199 research outputs found
Gravitational-wave Detection and Parameter Estimation for Accreting Black-hole Binaries and Their Electromagnetic Counterpart
No full textWe study the impact of gas accretion on the orbital evolution of black-hole binaries initially at large separation in the band of the planned Laser Interferometer Space Antenna (LISA). We focus on two sources: (i) stellar-origin black-hole binaries (SOBHBs) that can migrate from the LISA band to the band of ground-based gravitational-wave (GW) observatories within weeks/months; and (ii) intermediate-mass black-hole binaries (IMBHBs) in the LISA band only. Because of the large number of observable GW cycles, the phase evolution of these systems needs to be modeled to great accuracy to avoid biasing the estimation of the source parameters. Accretion affects the GW phase at negative (-4) post-Newtonian order, being thus dominant for binaries at large separations. Accretion at the Eddington or at super-Eddington rate will leave a detectable imprint on the dynamics of SOBHBs. For super-Eddington rates and a 10 yr mission, a multiwavelength strategy with LISA and a ground-based interferometer can detect about 10 (a few) SOBHB events for which the accretion rate can be measured at 50% (10%) level. In all cases, the sky position can be identified within much less than 0.4 deg2 uncertainty. Likewise, accretion at ⪆100% of the Eddington rate can be measured in IMBHBs up to redshift z ≈ 0.1, and the position of these sources can be identified within less than uncertainty. Altogether, a detection of SOBHBs or IMBHBs would allow for targeted searches of electromagnetic counterparts to black-hole mergers in gas-rich environments with future X-ray detectors (such as Athena) and/or radio observatories (such as SKA)
Discriminating between different scenarios for the formation and evolution of massive black holes with LISA
No full textElectromagnetic observations have provided strong evidence for the existence of massive black holes in the center of galaxies, but their origin is still poorly known. Different scenarios for the formation and evolution of massive black holes lead to different predictions for their properties and merger rates. LISA observations of coalescing massive black hole binaries could be used to reverse engineer the problem and shed light on these mechanisms. In this paper, we introduce a pipeline based on hierarchical Bayesian inference to infer the mixing fraction between different theoretical models by comparing them to LISA observations of massive black hole mergers. By testing this pipeline against simulated LISA data, we show that it allows us to accurately infer the properties of the massive black hole population as long as our theoretical models provide a reliable description of the Universe. We also show that measurement errors, including both instrumental noise and weak lensing errors, have little impact on the inference
Detectable Environmental Effects in GW190521-like Black-Hole Binaries with LISA
No full textGW190521 is the compact binary with the largest masses observed to date, with at least one black hole in the pair-instability gap. This event has also been claimed to be associated with an optical flare observed by the Zwicky Transient Facility in an active galactic nucleus (AGN), possibly due to the postmerger motion of the merger remnant in the AGN gaseous disk. The Laser Interferometer Space Antenna (LISA) may detect up to ten such gas-rich black-hole binaries months to years before their detection by Laser Interferometer Gravitational Wave Observatory or Virgo-like interferometers, localizing them in the sky within ≈1°2. LISA will also measure directly deviations from purely vacuum and stationary waveforms arising from gas accretion, dynamical friction, and orbital motion around the AGN's massive black hole (acceleration, strong lensing, and Doppler modulation). LISA will therefore be crucial to enable us to point electromagnetic telescopes ahead of time toward this novel class of gas-rich sources, to gain direct insight on their physics, and to disentangle environmental effects from corrections to general relativity that may also appear in the waveforms at low frequencies
Bayesian Treatment of Prospective LISA Parameter Estimation for Massive Black Hole Mergers
No full textA full understanding of LISA (Laser Interferometer Space Antenna)'s science capability will require accurate models of incident waveform signals and the instrumental response. While Fisher matrix analysis is useful for some estimates, a full Bayesian treatment is needed for important cases at the limit of LISA's capability. We will apply fast analysis algorithms enabling accurate treatment with EOB (effective-one-body) waveforms and the full-featured LISA response to study the significance of higher spherical harmonics and mergers in LISA analysis
Assurer à la fois la gestion des visiteurs et un développement socio-économique dans une aire protégée labellisée : le rôle d'un Parc Naturel Régional (PNR)
