A Novel Approach to Constrain the Mass Ratio of Minor Mergers in Elliptical Galaxies: Application to NGC 4889, the Brightest Cluster Galaxy in Coma

Gu, Meng; Ho, Luis C.; Peng, Chien Y.; Huang, Song

doi:10.1088/0004-637x/773/1/34

Cited by 18 publications

(18 citation statements)

References 73 publications

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“…The observed ∆(g − i) does not have a strong dependence on the mass of the host galaxy. This finding is in agreement with the majority of individual systems in the literature for which the color of the shells have been measured (Quinn 1983;Gu et al 2013;Foster et al 2014). The color difference between the shells and their hosts then suggests that our sample is dominated by mergers where the infalling satellite is significantly less massive than the host.…”

Section: Shell Colorssupporting

confidence: 90%

Tidal Features at 0.05 < z < 0.45 in the Hyper Suprime-Cam Subaru Strategic Program: Properties and Formation Channels

Kado-Fong

Greene

Hendel

et al. 2018

ApJ

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We present 1,201 galaxies at 0.05 < z < 0.45 that host tidal features, detected from the first ∼ 200 deg 2 of imaging from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). All galaxies in the present sample have spectroscopic observations from the Sloan Digital Sky Survey (SDSS) spectroscopic campaigns, generating a sample of 21,208 galaxies. Of these galaxies, we identify 214 shell systems and 987 stream systems. For 575 of these systems, we are additionally able to measure the (g − i) colors of the tidal features. We find evidence for star formation in a subset of the streams, with the exception of streams around massive ellipticals, and find that stream host galaxies span the full range of stellar masses in our sample. Galaxies which host shells are predominantly red and massive: we find that observable shells form more frequently around ellipticals than around disc galaxies of the same stellar mass. Although the majority of the shells in our sample are consistent with being formed by minor mergers, 15% ± 4.4% of shell host galaxies have (g − i) colors as red as their host galaxy, consistent with being formed by major mergers. These "red shell" galaxies are additionally preferentially aligned with the major axis of the host galaxy, as previously predicted from simulations. We suggest that although the bulk of the observable shell population originates from fairly minor mergers, which preferentially form shells that are not aligned with the major axis of the galaxy, major mergers produce a significant number of observable shells.

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Section: Shell Colorssupporting

confidence: 90%

Tidal Features at 0.05 < z < 0.45 in the Hyper Suprime-Cam Subaru Strategic Program: Properties and Formation Channels

Kado-Fong

Greene

Hendel

et al. 2018

ApJ

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“…This is why it is so relevant to develop methods for quantifying the cumulative effects of mergers in the settlement of the dynamical status of current galaxies (and in particular, of S0s). Fortunately, some studies have started to directly face this question (see, e.g., Gu et al 2013;Privon et al 2013), but much more work needs to be done in this direction.…”

