasting more than 2 minutes (OR 6.3, 95% CI, 1.11–18.92;P=.042) and strokes (high signal on Diffusion Weighted Imaging) (OR 4.3, 95% CI, 5–36.3;P=.041) predicted PAF. Patients with multiple DWI signals were more likely than solitary signals to have PAF (OR 11.1, 95% CI, 2.5–48.5,P<.01).Conclusion. Occult PAF is common in cryptogenic strokes, and is often asymptomatic. Our data suggests that up to one in five patients with suspected cryptogenic strokes and TIAs have PAF, especially if they have PVCs and multiple high DWI signals on MRI.

Pulsar–black hole binaries as a window on quantum gravity

2017 ◽  
Vol 26 (12) ◽  
pp. 1743004 ◽  
Author(s):  
John Estes ◽  
Michael Kavic ◽  
Matthew Lippert ◽  
John H. Simonetti
Keyword(s):  
Quantum Gravity ◽  
Laser Interferometer ◽  
Mean Square ◽  
Mean Square Deviation ◽  
Space Antenna ◽  
Gravitational Effects ◽  
Arrival Times ◽  
Black Hole Binaries ◽  
Laser Interferometer Space Antenna ◽  
Square Kilometer Array

Pulsars (PSRs) are some of the most accurate clocks found in nature, while black holes (BHs) offer a unique arena for the study of quantum gravity. As such, PSR–BH binaries provide ideal astrophysical systems for detecting effects of quantum gravity. With the success of aLIGO and the advent of instruments like the Square Kilometer Array (SKA) and Evolved Laser Interferometer Space Antenna (eLISA), the prospects for discovery of such PSR–BH binaries are very promising. We argue that PSR–BH binaries can serve as ready-made testing grounds for proposed resolutions to the BH information paradox. We propose using timing signals from a PSR beam passing through the region near a BH event horizon as a probe of quantum gravitational effects. In particular, we demonstrate that fluctuations of the geometry outside a BH lead to an increase in the measured root-mean-square deviation of arrival times of PSR pulsar traveling near the horizon.

In-orbit performance of the laser interferometer of Taiji-1 experimental satellite

2021 ◽  
pp. 2140004
Author(s):  
He-Shan Liu ◽  
Zi-Ren Luo ◽  
Wei Sha ◽  
Keyword(s):  
Laser Interferometer ◽  
Fused Silica ◽  
Test Mass ◽  
Frequency Range ◽  
Space Antenna ◽  
Satellite Platform ◽  
Laser Interferometer Space Antenna ◽  
Key Technologies ◽  
Carrier Rocket ◽  
Reference Sensor

Taiji-1, which is the first experimental satellite for space gravitational wave detection in China, relies on key technologies which include the laser interferometer, the gravitational reference sensor (GRS), the micro-thruster and the satellite platform. Similarly to the Laser Interferometer Space Antenna (LISA) pathfinder, except for the science interferometer, the optical bench (OB) of Taiji-1 contains reference and test mass (TM) interferometers. Limited by the lower mechanical strength of the carrier rocket and by the orbit environment, the OB of Taiji-1 is made of invar steel and fused silica, and it is aimed to achieve a sensitivity of the order of 100[Formula: see text]pm/[Formula: see text]. The experimental results from in-orbit tests of Taiji-1 demonstrate that the interferometer can reach a sensitivity of 30[Formula: see text]pm/[Formula: see text] in the frequency range of 0.01–10[Formula: see text]Hz, which satisfies the requirements of Taiji-1 mission.

The Onset of the Common Envelope

2020 ◽  
Author(s):  
Natalia Ivanova ◽  
Stephen Justham ◽  
Paul Ricker
Keyword(s):  
Common Envelope ◽  
The Common

scholarly journals Energy Transfer by Circulation in W Ursae Majoris Systems

1980 ◽  
Vol 88 ◽  
pp. 495-499
Author(s):  
David H. Smith ◽  
Robert Connon Smith ◽  
J. Alistair Robertson
Keyword(s):  
Large Scale ◽  
Vertical Motion ◽  
Spherically Symmetric ◽  
Convective Envelope ◽  
Common Envelope ◽  
Binary Model ◽  
Contact Binaries ◽  
Contact Binary ◽  
Horizontal Pressure ◽  
The Common