No full text[Departement_IRSTEA]Territoires [TR1_IRSTEA]DTAM [ADD1_IRSTEA]Adaptation des territoires au changement global9th International Conference on Monitoring and Management of Visitors in recreational and protected Areas (MMV), Bordeaux, FRA, 28-/08/2018 - 31/08/2018International audienceNatural areas are often settings of diverse activities, either productive ones or leisure ones. Furthermore we talk here about inhabited areas. Hence the relative stakes are numerous and contradicting : to protect nature and landscapes, to maintain or to develop the human social and economic activities. Management of these areas is then organizing and designing policies and action devices which fit. Protected areas are governed by various forms of organization in Europe, which are more and more considered as being instruments for protection of the environment but also for regional development (Mose 2016). In France the Regional Nature Parks (RNPs) are managed by groups of local communities, hence they stem from bottom-up processes, but they are also endowed with legal missions. Since the origin (1967) the latter ones are equilibrated between protection and development : RNPs may be called "integrating actors" (Marsat 2009).The subject of our analysis concerns the management of the site "la Chaîne des puys". It is a volcanic area located in the Auvergne (France). Its summit and emblem, the Puy de Dôme is labelled as « Grand Site de France », and the whole site candidates to be on the Unesco World Heritage list. Finally it is included in a much more extended volcanic area, labelled as RNP, the RNP des Volcans d'auvergne. The RNP as organization is in charge of leading the management of the site.Here the main tension occurs between the leisure activities of visitors, and the protection of environment and also other economic activities. The visits endanger quality of the milieux (erosion, stamping on flora, disturbing fauna). Labels (Grands sites, Unesco) will cause enhanced frequenting of the site. Inversely protection of the site may include ban of accessing some parts of the site, hence limitation of leisure and tourism activity. Another tension occurs between leisure and agriculture or forestry.The communication tells an analysis of the way the RNP of the Volcans d'Auvergne carries out its integrating remits. It is based on three main empirical sources : 1- the telling of her activity by one of the authors, who is in charge in the RNP, 2- the documents which set the diagnoses and the frames of management of the site, and 3- the observation of the on-going processes by the other author. The conceptual framework of this analysis is the theory of paradox (Poole et Van de Ven 1989; Smith et Lewis 2011). Coping with opposite stakes and objectives, interaction may take diverse forms, some of them (in italic, below) relate to what can be called "paradoxical management » (Josserand et Perret 2003) : • Calling-off of one of the items : either by force, after conflicting or resigning, or by the change of the objectives of any stakeholder (especially after some change in its representation, that is after re-framing) , or through any innovation which changes the objective features of the problem• Trade-off, or long term sharing, by which none of the stakeholder realizes totally its objectives. For example it may be a partition of the area (zoning). • Finally the dynamical process of dialogue between the actors, of « round trips » between opposite situations, may favour the previous cited forms (reframing, innovation, trade-off). The studied management system of the site shows some distinctive features. The action led include : laying out, protecting or restoring the milieux, monitoring visitors, regulating sport events, driving stakeholders, coaching (farmers, ...), valorizing heritage, educating the public. The stakeholders and their main objectives are diverse as in other sites, with some particularities (complex landownership, proximity with urban area, interest of local great businesses...). The frames for this management are particularly numerous: objectives and constraints of Natura 2000, of the procedure "site classé", of RNP, management plans of Grand site de France, of Unesco WHL. Regarding the requirements of the Unesco WHL, no new organization was created for the management of the site; the decision was to rely on existing actors. An agreement links the main institutional actors. In parallel a trust was built by big local firms in order to bring also support and financial means.The action of the RNP integrates protection and development, with a potentially exemplar balance. The opportunity of more tourism is acknowledged : "it lacks a real project of tourism development in the site...". But this is expressed mainly in terms of better coordination, more than quantative growth, and in a vision of protection of the places "...out of those dedicated to tourism". We identify here an example of "trade-off", by splitting the area. More generally a "differentiated management" of the site is being carried