Laser phase noise is the dominant noise source in the on-board measurements of the space-based gravitational wave detector LISA (Laser Interferometer Space Antenna). A well-known data analysis technique, the so-called timedelay interferometry (TDI), provides synthesized data streams free of laser phase noise. At the same time, TDI also removes the next largest noise source: phase fluctuations of the on-board clocks which distort the sampling process. TDI needs precise information about the spacecraft separations, sampling times and differential clock noise between the three spacecrafts. These are measured using auxiliary modulations on the laser light. Hence, there is a need for algorithms that account for clock noise removal schemes combined with TDI while preserving the gravitational wave signal. In this paper, we will present the mathematical formulation of the LISA-like data streams and discuss a compliant algorithm that corrects for both clock and laser noise in the case of a rotating, non-breathing LISA constellation. In contrast to previous papers, we consider the current optical bench design (split interferometry configuration), i.e. the test mass readout is done by the local oscillators only, instead of reflecting the weak inter-spacecraft light off the test mass. Furthermore, the absolute order of laser frequencies is taken into account and it can be shown that the TDI equations remain invariant. This is a crucial issue and was, up to now, completely neglected in the analysis.

In this paper, we present a successful implementation of a subtraction-noise projection method into a simple, simulated data analysis pipeline of a gravitational-wave search. We investigate the problem to reveal a weak stochastic background signal which is covered by a strong foreground of compact-binary coalescences. The foreground, which is estimated by matched filters, has to be subtracted from the data. Even an optimal analysis of foreground signals will leave subtraction noise due to estimation errors of template parameters which may corrupt the measurement of the background signal. The subtraction noise can be removed by a noise projection. We apply our analysis pipeline to the proposed future-generation space-borne Big Bang Observer mission which seeks for a stochastic background of primordial gravitational waves in the frequency range ~0.1 Hz—1 Hz covered by a foreground of black-hole and neutron-star binaries. Our analysis is based on a simulation code which provides a dynamical model of a time-delay interferometer network. It generates the data as time series and incorporates the analysis pipeline together with the noise projection. Our results confirm previous ad hoc predictions which say that the Big Bang Observer will be sensitive to backgrounds with fractional energy densities below Omega=10-16

LISA is required to reduce two important noise sources by post-processing on ground using time-delay interferometry (TDI): phase-noise of the on-board reference clocks and laser frequency noise. To achieve the desired suppression, the TDI algorithm needs measurements of the differential clock noise between any two spacecraft and inter-spacecraft ranging measurements with at least 1 m accuracy, which is beyond the precision of ground-based measurements for deep space missions. Therefore, we need on-board measurements by transmitting clock noise and ranging information between the spacecraft as auxiliary functions of the laser link. This paper reports our current experimental results in clock noise transfer and ranging for noise subtraction via postprocessing as well as additional data transfer.

Under suitable conditions, roseoflavin [7-methy-8-dimethylamino-10-(1'-D-ribityl)isoalioxazine] replaces riboflavin to about 80% in the photoreceptor of Phycomyces. The substitute-bearing photoreceptor functions with an efficiency ofabout 0.1% of that of the normal receptor. The substitution is proven by (i) a decrease ofthe effective light flux by a factor of4.7, expressed as a corresponding increase in threshold, and (ii) an increase of the effectiveness of 529-nm light relative to 380-nm light. It has also been shown that roseoflavin is taken up by the mycelium, translocated to the sporangiophore, and effectively phosphorylated by the riboflavin kInase of Phycomyces.The action spectra for the growth and tropic responses of Phycomyces sporangiophores to light suggest that the primary photoreceptor is riboflavin (1). The absolute extinction coefficient ofthe receptor pigment has been estimated and has been found to match that of riboflavin (2). It has also been demonstrated that the action spectrum of the growth response to light of Phycomyces, in addition to its general resemblance to the absorption spectrum of riboflavin, has a shoulder corresponding to a small peak at 595 nm, consistent with respect to location and intensity to the transition from the ground state to the lowest triplet state ofriboflavin (3). Ifaflavin moiety does form the chromophore of the photoreceptor, it might be possible to replace it by a flavin analogue. If this analogue had absorption peaks different from those of riboflavin and if the new receptor were functional, one could expect changes in the action spectrum as compared to undoped controls and could thus distinguish substitution in the photopigment from substitution in other enzymes. In this paper we present evidence for such changes when the analogue roseoflavin is added to the growth medium.Roseoflavin [7-methyl-8-dimethylamino-10-(1'-D-ribityl)isoalloxazine], an antibiotic produced by a Streptomyces strain (4, 5), has a strong absorption maximum in aqueous solutions at 505 nm (e = 31,000) compared to the much weaker ones of riboflavin at 480 nm (E = 8,000) and 445 nm (E = 12,500). In addition, roseoflavin has an absorption minimum near 380 nm, where riboflavin has a maximum (Fig. 1). Therefore, if roseoflavin substitutes for riboflavin to form a functional receptor, one would expect a considerable red shift in the blue maximum and an abolition of the 380-nm maximum of the normal wildtype action spectrum.The idea of replacing riboflavin in the photoreceptor of Phycomyces by an analogue was originated by J. L. Reissig 6 years ago in this laboratory, and several analogues were tested by Reissig at that time. The list was extended by one ofthe present authors in subsequent years. The suggestion to try roseoflavin, a natural product, was made by A. Bacher, and this compound, both unlabeled and 14C-labeled, was very kindly supplied by Kunio Matsui (Research Institute for Atomic Energy, University of Osaka). Careful studies on phototropic balance and on the light-growth nul...