Circumbinary exoplanets and brown dwarfs with the Laser Interferometer Space Antenna

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.

Download Full-text

Time-delay interferometry

Living Reviews in Relativity ◽

10.1007/s41114-020-00029-6 ◽

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.

Download Full-text

Pulsar–black hole binaries as a window on quantum gravity

International Journal of Modern Physics D ◽

10.1142/s0218271817430040 ◽

2017 ◽

Vol 26 (12) ◽

pp. 1743004 ◽

Cited By ~ 1

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.

Download Full-text

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

International Journal of Modern Physics A ◽

10.1142/s0217751x21400042 ◽

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.

Download Full-text