Data di Pubblicazione:
2022
Abstract:
We present a method for fast evaluation of the covariance matrix for a two-point galaxy correlation function (2PCF) measured with the Landy- Szalay estimator. The standard way of evaluating the covariance matrix consists in running the estimator on a large number of mock catalogs, and evaluating their sample covariance. With large random catalog sizes (random-to-data objects'ratio M≫ 1) the computational cost of the standard method is dominated by that of counting the data-random and random-random pairs, while the uncertainty of the estimate is dominated by that of data-data pairs. We present a method called Linear Construction (LC), where the covariance is estimated for small random catalogs with a size of M = 1 and M = 2, and the covariance for arbitrary M is constructed as a linear combination of the two. We show that the LC covariance estimate is unbiased. We validated the method with PINOCCHIO simulations in the range r = 20-200 h-1 Mpc. With M = 50 and with 2 h-1 Mpc bins, the theoretical speedup of the method is a factor of 14. We discuss the impact on the precision matrix and parameter estimation, and present a formula for the covariance of covariance.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
Cosmology: observations; Large-scale structure of Universe; Methods: data analysis; Methods: statistical
Elenco autori:
Keihanen E.; Lindholm V.; Monaco P.; Blot L.; Carbone C.; Kiiveri K.; Sanchez A.G.; Viitanen A.; Valiviita J.; Amara A.; Auricchio N.; Baldi M.; Bonino D.; Branchini E.; Brescia M.; Brinchmann J.; Camera S.; Capobianco V.; Carretero J.; Castellano M.; Cavuoti S.; Cimatti A.; Cledassou R.; Congedo G.; Conversi L.; Copin Y.; Corcione L.; Cropper M.; Da Silva A.; Degaudenzi H.; Douspis M.; Dubath F.; Duncan C.A.J.; Dupac X.; Dusini S.; Ealet A.; Farrens S.; Ferriol S.; Frailis M.; Franceschi E.; Fumana M.; Gillis B.; Giocoli C.; Grazian A.; Grupp F.; Guzzo L.; Haugan S.V.H.; Hoekstra H.; Holmes W.; Hormuth F.; Jahnke K.; Kummel M.; Kermiche S.; Kiessling A.; Kitching T.; Kunz M.; Kurki-Suonio H.; Ligori S.; Lilje P.B.; Lloro I.; Maiorano E.; Mansutti O.; Marggraf O.; Marulli F.; Massey R.; Melchior M.; Meneghetti M.; Meylan G.; Moresco M.; Morin B.; Moscardini L.; Munari E.; Niemi S.M.; Padilla C.; Paltani S.; Pasian F.; Pedersen K.; Pettorino V.; Pires S.; Polenta G.; Poncet M.; Popa L.; Raison F.; Renzi A.; Rhodes J.; Romelli E.; Saglia R.; Sartoris B.; Schneider P.; Schrabback T.; Secroun A.; Seidel G.; Sirignano C.; Sirri G.; Stanco L.; Surace C.; Tallada-Crespi P.; Tavagnacco D.; Taylor A.N.; Tereno I.; Toledo-Moreo R.; Torradeflot F.; Valentijn E.A.; Valenziano L.; Vassallo T.; Wang Y.; Weller J.; Zamorani G.; Zoubian J.; Andreon S.; Maino D.; De La Torre S.
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