Premature dismissal of high-redshift elliptical galaxies

Jiménez, Raúl; Friaça, Amâncio César Santos; Dunlop, James; Terlevich, Elena; Peacock, J. A.; Nolan, L. A.

doi:10.1046/j.1365-8711.1999.02587.x

Cited by 52 publications

(63 citation statements)

References 26 publications

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“…For all these redshifts, the Dunne et al objects are too bright in K to match the MAMBO galaxies and the other (sub)millimeter galaxies shown in the same diagram in the top left panel of Fig. 4. brightest millimeter sources is consistent with a model whereby spheroids are formed through a process similar to the '' monolithic collapse '' model, that is, through the rapid collapse of large amounts of gas that is maintained over several to many dynamical timescales (of order 100 Myr to 1 Gyr; see, e.g., Jimenez et al 1999). A model such as this has the attractive feature of being able to supply the gas necessary to maintain both the high UV extinction and the large fraction of the total bolometric luminosity that must be emitted in the infrared/submillimeter.…”

Section: Discussionsupporting

confidence: 81%

Untitled

2002

ApJ

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We have used the IRAM Plateau de Bure millimeter interferometer to locate with subarcsecond accuracy the dust emission of three of the brightest 1.2 mm sources in the NTT Deep Field selected from our 1.2 mm Max-Planck-Millimeter Bolometer Array survey at the IRAM 30 m telescope. We combine these results with deep B to K imaging and Very Large Array interferometry. Reliable identifications are an essential step toward an understanding of the high-redshift (sub)millimeter galaxy population, toward testing the common belief that they are scaled-up analogs of local dusty ultraluminous galaxies, and in shedding light on the possible connection to spheroid formation. Strikingly, none of the three accurately located millimeter galaxies MM J120546À0741.5, MM J120539À0745.4, and MM J120517À0743.1 has a K-band counterpart down to the faint limit of K s > 21:9. This implies that these three galaxies either are extremely obscured and/or are at very high redshifts (ze4). We combine our results with literature data for 11 more (sub)millimeter galaxies that are identified with similar reliability. In terms of their K-band properties, the sample divides into three roughly equal groups: (1) undetected to K $ 22, (2) detected in the near-infrared but not the optical, and (3) detected in the optical with the possibility of optical follow-up spectroscopy. We find a trend in this sample between near-infrared to submillimeter and submillimeter to radio spectral indexes, which in comparison to spectral energy distributions (SEDs) of low-redshift infrared-luminous galaxies suggests that the most plausible primary factor causing the extreme near-infrared faintness of our objects is their high redshift. We show that the near-infrared to radio SEDs of the sample are inconsistent with SEDs that resemble local far-infrared cool galaxies with moderate luminosities, which were proposed in some models of the submillimeter sky. We briefly discuss the implications of the results for our understanding of galaxy formation.

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Section: Discussionsupporting

confidence: 81%

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2002

ApJ

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“…In the literature, a distinction is often made between models in which elliptical galaxies form from the collapse of primordial gas clouds (''monolithic collapse''; e.g., Eggen et al 1962;Jimenez et al 1999) and those in which they are formed in mergers of smaller galaxies (''hierarchically''; e.g., Toomre & Toomre 1972;White & Frenk 1991). Within the framework of a merger model, the question of assembly can be specified as, first, the typical age of the last major merger and, second, the nature of the progenitor galaxies.…”

