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Kim, Myung-Sook,Abbott, Isabella A. Blackwell Publishing Asia 2006 Phycological research Vol.54 No.1
<P>SUMMARY</P><P>After detailed observations of type material and other collections, five Hawaiian species of <I>Polysiphonia</I> Greville, <I>nom. cons.</I> are recognized to be species of <I>Neosiphonia</I> M. S. Kim et I. K. Lee; namely, <I>Neosiphonia apiculata</I> (Hollenberg) Masuda et Kogame, <I>Neosiphonia beaudettei</I> (Hollenberg) M. S. Kim et Abbott<I>, comb. nov., Neosiphonia hawaiiensis</I> (Hollenberg) M. S. Kim et Abbott<I>, comb. nov., Neosiphonia profunda</I> (Hollenberg) M. S. Kim et Abbott, <I>comb. nov.,</I> and <I>Neosiphonia rubrorhiza</I> (Hollenberg) M. S. Kim et Abbott, <I>comb. nov.</I> These five species are ecorticate, having lateral branch initials and trichoblasts produced on successive segments, rhizoids separated from pericentral cells by a cross wall, three-celled carpogonial branches (not seen in <I>N. beaudettei</I> and <I>N. rubrorhiza</I>), spermatangial branches arising on a primary branch of the trichoblasts, and tetrasporangia in a spiral series. Although certain characters were not available for some species, all other characters occur in a combination that is unique for members of <I>Neosiphonia</I>.</P>
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M. R.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. American Physical Society 2016 Physical Review D Vol.94 No.6
<P>We compare GW150914 directly to simulations of coalescing binary black holes in full general relativity, including several performed specifically to reproduce this event. Our calculations go beyond existing semianalytic models, because for all simulations-including sources with two independent, precessing spins - we perform comparisons which account for all the spin-weighted quadrupolar modes, and separately which account for all the quadrupolar and octopolar modes. Consistent with the posterior distributions reported by Abbott et al. [Phys. Rev. Lett. 116, 241102 (2016)] (at the 90% credible level), we find the data are compatible with a wide range of nonprecessing and precessing simulations. Follow-up simulations performed using previously estimated binary parameters most resemble the data, even when all quadrupolar and octopolar modes are included. Comparisons including only the quadrupolar modes constrain the total redshifted mass M-z epsilon [64 M-circle dot - 82 M-circle dot], mass ratio 1/q = m(2)/m(1) epsilon [0.6; 1], and effective aligned spin chi(eff) epsilon [-0.3, 0.2] where chi(eff) = (S-1/m(1)+S-2/m(2)). (L) over cap /M. Including both quadrupolar and octopolar modes, we find the mass ratio is even more tightly constrained. Even accounting for precession, simulations with extreme mass ratios and effective spins are highly inconsistent with the data, at any mass. Several nonprecessing and precessing simulations with similar mass ratio and chi(eff) are consistent with the data. Though correlated, the components' spins (both in magnitude and directions) are not significantly constrained by the data: the data is consistent with simulations with component spin magnitudes a(1,2) up to at least 0.8, with random orientations. Further detailed follow-up calculations are needed to determine if the data contain a weak imprint from transverse (precessing) spins. For nonprecessing binaries, interpolating between simulations, we reconstruct a posterior distribution consistent with previous results. The final black hole's redshifted mass is consistent with M-f,M-z in the range 64.0 M-circle dot - 73.5 M-circle dot and the final black hole's dimensionless spin parameter is consistent with a(f) = 0.62-0.73. As our approach invokes no intermediate approximations to general relativity and can strongly reject binaries whose radiation is inconsistent with the data, our analysis provides a valuable complement to Abbott et al.</P>
THE RATE OF BINARY BLACK HOLE MERGERS INFERRED FROM ADVANCED LIGO OBSERVATIONS SURROUNDING GW150914
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M. R.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. American Astronomical Society 2016 ASTROPHYSICAL JOURNAL LETTERS - Vol.833 No.1
