A Spitzer Study of Pseudobulges in S0 Galaxies: Secular Evolution of Disks

AbstractA comparison of pseudobulges in S0 and spiral galaxies is presented using structural parameters derived from 2-d decomposition of mid-infrared images taken at 3.6 μm by Spitzer IRAC. The position of the bulges on the Kormendy diagram has been used as an initial classification criterion for determining the nature of the bulge. To make the classification more secure, the criterion proposed by Fisher and Drory (2008) has also been used, which involves using the n = 2 division line on Sérsic index. We find that among the 185 S0 galaxies, 27 are pseudobulge hosts while 160 are classical. Of these 25 pseudobulge hosts, only two belong to the bright luminosity class (MK < 22.66, AB system) while rest belong to the faint luminosity class (MK > 22.66, AB system). We find that among spiral galaxies, 77 % (24 of 31) of the bulges are classified as pseudobulges. As pointed out by various studies, the presence of such a large fraction poses problems to our current picture of galaxy formation. How ever, our primary result is that the disk scale length of pseudobulge hosting S0s is significantly smaller on average than that of their spiral counterparts. This can be explained as a lowered disk luminosity which in turn implies that S0s have evolved from spiral progenitors. We also argue that early type spirals are more likely to be the progenitors based on bulge and total luminosity arguments. We speculate that if late type spirals hosting pseudobulges have to evolve into S0s, an additional mechanism along with gas stripping of spirals is needed. We have also investigated the effect of environment on pseudobulges in the two samples, but no significant trends were found in the properties of the pseudobulges as a function of the various structural parameters. The study is made more difficult because of the low number statistics one deals with when the sample is sub-divided based on whether it is in a field or group/cluster environment. The study of pseudobulges based on environment, however, is an interesting one and is something that can be considered for the future by carefully selecting a sample with statistically meaningful number of objects from diverse environments.

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Kinematics of the outskirts of S0 galaxies from PNe and GCs

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316011376 ◽

2016 ◽

Vol 11 (S321) ◽

pp. 290-290

Author(s):

A. Cortesi ◽

C. Mendes de Oliveira

Keyword(s):

Galaxy Formation ◽

Globular Clusters ◽

Velocity Dispersion ◽

Spiral Galaxies ◽

Formation Mechanisms ◽

Stellar Kinematics ◽

Lenticular Galaxies ◽

Star Forming ◽

Flat Rotation Curves ◽

S0 Galaxies

AbstractThe stellar kinematics of the discs of S0 galaxies (as obtained using planetary nebulae, PNe, and integrated stellar light data) is comparable to that of spiral galaxies, with similar flat rotation curves and falling velocity dispersion profiles, but they present a larger amount of random motions. The only other tracer available to probe the kinematics of individual early-type galaxies are globular clusters (GCs). GCs’ formation is intimately connected to a galaxy major star forming event(s) and GCs are, therefore, good proofs of galaxy formation histories. We directly compare a sample of PNe, GCs, and stellar velocities out to 4 effective radii, in the S0 galaxies NGC 2768 and NGC 1023. In particular, we test a new method for studying GC properties and we find that these two lenticular galaxies are consistent with being formed through different formation mechanisms.

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On the origin of dust in galaxy clusters at low-to-intermediate redshift

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa431 ◽

2020 ◽

Vol 493 (2) ◽

pp. 2782-2792

Author(s):

Eda Gjergo ◽

Marco Palla ◽

Francesca Matteucci ◽

Elena Lacchin ◽

Andrea Biviano ◽

...

