Conveners
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 Cรดte d'Azur)
12/16/15, 2:00โฏPM
Talk
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, 2:21โฏPM
Talk
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, 2:42โฏPM
Talk
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, 3:03โฏPM
Talk
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, 3:24โฏPM
Talk
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, 4:15โฏPM
Talk
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, 4:35โฏPM
Talk
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, 4:55โฏPM
Talk
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, 5:15โฏPM
Talk
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.
Kenta Hotokezaka
(Hebrew University)
12/16/15, 5:55โฏPM
Talk
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...
Haakon Andresen
(Max Planck Institut fรผr Astrophysik)
12/16/15, 6:15โฏPM
Talk
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, 2:00โฏPM
Talk
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, 2:20โฏPM
Talk
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.ย This instability provides a natural...
Pantelis Pnigouras
12/17/15, 2:40โฏPM
Talk
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, 3:00โฏPM
Poster
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, 3:03โฏPM
Poster
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, 4:15โฏPM
Talk
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...
Dr
Antoine Lassus
(Max Planck Institute fรผr Radioastronomie)
12/17/15, 4:57โฏPM
Talk
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...
Dr
Lindley Lentati
(Cambridge University)
12/17/15, 5:19โฏPM
Talk
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, 5:41โฏPM
Talk
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, 6:03โฏPM
Talk
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...
Alexander Rasskazov
12/17/15, 6:25โฏPM
Pulsar timing arrays โ๏ธ (6 talks)
Talk
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 SBHBโs orbital plane - and significantly affects its eccentricity evolution. The result of our work is a model spectrum of stochastic...
