BULGE n AND B/T IN HIGH-MASS GALAXIES: CONSTRAINTS ON THE ORIGIN OF BULGES IN HIERARCHICAL MODELS

By T. Weinzirl, S. Jogee, S. Khochfar, A. Burkert, J. Kormendy. 2008

222 citations recorded by the source corpus.

We use the bulge Sérsic index n and bulge-to-total mass ratio (B/T) to explore the fundamental question of how bulges form. We perform two-dimensional bulge–disk–bar decomposition on H-band images of 143 bright, high-mass (M⋆ ⩾ 1.0 × 1010M☉) low-to-moderately inclined (i < 70°) spirals. Our results are as follows. (1) Our H-band bar fraction (∼58%) is consistent with that from ellipse fits. (2) 70% of the stellar mass is in disks, 10% in bars, and 20% in bulges. (3) A large fraction (∼69%) of bright spirals have B/T⩽ 0.2, and ∼76% have low n ⩽ 2 bulges. These bulges exist in barred and unbarred galaxies across a wide range of Hubble types. (4) About 65% (68%) of bright spirals with n ⩽ 2 (B/T ⩽ 0.2) bulges host bars, suggesting a possible link between bars and bulges. (5) We compare the results with predictions from a set of ΛCDM models. In the models, a high-mass spiral can have a bulge with a present-day low B/T⩽ 0.2 only if it did not undergo a major merger since z ⩽ 2. The predicted fraction (∼ 1.6%) of high-mass spirals, which have undergone a major merger since z ⩽ 4 and host a bulge with a present-day low B/T ⩽ 0.2, is a factor of over 30 smaller than the observed fraction (∼66%) of high-mass spirals with B/T ⩽ 0.2. Thus, contrary to common perception, bulges built via major mergers since z ⩽ 4 seriously fail to account for the bulges present in ∼66% of high mass spirals. Most of these present-day low B/T ⩽ 0.2 bulges are likely to have been built by a combination of minor mergers and/or secular processes since z ⩽ 4.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/3515827f7139d35edbf55c61eddcc7c79c12fd8a

