Thick disks of edge-on galaxies seen through the Spitzer Survey of Stellar Structure in Galaxies (S4G): Lair of missing baryons?

Abstract

Most, if not all, disk galaxies have a thin (classical) disk and a thick disk. In most models thick disks are thought to be a necessary consequence of the disk formation and/or evolution of the galaxy. We present the results of a study of the thick disk properties in a sample of carefully selected edge-on galaxies with types ranging from T=3 to T=8. We fitted one-dimensional luminosity profiles with physically motivated functions - the solutions of two stellar and one gaseous isothermal coupled disks in equilibrium - which are likely to yield more accurate results than other functions used in previous studies. The images used for the fits come from the Spitzer Survey of Stellar Structure in Galaxies (S4G). We found that thick disks are on average more massive than previously reported, mostly due to the selected fitting function. Typically, the thin and the thick disk have similar masses. We also found that thick disks do not flare significantly within the observed range in galactocentric radii and that the ratio of thick to thin disk scaleheights is higher for galaxies of earlier types. Our results tend to favor an in situ origin for most of the stars in the thick disk. In addition the thick disk may contain a significant amount of stars coming from satellites accreted after the initial build-up of the galaxy and an extra fraction of stars coming from the secular heating of the thin disk by its own overdensities. Assigning thick disk light to the thin disk component may lead to an underestimate of the overall stellar mass in galaxies, because of different mass to light ratios in the two disk components. On the basis of our new results, we estimate that disk stellar masses are between 10% and 50% higher than previously thought and we suggest that thick disks are a reservoir of "local missing baryons".

Accepted for publication in ApJ

References in corpus (17)

• High-Resolution Rotation Curves and Galaxy Mass Models from THINGS
• The Spitzer Survey of Stellar Structure in Galaxies (S^4G)
• Thin, thick and dark discs in LCDM
• Observations of Thick Disks in the Hubble Space Telescope Ultra Deep Field
• K-Band Observations of Boxy Bulges. I. Morphology and Surface Brightness Profiles
• X-Ray Absorption from the Milky Way Halo and the Local Group
• Discovery of a Giant Stellar Tidal Stream Around the Disk Galaxy NGC 4013
• Two Disk Components from a Gas Rich Disk-Disk Merger
• The Kinematics of Thick Disks in Nine External Galaxies
• Characteristics of thick disks formed through minor mergers: stellar excesses and scale lengths
• Truncations of stellar disk and warps of HI-layers in edge-on spiral galaxies
• Lick Indices in the Thin and Thick Disks of Edge-On Disk Galaxies
• The thick disk in the galaxy NGC 4244 from S4G imaging
• No evidence for a dark matter disk within 4 kpc from the Galactic plane
• The unusual vertical mass distribution of NGC 4013 seen through the Spitzer Survey of Stellar Structure in Galaxies (S4G)
• On the vertical equilibrium of the local Galactic disk and the search for disk dark matter
• The Galactic thick and thin disks: differences in evolution

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