The Impact of Surveys
Date Issued
2016
Author(s)
•
D'ONOFRIO, MAURO
•
•
Paturel, George
•
Boselli, Alessandro
•
Ferrarese, Laura
•
•
Bergvall, Nils A. S.
•
Karachentseva, Valentina
•
Haynes, Martha P.
•
Giovanelli, Riccardo
•
Bianchi, Luciana
•
•
Bland-Hawthorn, Jonathan
Abstract
Since the most ancient times astronomers felt the need to collect and list in atlases
and catalogs all the visible objects in the sky the first stellar catalog known in the
western world being the one of Hipparchus (II century BC). We have to wait until
Charles Messier at the end of the XVIII century to have the first incidental catalog
of nebulae, i.e. including a mixture of fuzzy objects, nebulæ, that telescopes of the
epoch could detect. In Chapter 1 we have already discussed the atlases and catalogs
that soon after the discovery of galaxies appeared in the literature describing the
properties of the nearby galaxies, in particular their morphologies in Chapter 3. The
subject of extragalactic papers, during the photographic plate era, were one or few
galaxies, whose properties were carefully scrutinized looking at all details resolved
by telescopes in the optical waveband. This happens also today, of course, basically
at all wavelengths. However, the impact of new technologies permits in the last two decades to tackle survey programs addressed to the study of specific extragalactic
problems considering millions of galaxies.
These systematic investigations of enormous galaxy samples requires dedicated
observing, reduction and storing/retrieval facilities provided, in the Big Science era,
by international consortia. Data are treated in a statistically way, combining the
multi-wavelength information coming from several instruments, scanning galaxy
properties as a function of the redshift and of the environment. The big teams of scientists
and engineers that has planned and built the instrumental facilities, including
sometimes the telescopes themselves, are also charged of providing a nearly immediate
access to the data, as well as their maintenance and calibration. The data
are easy available through simple queries on the web. Usually one of the main step
of these large teams is to build a catalog of the detected sources, providing the
first measures typically obtained from automatic softwares of analysis. These data
are then cross-correlated with other data available for the same sources in the web
databases, possibly refined with better calibration. Relations between entries are
evaluated and discussed at the light of theoretical models and simulations by members
of the same team. Observations have the strong tendency to produce facts so
models are refined and data-set revisited and/or integrated with new observations.
This Chapter is dedicated to galaxy surveys. It is even difficult to offer a complete
overview of the enormous number of galaxy surveys today available and/or ongoing.
We interviewed scientists asking them to present the most significant surveys,
in their view, in their area of scientific interest and emphasized the main results
obtained by the surveys that have seen their active collaboration.
Before entering the core of such discussion George Paturel will provide us in
Section 5.2 a much clear idea of the efforts that are necessary to build a good galaxy
catalogue and to homogenize the entries in a database. The information about the
single galaxies are indeed so wide that a new concept of data managing has been
developed: the Virtual Observatory (see Section 9.9). Since the beginning of the
astronomical use of photographic techniques, big plates archives are preserved basically
in all observatories. Thanks to their large field of view and easy storability,
astronomers often re-used this patrimony over the time, e.g. to follow time variable
phenomena or to inspect several different objects in the field of view of the plates.
Along this line Virtual Observatories have been conceived for providing an easy
retrieval of the multiple types of data available for individual objects.
In Section 5.3 Alessandro Boselli and Laura Ferrarese will characterize the
galaxy environments that are coming out from the various sky surveys, dealing
in particular with the Virgo and Fornax clusters, our closer biggest associations
of galaxies. Then, in Section 5.3.1 Bianca Poggianti will draw the picture emerging
from WINGS, the WIde field Galaxy cluster Survey, dedicated to the study of
the nearby (z < 0.07) galaxy clusters. Nils Bergvall (Section 5.3.2) and Valentina
Karachentseva (Section 5.3.2) will present the properties of galaxies inhabiting the
low density environments up to isolation. Martha Haynes and Riccardo Giovanelli
will discuss the HI surveys in Section 5.4 and related subsections. Luciana Bianchi
will introduce the UV surveys, with a particular emphasis for the results obtained
by GALEX in Section 5.5.1. The most important IR and X ray surveys will be discussed by Alessandro Boselli and Ginevra Trinchieri respectively in Section 5.5.2
and 5.5.3. Finally, in Section 5.6 Jonathan Bland-Hawthorn and Bianca Poggianti
will give a panoramic sketch of the main spectroscopic surveys.
Coverage
From the Realm of the Nebulae to Populations of Galaxies
Volume
435
Start page
381
Ads BibCode
2016ASSL..435..381R
Rights
restricted
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