Investigation of straightforward impedance eduction in the presence of shear flow

Ji, Xiaodong; Peng, Sen; Wang, Lixun; Sun, Xiaofeng

doi:10.1016/j.jsv.2014.08.031

Cited by 49 publications

(11 citation statements)

References 33 publications

(48 reference statements)

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“…We will adopt this less stringent limit when modelling the shapes of central early-type galaxies. These lower limits on particle numbers for shape computation are of the same order as those deduced by Jing (2002) and Pereira et al (2008), the latter paper presenting a similar approach based on mock NFW haloes for the reduced inertia tensor M red µν = Np i=1 ri,µri,ν/r 2 i . Jing (2002) derive a minimum number of 160 for which ellipticity correlations are underestimated not more than 5 % with respect to high-resolution simulations 7 .…”

Section: Halo Shapes and Angular Momentasupporting

confidence: 64%

Intrinsic galaxy shapes and alignments – I. Measuring and modelling COSMOS intrinsic galaxy ellipticities

Joachimi¹,

Semboloni²,

Bett³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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The statistical properties of the ellipticities of galaxy images depend on how galaxies form and evolve, and therefore constrain models of galaxy morphology, which are key to the removal of the intrinsic alignment contamination of cosmological weak lensing surveys, as well as to the calibration of weak lensing shape measurements. We construct such models based on the halo properties of the Millennium Simulation and confront them with a sample of 90, 000 galaxies from the COSMOS Survey, covering three decades in luminosity and redshifts out to z = 2. The ellipticity measurements are corrected for effects of point spread function smearing, spurious image distortions, and measurement noise. Dividing galaxies into early, late, and irregular types, we find that early-type galaxies have up to a factor of two lower intrinsic ellipticity dispersion than late-type galaxies. None of the samples shows evidence for redshift evolution, while the ellipticity dispersion for late-type galaxies scales strongly with absolute magnitude at the bright end. The simulation-based models reproduce the main characteristics of the intrinsic ellipticity distributions although which model fares best depends on the selection criteria of the galaxy sample. We observe fewer close-to-circular late-type galaxy images in COSMOS than expected for a sample of randomly oriented circular thick disks and discuss possible explanations for this deficit.

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Section: Halo Shapes and Angular Momentasupporting

confidence: 64%

Intrinsic galaxy shapes and alignments – I. Measuring and modelling COSMOS intrinsic galaxy ellipticities

Joachimi¹,

Semboloni²,

Bett³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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“…to have less than 5 % deviation of the measured axis ratios from the truth, and less than 5 degrees uncertainty in the direction of the largest eigenvector (see also Bett et al 2007). Sparsely sampled haloes tend to produce smaller axis ratios (and hence larger ellipticity on average) as well as rapidly increasing uncertainty in the halo orientation, leading to an underestimation of ellipticity correlations (Jing 2002).…”

Section: Halo Shapes and Angular Momentamentioning

confidence: 99%

Intrinsic galaxy shapes and alignments – II. Modelling the intrinsic alignment contamination of weak lensing surveys

Joachimi

Semboloni

Hilbert

et al. 2013

Monthly Notices of the Royal Astronomical Society

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Intrinsic galaxy alignments constitute the major astrophysical systematic of forthcoming weak gravitational lensing surveys but also yield unique insights into galaxy formation and evolution. We build analytic models for the distribution of galaxy shapes based on halo properties extracted from the Millennium Simulation, differentiating between early-and late-type galaxies as well as central galaxies and satellites. The resulting ellipticity correlations are investigated for their physical properties and compared to a suite of current observations. The best-faring model is then used to predict the intrinsic alignment contamination of planned weak lensing surveys. We find that latetype galaxy models generally have weak intrinsic ellipticity correlations, marginally increasing towards smaller galaxy separation and higher redshift. The signal for earlytype models at fixed halo mass strongly increases by three orders of magnitude over two decades in galaxy separation, and by one order of magnitude from z = 0 to z = 2. The intrinsic alignment strength also depends strongly on halo mass, but not on galaxy luminosity at fixed mass, or galaxy number density in the environment. We identify models that are in good agreement with all observational data, except that all models over-predict alignments of faint early-type galaxies. The best model yields an intrinsic alignment contamination of a Euclid -like survey between 0.5 − 10 % at z > 0.6 and on angular scales larger than a few arcminutes. Cutting 20 % of red foreground galaxies using observer-frame colours can suppress this contamination by up to a factor of two.

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“…It is seen that the sensitivity to transmission errors is much higher at low frequencies because of the low dissipation, where the value of jk x j approaches to zero in Eqs. (27), (28) and (31) and makes the value of Jacobian matrix in Eq. (32) relatively high.…”

Section: Uncertainty Results For Impedance Eductionmentioning

confidence: 99%

“…The reason for distortion at high frequencies could instead lie in the uncertainty in mean Mach number estimate for the wave propagation (dispersion equation). Recently Jing [31] shows that estimating the mean Mach number from the midspan profile results in a slight overestimation of the mean Mach number in the two-dimensional acoustic modeling and can affect the accuracy of the impedance results.…”

Section: Systematic Uncertainty For Mach Number Used In the Ingard-mymentioning

confidence: 99%

A systematic uncertainty analysis for liner impedance eduction technology

Zhou¹,

Bodén

2015

Journal of Sound and Vibration

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Investigation of straightforward impedance eduction in the presence of shear flow

Cited by 49 publications

References 33 publications

Intrinsic galaxy shapes and alignments – I. Measuring and modelling COSMOS intrinsic galaxy ellipticities

Intrinsic galaxy shapes and alignments – I. Measuring and modelling COSMOS intrinsic galaxy ellipticities

Intrinsic galaxy shapes and alignments – II. Modelling the intrinsic alignment contamination of weak lensing surveys

A systematic uncertainty analysis for liner impedance eduction technology

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