11 - Gravitational waves
- Chiara Caprini (CEA-Saclay)
11 - Gravitational waves
- Chiara Caprini (CEA-Saclay)
11 - Gravitational waves
- Chiara Caprini (CEA-Saclay)
11 - Gravitational waves: Pulsar Timing Array
- Victoria Kaspi ()
- Michael Kramer (Max-Planck-Institut fuer Radioastronomie)
Tania Regimbau (Observatoire de la Côte d'Azur)
12/16/15, 2:00 PM
According to various cosmological scenarios, we are bathed in a stochastic background of gravitational waves generated in the first instants after the Big Bang. Detection of this background would have a profound impact on our understanding of the evolution of the Universe, as it represents a unique window on the very early Universe and on the physical laws that apply at the highest energy...
Elinore Roebber (McGill University)
12/16/15, 2:21 PM
We use large N-body simulations and empirical scaling relations between dark matter halos, galaxies, and supermassive black holes to estimate the formation rates of supermassive black hole binaries and the resulting low-frequency stochastic gravitational wave background (GWB). We find that uncertainty in the astrophysical scaling relations systematically changes the amplitude of the GWB by a...
Pedro Klaus Schwaller
12/16/15, 2:42 PM
A large class of models with a composite dark sector undergo a strong first order phase transition in the early universe, which could lead to a detectable gravitational wave signal. I will summarise the basic conditions for a strong first order phase transition for SU(N) dark sectors, calculate the gravitational wave spectrum and show that, depending on the dark confinement scale, it can be...
Mark Hindmarsh (University of Sussex)
12/16/15, 3:03 PM
Recent numerical simulations have demonstrated that the most important source of gravitational radiation from a thermal first order phase transition in the early Universe is the sound waves it produces. I outline the theory of the acoustic production of gravitational waves from phase transitions, showing how both the amplitude and shape of the power spectrum can be simply understood....
David Weir (University of Stavanger)
12/16/15, 3:24 PM
We present large-scale numerical simulations of the gravitational radiation produced by a first order thermal phase transition in the early universe. The dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. The resulting gravitational wave power spectrum has a power-law form between scales set by the average bubble separation...
Nicola Tamanini (CEA - France)
12/16/15, 4:15 PM
In this talk I will consider the application of eLISA as a probe of the late-time cosmological expansion. In particular I will first review the concept of standard sirens and how these can be used to investigate the distant-to-redshift relation. I will then discuss the best strategies to obtain as many standard sirens as possible, taking into account what kinds of electro-magnetic counterparts...
Prof. Zoltan Haiman (Columbia University)
12/16/15, 4:35 PM
In this talk, I will discuss possible characteristics of electromagnetic (EM) emission from supermassive black hole (SMBH) binaries. In particular, any detectable EM emission is likely to be time-variable, and contain unique spectral signatures, which should aid identifying SMHB binaries. I will discuss recent hydrodynamical simulations, which suggest quasiperiodic modulations in the...
Prof. Andres Escala (Universidad de Chile)
12/16/15, 4:55 PM
We study numerically the fate of SMBHs in galaxy mergers. If the galaxies involved in these mergers have a gas fraction of at least %1 is expected that a massive gaseous disk with a mass of ten to hundred times the mass of the SMBHs will be formed in the central kilo parsec of the merger remnant. The SMBHs in these nuclear region will form a SMBH binary which separation will shrink mainly due...
Mark Hannam (Cardiff University)
12/16/15, 5:15 PM
Modelling the inspiral, merger and ringdown of generic (i.e., precessing) black-hole binaries has long been a major challenge for theoretical gravitational-wave astronomy. I will present a simple picture of the underlying phenomenology of these systems, which has lead to a novel technique to produce accurate generic waveform models.
12/16/15, 5:35 PM
This talk will discuss the current state of the phenomenological waveform approach for non-precessing black hole binaries, and recent numerical relativity simulations used in the modelling and performed with the BAM code. Using these simulations, we have extended the calibration range of our inspiral-merger-ringdown model to mass ratio 18. The talk will in particular also discuss the anatomy...
295. Gravitational waveform from binary neutron star mergers: Numerical relativity and Effective-one body
Kenta Hotokezaka (Hebrew University)
12/16/15, 5:55 PM
Measuring the neutron-star equation of state with gravitational waves is one of the scientific goal of grand-based gravitational-wave laser interferometers. To achieve this, we need end-to-end waveforms of binary neutron star mergers. Here we present waveforms that are computed with a long-term numerical relativity simulation. Then the waveforms are compared with those computed with effective...
350. Gravitational Wave Signals from 3D Neutrino Simulations of Core-Collapse Supernovae Hydrodynamics
Haakon Andresen (Max Planck Institut für Astrophysik)
12/16/15, 6:15 PM
To this day the exact nature of the detonation mechanise in core collapse supernovae reminds somewhat of a mystery. While numerical models are becoming more and more sophisticated, observations of the inner engine remain elusive. Because he core surrounded by dens stellar matter, electromagnetic radiation can only provide indirect information. Neutrinos and gravitational waves on the other...
