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Digitized Sky Survey image of the Sb spiral galaxy NGC 1055 with the location of the WIYN Minimosaic pointing indicated by a large box.
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We present results from a study of the globular cluster (GC) systems of four spiral and S0 galaxies imaged as part of an ongoing wide-field survey of the GC systems of giant galaxies. The target galaxies—the SB0 galaxy NGC 1023, the SBb galaxy NGC 1055, and an isolated pair comprised of the Sbc galaxy NGC 7339 and the S0 galaxy NGC 7332—were observ...
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Citations
... For example, Chandar et al. 2004 carried out a study of GCs in five spiral galaxies and Goudfrooij et al. (2003) of seven edge-on disk galaxies, both using HST/WFPC2 fields, but covered relatively small areas in each galaxy. Study by Young et al. (2012) of two edgeon spirals covered spatially their entire optical extents, but had a limiting magnitude slightly brighter than the expected TO. Other works on spiral galaxies include Santiago-Cortés et al. 2010 andNantais et al. 2010b (M81;Sab), Hwang & Lee 2008 (M51;Sbc), Barmby et al. 2006;Simanton et al. 2015 (M101;Scd), Cantiello et al. 2017 (NGC 253;Sc) and González-Lópezlira et al. 2017 (NGC 4258 Sbc). ...
We here present the luminosity function (LF) of globular clusters (GCs) in five nearby spiral galaxies using the samples of GC candidates selected in Hubble Space Telescope mosaic images in F435W, F555W and F814W filters. Our search, which surpasses the fractional area covered by all previous searches in these galaxies, has resulted in the detection of 158 GC candidates in M81, 1123 in M101, 226 in NGC4258, 293 in M51 and 173 in NGC628. The LFs constructed from this dataset, after correcting for relatively small contamination from reddened young clusters, are log-normal in nature, which was hitherto established only for the Milky Way (MW) and Andromeda among spiral galaxies. The magnitude at the turn-over (TO) corresponds to Mv(TO)=-7.41+/-0.14 in four of the galaxies with Hubble types Sc or earlier, in excellent agreement with Mv(TO)=-7.40+/-0.10 for the MW. The TO magnitude is equivalent to a mass of ~3x10^5 Msun for an old, metal-poor population. Mv(TO) is fainter by ~1.16 magnitude for the fifth galaxy, M101, which is of Hubble type Scd. The TO dependence on Hubble type implies that the GCs in early-type spirals are classical GCs, which have a universal TO, whereas the GC population in late-type galaxies is dominated by old disk clusters, which are in general less massive. The radial density distribution of GCs in our sample galaxies follows the S\'ersic function with exponential power-law indices, and effective radii of 4.0-9.5 kpc. GCs in the sample galaxies have a mean specific frequency of 1.10+/-0.24, after correcting for magnitude and radial incompleteness factors.
... As it is seen from equations (1), the specific frequency depends on the absolute value of the host galaxy and the number of GCs in the system. The values of the specific frequency are taken mainly from the following works [13][14][15][16][17][18]. At Fig. 1 the dependence of the specific frequency on the absolute value of the host galaxy is shown based on the above data. ...
... Dependence of the specific frequency on the absolute value of the host galaxies. Designation: St01 [13], Lo01 [14], Ma02 [15], Pe08 [16], Bu10 [17], Yo12 [18] ...
In the article, on the basis of observational data the problems of the specific frequency of globular clusters are studied. Possible relationships between them and the absolute stellar magnitude of their host galaxy are considered, where the observational data published in the literature were presented. It should be noted that before us the relationship between the specific frequency and the absolute magnitude is shown as exponential functions. An empirical relationship between the specific frequency and the absolute value of the host galaxy were obtained and showed that the dependence of the specific frequency on the absolute magnitude is not linear, but has a quadratic function. It is also shown that the specific frequency determines the number of globular clusters in a given galaxy relative to our Galaxy. Also in the article, based on the results of studies of the specific frequency, some discussions are presented related to the origin and evolution of globular clusters. The results obtained show that the ratios of the specific frequency to the luminosity of the host galaxy are different. Variations in the specific frequency of elliptical galaxies are associated with variations in the mass-to-luminous flux ratio. This may be due to the fact that the number of globular clusters in spiral galaxies per unit of luminosity of the halo and not of the entire galaxy. Analysis of the observational data shows that the values of the specific frequency of spiral galaxies are 5–6 times less than that of giant elliptical ones. As a result of the results of studies of the specific frequency of the globular clusters, unsolved problems are listed and possible solutions are shown. It is noted that the problem posed will be solved even more accurately if it is considered by the types of galaxies
