10th LISA PE telecon 27.03.2008 ================================================ Partial list of participants: Curt Cutler Alicia M Sintes B.S.Sathyaprakash Chris van den Broeck Miquel Trias Emanuele Berti Neil Cornish Marta volonteri ========================================================= 0- News about Nasa's head of science that resigned for unexplained reasons. 1. presentation of the results for SMBHB for different descope LISA missions (see link on the wiki): Curt points out that this work is part of a much larger effort, especially by Neil Cornish and Jonathan Gair, to look at the effect of descopes on Galactic binaries, EMRIs, and MBHBs. The parameters of the baseline and 2 descopes used are: Baseline: 5e9 m arms, 5 years, position noise 3.24e-22 m/Hz, acceleration noise 9e-30 m^2 s^-4/Hz. Descope 1: 2.5e9 m arms, 3 years, position noise 3.24e-22 m/Hz, acceleration noise 9e-30 m^2 s^-4/Hz. Descope 2: 1e9 m arms, 2 years, position noise 1.17e-22 m/Hz, acceleration noise 9e-30 m^2 s^-4/Hz. **) For the MBH, 3 different models of MBH birth/growth/spinup were studies. The source distributions for these 3 models were provided by Marta Volonteri, based on her merger tree simulations. Distribution 1: MBHs from small seeds, with isotropic spins and efficient spin-up from accretion. This is a high-spin model. Distribution 2: MBHs from small seeds, with isotropic spins but inefficient spin-up from accretion. This is a low-spin model Distribution 3: MBHs from large-ish seeds, with isotropic spins. There wasnÕt time for Marta to do a full simulation with spins, so spins were just randomly assigned: half with a/M = 0.01 and half with a/M = 0.8 The results were presented for the X channel alone and also the A+E channels. Please see the results on the wiki, but in short with the descope missions you can still detect SMBH, but one pays a penalty in having them well localized. Neil and Jonathan have done a lot of work on other sources and for EMRIs the result is that you could loose them completely. All these results would be presented at NASA HQ next wednesday. Discussions continues about the no over-run policy by NASA and ESA and how this affects other missions as well. Neil also clarifies how the confusion noise was computed from population synthesis models, for different mission duration that also depending on how well one can do the galactic removal. So 6 different confusion noises were used, 3 different time duration and depending if 2 channels were used or only 1 individual channel. Regarding the low frequency cut off and the instrumental noise, the most pessimistic model of Bender was used. Action items: Marta will produce more simulations Curt will produce more figures of merit, and more post-processing for presentation. **) Neil has done a similar exercise for EMRIs using Gair'04 paper regarding certain event rate/year. He will post some results. The problem for the EMRIs is completely different than for SMBH. Here it really matters how many sources you will detect, the parameter estimation is not an issue. The problem is that for the descope2 the rates drop too much that they could be all lost (by a factor of 100 ?). For the descope 1 the event rate is reduced by ~10. For the SMBH and descope2 the lost factor is about 4 and that includes already a factor 2 due to the shorter duration. Again one insists to point out that for SMBH is the quality of the measurement what matters. The well determined sources drop 1 order of magnitude, from 30 to 2. 2- f2f meeting during the LISA symposium in Barcelona. We will try to arrange for a meeting later on in the week when more members are present 3-Clarifications on SMBH inspiral waveforms. Chris and Neil clarify some of the truncation issues. Neil clarifies that the truncation of all harmonics at a given frequency was just an exercise we all did, in order to cut the signal in the frequency domain in a regime in which all codes will have accumulated the same SNR, for code comparison purposes only. That truncation is NOT done in any of the codes and ALL codes were modified to do this test exercise. We all agree that codes have been properly cross-checked. This high frequency cut-off exercise has nothing to do with the time-domain tapering window used by the time-domain codes. The discussion continues regarding the improvement seen by AISSV in PRD76(2007)104016 on the improvement of more than 1 order of magnitude. Neil points out that angular resolution might not be the relevant quantity to look at but the semimajor axis, since the shape of the ellipses could be very eccentric. ========================================================= Next telecon: April 10th at 8:15 PDT, 11:15 EDT, 15:15 UTC, 17:15 CEST Please send comments or correction to sintes (@) aei.mpg.de