[SEMINARI] seminario: Detecting filamentary pattern in the Universe: a catalogue and applications

[Enric Marco]

-------- Missatge original --------
Assumpte: 	Anuncio de seminario
Data: 	Tue, 26 Nov 2013 17:41:59 +0100
De: 	Vicent J. Martínez <vicent.martinez en uv.es>
Respon a: 	Astronomia i Astrofisica <DAA en listserv.uv.es>
A: 	DAA en listserv.uv.es



Anuncio de Seminario

Title: Detecting filamentary pattern in the Universe: a catalogue and 
applications

by Dr. Elmo Tempel (Tartu Observatory, NICPB - Tallin, Estonia)

Viernes 29 de noviembre, 12:30h

Lugar: Seminario del Observatorio Astronómico (Parque Científico) Paterna

Abstract

The main feature of the spatial large-scale galaxy distribution is its 
intricate network of galaxy filaments. This network is spanned by the 
galaxy locations that can be interpreted as a three-dimensional point 
distribution. In my talk I give an overview about an object point 
process with interactions (the Bisous model) to trace and extract the 
filamentary network. This method works directly on the galaxy 
distribution and does not require any additional smoothing, it only 
requires fixing the scale of structures. The main advantage of our 
method is in its probabilistic nature. I give an example, how single 
realisations of the model are sensitive to noise (observational 
uncertainties and small number densities of galaxies). Still, averaging 
many realisations reduces the noise influence, and allows computation of 
robust statistical quantities.

Our filament finder (the Bisous model) is probabilistic in the sense 
that it gives us the filament detection probability field together with 
the filament orientation field. Using these two fields, we define the 
spines of the filaments and extract single filaments from the data. To 
trace and extract the filamentary network, we applied our model to the 
presently largest galaxy redshift survey, the Sloan Digital Sky Survey 
(SDSS). We divided the detected network into single filaments and 
constructed a catalogue of filaments. In my talk, I give an overview 
about the detected filaments in the SDSS and present some basic 
properties (e.g. length distribution, radial profiles) of filaments.

Using the SDSS filaments, we have studied the correlation between galaxy 
spin axes and filament spines. I give an brief overview, how filaments 
affect the orientation of galaxy spin axes.
--
Vicent J. Martínez. Observatori Astronòmic - Universitat de València,
Edificio de Institutos de Investigación
c/ Catedrático José Beltrán,2
  E- 46980 Paterna (Valencia) Spain
Tel:+34-963543484 Fax:+34-963543744 mailto:vicent.martinez en uv.es
http://www.uv.es/obsast http://www.uv.es/~martinez 
<http://www.uv.es/%7Emartinez>





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