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Citations in the corpus

The effects of gas on morphological transformation in mergers: implications for bulge and disc demographics (2009, background): “In practice, many of these bulges are made by minor mergers, but the relative suppression is similar (Hopkins et al. 2009e; Weinzirl et al. 2009).”
The formation of disc galaxies in a ΛCDM universe (2010, unknown): “Weinzirl et al. (2009) (see also Laurikainen et al. 2010), recently analysed 182 H-band images from the OSUBSGS survey (Eskridge et al. 2002) to obtain B/D and B/T values across the Hubble sequence.”
Galaxies as simple dynamical systems: observational data disfavor dark matter and stochastic star formation (2014, background): “This is qualitatively consistent with the conclusion by [142] and [143] that too many (> 50 %, 94 % according to [144]) of all late-type galaxies (with baryonic mass >∼ 10(10)M ) do not have a classical bulge, being at odds with the merging-dominated growth history of galaxies if the SMoC were true.”
FORMING REALISTIC LATE-TYPE SPIRALS IN A ΛCDM UNIVERSE: THE ERIS SIMULATION (2011, background): “The bulge Sérsic index, ns = 1.4, is indicative of a “pseudobulge” rather than a classical one: according to Weinzirl et al. (2009), ∼ 3/4 of all bright spirals have low ns ≤ 2 bulges.”
HYDRODYNAMICS OF HIGH-REDSHIFT GALAXY COLLISIONS: FROM GAS-RICH DISKS TO DISPERSION-DOMINATED MERGERS AND COMPACT SPHEROIDS (2010, background): “The frequency of violent mergers could indeed call into question the survival of disk-dominated galaxies (Weinzirl et al. 2009).”
MERGERS IN ΛCDM: UNCERTAINTIES IN THEORETICAL PREDICTIONS AND INTERPRETATIONS OF THE MERGER RATE (2010, background): “(b) Khochfar & Silk (2009) (see also Weinzirl et al. 2009): This semi-analytic model differs from that of Somerville et al. (2008a) primarily in that there is no “quasar mode” of feedback, and the prescriptions for the lowluminosity “radio mode” of AGN feedback and stellar wind feedback differ…”
HISTORY OF GALAXY INTERACTIONS AND THEIR IMPACT ON STAR FORMATION OVER THE LAST 7 Gyr FROM GEMS (2009, background): “…and ΛCDM models of galaxy evolution, such as the angular momentum crisis, the problem of bulgeless and low bulge-to-total (B/T ) ratio galaxies (Navarro & Benz 1991; D’Onghia & Burkert & 2004; Kautsch et al. 2006; Barazza, Jogee, & Marinova 2008; Weinzirl et al. 2009), and the substructure problem.”
MERGERS AND BULGE FORMATION IN ΛCDM: WHICH MERGERS MATTER? (2009, background): “In fact, these conclusions appear to be quite general, similarto those found from other models that adopt different models for bulge formation in mergers (see e.g. Khochfar & Silk 2008; Weinzirl et al. 2009). on bulge formation (Figure 7).”
SIMULATION OF THE COSMIC EVOLUTION OF ATOMIC AND MOLECULAR HYDROGEN IN GALAXIES (2009, methodology): “Here we shall use the relation B = (10 − T )2/256, (18) which approximately parameterizes the mean behavior of 146 moderately inclined barred and unbarred local spiral galaxies analyzed by Weinzirl et al. (2009).”
Photometric scaling relations of lenticular and spiral galaxies (2010, background): “Bars in the decompositions have been modeled also by Prieto et al. (1997), Aguerri et al. (2005a), Reese et al. (2007), Gadotti (2008) and Weinzirl et al. (2009).”
THE HERSCHEL REFERENCE SURVEY: DUST IN EARLY-TYPE GALAXIES AND ACROSS THE HUBBLE SEQUENCE (2011, background): “Weinzirl et al. (2009) have found that the proportion of the total mass of a galaxy that is in the bulge increases from ∼0.1 for Sbc galaxies to ∼0.2 for S0+S0a galaxies (their Figure 14).”
Alpha element abundances and gradients in the Milky Way bulge from FLAMES-GIRAFFE spectra of 650 K giants (2011, background): “…age, metallicity and chemical enrichment in the bulge point to a formation scenario similar to that of early-type galaxies through one or more starburst events triggered by mergers in the early ages of the universe (Weinzirl et al. 2009; Hopkins et al. 2010) – in other words, as a classical bulge.”
The impact of gas inflows on star formation rates and metallicities in barred galaxies (2011, background): “In particular, the relative contributions of secular galaxy evolution, whereby galaxies develop a prominent bulge in the absence of exterior influence, and galaxy–galaxy interactions is an ongoing debate (e.g. Kormendy & Kennicutt 2004; Weinzirl et al. 2009).”
Forming a large disc galaxy from a z < 1 major merger (2008, background): “Also, higher resolution cosmological simulations will have to address the role of secular processes on the detailed structure of the bulge and thin-disc components and their role in setting the B/D ratio of galaxies (Debattista et al. 2004; Genzel et al. 2008; Weinzirl et al. 2009).”
Adaptive Optics for Astronomy (2012, unknown): “Adapted from Müller Sánchez et al. (2009). pseudo-bulge component to their central regions (Fisher & Drory 2011, Weinzirl et al. 2009), and so this may contribute to the scatter of disk galaxies on the MBH − σ∗ plane.”
Physical properties and environments of nearby galaxies (2009, background): “In particular, investigators have recognized that the bar component has a strong influence on the fits (e.g. de Jong 1996; Wadadekar, Robbason & Kembhavi 1999; Laurikainen, Salo & Buta 2005; Reese et al. 2007; Gadotti 2008b; Weinzirl et al. 2009).”