Ms Laura BERNARD (IAP)
12/17/15, 2:00 PM
Coalescing compact binary systems are among the most promising sources of gravitational waves for the next generations of interferometers. Due to the faintness of the signal, one needs to construct highly accurate templates to be match-filtered against the detector data, for both detection and parameter estimation. During the inspiralling phase of the coalescence, when the two objects are...
Davide Gerosa (University of Cambridge)
12/17/15, 2:20 PM
We unveil a new dynamical instability in binary black holes with aligned spins. If the spin of the more massive black hole is aligned with the orbital angular momentum while the spin of the less massive black hole is anti-aligned, spins suddenly start to precess when the binary separation falls below the threshold of our newly discovered instability. This instability provides a natural...
12/17/15, 2:40 PM
Due to the Chandrasekhar-Friedman-Schutz (CFS) instability, the f-mode (fundamental oscillation) in a newborn neutron star is driven unstable by the emission of gravitational waves. This star is usually the result of a core-collapse supernova explosion, but may also be the aftermath of a binary neutron star merger, where a rapidly rotating, supramassive configuration is formed, before its...
Joseph Avenoso (The College of New Jersey), Tyler Viducic (The College of New Jersey)
12/17/15, 3:00 PM
It has been previously shown that the energy lost from an incident gravitational wave (GW) on a cloud of charged particles can manifest itself an electromagnetic field, causing the GW to attenuate. Furthermore, it can be shown that the presence of the field and the circumstances in which it was generated leads to currents and subsequently magnetic fields. We plan to calculate how much energy...
Dr Oleg Titov (Geoscience Australia)
12/17/15, 3:03 PM
Some models of the expanding Universe predict that the astrometric proper motion of distant radio sources embedded in space-time are non-zero as radial distance from observer to the source grows. Systematic proper motion effects would produce a predictable quadrupole pattern on the sky that could be detected using Very Long Baseline Interferometry (VLBI) technique. This quadrupole pattern...
Dr Stefan Oslowski (Bielefeld University / MPIfR Bonn)
12/17/15, 4:15 PM
Gravitational waves are expected to be radiated by supermassive black hole binaries formed during galaxy mergers. A stochastic superposition of gravitational waves from all such binary systems will modulate the arrival times of pulses from radio pulsars. Using observations of millisecond pulsars obtained with the Parkes radio telescope, we constrain the characteristic amplitude of this...
12/17/15, 4:36 PM
The European Pulsar Timing Array is a collaboration between European research institutes and radio observatories that was established in 2006. The EPTA makes use of the five largest radio telescopes at decimetric wavelengths in Europe: the Effelsberg Radio Telescope, the Lovell Radio Telescope, the Nançay Radio Telescope, the Westerbork Synthesis Radio Telescope and the Sardinia Radio...
Dr Antoine Lassus (Max Planck Institute für Radioastronomie)
12/17/15, 4:57 PM
We have searched for continuous gravitational wave (CGW) signals produced by individually resolvable, circular supermassive black hole binaries (SMBHBs) in the latest EPTA dataset, which consists of ultra-precise timing data on 41 millisecond pulsars. Several algorithms have been used and depending on the adopted detection algorithm, the 95% upper limit on the sky-averaged strain amplitude...
409. Limits on the amplitude of the nanohertz gravitational wave Universe from the European Pulsar Timing Array
Dr Lindley Lentati (Cambridge University)
12/17/15, 5:19 PM
The European Pulsar Timing Array (EPTA) was established in 2006 as a collaboration between European research institutes and radio observatories. The key mission of the EPTA is the direct detection of nanohertz gravitational waves (GWs) using the high-precision timing of an ensemble of millisecond pulsars. The primary source of GWs in the nanohertz band is expected to be merging supermassive...
Dr Alberto Sesana (University of Birmingham)
12/17/15, 5:41 PM
Pulsar timing arrays (PTAs) are dramatically improving their sensitivity. Current upper limits start to be in tension with vanilla models of gravitational wave driven, circular supermassive black hole binaries (SMBHBs), although nothing can be safely ruled out yet. I will discuss how we can use current and future PTA limits to investigate the nature of SMBHBs and learn about their overall...
Dr Sotiris Sanidas (University of Amsterdam)
12/17/15, 6:03 PM
Pulsar Timing Arrays observe a set of millisecond pulsars at high timing precision over long periods of time, aiming to directly detect gravitational waves. Probing the nHz frequency regime, PTAs are sensitive also to many primordial GW sources, with one of them being cosmic strings; a web of string-like energy concentrations that may have formed right after Inflation and permeates the...
504. Pulsar timing detection of gravitational waves from supermassive black hole binaries in stellar environment
12/17/15, 6:25 PM
Pulsar timing arrays ✔︎ (6 talks)
We study the effect of stellar environment on gravitational wave spectrum produced by supermassive black hole binaries (SBHB). Our model includes the possibility of rotating galactic nucleus, which opens a new degree of freedom - the orientation of SBHB’s orbital plane - and significantly affects its eccentricity evolution. The result of our work is a model spectrum of stochastic...