out.Finally, inside of the RNP, the action oriented to the professional actors of development is achieved by two different internal teams, who converse: the one dedicated to the site, and the other dedicated to economy and tourism. In conclusion the case presents interesting particular features : the peri-urban context, a policy seeking well-known labels, the existence of the trust of local businesses, and a particular form of governance, where the RNP applies a "paradoxical management". On the side of the theory, the case suggests that "paradoxical management" of the tension "protection-development" may refer to a mix of solutions : some trade-off (splitting the area, limiting activities), some innovation (including lay-out which changes locally some features of the problem), some re-framing (through teaching professional actors of tourism), and some dialogue (in particular inside of the RNP)
Assurer à la fois la gestion des visiteurs et un développement socio-économique dans une aire protégée labellisée : le rôle d'un Parc Naturel Régional (PNR)
No full text[Departement_IRSTEA]Territoires [TR1_IRSTEA]DTAM [ADD1_IRSTEA]Adaptation des territoires au changement global9th International Conference on Monitoring and Management of Visitors in recreational and protected Areas (MMV), Bordeaux, FRA, 28-/08/2018 - 31/08/2018International audienceNatural areas are often settings of diverse activities, either productive ones or leisure ones. Furthermore we talk here about inhabited areas. Hence the relative stakes are numerous and contradicting : to protect nature and landscapes, to maintain or to develop the human social and economic activities. Management of these areas is then organizing and designing policies and action devices which fit. Protected areas are governed by various forms of organization in Europe, which are more and more considered as being instruments for protection of the environment but also for regional development (Mose 2016). In France the Regional Nature Parks (RNPs) are managed by groups of local communities, hence they stem from bottom-up processes, but they are also endowed with legal missions. Since the origin (1967) the latter ones are equilibrated between protection and development : RNPs may be called "integrating actors" (Marsat 2009).The subject of our analysis concerns the management of the site "la Chaîne des puys". It is a volcanic area located in the Auvergne (France). Its summit and emblem, the Puy de Dôme is labelled as « Grand Site de France », and the whole site candidates to be on the Unesco World Heritage list. Finally it is included in a much more extended volcanic area, labelled as RNP, the RNP des Volcans d'auvergne. The RNP as organization is in charge of leading the management of the site.Here the main tension occurs between the leisure activities of visitors, and the protection of environment and also other economic activities. The visits endanger quality of the milieux (erosion, stamping on flora, disturbing fauna). Labels (Grands sites, Unesco) will cause enhanced frequenting of the site. Inversely protection of the site may include ban of accessing some parts of the site, hence limitation of leisure and tourism activity. Another tension occurs between leisure and agriculture or forestry.The communication tells an analysis of the way the RNP of the Volcans d'Auvergne carries out its integrating remits. It is based on three main empirical sources : 1- the telling of her activity by one of the authors, who is in charge in the RNP, 2- the documents which set the diagnoses and the frames of management of the site, and 3- the observation of the on-going processes by the other author. The conceptual framework of this analysis is the theory of paradox (Poole et Van de Ven 1989; Smith et Lewis 2011). Coping with opposite stakes and objectives, interaction may take diverse forms, some of them (in italic, below) relate to what can be called "paradoxical management » (Josserand et Perret 2003) : • Calling-off of one of the items : either by force, after conflicting or resigning, or by the change of the objectives of any stakeholder (especially after some change in its representation, that is after re-framing) , or through any innovation which changes the objective features of the problem• Trade-off, or long term sharing, by which none of the stakeholder realizes totally its objectives. For example it may be a partition of the area (zoning). • Finally the dynamical process of dialogue between the actors, of « round trips » between opposite situations, may favour the previous cited forms (reframing, innovation, trade-off). The studied management system of the site shows some distinctive features. The action led include : laying out, protecting or restoring the milieux, monitoring visitors, regulating sport events, driving stakeholders, coaching (farmers, ...), valorizing heritage, educating the public. The stakeholders and their main objectives are diverse as in other sites, with some particularities (complex landownership, proximity with urban area, interest