Section: Introductionmentioning

confidence: 99%

The Recent and Continuing Assembly of Field Elliptical Galaxies by Red Mergers

2005

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We present a study of tidal debris associated with 126 nearby red galaxies, selected from the 1.2 deg 2 Multiwavelength Survey by Yale-Chile and the 9.3 deg 2 NOAO Deep Wide-Field Survey. In the full sample, 67 galaxies (53%) show morphological signatures of tidal interactions consisting of broad fans of stars, tails, and other asymmetries at very faint surface brightness levels. When restricting the sample to the 86 bulge-dominated early-type galaxies, the fraction of tidally disturbed galaxies rises to 71%, which implies that for every ''normal'' undisturbed elliptical there are two that show clear signs of interactions. The tidal features are red and smooth and often extend over >50 kpc. Of the tidally distorted galaxies, about two-thirds are remnants, and one-third are interacting with a companion galaxy. The companions are usually bright red galaxies as well; the median R-band luminosity ratio of the tidal pairs is 0.31, and the median color difference after correcting for the slope of the color-magnitude relation is À0.02 in B À R. If the ongoing mergers are representative for the progenitors of the remnants, $35% of bulgedominated galaxies experienced a merger with mass ratio >1:4 in the recent past. With further assumptions it is estimated that the present-day mass accretion rate of galaxies on the red sequence Á M /M ¼ 0:09 AE 0:04 Gyr À1. For a constant or increasing mass accretion rate with redshift, we find that red mergers may lead to an evolution of a factor of k2 in the stellar mass density in luminous red galaxies over the redshift range 0 < z < 1, consistent with recent studies of the evolution of the luminosity density. We conclude that the majority of today's most luminous field elliptical galaxies were assembled at low redshift through mergers of gas-poor, bulge-dominated systems. These ''dry'' mergers are consistent with the high central densities of ellipticals, their old stellar populations, and the strong correlations of their properties. It will be interesting to determine whether this mode of merging only plays an important role at low redshift or is relevant for galaxies at any redshift if they exceed a critical mass scale.

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“…Spheroids, on the other hand, are thought to form either by a '' monolithic collapse '' (Eggen, Lyden-Bell, & Sandage 1962;Jimenez et al 1999) or as a result of mergers of preexisting galaxies (Toomre 1977;Barnes & Hernquist 1992 and references therein). Detailed theoretical predictions for the statistical morphological properties of galaxies and their evolution have been calculated for the hierarchical merging formation mechanism appropriate to cold dark matter cosmologies (Kauffmann, White, & Guiderdoni 1993;Kauffmann 1995Kauffmann , 1996Baugh, Cole, & Frenk 1996a, 1996bSomerville, Primack, & Faber 2001).…”

Section: Introductionmentioning

confidence: 99%

The Luminosity Functions and Stellar Masses of Galactic Disks and Spheroids

Benson

Frenk

Sharples

2002

ApJ

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We present a method to obtain quantitative measures of galaxy morphology and apply it to a spectroscopic sample of field galaxies in order to determine the luminosity and stellar mass functions of galactic disks and spheroids. For our sample of approximately 600 galaxies, we estimate, for each galaxy, the bulge-to-disk luminosity ratio in the I band using a two-dimensional image fitting procedure. Monte Carlo simulations indicate that reliable determinations are only possible for galaxies approximately 2 mag brighter than the photometric completeness limit, leaving a sample of 90 galaxies with well-determined bulge-to-total light ratios. Using our measurements of individual disk and bulge luminosities for these 90 galaxies, we construct the luminosity functions of disks and spheroids and, using a stellar population synthesis model, we estimate the stellar mass functions of each of these components. The disk and spheroid luminosity functions are remarkably similar, although our rather small sample size precludes a detailed analysis. We do, however, find evidence in the bivariate luminosity function that spheroid-dominated galaxies occur only among the brightest spheroids, while disk-dominated galaxies span a much wider range of disk luminosities. Remarkably, the total stellar mass residing in disks and spheroids is approximately the same. For our sample (which includes galaxies brighter than M Ã þ 2, where M Ã is the magnitude corresponding to the characteristic luminosity), we find the ratio of stellar masses in disks and spheroids to be 1:3 AE 0:2. This agrees with the earlier estimates of Schechter & Dressler but differs significantly from that of Fukugita, Hogan, & Peebles. Ongoing large photometric and redshift surveys will lead to a large increase in the number of galaxies to which our techniques can be applied and thus to an improvement in the current estimates.

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Premature dismissal of high-redshift elliptical galaxies

Cited by 52 publications

References 26 publications

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The Recent and Continuing Assembly of Field Elliptical Galaxies by Red Mergers

The Luminosity Functions and Stellar Masses of Galactic Disks and Spheroids

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