<P>A transient gravitational-wave signal, GW150914, was identified in the twin Advanced LIGO detectors on 2015 September 2015 at 09: 50: 45 UTC. To assess the implications of this discovery, the detectors remained in operation with unchanged configurations over a period of 39 days around the time of the signal. At the detection statistic threshold corresponding to that observed for GW150914, our search of the 16 days of simultaneous two-detector observational data is estimated to have a false-alarm rate (FAR) of <4.9 x 10(-6) yr(-1), yielding a p-value for GW150914 of <2 x 10(-7). Parameter estimation follow-up on this trigger identifies its source as a binary black hole (BBH) merger with component masses (m(1), m(2)) = (36(-4)(+5), 29(-4)(+4))M-circle dot at redshift z = 0.09(-0.04)(+0.03) (median and 90% credible range). Here, we report on the constraints these observations place on the rate of BBH coalescences. Considering only GW150914, assuming that all BBHs in the universe have the same masses and spins as this event, imposing a search FAR threshold of 1 per 100 years, and assuming that the BBH merger rate is constant in the comoving frame, we infer a 90% credible range of merger rates between 2-53 Gpc(-3) yr(-1)(comoving frame). Incorporating all search triggers that pass a much lower threshold while accounting for the uncertainty in the astrophysical origin of each trigger, we estimate a higher rate, ranging from 13-600 Gpc(-3) yr(-1) depending on assumptions about the BBH mass distribution. All together, our various rate estimates fall in the conservative range 2-600 Gpc(-3) yr(-1).</P>
Gravitational Waves and Gamma-Rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Afrough, M.,Agarwal, B.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Agu American Astronomical Society 2017 ASTROPHYSICAL JOURNAL LETTERS - Vol.848 No.2
<P>On 2017 August 17, the gravitational-wave event GW170817 was observed by the Advanced LIGO and Virgo detectors, and the gamma-ray burst (GRB) GRB. 170817A was observed independently by the Fermi Gamma-ray Burst Monitor, and the Anti-Coincidence Shield for the Spectrometer for the International Gamma-Ray Astrophysics Laboratory. The probability of the near-simultaneous temporal and spatial observation of GRB. 170817A and GW170817 occurring by chance is 5.0 x 10(-8). We therefore confirm binary neutron star mergers as a progenitor of short GRBs. The association of GW170817 and GRB. 170817A provides new insight into fundamental physics and the origin of short GRBs. We use the observed time delay of (+ 1.74 +/- 0.05) s between GRB. 170817A and GW170817 to: (i) constrain the difference between the speed of gravity and the speed of light to be between -3 x 10(-15) and + 7 x 10(-16) times the speed of light, (ii) place new bounds on the violation of Lorentz invariance, (iii) present a new test of the equivalence principle by constraining the Shapiro delay between gravitational and electromagnetic radiation. We also use the time delay to constrain the size and bulk Lorentz factor of the region emitting the gamma-rays. GRB. 170817A is the closest short GRB with a known distance, but is between 2 and 6 orders of magnitude less energetic than other bursts with measured redshift. A new generation of gamma-ray detectors, and subthreshold searches in existing detectors, will be essential to detect similar short bursts at greater distances. Finally, we predict a joint detection rate for the Fermi Gamma-ray Burst Monitor and the Advanced LIGO and Virgo detectors of 0.1-1.4 per year during the 2018-2019 observing run and 0.3-1.7 per year at design sensitivity.</P>
Characterization of transient noise in Advanced LIGO relevant to gravitational wave signal GW150914
Abbott, B P,Abbott, R,Abbott, T D,Abernathy, M R,Acernese, F,Ackley, K,Adamo, M,Adams, C,Adams, T,Addesso, P,Adhikari, R X,Adya, V B,Affeldt, C,Agathos, M,Agatsuma, K,Aggarwal, N,Aguiar, O D,Aiello, L Institute of Physics 2016 Classical and quantum gravity Vol.33 No.13
<P>On 14 September 2015, a gravitational wave signal from a coalescing black hole binary system was observed by the Advanced LIGO detectors. This paper describes the transient noise backgrounds used to determine the significance of the event (designated GW150914) and presents the results of investigations into potential correlated or uncorrelated sources of transient noise in the detectors around the time of the event. The detectors were operating nominally at the time of GW150914. We have ruled out environmental influences and non-Gaussian instrument noise at either LIGO detector as the cause of the observed gravitational wave signal.</P>
