J/A+A/576/A14 VEGAS-SSS photometry of NGC3115 (Cantiello+, 2015)
VEGAS-SSS. A VST early-type galaxy survey: analysis of small stellar systems.
Testing the methodology on the globular cluster system in NGC3115.
Cantiello M., Capaccioli M., Napolitano N., Grado A., Limatola L.,
Paolillo M., Iodice E., Romanowsky A.J., Forbes D.A., Raimondo G.,
Spavone M., La Barbera F., Puzia T.H., Schipani P.
<Astron. Astrophys. 576, A14 (2015)>
=2015A&A...576A..14C 2015A&A...576A..14C
ADC_Keywords: Galaxies, nearby ; Clusters, globular ; Morphology ;
Photometry, SDSS
Keywords: galaxies: stellar content - galaxies: statistics -
galaxies: individual: NGC 3115 - galaxies: star clusters: general -
surveys - catalogs
Abstract:
We present a study of globular clusters (GCs) and other small stellar
systems (SSSs) in the field of NGC 3115, observed as part of the
ongoing wide-field imaging survey VEGAS, carried out with the 2.6m VST
telescope. We used deep g and i observations of NGC 3115, a
well-studied lenticular galaxy that is covered excellently well in the
scientific literature. This is fundamental to test the methodologies,
verify the results, and probe the capabilities of the VEGAS-SSS.
Leveraging the large field of view of the VST allowed us to accurately
study the distribution and properties of SSSs as a function of
galactocentric distance, well beyond ∼20 galaxy effective radii, in a
way that is rarely possible. Our analysis of colors, magnitudes, and
sizes of SSS candidates confirms the results from existing studies,
some of which were carried out with 8-10m class telescopes, and
further extends them to previously unreached galactocentric distances
with similar accuracy. In particular, we find a color bimodality for
the GC population and a de Vaucouleurs profile for the surface density
of GCs similar to the galaxy light profile. The radial color gradient
of blue and red GCs previously found, for instance, by the SLUGGS
survey with Subaru and Keck data, is further extended out to the
largest galactocentric radii inspected, ∼65kpc. In addition, the
surface density profiles of blue and red GCs taken separately are well
approximated by a r1/4 density profile, with the fraction of blue GCs
being slightly larger at larger radii. We do not find hints of a trend
for the red GC subpopulation and for the GC turnover magnitude to vary
with radius, but we observe a ∼0.2mag difference in the turnover
magnitude of the blue and red GC subpopulations. Finally, from
inspecting SSS sizes and colors, we obtain a list of ultracompact
dwarf galaxies and GC candidates suitable for future spectroscopic
follow-up. In conclusion, our study shows i) the reliability of the
methodologies developed to study SSSs in the field of bright
early-type galaxies, and ii) the great potential of the VEGAS survey
to produce original results on SSSs science, mainly thanks to the
wide-field imaging adopted.
Description:
We present g and i band photometry for ∼47000 extended and point-like
objects in the ∼0.8 square degree area centred on NGC3115. For ∼30000
object in the catalogue, structural parameters are also available. For
each object equatorial coordinates, galactocentric distance from the
photometric center of NGC3115, magnitudes in g and i bands (SDSS
calibrated), colour, local extinction and sctructural parameters.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 154 47080 Positions, g and i magnitudes and sizes of the
objects in the field of NGC 3115
--------------------------------------------------------------------------------
See also:
J/A+A/564/L3 : JHK photometry of NGC 3115 globular clusters (Cantiello+, 2014)
J/AJ/148/32 : Globular cluster candidates in NGC 3115 (Jennings+, 2014)
J/A+A/611/A93 : NGC3115 & NGC1399 VEGAS-SSS globular clusters (Cantiello+ 2018)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 I5 --- ID [4/64352] VEGAS-SSS internal designation
(VEGAS-SSS-N3115-NNNNN)
7- 17 F11.7 deg RAdeg Right ascension (J2000.0)
19- 28 F10.7 deg DEdeg Declination (J2000.0)
30- 33 F4.1 arcmin Rgc [0.3/37.1] Distance from centre
35- 41 F7.3 mag gmag ?=-99 VST g-band magnitude
43- 49 F7.3 mag e_gmag ?=-99 g-band magnitude error
51- 55 F5.3 --- CSg [0/1] Sextractor g-band Class-Star parameter (2)
57- 63 F7.3 mag imag ?=-99 VST i-band magnitude
65- 71 F7.3 mag e_imag ?=-99 i-band magnitude error
73- 77 F5.3 --- CSi [0/1] Sextractor i-band Class-Star parameter (2)
79- 85 F7.3 mag g-i ?=-99 VST g-i colour index
87- 91 F5.3 mag E(B-V) [0.03/0.06] Local reddening value
93-100 F8.3 --- S/N [4.5/6892]?=-999 Ishape S/N ratio
104-111 F8.3 arcsec FWHM [-564/970]?=-999 Full width at half maximum
115-122 F8.3 arcsec E_FWHM ?=-999 FWHM positive uncertainty
125-132 F8.3 arcsec e_FWHM ?=-999 FWHM negative uncertainty
135-143 F9.3 pc Rh [-3960/6879]?=-999 Half light radius form Ishape
(adopted distance of NGC3115: 9.4Mpc)
145-152 F8.3 --- b/a [-1/1]?=-999 Object minor to major axis ratio
154 I1 --- Com [0/2] Object classification, 2=best (1)
--------------------------------------------------------------------------------
Note (1): Object classification as follows:
0 = sources common to both g and i-band catalogues, but no morphological
information from Ishape, or rejected from the reference and best samples
1 = sources in the reference sample (2.5%)
2 = source in the best sample (0.4%)
Note (2): 1=point source (stellar), 0=extended (galaxy)
--------------------------------------------------------------------------------
Acknowledgements:
PRIN-INAF 2011 (P.I.: G. Marconi), FIRB-MIUR 2008 (P.I. G. Imbriani),
PRIN-INAF 2011 (P.I.: A. Grado), PO-FSE Abruzzo "Sapere e Crescita"
Michele Cantiello, cantiello(at)oa-teramo.inaf.it
References:
Cantiello et al., Paper II 2018A&A...611A..93C 2018A&A...611A..93C, Cat. J/A+A/611/A93
(End) M. Cantiello [INAF-OA Teramo, Italy], P. Vannier [CDS] 12-Mar-2015