# Uncertainty in the visibility mask of a survey and its effects on the clustering of biased tracers

## Abstract

The forecasted accuracy of upcoming surveys of large-scale structure cannot be achieved without a proper quantification of the error induced by foreground removal (or other systematics like 0-point photometry offset). Because these errors are highly correlated on the sky, their influence is expected to be especially important at very large scales, at and beyond the first Baryonic Acoustic Oscillation (BAO). In this work we quantify how the uncertainty in the visibility mask of a survey, that gives the survey depth in a specific sky area, influences the measured power spectrum of a sample of tracers of the density field and its covariance matrix. We start from a very large set of 10,000 catalogs of dark matter (DM) halos in periodic cosmological boxes, produced with the PINOCCHIO approximate method. To make an analytic approach feasible, we assume luminosity-independent halo bias and an idealized geometry for the visibility mask, that is constant in square tiles of physical length l ; this should be interpreted as the projection, at the observation redshift, of the angular correlation scale of the foreground residuals. We find that the power spectrum of these biased tracers can be expressed as the sum of a cosmological term, a maskmore »

- Authors:

- Dipartimento di Fisica, Università di Trieste, via G.B. Tiepolo 11, I-34131 Trieste (Italy)
- INAF—Osservatorio Astronomico di Brera, via E. Bianchi 46, I-23807 Merate (Italy)

- Publication Date:

- OSTI Identifier:
- 22679954

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 03; Other Information: Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; ANGULAR CORRELATION; APPROXIMATIONS; BARYONS; CALIBRATION; COUPLING; DENSITY; ERRORS; FLUCTUATIONS; LUMINOSITY; NONLUMINOUS MATTER; OSCILLATIONS; PERIODICITY; PHOTOMETRY; RED SHIFT; SPACE; SPECTRA; VISIBILITY

### Citation Formats

```
Colavincenzo, M., Monaco, P., Borgani, S., and Sefusatti, E., E-mail: colavincenzo@oats.inaf.it, E-mail: monaco@oats.inaf.it, E-mail: emiliano.sefusatti@brera.inaf.it, E-mail: borgani@oats.inaf.it.
```*Uncertainty in the visibility mask of a survey and its effects on the clustering of biased tracers*. United States: N. p., 2017.
Web. doi:10.1088/1475-7516/2017/03/052.

```
Colavincenzo, M., Monaco, P., Borgani, S., & Sefusatti, E., E-mail: colavincenzo@oats.inaf.it, E-mail: monaco@oats.inaf.it, E-mail: emiliano.sefusatti@brera.inaf.it, E-mail: borgani@oats.inaf.it.
```*Uncertainty in the visibility mask of a survey and its effects on the clustering of biased tracers*. United States. doi:10.1088/1475-7516/2017/03/052.

```
Colavincenzo, M., Monaco, P., Borgani, S., and Sefusatti, E., E-mail: colavincenzo@oats.inaf.it, E-mail: monaco@oats.inaf.it, E-mail: emiliano.sefusatti@brera.inaf.it, E-mail: borgani@oats.inaf.it. Wed .
"Uncertainty in the visibility mask of a survey and its effects on the clustering of biased tracers". United States.
doi:10.1088/1475-7516/2017/03/052.
```

```
@article{osti_22679954,
```

title = {Uncertainty in the visibility mask of a survey and its effects on the clustering of biased tracers},

author = {Colavincenzo, M. and Monaco, P. and Borgani, S. and Sefusatti, E., E-mail: colavincenzo@oats.inaf.it, E-mail: monaco@oats.inaf.it, E-mail: emiliano.sefusatti@brera.inaf.it, E-mail: borgani@oats.inaf.it},

abstractNote = {The forecasted accuracy of upcoming surveys of large-scale structure cannot be achieved without a proper quantification of the error induced by foreground removal (or other systematics like 0-point photometry offset). Because these errors are highly correlated on the sky, their influence is expected to be especially important at very large scales, at and beyond the first Baryonic Acoustic Oscillation (BAO). In this work we quantify how the uncertainty in the visibility mask of a survey, that gives the survey depth in a specific sky area, influences the measured power spectrum of a sample of tracers of the density field and its covariance matrix. We start from a very large set of 10,000 catalogs of dark matter (DM) halos in periodic cosmological boxes, produced with the PINOCCHIO approximate method. To make an analytic approach feasible, we assume luminosity-independent halo bias and an idealized geometry for the visibility mask, that is constant in square tiles of physical length l ; this should be interpreted as the projection, at the observation redshift, of the angular correlation scale of the foreground residuals. We find that the power spectrum of these biased tracers can be expressed as the sum of a cosmological term, a mask term and a term involving their convolution. The mask and convolution terms scale like P ∝ l {sup 2}σ {sub A} {sup 2}, where σ {sub A} {sup 2} is the variance of the uncertainty on the visibility mask. With l = 30−100 Mpc/ h and σ {sub A} = 5−20%, the mask term can be significant at k ∼ 0.01−0.1 h /Mpc, and the convolution term can amount to ∼ 1−10% of the total. The influence of mask uncertainty on power spectrum covariance is more complicated: the coupling of the convolution term with the other two gives rise to several mixed terms, that we quantify by difference using the mock catalogs. These are found to be of the same order of the mask covariance, and to introduce non-diagonal terms at large scales. As a consequence, the power spectrum covariance matrix cannot be expressed as the sum of a cosmological and of a mask term. More realistic settings (realistic foregrounds, luminosity-dependent bias) make the analytical approach not feasible, and the problem requires on the one hand usage of extended sets of mock catalogs, on the other hand detailed knowledge of the correlations among errors in the visibility masks. Our results lie down the theoretical bases to quantify the impact that uncertainties in the mask calibration have on the derivation of cosmological constraints from large spectroscopic surveys.},

doi = {10.1088/1475-7516/2017/03/052},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 03,

volume = 2017,

place = {United States},

year = {Wed Mar 01 00:00:00 EST 2017},

month = {Wed Mar 01 00:00:00 EST 2017}

}