940 research outputs found
Erratum: Observational black hole spectroscopy: A time-domain multimode analysis of GW150914 [Phys. Rev. D 99 , 123029 (2019)]
No full textObservational black hole spectroscopy: a time-domain multimode analysis of GW150914
Get PDFThe detection of the least damped quasinormal mode from the remnant of the gravitational wave event GW150914 realized the long-sought possibility of observationally studying the properties of quasistationary black hole spacetimes through gravitational waves. Past literature has extensively explored this possibility, and the emerging field has been named “black hole spectroscopy.” In this study, we present results regarding the ringdown spectrum of GW150914, obtained by application of Bayesian inference to identify and characterize the ringdown modes. We employ a pure time-domain analysis method, which infers from the data the time of transition between the nonlinear and quasilinear regimes of the postmerger emission in concert with all other parameters characterizing the source. We find that the data provide no evidence for the presence of more than one quasinormal mode. However, from the central frequency and damping time posteriors alone, no unambiguous identification of a single mode is possible. More in-depth analysis adopting a ringdown model based on results in perturbation theory over the Kerr metric confirms that the data do not provide enough evidence to discriminate among an l = 2 and the l = 3 subset of modes. Our work provides the first comprehensive agnostic framework to observationally investigate astrophysical black holes’ ringdown spectra
Bekenstein-Hod universal bound on information emission rate is obeyed by LIGO-Virgo binary black hole remnants
Get PDFCausality and the generalized laws of black hole thermodynamics imply a bound, known as the Bekenstein-Hod universal bound, on the information emission rate of a perturbed system. Using a time-domain ringdown analysis, we investigate whether remnant black holes produced by the coalescences observed by Advanced LIGO and Advanced Virgo obey this bound. We find that the bound is verified by the astrophysical black hole population with 94% probability, providing a first confirmation of the Bekenstein-Hod bound from black hole systems
Quantum black hole spectroscopy: probing the quantum nature of the black hole area using LIGO-Virgo ringdown detections
Get PDFWe present a thorough observational investigation of the heuristic quantised ringdown model presented in [FOIT-KLEBAN (2019)]. This model is based on the Bekenstein-Mukhanov conjecture, stating that the area of a black hole horizon is an integer multiple of the Planck area~ multiplied by a phenomenological constant, α, which can be viewed as an additional black hole intrinsic parameter. Our approach is based on a time-domain analysis of the gravitational wave signals produced by the ringdown phase of binary black hole mergers detected by the LIGO and Virgo collaboration. Employing a full Bayesian formalism and taking into account the complete correlation structure among the black hole parameters, we show that the value of α cannot be constrained using only GW150914, in contrast to what was suggested in [FOIT-KLEBAN (2019)]. We proceed to repeat the same analysis on the new gravitational wave events detected by the LIGO and Virgo Collaboration up to 1 October 2019, obtaining a combined-event measure equal to and a combined log odds ratio of , implying that current data are not informative enough to favour or discard this model against general relativity. We then show that using a population of GW150914-like simulated events -- detected by the current infrastructure of ground-based detectors at their design sensitivity -- it is possible to confidently falsify the quantised model or prove its validity, in which case probing α at the few % level. Finally we classify the stealth biases that may show up in a population study
Searching for ringdown higher modes with a numerical relativity-informed post-merger model
No full textRobust measurements of multiple black hole vibrational modes provide a unique opportunity to characterise gravity in extreme curvature and dynamical regimes, to better investigate the nature of compact objects and search for signs of new physics. We use a numerically-tuned quasicircular non-precessing ringdown model, TEOBPM, and the pyRing analysis infrastructure to perform a time-domain spectroscopic analysis of the third catalog of transient gravitational-wave signals, GWTC-3, searching for higher angular modes. The TEOBPM model effectively includes non-linearities in the early post-merger signal portion, and carries information about the progenitors parameters through time-dependent excitation amplitudes of the black hole quasinormal modes. Such a strategy allows us to accurately model the full post-merger emission, recovering higher signal-to-noise ratios compared to templates based on more agnostic superpositions of damped-sinusoids. We find weak evidence for the presence of [] mode in several events, with the largest Bayes factor in favour of this mode being [] within the support of the peak time distribution. For GW190521, we observe , but only for times outside the peak time support reconstructed using the highly accurate NRSur7dq4 model, indicating significant systematics affecting such putative detection. Allowing for deviations from general relativity under the assumption of the presence of two modes, we find tentative support for the Kerr “final state conjecture”. Our work showcases a systematic methodology to robustly identify and characterise higher angular modes in ringdown-only signals, highlighting the significant impact of modelling assumptions and peak time uncertainty on spectroscopic measurements, at current signal-to-noise ratios
Instantaneous Kinematics and Singularities of Two Types of Under-Actuated Parallel Wrists
No full textS-(nS)PU-SPU and S-(nS)PU-2SPU are two out of three types of under-actuated wrists that are generated from the “ordinary” wrists of type S-3SPU (fully-parallel wrists), by replacing a spherical pair (S) with a nonholonomic spherical pair (nS) according to the rules stated in [1]. Position analysis, controllability, and path planning of these two wrist types have been addressed and solved in two previous papers [2, 3] of this author. Their kinetostatics and singularity analysis have not been addressed, yet; and they are studied in this paper.
