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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>
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 The Astrophysical journal Supplement series Vol.225 No.1
<P>This Supplement provides supporting material for Abbott et al. (2016a). We briefly summarize past electromagnetic (EM) follow-up efforts as well as the organization and policy of the current EM follow-up program. We compare the four probability sky maps produced for the gravitational-wave transient GW150914, and provide additional details of the EM follow-up observations that were performed in the different bands.</P>
GW150914: The Advanced LIGO Detectors in the Era of First Discoveries
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 Letters Vol.116 No.13
<P>Following a major upgrade, the two advanced detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) held their first observation run between September 2015 and January 2016. With a strain sensitivity of 10(-23) / root Hz at 100 Hz, the product of observable volume and measurement time exceeded that of all previous runs within the first 16 days of coincident observation. On September 14, 2015, the Advanced LIGO detectors observed a transient gravitational-wave signal determined to be the coalescence of two black holes [B. P. Abbott et al., Phys. Rev. Lett. 116, 061102 (2016)], launching the era of gravitational-wave astronomy. The event, GW150914, was observed with a combined signal-to-noise ratio of 24 in coincidence by the two detectors. Here, we present the main features of the detectors that enabled this observation. At full sensitivity, the Advanced LIGO detectors are designed to deliver another factor of 3 improvement in the signal-to-noise ratio for binary black hole systems similar in mass to GW150914.</P>
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.9
<P>The LIGO Scientific and Virgo Collaborations have announced the event GW170817, the first detection of gravitational waves from the coalescence of two neutron stars. The merger rate of binary neutron stars estimated from this event suggests that distant, unresolvable binary neutron stars create a significant astrophysical stochastic gravitational-wave background. The binary neutron star component will add to the contribution from binary black holes, increasing the amplitude of the total astrophysical background relative to previous expectations. In the Advanced LIGO-Virgo frequency band most sensitive to stochastic backgrounds (near 25 Hz), we predict a total astrophysical background with amplitude Omega(GW) (f = 25 Hz) = 1.8(-1.3)(+2.7) x 10(-9) with 90% confidence, compared with Omega(GW) (f = 25 Hz) = 1.1(-0.7)(+1.2) x 10(-9) from binary black holes alone. Assuming the most probable rate for compact binary mergers, we find that the total background may be detectable with a signal-to-noise-ratio of 3 after 40 months of total observation time, based on the expected timeline for Advanced LIGO and Virgo to reach their design sensitivity.</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>
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>
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>
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>
GW170608: Observation of a 19 Solar-mass Binary Black Hole Coalescence
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.851 No.2
<P>On 2017 June 8 at 02:01:16.49 UTC, a gravitational-wave (GW) signal from the merger of two stellar-mass black holes was observed by the two Advanced Laser Interferometer Gravitational-Wave Observatory detectors with a network signal-to-noise ratio of. 13. This system is the lightest black hole binary so far observed, with component masses of 12(2)(+7) M-circle dot and 7(2)(+2) M-circle dot (90% credible intervals). These lie in the range of measured black hole masses in low-mass X-ray binaries, thus allowing us to compare black holes detected through GWs with electromagnetic observations. The source's luminosity distance is 340(-140)(+140) Mpc, corresponding to redshift 0.07(-0.03)(+0.03). We verify that the signal waveform is consistent with the predictions of general relativity.</P>