Keyword(s):

Galaxy Clusters ◽

Galaxy Formation ◽

Spiral Galaxies ◽

Intracluster Medium ◽

Mass Ratio ◽

Luminosity Functions ◽

Galactic Sources ◽

S0 Galaxies ◽

Intermediate Redshift ◽

Detailed Chemical

ABSTRACT Stacked analyses of galaxy clusters at low-to-intermediate redshift show signatures attributable to dust, but the origin of this dust is uncertain. We test the hypothesis that the bulk of cluster dust derives from galaxy ejecta. To do so, we employ dust abundances obtained from detailed chemical evolution models of galaxies. We integrate the dust abundances over cluster luminosity functions (one-slope and two-slope Schechter functions). We consider both a hierarchical scenario of galaxy formation and an independent evolution of the three main galactic morphologies: elliptical/S0, spiral and irregular. We separate the dust residing within galaxies from the dust ejected in the intracluster medium. To the latter, we apply thermal sputtering. The model results are compared to low-to-intermediate redshift observations of dust masses. We find that in any of the considered scenarios, elliptical/S0 galaxies contribute negligibly to the present-time intracluster dust, despite producing the majority of gas-phase metals in galaxy clusters. Spiral galaxies, instead, provide both the bulk of the spatially unresolved dust and of the dust ejected into the intracluster medium. The total dust-to-gas mass ratio in galaxy clusters amounts to 10−4, while the intracluster medium dust-to-gas mass ratio amounts to 10−6 at most. These dust abundances are consistent with the estimates of cluster observations at 0.2 < z < 1. We propose that galactic sources, spiral galaxies in particular, are the major contributors to the cluster dust budget.

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The dust effects on galaxy scaling relations

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa477 ◽

2020 ◽

Vol 493 (3) ◽

pp. 3580-3607

Author(s):

Bogdan A Pastrav

Keyword(s):

Galaxy Formation ◽

Spiral Galaxies ◽

Structural Parameters ◽

Cosmic Time ◽

Stellar Mass ◽

Scaling Relations ◽

Successful Model ◽

Galaxy Formation And Evolution ◽

Galaxy Environment ◽

Galaxy Assembly

ABSTRACT Accurate galaxy scaling relations are essential for a successful model of galaxy formation and evolution as they provide direct information about the physical mechanisms of galaxy assembly over cosmic time. We present here a detailed analysis of a sample of nearby spiral galaxies taken from the KINGFISH survey. The photometric parameters of the morphological components are obtained from bulge–disc decompositions using galfit data analysis algorithm, with surface photometry of the sample done beforehand. Dust opacities are determined using a previously discovered correlation between the central face-on dust opacity of the disc and the stellar mass surface density. The method and the library of numerical results previously obtained in Pastrav et al. (2013a,b) are used to correct the measured photometric and structural parameters for projection (inclination), dust, and decomposition effects in order to derive their intrinsic values. Galaxy disc scaling relations are then presented, both the measured (observed) and the intrinsic (corrected) ones, in the optical regime, to show the scale of the biases introduced by the aforementioned effects. The slopes of the size–luminosity relations and the dust versus stellar mass are in agreement with values found in other works. We derive mean dust optical depth and dust/stellar mass ratios of the sample, which we find to be consistent with previous studies of nearby spiral galaxies. While our sample is rather small, it is sufficient to quantify the influence of galaxy environment (dust, in this case) when deriving scaling relations.

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Globular Cluster and Galaxy Formation: M31, the Milky Way, and Implications for Globular Cluster Systems of Spiral Galaxies

The Astrophysical Journal ◽

10.1086/423334 ◽

2004 ◽

Vol 614 (1) ◽

pp. 158-166 ◽

Cited By ~ 42

Author(s):

David Burstein ◽

Yong Li ◽

Kenneth C. Freeman ◽

John E. Norris ◽

Michael S. Bessell ◽

...

