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Near-Field Cosmology with Southern Group Dwarf Galaxies

Applicant Binggeli Bruno
Number 140244
Funding scheme Project funding (Div. I-III)
Research institution Departement Physik Universität Basel
Institution of higher education University of Basel - BS
Main discipline Astronomy, Astrophysics and Space Sciences
Start/End 01.03.2013 - 30.09.2016
Approved amount 155'421.00
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Keywords (4)

Cosmology; Dark Matter; Dwarf Galaxies; Galaxies

Lay Summary (German)

Lead
Zwerggalaxien sind Schlüsselobjekte zur Untersuchung der nach wie vor rätselhaften Dunklen Materie. In diesem Projekt suchen wir mit Hilfe von Weitwinkelkameras an Grossteleskopen neue, schwache Zwerggalaxien in zwei benachbarten Galaxiengruppen am Südhimmel. Ca. 50 neue Objekte in der Centaurus-Gruppe wurden bereits entdeckt und werden zur Zeit weiter untersucht.
Lay summary

Zwerggalaxien sind sehr leuchtschwache Sternsysteme, die bis zu 90% von Dunkler Materie dominiert werden. Sie sind deswegen wichtige Laboratorien zur Erforschung der Dunklen Materie, deren Natur immer noch völlig rätselhaft ist. Kürzliche Untersuchungen haben gezeigt, dass die Zwergsatelliten um die Milchstrasse und Andromeda herum stark anisotrop verteilt sind, was dem Standardszenarium der Strukturbildung mit kalter Dunkler Materie konträr zuwider läuft. Findet man dasselbe Bild auch in anderen Galaxiengruppen, oder ist das bloss eine lokale "Laune der Natur"? Unser Projekt will zur Beantwortung dieser entscheidenden Frage beitragen, indem wir in den nahen südlichen 'Centaurus' und 'Sculptor' Galaxiengruppen nach weiteren, schwächeren Zwerggalaxien suchen, die dann für solche Studien benutzt werden können. Wir erhalten Aufnahmen von der Dark Energy Survey’ Kamera in Chile und der Weitwinkelkamera des neuen SkyMapper-Teleskops in Australien, die dann unter Zuhilfenahme von computergestützten Bildverarbeitungsprogrammen ausgewertet werden. Unser Ziel: die Entdeckung von ca. 10 bis 30 neuen Zwerggalaxien in den Gruppen, ist inzwischen bereits übertroffen. Für die Centaurus-Gruppe allein werden wir am Ende die Anzahl bekannter Mitglieder verdoppelt haben (von 50 auf 100). Ihre 2D-Verteilung wird bereits erste Rückschlüsse auf die Existenz von Asymmetrien ermöglichen. Wir versuchen mittels Nachbeobachtungen, wenigstens einen Teil der Zwerge auch in der Distanz lokalisieren zu können.

Direct link to Lay Summary Last update: 17.12.2015

Responsible applicant and co-applicants

Name Institute

Employees

Publications

Publication
New low surface brightness dwarf galaxies in the Centaurus group
Müller Oliver, Jerjen Helmut, Binggeli Bruno (2017), New low surface brightness dwarf galaxies in the Centaurus group, in Astronomy & Astrophysics, 597(A7), 1-14.
Testing the two planes of satellites in the Centaurus group
Müller Oliver, Jerjen Helmut, Pawlowski Marcel, Binggeli Bruno (2016), Testing the two planes of satellites in the Centaurus group, in Astronomy & Astrophysics, 595(A119), 1-9.
New dwarf galaxy candidates in the Centaurus group
Müller Oliver, Jerjen Helmut, Binggeli Bruno (2015), New dwarf galaxy candidates in the Centaurus group, in Astronomy & Astrophysics, 583(A79), 1-9.

Collaboration

Group / person Country
Types of collaboration
Dr. Helmut Jerjen, Australian National University Australia (Oceania)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Dr. Thorsten Lisker, Zentrum für Astronomie Heidelberg Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Near Field Cosmology 2016 (13th Potsdam Thinkshop Near Field Cosmology) Talk given at a conference Shooting Centaurus: new dwarf galaxies in the multipacks 29.03.2016 Obergurgl, Austria Müller Oliver;
The Journey of Dwarf Galaxies, EWASS 2015 Talk given at a conference Our Journey to Dwarf Galaxies -- Progress and Problems 22.06.2015 La Laguna, Tenerife, Spain Binggeli Bruno;


Associated projects

Number Title Start Funding scheme
181808 Small-scale cosmology with dwarf galaxies 01.11.2018 Early Postdoc.Mobility
168991 Probing the structure of neighbouring galaxy groups with newly discovered dwarf galaxies 01.10.2016 Project funding (Div. I-III)

Abstract

NEAR-FIELD COSMOLOGY WITH SOUTHERN GROUP DWARF GALAXIESDwarf galaxies are optically elusive stellar systems that consist of up to 90% of dark matter (DM) and thus represent the prime laboratory for DM astrophysics. However, extremely faint dwarf galaxies, as the most sensitive DM tracers, have been detected only in the near field around our Milky Way to date. Ever fainter dwarfs in the “local volume” out to distances of a few Mpcs are being hunted for worldwide to serve “near-field cosmology”. In line with these efforts we propose to conduct a search for faint, hitherto undetected dwarf galaxy members of the nearby southern groups of galaxies in Sculptor and Centaurus, based on dedicated observations with the 268 Megapixel wide-field CCD camera of the new SkyMapper telescope of the Australian National University at Siding Spring Observatory. A sky area of totally 750 square degree covering essential parts of the two groups will be imaged down to a limiting (stellar) magnitude about three times deeper than previously reached by photographic surveys. Drawing on direct inspection and the application of sophisticated data mining techniques to the deep CCD frames we estimate to find 10-30 low-surface brightness, dark-matter dominated dwarf galaxies in each group. Multicolor surface photometry and light profile modelling for the new (and previously known) dwarf members will yield a complete set of structural parameters for the low luminosity galaxies in each group. The following scientific questions will be addressed in our program: (1) The newly discovered dwarfs will trace the galaxy luminosity function (LF) of the two groups down to unprecedented faint magnitudes, comparable in depth to the Local Group (LG). The slope of the faint end of the LF and its variation with environment (groups vs clusters) is providing important constraints on the processes of baryon settlement in the DM halos at an early phase of structure formation. (2) The spatial distribution of the new and old dwarfs in the groups will be searched for anisotropies of the kind known to exist in the neighbourhood of the Milky Way Galaxy. Such anisotropies constitute a challenge to the standard ?CDM scenario of structure formation. (3) With the structural and color information for all dwarfs we will study the systematic differences in evolutionary stage and stellar composition with respect to environment, providing constraints for the modelling of dwarf galaxy evolution. The proposed project is conducted in collaboration with Dr. Helmut Jerjen from the Australian National University who is a member of the SkyMapper science team. He has privileged access to the SkyMapper survey telescope and the CCD data, well before they become publicly available. We are seeking financial support to hire a PhD student for 4 years duration, the first two years of which (covering the present proposal period) will be dedicated to develop and test specialised data mining algorithms, to reduce the CCD image and to search for new very faint dwarfs. A follow-up proposal (for an additional two years) will focus on the photometric and structural analysis of the galaxies and the publication of the results in international astronomy journals.
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