of local great businesses...). The frames for this management are particularly numerous: objectives and constraints of Natura 2000, of the procedure "site classé", of RNP, management plans of Grand site de France, of Unesco WHL. Regarding the requirements of the Unesco WHL, no new organization was created for the management of the site; the decision was to rely on existing actors. An agreement links the main institutional actors. In parallel a trust was built by big local firms in order to bring also support and financial means.The action of the RNP integrates protection and development, with a potentially exemplar balance. The opportunity of more tourism is acknowledged : "it lacks a real project of tourism development in the site...". But this is expressed mainly in terms of better coordination, more than quantative growth, and in a vision of protection of the places "...out of those dedicated to tourism". We identify here an example of "trade-off", by splitting the area. More generally a "differentiated management" of the site is being carried out.Finally, inside of the RNP, the action oriented to the professional actors of development is achieved by two different internal teams, who converse: the one dedicated to the site, and the other dedicated to economy and tourism. In conclusion the case presents interesting particular features : the peri-urban context, a policy seeking well-known labels, the existence of the trust of local businesses, and a particular form of governance, where the RNP applies a "paradoxical management". On the side of the theory, the case suggests that "paradoxical management" of the tension "protection-development" may refer to a mix of solutions : some trade-off (splitting the area, limiting activities), some innovation (including lay-out which changes locally some features of the problem), some re-framing (through teaching professional actors of tourism), and some dialogue (in particular inside of the RNP)
Tests of general relativity with stellar-mass black hole binaries observed by LISA
No full textInternational audienceWe consider the observation of stellar-mass black holes binaries with the Laser Interferometer Space Antenna (LISA). Preliminary results based on Fisher information matrix analyses have suggested that gravitational waves from those sources could be very sensitive to possible deviations from the theory of general relativity and from the strong equivalence principle during the low-frequency binary inspiral. We perform a full Markov Chain Monte Carlo Bayesian analysis to quantify the sensitivity of these signals to two phenomenological modifications of general relativity, namely a putative gravitational dipole emission and a nonzero mass for the graviton, properly accounting for the detector’s response. Moreover, we consider a scenario where those sources could be observed also with Earth-based detectors, which should measure the coalescence time with precision better than 1 ms. This constraint on the coalescence time further improves the bounds that we can set on those phenomenological deviations from general relativity. We show that tests of dipole radiation and the graviton’s mass should improve respectively by seven and half an order(s) of magnitude over current bounds. Finally, we discuss under which conditions one may claim the detection of a modification to general relativity
Temporal coding and auditory processing in the prothoracic ganglion of crickets
No full textWe used the auditory system of crickets as a model system to examine the importance of temporal coding in sensory processing. The bilaterally paired Ascending Neurons 1 and 2 (AN1 and AN2) of crickets receive inputs from the auditory receptors on one side and carry the information to the brain. We used stimuli with either conspecific-like or predator-like (i.e. bats) carrier frequency to quantify the accuracy with which the interneurons code the information contained within the amplitude modulation (AM) envelope of the stimulus. AN1, which is tuned to the dominant carrier frequency of cricket songs, selectively codes the limited range of amplitude-modulation frequencies that occur in these signals. AN2, which is most sensitive to ultrasound, serves as a "bat-detector" and codes a broader range of AM frequencies, as occur in bat calls.A striking characteristic in AN2's responses to ultrasound is the presence of bursts of high-frequency spiking separated by relatively sparse spikes. We examined the relative importance of isolated spikes and bursts in the processing of ultrasound. We showed that bursts reliably signal the occurrence of salient amplitude increases. Furthermore, we showed that burst, but not isolated spikes, reliably predict behavioural responses. We suggest AN2 encodes behaviourally important information with bursts.The Omega Neuron 1 (ON1) responds to conspecific signals and to the ultrasonic echolocation sounds. ON1's temporal coding properties vary with carrier frequency, allowing it to encode both of these behaviourally important