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M. R.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. American Physical Society 2016 Physical Review D Vol.93 No.12
<P>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.</P>
Comprehensive all-sky search for periodic gravitational waves in the sixth science run LIGO data
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M. R.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. American Physical Society 2016 Physical Review D Vol.94 No.4
<P>We report on a comprehensive all-sky search for periodic gravitational waves in the frequency band 100-1500 Hz and with a frequency time derivative in the range of [-1.18; +1.00] x 10(-8) Hz/s. Such a signal could be produced by a nearby spinning and slightly nonaxisymmetric isolated neutron star in our galaxy. This search uses the data from the initial LIGO sixth science run and covers a larger parameter space with respect to any past search. A Loosely Coherent detection pipeline was applied to follow up weak outliers in both Gaussian (95% recovery rate) and non-Gaussian (75% recovery rate) bands. No gravitational wave signals were observed, and upper limits were placed on their strength. Our smallest upper limit on worst-case (linearly polarized) strain amplitude h(0) is 9.7 x 10(-25) near 169 Hz, while at the high end of our frequency range we achieve a worst-case upper limit of 5.5 x 10(-24). Both cases refer to all sky locations and entire range of frequency derivative values.</P>
Exploring the sensitivity of next generation gravitational wave detectors
Abbott, B P,Abbott, R,Abbott, T D,Abernathy, M R,Ackley, K,Adams, C,Addesso, P,Adhikari, R X,Adya, V B,Affeldt, C,Aggarwal, N,Aguiar, O D,Ain, A,Ajith, P,Allen, B,Altin, P A,Anderson, S B,Anderson, W Institute of Physics 2017 Classical and quantum gravity Vol.34 No.4
<P>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.</P>
Search for Tensor, Vector, and Scalar Polarizations in the Stochastic Gravitational-Wave Background
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Afrough, M.,Agarwal, B.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Agu American Physical Society 2018 Physical review letters Vol.120 No.20
<P>The detection of gravitational waves with Advanced LIGO and Advanced Virgo has enabled novel tests of general relativity, including direct study of the polarization of gravitational waves. While general relativity allows for only two tensor gravitational-wave polarizations, general metric theories can additionally predict two vector and two scalar polarizations. The polarization of gravitational waves is encoded in the spectral shape of the stochastic gravitational-wave background, formed by the superposition of cosmological and individually unresolved astrophysical sources. Using data recorded by Advanced LIGO during its first observing run, we search for a stochastic background of genetically polarized gravitational waves. We find no evidence for a background of any polarization, and place the first direct bounds on the contributions of vector and scalar polarizations to the stochastic background. Under log-uniform priors for the energy in each polarization, we limit the energy densities of tensor, vector, and scalar modes at 95% credibility to Omega(T)(0) < 5.58 x 10(-8), Omega(V)(0) < 6.35 x 10(-8), and Omega(S)(0) < 1.08 x 10(-7) at a reference frequency f(0) = 25 Hz.</P>
GW150914: First results from the search for binary black hole coalescence with Advanced LIGO
Abbott, B. P.,Abbott, R.,Abbott, T. D.,Abernathy, M. R.,Acernese, F.,Ackley, K.,Adams, C.,Adams, T.,Addesso, P.,Adhikari, R. X.,Adya, V. B.,Affeldt, C.,Agathos, M.,Agatsuma, K.,Aggarwal, N.,Aguiar, O. American Physical Society 2016 Physical Review D Vol.93 No.12
<P>On September 14, 2015, at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) simultaneously observed the binary black hole merger GW150914. We report the results of a matched-filter search using relativistic models of compact-object binaries that recovered GW150914 as the most significant event during the coincident observations between the two LIGO detectors from September 12 to October 20, 2015 GW150914 was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203000 years, equivalent to a significance greater than 5.1 sigma.</P>