[1] Grosch, P., Di Gregorio, R., and Thomas, F., 2010, “Generation of under-actuated manipulators with nonholonomic joints from ordinary manipulators,” ASME J. of Mechanisms and Robotics, 2(1): 011005-(8 pages).
[2] Di Gregorio R., 2011, “Under-Actuated Nonholonomic Parallel Wrists,” In: Proc. of the 13th World Congress in Mechanism and Machine Science (IFToMM 2011), Guanajuato, México, 19-25 June, 2011, Paper No. A12-264
[3] Di Gregorio, R., 2011, “On the S-(nS)PU-SPU and S-(nS)PU-2SPU under-actuated wrists,” Procs. of the ASME 2011 International Design Engineering Technical Conference & Computers and Information in Engineering Conference, IDETC/CIE 2011, August 28-31, 2011, Washington (DC, USA), Paper No.: DETC2011-47541
Co-authorship network dataset on psoriasis research papers from Medline database (1942-2013).
No full textA ".xlsx" file which provides data used by Gregorio González-Alcaide & collaborators in the article “Evolution of cooperation patterns in psoriasis research: co-authorship network analysis of papers in Medline (1942-2013).” The worksheet “labels” describes every variable. The worksheet “dataset” presents the following data:
PMID: PubMed Identifier for indexed documents in Pubmed used for the study. PMIDs do not change over time or during processing and are never reused.
DP: Date that the article was published.
FAU: Author name for articles published. From 2002 forward, the full author name of authors is provided, if available.
FAU-Revised: Author name after cleansing process. A standardization process of the variations in signatures from single authors was carried out. The main discrepancies we found were caused by one or more first or last names being included, the authors’ first names being either spelled out or abbreviated to the initials, and typos
Co-authorship network dataset on psoriasis research papers from Medline database (1942-2013).
No full textA ".xlsx" file which provides data used by Gregorio González-Alcaide & collaborators in the article “Evolution of cooperation patterns in psoriasis research: co-authorship network analysis of papers in Medline (1942-2013).” The worksheet “labels” describes every variable. The worksheet “dataset” presents the following data:
PMID: PubMed Identifier for indexed documents in Pubmed used for the study. PMIDs do not change over time or during processing and are never reused.
DP: Date that the article was published.
FAU: Author name for articles published. From 2002 forward, the full author name of authors is provided, if available.
FAU-Revised: Author name after cleansing process. A standardization process of the variations in signatures from single authors was carried out. The main discrepancies we found were caused by one or more first or last names being included, the authors’ first names being either spelled out or abbreviated to the initials, and typos
Scientometrics analysis of research activity and collaboration patterns in Chagas cardiomyopathy
No full textAn XLSX Excel file which provides data used by Gregorio González-Alcaide & collaborators in the article “Scientometrics analysis of research activity and collaboration patterns in Chagas cardiomyopathy”
The worksheet “labels” describes the variables of the bibliographic databases that allow identifying the documents used to carry out the study.
The worksheet “documents” present the following data:
PMID: PubMed Identifier.
TI: Title of journal article.
AU: Author(s) of the document.
SO: Source/journal title.
PY: Publication year.
MH: Medical Subject Headings (controlled vocabulary of biomedical terms) that is used to describe the subject of each journal article in MEDLINE.
UT-WOS: Article Identifier in Web of Science (only present in articles indexed in Web of Science).
TC: Times Cites in Web of Science Core Collection
Scientometrics analysis of research activity and collaboration patterns in Chagas cardiomyopathy
No full textAn XLSX Excel file which provides data used by Gregorio González-Alcaide & collaborators in the article “Scientometrics analysis of research activity and collaboration patterns in Chagas cardiomyopathy”
The worksheet “labels” describes the variables of the bibliographic databases that allow identifying the documents used to carry out the study.
The worksheet “documents” present the following data:
PMID: PubMed Identifier.
TI: Title of journal article.
AU: Author(s) of the document.
SO: Source/journal title.
PY: Publication year.
MH: Medical Subject Headings (controlled vocabulary of biomedical terms) that is used to describe the subject of each journal article in MEDLINE.
UT-WOS: Article Identifier in Web of Science (only present in articles indexed in Web of Science).
TC: Times Cites in Web of Science Core Collection
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