1,615 research outputs found
Pre-Merger Localization of Gravitational-Wave Standard Sirens With LISA I: Harmonic Mode Decomposition
The continuous improvement in localization errors (sky position and distance)
in real time as LISA observes the gradual inspiral of a supermassive black hole
(SMBH) binary can be of great help in identifying any prompt electromagnetic
counterpart associated with the merger. We develop a new method, based on a
Fourier decomposition of the time-dependent, LISA-modulated gravitational-wave
signal, to study this intricate problem. The method is faster than standard
Monte Carlo simulations by orders of magnitude. By surveying the parameter
space of potential LISA sources, we find that counterparts to SMBH binary
mergers with total mass M~10^5-10^7 M_Sun and redshifts z<~3 can be localized
to within the field of view of astronomical instruments (~deg^2) typically
hours to weeks prior to coalescence. This will allow targeted searches for
variable electromagnetic counterparts as the merger proceeds, as well as
monitoring of the most energetic coalescence phase. A rich set of astrophysical
and cosmological applications would emerge from the identification of
electromagnetic counterparts to these gravitational-wave standard sirens.Comment: 29 pages, 12 figures, version accepted by Phys Rev
Csigasorral függesztett gerenda szabadrezgése modálanalízissel
Egy csigasorral függesztett gerenda szabadrezgését vizsgáljuk. A gerendát Bernoulli-Euler rúdként modellezzük, és bemutatjuk a szerkezet sajátrezgésalakjait és sajátkörfrekvenciáit feszített és feszítetlen függesztőkábel esetén a folytonos rúd differenciálegyenletének megoldásával. A kábel feszített, vagy feszítetlen voltától függ ̋oen beszélünk aktív és passzív függesztésr ̋ol. Az aktív és passzív függesztés
rezgésalakjai egymásnak megfeleltethet ̋oek, az állapotváltozások során a modális koordináták transzformációja id ̋ofüggetlen módon végezhető.
Numerikus módszert mutatunk a rezgés számítására, az aktív és passzív állapotok közötti váltás kezelésére. Különböző kezdőállapotokat használva szimuláljuk a tartó szabadrezgését. Megmutatjuk, hogy még az aktív és passzív függesztések közötti váltás okozta erős nemlinearitás
mellett is képes a szerkezet periodikus szabadrezgést végezni
Dynamic analysis of a beam on block-and-tackle suspension system: A continuum approach
In this paper the dynamic analysis of a beam on a block-and-tackle suspension system is accomplished using a continuum approach. The modal shape functions and the natural frequencies of the structure are derived in a dimensionless form for both slacked and stressed cables. A procedure is developed to handle the nonlinearity originated from the consecutive slacking and stressing of the suspension cable. Vibration analysis of the bilinear, multi-degree-of-freedom structure is accomplished for a vortex-shedding generated lift force and for a continuous pedestrian flow
White dwarfs stripped by massive black holes: sources of coincident gravitational and electromagnetic radiation
White dwarfs inspiraling into black holes of mass \MBH\simgt 10^5M_\odot
are detectable sources of gravitational waves in the LISA band. In many of
these events, the white dwarf begins to lose mass during the main observational
phase of the inspiral. The mass loss starts gently and can last for thousands
of orbits. The white dwarf matter overflows the Roche lobe through the
point at each pericenter passage and the mass loss repeats periodically. The
process occurs very close to the black hole and the released gas can accrete,
creating a bright source of radiation with luminosity close to the Eddington
limit, ~erg~s. This class of inspirals offers a promising
scenario for dual detections of gravitational waves and electromagnetic
radiation.Comment: 5 pages, 3 figures. Minor changes. Accepted in MNRAS Letters on
August 6 201
COMPARATIVE ANALYSIS OF THE CHANGES OF THE MASS MOMENTS OF INERTIA DURING A BREAST-STROKE
A new method of investigation of athletes' motion takes into consideration the changes of the principal moments of inertia and their directions during the interval of the motion, because these characterise the efficiency and the neuro-muscular regulation of the motion. This paper presents a comparative analysis of two top swimmers (Swl=Rozsa, Sw2=Guttler) and points out the significant difference caused by their alternate motion pattern
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