signals. Furthermore, the temporal coding properties of ON1 in response to cricket-like sound and bat-like sound match those of AN1 and AN2 respectively.ON1 is a source of contralateral inhibition to AN1 and AN2, enhancing binaural contrast and facilitating sound localization. We used dichotic stimulation to examine the importance of the temporal structure of contralateral inhibition for enhancing binaural contrast. Contralateral inhibition degrades the accuracy with which amplitude modulation is encoded by AN 1 and AN2, but only if the temporal pattern of inhibitory input matches that of excitation. Our results show that the CF-specific coding properties of ON1 allow this single neuron to enhance localization cues most effectively for both cricket-like and bat-like acoustic signals
Réflexions stratégiques pour le développement d'un tourisme rural durable
No full text[Departement_IRSTEA]GT [TR1_IRSTEA]RURAMEN / AMANDELe discours du développement durable s`est largement répandu en France depuis les années quatre vingt dix. Le domaine du tourisme rural, parce qu`il repose sur les ressources de l`environnement et du patrimoine rural, qu`il valorise la dimension humaine de l`accueil, qu`il s`inscrit dans le cadre des terroirs et des communautés locales, apparaît propice à son application. Pourtant les pratiques de tourisme durable tardent à s`imposer.Comment expliquer cette lenteur à intégrer les changements attendus d`un développement plus durable, auxquels aspirent la société, les touristes, la population locale ? L`analyse stratégique d`expériences locales permet-elle de comprendre les processus émergeants et les obstacles à leur aboutissement ? Quels enseignements retenir, quels voies et moyens pour promouvoir un tourisme rural plus durable ?Le propos de cette communication se développe sur la base d`un modèle de processus de changement des pratiques au sein d`un territoire. Un acteur ou un collectif d`acteurs initiateurs entendent promouvoir un mode de développement durable du tourisme en mobilisant les autres acteurs dans l`action collective à l`échelle d`un territoire rural. L`analyse porte d`abord sur les acteurs initiateurs : Qui sont-ils ? Comment opèrent-ils ? Quelles approches privilégient-ils ? On parlera notamment de perceptions, de connaissances et d`évaluation, d`animation et de communication, de coordination. Puis le raisonnement se développe sur l`action collective au sein des territoires : Quels processus ? Quels jeux d`acteurs ? Quels instruments ? Quels accords ? Quels effets ? Deux cas d`études seront alors analysés. Le propos s`achève par une réflexion sur les voies et moyens aptes à promouvoir des dynamiques de développement durable au sein des territoires touristiques ruraux.La matériau de l`analyse est issu de recherches en gestion sur des cas territoriaux (Chaîne des Puys en Auvergne, Gorges du Tarn en Lozère), de travaux de recherche-action (Parc national des Cévennes), de séminaires de réflexion sur le tourisme durable (Conférence permanente du tourisme rural)
Fourier-domain modulations and delays of gravitational-wave signals
No full textWe present a Fourier-domain approach to modulations and delays of gravitational wave signals, a problem which arises in two different contexts. For space-based detectors like LISA, the orbital motion of the detector introduces a time-dependency in the response of the detector, consisting of both a modulation and a varying delay. In the context of signals from precessing spinning binary systems, a useful tool for building models of the waveform consists in representing the signal as a time-dependent rotation of a quasi-non-precessing waveform. In both cases, being able to compute transfer functions for these effects directly in the Fourier domain may enable performance gains for data analysis applications by using fast frequency-domain waveforms. Our results generalize previous approaches based on the stationary phase approximation for inspiral signals, extending them by including delays and computing corrections beyond the leading order, while being applicable to the broader class of inspiral-merger-ringdown signals. In the LISA case, we find that a leading-order treatment is accurate for high-mass and low-mass signals that are chirping fast enough, with errors consistently reduced by the corrections we derived. By contrast, low-mass binary black holes, if far away from merger and slowly-chirping, cannot be handled by this formalism and we develop another approach for these systems. In the case of precessing binaries, we explore the merger-ringdown range for a handful of cases, using a simple model for the post-merger precession. We find that deviations from leading order can give large fractional errors, while affecting mainly subdominant modes and giving rise to a limited unfaithfulness in the full waveform. Including higher-order corrections consistently reduces the unfaithfulness, and we further develop an alternative approach to accurately represent post-merger features
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