The Buildup of E–S0 Galaxies at z < 2 from Pure Luminosity Evolution Models

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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A new jet/outflow maser in the nucleus of the Compton-thick AGN IRAS 15480-0344

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317010596 ◽

2017 ◽

Vol 13 (S336) ◽

pp. 129-132

Author(s):

Paola Castangia ◽

Andrea Tarchi ◽

Alessandro Caccianiga ◽

Paola Severgnini ◽

Gabriele Surcis ◽

...

Keyword(s):

Detection Rate ◽

Radio Continuum ◽

Continuum Emission ◽

Maser Emission ◽

X Ray ◽

Vlbi Observations ◽

S0 Galaxies ◽

Water Maser

AbstractInvestigations of H2O maser galaxies at X-ray energies reveal that most harbor highly absorbed AGN. Possible correlations between the intrinsic X-ray luminosity and the properties of water maser emission have been suggested. With the aim of looking into these correlations on a more solid statistical basis, we have search for maser emission in a well-defined sample of Compton-thick AGN. Here we report the results of the survey, which yielded a surprisingly high maser detection rate, with a particular focus on the newly discovered luminous water maser in the lenticular (field) S0 galaxy IRAS 15480-0344. Recently, VLBI observations have been obtained to image the line and continuum emission in the nucleus of this galaxy. The radio continuum emission at VLBI scales is resolved into two compact components that are interpreted as jet knots. Based on the single-dish profile, the variability of the maser emission, and the position of the maser spots with respect to these continuum sources, we favor of a jet/outflow origin for the maser emission, consistent with similar cases found in other radio-quiet AGN. This scenario is consistent with the hypothesis of the presence of strong nuclear winds recently invoked to explain the main characteristics of field S0 galaxies.

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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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Infrared Observations of Giant Elliptical Galaxies: (V-K) Colors and the Infrared Hubble Diagram

Symposium - International Astronomical Union ◽

10.1017/s0074180900068650 ◽

1980 ◽

Vol 92 ◽

pp. 269-277

Author(s):

Gary L. Grasdalen

Keyword(s):

Elliptical Galaxies ◽

Cosmological Models ◽

Hubble Diagram ◽

Infrared Observations ◽

Color Evolution ◽

Magnitude Diagram ◽

Luminosity Evolution

The (V-K) colors of giant elliptical galaxies as a function of redshift are discussed. Present data are consistent with mild color evolution at z ~ 0.45. An infrared Hubble (redshift-magnitude) diagram is given. Cosmological models with qo = 0 and no luminosity evolution are clearly excluded by the present data. A wide variety of models including those with qo = 0 are permissible if luminosity evolution is included. Instrumental and programmatic implications of these results are summarized.

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