Stellar Disks and Halos of Edge-on Spiral Galaxies: NGC 891, NGC 4144, and NGC 4244

Тихонов, Н. А.; Galazutdinova, O. A.

doi:10.1007/s10511-005-0021-8

Cited by 31 publications

(28 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A few Hubble Space Telescope (HST) studies have measured the properties of resolved stars in nearby edge-on disk galaxies and found older stars at large scale heights, but they do not probe the radial structure of the thick disk (Mould 2005;Seth et al 2005;Tikhonov & Galazutdinova 2005). An exception is Rejkuba et al (2009), who study RGB stars in NGC 891 with HST and do not find any radial color or metallicity gradient along the thick disk.…”

Section: The Milky Way Compared To Nearby Galaxiesmentioning

confidence: 99%

A Radial Age Gradient in the Geometrically Thick Disk of the Milky Way

Martig

Minchev

Ness

et al. 2016

ApJ

View full text Add to dashboard Cite

A Radial Age Gradient in the Geometrically Thick Disk of the Milky Wayhttp://researchonline.ljmu.ac.uk/7280/ Article LJMU has developed LJMU Research Online for users to access the research output of the University more effectively. Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Users may download and/or print one copy of any article(s) in LJMU Research Online to facilitate their private study or for non-commercial research. You may not engage in further distribution of the material or use it for any profit-making activities or any commercial gain.The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription. ABSTRACTIn the Milky Way, the thick disk can be defined using individual stellar abundances, kinematics, or age, or geometrically, as stars high above the midplane. In nearby galaxies, where only a geometric definition can be used, thick disks appear to have large radial scale lengths, and their red colors suggest that they are uniformly old. The Milky Way's geometrically thick disk is also radially extended, but it is far from chemically uniform: α-enhanced stars are confined within the inner Galaxy. In simulated galaxies, where old stars are centrally concentrated, geometrically thick disks are radially extended, too. Younger stellar populations flare in the simulated disks' outer regions, bringing those stars high above the midplane. The resulting geometrically thick disks therefore show a radial age gradient, from old in their central regions to younger in their outskirts. Based on our age estimates for a large sample of giant stars in the APOGEE survey, we can now test this scenario for the Milky Way. We find that the geometrically defined thick disk in the Milky Way has indeed a strong radial age gradient: the median age for red clump stars goes from ∼9 Gyr in the inner disk to 5 Gyr in the outer disk. We propose that at least some nearby galaxies could also have thick disks that are not uniformly old, and that geometrically thick disks might be complex structures resulting from different formation mechanisms in their inner and outer parts.

show abstract

Section: The Milky Way Compared To Nearby Galaxiesmentioning

confidence: 99%

A Radial Age Gradient in the Geometrically Thick Disk of the Milky Way

Martig

Minchev

Ness

et al. 2016

ApJ

View full text Add to dashboard Cite

show abstract

“…9 in the latter reference since the figure is so small (some of the data points are also reproduced in a larger figure in Morrison 1999). Tikhonov & Galazutdinova (2005) and Seth et al (2005) use HST data and count resolved red-giant stars out to large vertical distances. The re-analysed and scaled data points of the second data set (Streich et al, in prep.…”

Section: C2 the Thick Disc And The Halo Of Ngc 4565mentioning

confidence: 99%

“…C.3a. The data of Tikhonov & Galazutdinova (2005) were scaled to match the second data set where r > ∼ 80 .…”

Section: C2 the Thick Disc And The Halo Of Ngc 4565mentioning

confidence: 99%

The influence of diffuse scattered light

Sandín

2015

A&A

View full text Add to dashboard Cite

Studies of deep photometry of galaxies have presented discoveries of excess light in surface-brightness and colour profiles at large radii in the form of diffuse faint haloes and thick discs. In a majority of the cases, it has seemed necessary to use exotic stellar populations or alternative physical solutions to explain the excess. Few studies have carefully scrutinized the role of scattered light in this context. I explore the influence of scattered light on ground-based observations of haloes and thick discs around edge-on galaxies, haloes around face-on disc galaxies, host galaxies around blue compact galaxies (BCGs), and haloes around elliptical galaxies. Surfacebrightness structures of all considered types of galaxies are modelled and analysed to compare scattered-light haloes and thick discs with measurements. I simulate the influence of scattered light and accurate sky subtraction on simplified Sérsic-type and face-on disc galaxy models. All galaxy models are convolved with both lower-limit and brighter point spread functions (PSFs); for a few galaxies it was possible to use dedicated PSFs. The results show bright scattered-light haloes and high amounts of red excess at large radii and faint surface brightnesses for nearly all types of galaxies; exceptions are the largest elliptical-type galaxies where the influence of scattered light is smaller. Studies have underestimated the role of scattered light to explain their surface-brightness profiles. My analysis shows surface-brightness profiles that include scattered light that are very similar to and overlap measurements at all radii. The derivation of physical properties of haloes, thick discs, and BCG hosts from diffuse data is misleading since accurate and radially extended PSFs are non-existent. Significantly improved analyses that include new measurements of PSFs are required to study diffuse faint structures further.

show abstract

“…In a series of papers, Tikhonov & Galazutdinova studied the resolved stellar populations of a number of galaxies. Tikhonov & Galazutdinova (2005) analyzed NGC 4244, among other galaxies. They used one central ACS field (which in our field list is Field01) and two WFPC2 fields.…”

Section: Direct Comparison To Other Structural Measurements In These mentioning

confidence: 99%

Extragalactic archeology with the GHOSTS Survey

Streich

Jong

Bailin

et al. 2015

A&A

View full text Add to dashboard Cite

Aims. We study the individual evolution histories of three nearby low-mass edge-on galaxies (IC 5052, NGC 4244, and NGC 5023). Methods. Using resolved stellar populations, we constructed star count density maps for populations of different ages and analyzed the change of structural parameters with stellar age within each galaxy. Results. We do not detect a separate thick disk in any of the three galaxies, even though our observations cover a wider range in equivalent surface brightness than any integrated light study. While scale heights increase with age, each population can be well described by a single disk. Two of the galaxies contain a very weak additional component, which we identify as the faint halo. The mass of these faint halos is lower than 1% of the mass of the disk. The three galaxies show low vertical heating rates, which are much lower than the heating rate of the Milky Way. This indicates that heating agents, such as giant molecular clouds and spiral structure, are weak in low-mass galaxies. All populations in the three galaxies exhibit no or only little flaring. While this finding is consistent with previous integrated light studies, it poses strong constraints on galaxy simulations, where strong flaring is often found as a result of interactions or radial migration.

show abstract

Stellar Disks and Halos of Edge-on Spiral Galaxies: NGC 891, NGC 4144, and NGC 4244

Cited by 31 publications

References 35 publications

A Radial Age Gradient in the Geometrically Thick Disk of the Milky Way

A Radial Age Gradient in the Geometrically Thick Disk of the Milky Way

The influence of diffuse scattered light

Extragalactic archeology with the GHOSTS Survey

Contact Info

Product

Resources

About