Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain ... more Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain data with sufficient sensitivity to detect signals routinely. In this paper we describe the data recorded by these instruments during their first and second observing runs. The main data products are gravitational-wave strain time series sampled at 16384 Hz. The datasets that include this strain measurement can be freely accessed through the Gravitational Wave Open Science Center at http: //gw-openscience.org, together with data-quality information essential for the analysis of LIGO and Virgo data, documentation, tutorials, and supporting software.
We report a broadband mid-infrared frequency comb with three-optical-cycle pulse duration centere... more We report a broadband mid-infrared frequency comb with three-optical-cycle pulse duration centered around 4.2 µm, via half-harmonic generation using orientation-patterned GaP (OP-GaP) with ~43% conversion efficiency. We experimentally compare performance of GaP with GaAs and lithium niobate as the nonlinear element, and show how properties of GaP at this wavelength lead to generation of the shortest pulses and the highest conversion efficiency. These results shed new light on half-harmonic generation of frequency combs, and pave the way for generation of short-pulse intrinsically-locked frequency combs at longer wavelengths in the mid-infrared with high conversion efficiencies.
The second-generation of gravitational-wave detectors are just starting operation, and have alrea... more The second-generation of gravitational-wave detectors are just starting operation, and have already yielding their first detections. Research is now concentrated on how to maximize the scientific potential of gravitational-wave astronomy. To support this effort, we present here design targets for a new generation of detectors, which will be capable of observing compact binary sources with high signal-to-noise ratio throughout the Universe.
We present an archival search for transient gravitational wave bursts in coincidence with 27 sing... more We present an archival search for transient gravitational wave bursts in coincidence with 27 single pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo and GEO interferometer network. We also discuss a check for gravitational wave signals in coincidence with Parkes Fast Radio Bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short duration radio signals and transient gravitational wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second generation interferometers.
We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational-w... more We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We determine the expected sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron-star systems, which are considered the most promising for multi-messenger astronomy. The ability to localize the sources of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and 90% credible regions can be as large as thousands of square degrees when only two sensitive detectors are operational. Determining the sky position of a significant fraction of detected signals to areas of 5 deg 2 to 20 deg 2 will require at least three detectors of sensitivity within a factor of ∼ 2 of each other and with a broad frequency bandwidth. Should the third LIGO detector be relocated to India as expected, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.
Monthly Notices of the Royal Astronomical Society, 2014
We present results of an all-sky search in the Parkes Pulsar Timing Array (PPTA) Data Release 1 d... more We present results of an all-sky search in the Parkes Pulsar Timing Array (PPTA) Data Release 1 data set for continuous gravitational waves (GWs) in the frequency range from 5 × 10 −9 to 2 × 10 −7 Hz. Such signals could be produced by individual supermassive binary black hole systems in the early stage of coalescence. We phase up the pulsar timing array data set to form, for each position on the sky, two data streams that correspond to the two GW polarizations and then carry out an optimal search for GW signals on these data streams. Since no statistically significant GWs were detected, we place upper limits on the intrinsic GW strain amplitude h 0 for a range of GW frequencies. For example, at 10 −8 Hz our analysis has excluded with 95% confidence the presence of signals with h 0 1.7 × 10 −14. Our new limits are about a factor of four more stringent than those of Yardley et al. (2010) based on an earlier PPTA data set and a factor of two better than those reported in the recent Arzoumanian et al. (2014) paper. We also present PPTA directional sensitivity curves and find that for the most sensitive region on the sky, the current data set is sensitive to GWs from circular supermassive binary black holes with chirp masses of 10 9 M out to a luminosity distance of about 100 Mpc. Finally, we set an upper limit of 4 × 10 −3 Mpc −3 Gyr −1 at 95% confidence on the coalescence rate of nearby (z 0.1) supermassive binary black holes in circular orbits with chirp masses of 10 10 M .
We perform a wide parameter-space search for continuous gravitational waves over the whole sky an... more We perform a wide parameter-space search for continuous gravitational waves over the whole sky and over a large range of values of the frequency and the first spin-down parameter. Our search method is based on the Hough transform, which is a semicoherent, computationally efficient, and robust pattern recognition technique. We apply this technique to data from the second science run of the LIGO detectors and our final results are all-sky upper limits on the strength of gravitational waves emitted by unknown isolated spinning neutron stars on a set of narrow frequency bands in the range 200-400 Hz. The best upper limit on the gravitational-wave strain amplitude that we obtain in this frequency range is 4:43 10 ÿ23 .
We present the results obtained from an all-sky search for gravitational-wave (GW) bursts in the ... more We present the results obtained from an all-sky search for gravitational-wave (GW) bursts in the 64-2000 Hz frequency range in data collected by the LIGO detectors during the first year (November 2005-November 2006) of their fifth science run. The total analyzed live time was 268.6 days. Multiple hierarchical data analysis methods were invoked in this search. The overall sensitivity expressed in terms of the root-sum-square (rss) strain amplitude h rss for gravitational-wave bursts with various morphologies was in the range of 6  10 À22 Hz À1=2 to a few  10 À21 Hz À1=2. No GW signals were observed and a frequentist upper limit of 3.75 events per year on the rate of strong GW bursts was placed at the 90% confidence level. As in our previous searches, we also combined this rate limit with the detection efficiency for selected waveform morphologies to obtain event rate versus strength exclusion curves. In sensitivity, these exclusion curves are the most stringent to date.