After Lucy (1968) introduced the contact-binary model with a common convective envelope, it was envisaged by Hazlehurst & Meyer-Hofmeister (1973) that a sideways flow of convective elements would carry energy from the more luminous star, the primary, to the less luminous star, the secondary, as a result of horizontal pressure variations. Webbink (1977) extended this picture by noting that the interaction between vertical entropy gradients and large-scale smooth circulation currents in the common envelope would provide the necessary redistribution of flux. That is, energy is absorbed by the flow during its vertical motion in the primary and is released during its vertical motion in the secondary. Webbink (1977) mentioned two mechanisms by which a large-scale circulation could be generated: (1) the non-spherically symmetric force field due to rotation and tides which will drive an analogue of classical Eddington-Sweet circulation and (2) differential heating of the base of the common envelope. Although these mechanisms are conceptually different, they are not in practice easy to disentangle, and will certainly both be operating in contact binaries.

The Analysis and Design of a Large Stroke with High-Precision Polarized Laser Interferometer System

2016 ◽  
Vol 679 ◽  
pp. 129-134
Author(s):  
Wan Duo Wu ◽  
Qiang Xian Huang ◽  
Chao Qun Wang ◽  
Ting Ting Wu ◽  
Hong Xie
Keyword(s):  
High Precision ◽  
Measurement Accuracy ◽  
Laser Interferometer ◽  
Laser Interferometry ◽  
Phase Shifting ◽  
Single Frequency ◽  
Rejection Method ◽  
The Common ◽  
Frequency Laser ◽  
Polarization Phase

The technique utilizing single-frequency laser interferometry has very high measurement accuracy, but it has rigorous requirements for optical design which is affected by many factors. In order to achieve single-frequency laser interferometry with large stroke and high precision, the integral layout, the polarization phase shifting technique and the common mode rejection method are adopted to design the length interferometry system. This paper analyzes factors and design requirements which affect measurement accuracy with large stroke. Based on polarization phase shifting technique, the system employs the four-beam-signal detection technique and the common mode rejection method, to make a differential processing of four mutually orthogonal signals. Thus, the influences of zero-drift of intensity and environmental change on system are reduced. Combined with a 200 phase subdivision, the system achieves the resolution with 0.8 nm. Under the VC++ environment, the displacement measurement results are compensated and corrected according to the environmental parameters. Compared with the Renishaw XL-80 laser interferometer, the system has better stability in short term. In the measuring range of 60 mm, the effectiveness of the system is verified.

scholarly journals The frequency of gaseous debris discs around white dwarfs

2020 ◽  
Vol 493 (2) ◽  
pp. 2127-2139 ◽  
Author(s):  
Christopher J Manser ◽  
Boris T Gänsicke ◽  
Nicola Pietro Gentile Fusillo ◽  
Richard Ashley ◽  
Elmé Breedt ◽  
...  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Signal To Noise Ratio ◽  
Infrared Emission ◽  
Sloan Digital Sky Survey ◽  
Emission Lines ◽  
Occurrence Rate ◽  
Limited Sample ◽  
Sky Survey ◽  
Gaseous Disc

ABSTRACT A total of 1–3 per cent of white dwarfs are orbited by planetary dusty debris detectable as infrared emission in excess above the white dwarf flux. In a rare subset of these systems, a gaseous disc component is also detected via emission lines of the Ca ii 8600 Å triplet, broadened by the Keplerian velocity of the disc. We present the first statistical study of the fraction of debris discs containing detectable amounts of gas in emission at white dwarfs within a magnitude and signal-to-noise ratio limited sample. We select 7705 single white dwarfs spectroscopically observed by the Sloan Digital Sky Survey (SDSS) and Gaia with magnitudes g ≤ 19. We identify five gaseous disc hosts, all of which have been previously discovered. We calculate the occurrence rate of a white dwarf hosting a debris disc detectable via Ca ii emission lines as $0.067\, \pm \, ^{0.042}_{0.025}$ per cent. This corresponds to an occurrence rate for a dusty debris disc to have an observable gaseous component in emission as 4 ± $_{2}^{4}$ per cent. Given that variability is a common feature of the emission profiles of gaseous debris discs, and the recent detection of a planetesimal orbiting within the disc of SDSS J122859.93+104032.9, we propose that gaseous components are tracers for the presence of planetesimals embedded in the discs and outline a qualitative model. We also present spectroscopy of the Ca ii triplet 8600 Å region for 20 white dwarfs hosting dusty debris discs in an attempt to identify gaseous emission. We do not detect any gaseous components in these 20 systems, consistent with the occurrence rate that we calculated.

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