Keyword(s):

Galaxy Formation ◽

Globular Cluster ◽

Milky Way ◽

Spiral Galaxies ◽

Cluster Systems

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The Structure of the Stellar Hosts in Blue Compact Dwarf Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s174392130600665x ◽

2006 ◽

Vol 2 (S235) ◽

pp. 300-300

Author(s):

R.O. Amorín ◽

J.A.L. Aguerri ◽

L.M. Cairós ◽

N. Caon ◽

C. Muñoz-Tuñón

Keyword(s):

Galaxy Formation ◽

Dwarf Galaxies ◽

Dwarf Galaxy ◽

Structural Parameters ◽

Host Galaxy ◽

Host Galaxies ◽

Galaxy Formation And Evolution ◽

Radial Profiles ◽

Low Surface Brightness ◽

Formation And Evolution

AbstractBlue compact dwarf (BCD) galaxies are gas-rich, low-luminosity (Mb≳-18 mag) and compact systems, currently undergoing violent star-formation burst (Sargent & Searle 1970). While it was initially hypothesized that they were very young galaxies (e.g. Sargent & Searle 1970, et al. 1988), the subsecuent detection of an extended, redder stellar host galaxy showed that the vast majority of them are old systems (e.g. Gil de Paz et al. 2003,2005). BCDs play an important role for understanding the process of galaxy formation and evolution.The structural properties of the low surface brightness stellar host in BCDs are often studied by fitting r1/n models to the outer regions of their radial profiles. The limitations imposed by the presence of a large starburst emission overlapping the underlying component makes this kind of analysis a difficult task.We propose a two-dimensional fitting methodology in order to improve the extraction of the structural parameters of the LSB host Amorín et al. 2006, submitted). A set of ideal simulations are presented in order to test the reliability of the method and to determine its robustness and flexibility. We present the different steps of the method discussing its advantages and weaknesses. We compare the results for a sample of eight objects with those already obtained using a one-dimensional technique (Caon et al. 2005).We fit a PSF convolved Sérsic model to the BVR images with the GALFIT publicly software (Peng et al. 2002). We restrict the fit to the stellar host by masking out the starburst region and take special care to minimize the sky-subtraction uncertainties. Consistency checks are performed to assess the reliability and accuracy of the derived structural parameters.We obtain robust fits for all the sample galaxies, all of which, except one, show low Sérsic indices n—very close to 1—with good agreement in the three bands. These findings suggest that the stellar hosts in BCDs have near-exponential profiles. Since the Sérsic index n of host galaxies is important in the context of the possible structural and evolutionary connections among the different types of dwarf galaxies, we are currently extending the study to a larger sample of objects. This kind of studies will help us to understand the mechanisms that form and shape BCD galaxies, and how they relate to the other dwarf galaxy classes.

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Rotation of Galaxy Dark Matter Halos

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306005394 ◽

2006 ◽

Vol 2 (S235) ◽

pp. 104-104

Author(s):

Stéphane Herbert-Fort ◽

Dennis Zaritsky ◽

Yeun Jin Kim ◽

Jeremy Bailin ◽

James E. Taylor

Keyword(s):

Dark Matter ◽

Angular Momentum ◽

Numerical Simulations ◽

Galaxy Formation ◽

Spiral Galaxy ◽

Observational Studies ◽

Spiral Galaxies ◽

Satellite System ◽

Dark Matter Halos ◽

The Mean

AbstractThe degree to which outer dark matter halos of spiral galaxies rotate with the disk is sensitive to their accretion history and may be probed with associated satellite galaxies. We use the Steward Observatory Bok telescope to measure the sense of rotation of nearby isolated spirals and combine these data with those of their associated satellites (drawn from SDSS) to directly test predictions from numerical simulations. We aim to constrain models of galaxy formation by measuring the projected component of the halo angular momentum that is aligned with that of spiral galaxy disks, Jz. We find the mean bulk rotation of the ensemble satellite system to be co-rotating with the disk with a velocity of 22 ± 13 km/s, in general agreement with previous observational studies and suggesting that galaxy disks could be formed by halo baryons collapsing by a factor of ≈10. We also find a prograde satellite fraction of 51% and Jz, of the satellite system to be positively correlated with the disk, albeit at low significance (2655 ± 2232 kpc km/s).