We here present the luminosity function (LF) of globular clusters (GCs) in five nearby spiral galaxies using the samples of GC candidates selected in Hubble Space Telescope mosaic images in F435W, F555W and F814W filters. Our search, which surpasses the fractional area covered by all previous searches in these galaxies, has resulted in the detection of 158 GC candidates in M81, 1123 in M101, 226 in NGC 4258, 293 in M51 and 173 in NGC 628. The LFs constructed from this dataset, after correcting for relatively small contamination from reddened young clusters, are lognormal in nature, which was hitherto established only for the Milky Way (MW) and Andromeda among spiral galaxies. The magnitude at the turn-over (TO) corresponds to MV0(TO)=-7.41±0.14 in four of the galaxies with Hubble types Sc or earlier, in excellent agreement with MV(TO) = −7.40 ± 0.10 for the MW. The TO magnitude is equivalent to a mass of ∼3 × 105 M⊙ for an old, metal-poor population. MV0(TO) is fainter by ∼1.16 magnitude for the fifth galaxy, M 101, which is of Hubble type Scd. The TO dependence on Hubble type implies that the GCs in early-type spirals are classical GCs, which have a universal TO, whereas the GC population in late-type galaxies is dominated by old disk clusters, which are in general less massive. The radial density distribution of GCs in our sample galaxies follows the Sérsic function with exponential power-law indices, and effective radii of 4.0–9.5 kpc. GCs in the sample galaxies have a mean specific frequency of 1.10 ± 0.24, after correcting for magnitude and radial incompleteness factors
The formation and growth of globular cluster systems (GCSs) is closely related to the evolutionary processes experienced by their host galaxies. In particular, their radial distributions scale with several properties of the galaxies and their haloes. We performed a photometric study, by means of HST/ACS archival data of several intermediate luminosity galaxies located in low-density environments. It was supplemented with available photometric data of GCSs from the Virgo and Fornax clusters, resulting in a sample of almost 30 GCSs for which we fitted their radial profiles. The resulting overall properties agree with those from previous studies, as we found that the effective radius, extension, and concentration of the GCS radial profiles correlate with the stellar mass, effective radius, and number of globular clusters, presenting in some cases a bilinear relation. The extension also correlates with the central velocity dispersion for central galaxies, but not for satellites. From a statistical comparison with numerical simulations we obtained good agreement between the effective radius and extension of the GCS scale with the effective and virial radius of the haloes, respectively. Finally, we analysed these results in the literature context.
The globular cluster systems of galaxies are well-known to extend to large galactocentric radii. Here we quantify the size of GC systems using the half number radius of 22 GC systems around early-type galaxies from the literature. We compare GC system sizes to the sizes and masses of their host galaxies. We find that GC systems typically extend to 4$\times$ that of the host galaxy size, however this factor varies with galaxy stellar mass from about 3$\times$ for M$^{\ast}$ galaxies to 5$\times$ for the most massive galaxies in the universe. The size of a GC system scales approximately linearly with the virial radius (R$_{200}$) and with the halo mass (M$_{200}$) to the 1/3 power. The GC system of the Milky Way follows the same relations as for early-type galaxies. For Ultra Diffuse Galaxies their GC system size scales with halo mass and virial radius as for more massive, larger galaxies. UDGs indicate that the linear scaling of GC system size with stellar mass for massive galaxies flattens out for low stellar mass galaxies. Our scalings are different to those reported recently by Hudson \& Robison (2017).
The sizes of entire systems of globular clusters (GCs) depend on the formation and destruction histories of the GCs themselves, but also on the assembly, merger and accretion history of the dark matter (DM) haloes that they inhabit. Recent work has shown a linear relation between total mass of globular clusters in the globular cluster system and the mass of its host dark matter halo, calibrated from weak lensing. Here we extend this to GC system sizes, by studying the radial density profiles of GCs around galaxies in nearby galaxy groups. We find that radial density profiles of the GC systems are well fit with a de Vaucouleurs profile. Combining our results with those from the literature, we find tight relationship ($\sim 0.2$ dex scatter) between the effective radius of the GC system and the virial radius (or mass) of its host DM halo. The steep non-linear dependence of this relationship ($R_{e, GCS} \propto R_{200}^{2.5 - 3}$) is currently not well understood, but is an important clue regarding the assembly history of DM haloes and of the GC systems that they host.
Using 3.6 and 4.5$\mu$m images of 73 late-type, edge-on galaxies from the
S$^4$G survey, we compare the richness of the globular cluster populations of
these galaxies to those of early type galaxies that we measured previously. In
general, the galaxies presented here fill in the distribution for galaxies with
lower stellar mass, M$_*$, specifically $\log({\rm M}_*/{\rm M}_\odot) < 10$,
overlap the results for early-type galaxies of similar masses, and, by doing
so, strengthen the case for a dependence of the number of globular clusters per
$10^9\ {\rm M}_\odot$ of galaxy stellar mass, T$_{\rm N}$, on M$_*$. For $8.5 <
\log ({\rm M}_*/{\rm M}_\odot) < 10.5$ we find the relationship can be
satisfactorily described as T$_{\rm N} = ({\rm M}_*/10^{6.7})^{-0.56}$ when
M$_*$ is expressed in solar masses. The functional form of the relationship is
only weakly constrained and extrapolation outside this range is not advised.