Section: Discussionmentioning

confidence: 99%

Evolution induced by dry minor mergers onto fast-rotator S0 galaxies

Tapia

Eliche‐Moral

Balcells

et al. 2014

A&A

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Context. Numerical studies have shown that the properties of the S0 galaxies with kinematics intermediate between fast and slow rotators are difficult to explain by a scenario of major mergers. Aims. We investigate whether the smoother perturbation induced by minor mergers can reproduce these systems. Methods. We analysed collisionless N-body simulations of intermediate and minor dry mergers onto S0s to determine the structural and kinematic evolution induced by the encounters. The original primary galaxies represent gas-poor fast-rotator S0b and S0c galaxies with high intrinsic ellipticities. The original bulges are intrinsically spherical and have low rotation. Different mass ratios, parent bulges, density ratios, and orbits were studied. Results. Minor mergers induce a lower decrease of the global rotational support (as provided by λ e ) than encounters of lower mass ratios, which results in S0s with properties intermediate between fast and slow rotators. The resulting remnants are intrinsically more triaxial, less flattened, and span the whole range of apparent ellipticities up to e ∼ 0.8. They do not show lower apparent ellipticities in random projections than initially; on the contrary, the formation of oval distortions and the disc thickening increase the percentage of projections at 0.4 < e < 0.7. In the experiments with S0b progenitor galaxies, minor mergers tend to spin up the bulge and to slightly decrease its intrinsic ellipticity, whereas in the cases of primary S0c galaxies they keep the rotational support of the bulge nearly constant and significantly decrease its intrinsic ellipticity. The remnant bulges remain nearly spherical (B/A ∼ C/A > 0.9), but exhibit a wide range of triaxialities (0.20 < T < 1.00). In the plane of global anisotropy of velocities (δ) vs. intrinsic ellipticity ( e,intr ), some of our models extend the linear trend found in previous major merger simulations towards higher e,intr values, while others clearly depart from it (depending on the progenitor S0). This is consistent with the wide dispersion exhibited by real S0s in this diagram compared with ellipticals, which follow the linear trend drawn by major merger simulations. Conclusions. The smoother changes induced by minor mergers can explain the existence of S0s with intermediate kinematic properties between fast and slow rotators that are difficult to explain with major mergers. The different trends exhibited by ellipticals and S0 galaxies in the δ -e diagram may be pointing to the different role played by major mergers in the build-up of each morphological type.

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“…In this work, to subtract the massive foreground galaxies, we build upon the strategy used by Gu et al (2013) to detect faint substructures in NGC 4889. As a first attempt, we try to model the brightest galaxies in the reddest band F160W, which is our detection image, using GALAPAGOS (Barden et al 2012) as a stand alone application.…”

Section: Divide and Conquermentioning

confidence: 99%

Evolution of the galaxy stellar mass functions and UV luminosity functions at z = 6−9 in the Hubble Frontier Fields

Bhatawdekar

Conselice

Margalef-Bentabol

et al. 2019

Monthly Notices of the Royal Astronomical Society

159

166

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We present new measurements of the evolution of the galaxy stellar mass functions (GSMF) and UV luminosity functions (UV LF) for galaxies from z = 6 − 9 within the Frontier Field cluster MACSJ0416.1-2403 and its parallel field. To obtain these results, we derive the stellar masses of our sample by fitting synthetic stellar population models to their observed spectral energy distribution with the inclusion of nebular emission lines. This is the deepest and farthest in distance mass function measured to date and probes down to a level of M * = 10 6.8 M . The main result of this study is that the low-mass end of our GSMF to these limits and redshifts appears to become steeper from −1.98 +0.07 −0.07 at z = 6 to −2.38 +0.72 −0.88 at z = 9, steeper than previously observed mass functions at slightly lower redshifts, and we find no evidence of turnover in the mass range probed. We furthermore demonstrate that the UV LF for these system also appears to show a steepening at the highest redshifts, without any evidence of turnover in the luminosity range probed. Our M UV − M * relation exhibit shallower slopes than previously observed and are in accordance with a constant mass-to-light ratio. Integrating our GSMF, we find that the stellar mass density increases by a factor of ∼ 15 +21 −6 from z = 9 to z = 6. We estimate the dust-corrected star formation rates (SFRs) to calculate the specific star formation rates (sSFR = SFR/M * ) of our sample, and find that for a fixed stellar mass of 5 × 10 9 M , sSFR ∝ (1 + z) 2.01±0.16 . Finally, from our new measurements, we estimate the UV luminosity density (ρ UV ) and find that our results support a smooth decline of ρ UV towards high redshifts.

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A Novel Approach to Constrain the Mass Ratio of Minor Mergers in Elliptical Galaxies: Application to NGC 4889, the Brightest Cluster Galaxy in Coma

Cited by 18 publications

References 73 publications

Tidal Features at 0.05 < z < 0.45 in the Hyper Suprime-Cam Subaru Strategic Program: Properties and Formation Channels

Tidal Features at 0.05 < z < 0.45 in the Hyper Suprime-Cam Subaru Strategic Program: Properties and Formation Channels

Evolution induced by dry minor mergers onto fast-rotator S0 galaxies

Evolution of the galaxy stellar mass functions and UV luminosity functions at z = 6−9 in the Hubble Frontier Fields

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