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The impact of bars and interactions on optically selected AGNs in spiral galaxies

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832796 ◽

2018 ◽

Vol 618 ◽

pp. A149 ◽

Cited By ~ 7

Author(s):

Sol Alonso ◽

Georgina Coldwell ◽

Fernanda Duplancic ◽

Valeria Mesa ◽

Diego G. Lambas

Keyword(s):

Spiral Galaxies ◽

Control Sample ◽

Sloan Digital Sky Survey ◽

Blue Color ◽

Nuclear Activity ◽

Internal Process ◽

Two Samples ◽

Accretion Rates ◽

The Galaxy ◽

The Impact

Aims. With the aim of performing a suitable comparison of the internal process of galactic bars with respect to the external effect of interactions on driving gas toward the inner most region of the galaxies, we explored and compared the efficiency of both mechanisms on central nuclear activity in optically selected active galactic nuclei (AGNs) in spiral galaxies. Methods. We selected homogeneous samples of barred AGNs and active objects residing in pair systems, derived from the Sloan Digital Sky Survey (SDSS). In order to carry out a reliable comparison of both samples (AGNs in barred hosts in isolation and in galaxy pairs), we selected spiral AGN galaxies with similar distributions of redshift, magnitude, stellar mass, color and stellar age population from both catalogs. With the goal of providing an appropriate quantification of the influence of strong bars and interactions on nuclear activity, we also constructed a suitable control sample of unbarred spiral AGNs without a companion and with similar host properties to the other two samples. Results. We found that barred optically selected AGNs show an excess of nuclear activity (as derived from the Lum[OIII]) and accretion rate onto a central black hole (ℛ) with respect to AGNs in pairs. In addition, both samples show an excess of high values of Lum[OIII] and ℛ with respect to unbarred AGNs in the control sample. We also found that the fractions of AGNs with powerful nuclear activity and high accretion rates increase toward more massive hosts with bluer colors and younger stellar populations. Moreover, AGNs with bars exhibit a higher fraction of galaxies with powerful Lum[OIII] and efficient ℛ with respect to AGN galaxies inhabiting pair systems, in bins of different galaxy properties. Regarding AGNs belonging to pair systems, we found that the central nuclear activity is remarkably dependent on the galaxy pair companion features. The Lum[OIII] for AGNs in pairs is clearly enhanced when the galaxy companion exhibits a bright and more massive host with high metallicity, blue color, efficient star formation activity and young stellar population. The results of this work reveal an important capacity of both mechanisms, bars and interactions, to transport material towards the galaxy central regions. In this context, it should also be noted that the internal process of the bar is more efficient at improving the central nuclear activity in AGN objects than that corresponding to the external mechanism of the galaxy–galaxy interactions.

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Bar rejuvenation in S0 galaxies?

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1387 ◽

2020 ◽

Vol 495 (4) ◽

pp. 4548-4556

Author(s):

Sudhanshu Barway ◽

Kanak Saha

Keyword(s):

Star Formation ◽

Spiral Galaxies ◽

Theoretical Studies ◽

Tidal Interactions ◽

Colour Measurements ◽

Induce Star Formation ◽

Minor Mergers ◽

Stellar Masses ◽

S0 Galaxies ◽

Intermediate Density

ABSTRACT Based on the colour measurements from a multiband, multicomponent 2D decompositions of S0 and spiral galaxies using SDSS images, we found that bars are bluer in S0 galaxies compared to the spiral galaxies. Most of the S0s in our sample have stellar masses ∼L* galaxies. The environment might have played an important role as most of the S0s with bluer bars are in the intermediate-density environment. The possibility of minor mergers and tidal interactions that occurs frequently in the intermediate-density environment might have caused either a bar to form and/or induce star formation in the barred region of S0 galaxies. The underlying discs show the usual behaviour being redder in S0s compared to spiral galaxies while the bulges are red and old for both S0 and spiral galaxies. The finding of bluer bars in S0 galaxies is a puzzling issue and poses an interesting question at numerical and theoretical studies most of which shows that the bars are long-lived structures with old stellar populations.

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