We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsa... more We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10 ÿ24. These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10 ÿ5 for the four closest pulsars.
The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgr... more The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2 À 20 Â 10 À50 strain 2 Hz À1 and 5 À 35 Â 10 À49 strain 2 Hz À1 sr À1 for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as % 7 Â 10 À25 in the most sensitive frequency range near 160 Hz.
We present the results of a directed search for continuous gravitational waves from unknown, isol... more We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic center region, performed on two years of data from LIGO's fifth science run from two LIGO detectors. The search uses a semicoherent approach, analyzing coherently 630 segments, each spanning 11.5 hours, and then incoherently combining the results of the single segments. It covers gravitational wave frequencies in a range from 78 to 496 Hz and a frequency-dependent range of firstorder spindown values down to À7:86 Â 10 À8 Hz=s at the highest frequency. No gravitational waves were detected. The 90% confidence upper limits on the gravitational wave amplitude of sources at the Galactic center are $3:35 Â 10 À25 for frequencies near 150 Hz. These upper limits are the most constraining to date for a large-parameter-space search for continuous gravitational wave signals.
We report on a search for gravitational waves from coalescing compact binaries, of total mass bet... more We report on a search for gravitational waves from coalescing compact binaries, of total mass between 2 and 35 M⊙, using LIGO observations between November 14, 2006 and May 18, 2007. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass. The LIGO cumulative 90%-confidence rate upper limits of the binary coalescence of neutron stars, black holes and black hole-neutron star systems are 1.4 × 10 −2 , 7.3 × 10 −4 and 3.6 × 10 −3 yr −1 L −1 10 respectively, where L10 is 10 10 times the blue solar luminosity.
Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain ... more Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain data with sufficient sensitivity to detect signals routinely. In this paper we describe the data recorded by these instruments during their first and second observing runs. The main data products are gravitational-wave strain time series sampled at 16384 Hz. The datasets that include this strain measurement can be freely accessed through the Gravitational Wave Open Science Center at http: //gw-openscience.org, together with data-quality information essential for the analysis of LIGO and Virgo data, documentation, tutorials, and supporting software.
We report a broadband mid-infrared frequency comb with three-optical-cycle pulse duration centere... more We report a broadband mid-infrared frequency comb with three-optical-cycle pulse duration centered around 4.2 µm, via half-harmonic generation using orientation-patterned GaP (OP-GaP) with ~43% conversion efficiency. We experimentally compare performance of GaP with GaAs and lithium niobate as the nonlinear element, and show how properties of GaP at this wavelength lead to generation of the shortest pulses and the highest conversion efficiency. These results shed new light on half-harmonic generation of frequency combs, and pave the way for generation of short-pulse intrinsically-locked frequency combs at longer wavelengths in the mid-infrared with high conversion efficiencies.
The second-generation of gravitational-wave detectors are just starting operation, and have alrea... more The second-generation of gravitational-wave detectors are just starting operation, and have already yielding their first detections. Research is now concentrated on how to maximize the scientific potential of gravitational-wave astronomy. To support this effort, we present here design targets for a new generation of detectors, which will be capable of observing compact binary sources with high signal-to-noise ratio throughout the Universe.
We present an archival search for transient gravitational wave bursts in coincidence with 27 sing... more We present an archival search for transient gravitational wave bursts in coincidence with 27 single pulse triggers from Green Bank Telescope pulsar surveys, using the LIGO, Virgo and GEO interferometer network. We also discuss a check for gravitational wave signals in coincidence with Parkes Fast Radio Bursts using similar methods. Data analyzed in these searches were collected between 2007 and 2013. Possible sources of emission of both short duration radio signals and transient gravitational wave emission include starquakes on neutron stars, binary coalescence of neutron stars, and cosmic string cusps. While no evidence for gravitational wave emission in coincidence with these radio transients was found, the current analysis serves as a prototype for similar future searches using more sensitive second generation interferometers.
We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational-w... more We present a possible observing scenario for the Advanced LIGO and Advanced Virgo gravitational-wave detectors over the next decade, with the intention of providing information to the astronomy community to facilitate planning for multi-messenger astronomy with gravitational waves. We determine the expected sensitivity of the network to transient gravitational-wave signals, and study the capability of the network to determine the sky location of the source. We report our findings for gravitational-wave transients, with particular focus on gravitational-wave signals from the inspiral of binary neutron-star systems, which are considered the most promising for multi-messenger astronomy. The ability to localize the sources of the detected signals depends on the geographical distribution of the detectors and their relative sensitivity, and 90% credible regions can be as large as thousands of square degrees when only two sensitive detectors are operational. Determining the sky position of a significant fraction of detected signals to areas of 5 deg 2 to 20 deg 2 will require at least three detectors of sensitivity within a factor of ∼ 2 of each other and with a broad frequency bandwidth. Should the third LIGO detector be relocated to India as expected, a significant fraction of gravitational-wave signals will be localized to a few square degrees by gravitational-wave observations alone.