Our late-type galaxies, in contrast to our early-types, do not show the
tendency for low mass galaxies to split into two T$_{\rm N}$ families. Using
these results and a galaxy stellar mass function from the literature, we
calculate that in a volume limited, local Universe sample, clusters are most
likely to be found around fairly massive galaxies (M$_* \sim 10^{10.8}$
M$_\odot$) and present a fitting function for the volume number density of
clusters as a function of parent galaxy stellar mass. We find no correlation
between T$_{\rm N}$ and large-scale environment, but do find a tendency for
galaxies of fixed M$_*$ to have larger T$_{\rm N}$ if they have converted a
larger proportion of their baryons into stars.
Forbes et al. recently used the Hubble Space Telescope to localize hundreds
of candidate star clusters in NGC 1023, an early-type galaxy at a distance of
11.1 Mpc. Old stars dominate the light of 92% of the clusters and
intermediate-age stars dominate the light of the remaining 8%. Theory predicts
that clusters with such ages can host intermediate-mass black holes (IMBHs)
with masses M_BH \lesssim 10^5 M_sun. To investigate this prediction, we used
264 s of 5.5 GHz data from the Karl G. Jansky Very Large Array (VLA) to search
for the radiative signatures of IMBH accretion from 337 candidate clusters in
an image spanning 492 arcsec (26 kpc) with a resolution of 0.40 arcsec (22 pc).
None of the individual clusters are detected, nor are weighted-mean image
stacks of the 311 old clusters, the 26 intermediate-age clusters, and the 20
clusters with stellar masses M_star \gtrsim 7.5 x 10^5 M_sun. The clusters thus
lack radio analogs of HLX-1, a strong IMBH candidate in a cluster in the
early-type galaxy ESO 243-49. This suggests that HLX-1 is accreting gas related
to its cluster's light-dominating young stars. Alternatively, the HLX-1
phenomenon could be so rare that no radio analog is expected in NGC 1023. Also,
using a formalism heretofore applied to star clusters in the Milky Way, the
radio-luminosity upper limit for the massive-cluster stack corresponds to a
mean 3$\sigma$ IMBH mass of M_BH(massive) < 2.3 x 10^5 M_sun, suggesting mean
black-hole mass fractions of M_BH(massive)/M_star < 0.05-0.29.
Our composite catalog of globular cluster systems (GCS), which was studied in part I [1] of this paper , has been substantially extended because of a lack of data in it for use in searches for empirical relationships between the physical parameters of GCS of spiral and dwarf galaxies taking the characteristics of the parent galaxies into account. For the first time a number of empirical relationships are found for GCS of spiral and dwarf galaxies. These results differ significantly from the analogous relationships for GCS of elliptical and lenticular galaxies [1]. A possible new approach to the theory of the origin of poor GCS, which take a large part of the list of GCS of dwarf and spiral galaxies, is proposed.
An increasing body of data reveals a one-to-one linear correlation between
galaxy halo mass and the total mass in its globular cluster (GC) population,
M_{GCS} ~ M_h^{1.03 \pm 0.03}, valid over 5 orders of magnitude. We explore the
nature of this correlation for galaxies of different morphological types, and
for the subpopulations of metal-poor (blue) and metal-rich (red) GCs. For the
subpopulations of different metallicity we find M_{GCS}(blue) ~ M_h^{0.96 \pm
0.03} and M_{GCS}(red) ~ M_h^{1.21 \pm 0.03} with similar scatter. The
numerical values of these exponents can be derived from the detailed behavior
of the red and blue GC fractions with galaxy mass and provide a self-consistent
set of relations. In addition, all morphological types (E, S0, S/Irr) follow
the same relation, but with a second-order trend for spiral galaxies to have a
slightly higher fraction of metal-rich GCs for a given mass. These results
suggest that the amount of gas available for GC formation at high redshift was
in nearly direct proportion to the dark-matter halo potential, in strong
contrast to the markedly nonlinear behavior of total stellar mass versus halo
mass. Of the few available theoretical treatments that directly discuss the
formation of GCs in a hierarchical merging framework,the model of Kravtsov &
Gnedin (2005) best matches these observations. They find that the blue,
metal-poor GCs formed in small halos at $z > 3$ and did so in nearly direct
proportion to halo mass. Similar models addressing the formation rate of the
red, metal-richer GCs in the same detail and continuing to lower redshift are
still needed for a comprehensive picture.
