The SLUGGS (SAGES Legacy Unifying Globulars and GalaxieS) survey is an

astronomical survey An astronomical survey is a general celestial cartography, map or astrophotography, image of a region of the sky (or of the whole sky) that lacks a specific observational target. Alternatively, an astronomical survey may comprise a set of image ...

of 25 (and 3 `bonus') nearby early-type ( E and S0) galaxies. This survey uses a combination of imaging from

Subaru is the automaker, automobile manufacturing division of Japanese transportation conglomerate (company), conglomerate Subaru Corporation (formerly known as Fuji Heavy Industries), the Automotive industry#By manufacturer, twenty-first largest aut ...

/Suprime-Cam and spectroscopy from Keck/DEIMOS to investigate the chemo-dynamical properties of both the diffuse starlight and the

globular cluster A globular cluster is a spheroidal conglomeration of stars that is bound together by gravity, with a higher concentration of stars towards its center. It can contain anywhere from tens of thousands to many millions of member stars, all orbiting ...

systems of the target galaxies. Pilot data for the survey was obtained in 2006 and data acquisition was completed in 2017. The SLUGGS project was so named in honor of the

banana slug Banana slugs (''Ariolimax'') are a genus of Pulmonata, air-breathing, terrestrial mollusc, terrestrial Gastropoda, gastropod slugs in the family Ariolimacidae.MolluscaBase eds. (2021). MolluscaBase. Ariolimax Mörch, 1859. Accessed through: World ...

mascot of the

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SAGES

SAGES (Study of the Astrophysics of Globular Clusters in Extragalactic Systems) is an international network of researchers investigating the formation and evolution of globular clusters and their host galaxies, using observational facilities around the world, particularly the Keck and Subaru telescopes. It was founded by Jean Brodie, Duncan Forbes, Aaron Romanowsky and Jay Strader.

Method

Deep wide-field imaging from Subaru/Suprime-Cam is used to identify and measure the positions of candidate globular clusters around each survey galaxy. Several (up to 6) DEIMOS masks are then created which include slits corresponding to the locations of globular clusters, galaxy starlight and random background sky locations in the outer parts of the mask. The DEIMOS spectrograph, on the Keck telescope, is centred on wavelengths around the Calcium Triplet lines (~850 nm). After a typical 2 hour exposure per mask, spectra of globular clusters and galaxy starlight is obtained. Using a technique called SKiMS (Stellar Kinematics from Multiple Slits) it is possible to extract the kinematics (and metallicity) of galaxy starlight out to 3 effective radii. Equivalent data for the globular clusters is obtained out to ~10 effective radii. The DEIMOS instrument has the advantages of being a stable, high throughput, wide-field spectrograph coupled with excellent velocity resolution (~12 km/s) on a 10m telescope. This technique effectively uses DEIMOS as a pseudo wide area integral field unit.

Survey selection

The 25 target galaxies are chosen to be representative (i.e. cover the range of basic galaxy parameters and environments) of nearby (distance < 27 Mpc) early type (E and S0) galaxies. The survey also includes 3 `bonus’ galaxies which have been observed during times that the main sample galaxies are not available. All galaxies are accessible from the northern hemisphere. Although only a small sample, the data reach to large galactocentric radii with excellent velocity resolution and S/N compared to other surveys.

Key science questions

# What are the basic, global chemo-dynamical properties of early type galaxies? # What is the distribution of dark matter in early-type galaxies? # How are the outer regions of early-type galaxies assembled? # How does assembly depend on mass, environment, and other variables? # Do the observations agree with theoretical models of galaxy formation?

Target galaxies

NGC 720, NGC 821, NGC 1023, NGC 1400, NGC 1407, NGC 2768, NGC 2974,

NGC 3115 NGC 3115 (also called the Spindle Galaxy or Caldwell 53) is a field lenticular (S0) galaxy in the constellation Sextans. The galaxy was discovered by William Herschel on February 22, 1787. At about 32 million light-years away from Earth, it ...

NGC 3377 NGC 3377 is an elliptical galaxy in the constellation Leo. It is a member of the M96 Group and is about 26 Mly away, with a diameter of approximately 40 000 ly. The supermassive black hole A supermassive black hole (SMBH or sometimes SBH) ...

, NGC 3608, NGC 4111, NGC 4278, NGC 4365,

NGC 4374 Messier 84 or M84, also known as NGC 4374, is a giant elliptical galaxy, elliptical or lenticular galaxy in the constellation Virgo (constellation), Virgo. Charles Messier discovered the object in 1781 in a systematic search for "nebulous object ...

, NGC 4459, NGC 4473, NGC 4474, NGC 4486, NGC 4494,

NGC 4526 __NOTOC__ NGC 4526 (also listed as NGC 4560) is a lenticular galaxy with an embedded dusty disc, located approximately 55 million light-years from the Solar System in the Virgo constellation and discovered on 13 April 1784 by William Herschel. He ...

, NGC 4564, NGC 4649,

NGC 4697 NGC 4697 (also known as Caldwell 52) is an elliptical galaxy some 40 to 50 million light-years away in the constellation Virgo. It is a member of the NGC 4697 Group, a group of galaxies also containing NGC 4731 and several generally much smaller ...

, NGC 5846, NGC 7457. The bonus galaxies are NGC 3607,

NGC 4594 The Sombrero Galaxy (also known as Messier Object 104, M104 or NGC 4594) is a peculiar galaxy of unclear classification in the constellation borders of Virgo and Corvus, being about from the Milky Way galaxy. It is a member of the Virgo II Group ...

and

NGC 5866 NGC 5866 (also called the Spindle Galaxy or possibly Messier 102) is a lenticular galaxy in the constellation Draco. NGC 5866 was most likely discovered by Pierre Méchain or Charles Messier in 1781, and independently found by William Hersche ...

Notes

A complete list of publications using SLUGGS survey data can be foun

References

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