Monthly Notices of the Royal Astronomical Society, 2014
We present results of an all-sky search in the Parkes Pulsar Timing Array (PPTA) Data Release 1 d... more We present results of an all-sky search in the Parkes Pulsar Timing Array (PPTA) Data Release 1 data set for continuous gravitational waves (GWs) in the frequency range from 5 × 10 −9 to 2 × 10 −7 Hz. Such signals could be produced by individual supermassive binary black hole systems in the early stage of coalescence. We phase up the pulsar timing array data set to form, for each position on the sky, two data streams that correspond to the two GW polarizations and then carry out an optimal search for GW signals on these data streams. Since no statistically significant GWs were detected, we place upper limits on the intrinsic GW strain amplitude h 0 for a range of GW frequencies. For example, at 10 −8 Hz our analysis has excluded with 95% confidence the presence of signals with h 0 1.7 × 10 −14. Our new limits are about a factor of four more stringent than those of Yardley et al. (2010) based on an earlier PPTA data set and a factor of two better than those reported in the recent Arzoumanian et al. (2014) paper. We also present PPTA directional sensitivity curves and find that for the most sensitive region on the sky, the current data set is sensitive to GWs from circular supermassive binary black holes with chirp masses of 10 9 M out to a luminosity distance of about 100 Mpc. Finally, we set an upper limit of 4 × 10 −3 Mpc −3 Gyr −1 at 95% confidence on the coalescence rate of nearby (z 0.1) supermassive binary black holes in circular orbits with chirp masses of 10 10 M .
We perform a wide parameter-space search for continuous gravitational waves over the whole sky an... more We perform a wide parameter-space search for continuous gravitational waves over the whole sky and over a large range of values of the frequency and the first spin-down parameter. Our search method is based on the Hough transform, which is a semicoherent, computationally efficient, and robust pattern recognition technique. We apply this technique to data from the second science run of the LIGO detectors and our final results are all-sky upper limits on the strength of gravitational waves emitted by unknown isolated spinning neutron stars on a set of narrow frequency bands in the range 200-400 Hz. The best upper limit on the gravitational-wave strain amplitude that we obtain in this frequency range is 4:43 10 ÿ23 .
We present the results obtained from an all-sky search for gravitational-wave (GW) bursts in the ... more We present the results obtained from an all-sky search for gravitational-wave (GW) bursts in the 64-2000 Hz frequency range in data collected by the LIGO detectors during the first year (November 2005-November 2006) of their fifth science run. The total analyzed live time was 268.6 days. Multiple hierarchical data analysis methods were invoked in this search. The overall sensitivity expressed in terms of the root-sum-square (rss) strain amplitude h rss for gravitational-wave bursts with various morphologies was in the range of 6  10 À22 Hz À1=2 to a few  10 À21 Hz À1=2. No GW signals were observed and a frequentist upper limit of 3.75 events per year on the rate of strong GW bursts was placed at the 90% confidence level. As in our previous searches, we also combined this rate limit with the detection efficiency for selected waveform morphologies to obtain event rate versus strength exclusion curves. In sensitivity, these exclusion curves are the most stringent to date.
We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsa... more We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10 ÿ24. These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10 ÿ5 for the four closest pulsars.
The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgr... more The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2 À 20 Â 10 À50 strain 2 Hz À1 and 5 À 35 Â 10 À49 strain 2 Hz À1 sr À1 for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as % 7 Â 10 À25 in the most sensitive frequency range near 160 Hz.
We present the results of a directed search for continuous gravitational waves from unknown, isol... more We present the results of a directed search for continuous gravitational waves from unknown, isolated neutron stars in the Galactic center region, performed on two years of data from LIGO's fifth science run from two LIGO detectors. The search uses a semicoherent approach, analyzing coherently 630 segments, each spanning 11.5 hours, and then incoherently combining the results of the single segments. It covers gravitational wave frequencies in a range from 78 to 496 Hz and a frequency-dependent range of firstorder spindown values down to À7:86 Â 10 À8 Hz=s at the highest frequency. No gravitational waves were detected. The 90% confidence upper limits on the gravitational wave amplitude of sources at the Galactic center are $3:35 Â 10 À25 for frequencies near 150 Hz. These upper limits are the most constraining to date for a large-parameter-space search for continuous gravitational wave signals.
We report on a search for gravitational waves from coalescing compact binaries, of total mass bet... more We report on a search for gravitational waves from coalescing compact binaries, of total mass between 2 and 35 M⊙, using LIGO observations between November 14, 2006 and May 18, 2007. No gravitational-wave signals were detected. We report upper limits on the rate of compact binary coalescence as a function of total mass. The LIGO cumulative 90%-confidence rate upper limits of the binary coalescence of neutron stars, black holes and black hole-neutron star systems are 1.4 × 10 −2 , 7.3 × 10 −4 and 3.6 × 10 −3 yr −1 L −1 10 respectively, where L10 is 10 10 times the blue solar luminosity.
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Papers by Robert L. Byer