The surface brightness of 1550 galaxies in Fornax: automated galaxy surface photometry - II

Phillipps, S.; Disney, M. J.; Kibblewhite, E. J.; Cawson, M. G. M.

doi:10.1093/mnras/229.4.505

Cited by 32 publications

(20 citation statements)

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“…Recent observational studies have fully supported the view (expounded by, for example, Phillipps et al 1987; Impey, Bothun & Malin 1988) that low‐luminosity and low surface brightness galaxies numerically dominate the galaxy population in the local Universe (see e.g. McGaugh 1996; Cross et al 2001).…”

Section: Introductionmentioning

confidence: 94%

First results from the H i Jodrell All Sky Survey: inclination-dependent selection effects in a 21-cm blind survey

Lang

Boyce

Kilborn

et al. 2003

Monthly Notices of the Royal Astronomical Society

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Details are presented of the H i Jodrell All Sky Survey (HIJASS). HIJASS is a blind neutral hydrogen (H i) survey of the northern sky (δ > 22°), being conducted using the multibeam receiver on the Lovell Telescope (full width at half‐maximum beamwidth 12 arcmin) at Jodrell Bank. HIJASS covers the velocity range −3500 to 10 000 km s−1, with a velocity resolution of 18.1 km s−1 and spatial positional accuracy of ∼2.5 arcmin. Thus far about 1115 deg2 of sky have been surveyed. The average rms noise during the early part of the survey was around 16 mJy beam−1. Following the first phase of the Lovell Telescope upgrade (in 2001), the rms noise is now around 13 mJy beam−1. We describe the methods of detecting galaxies within the HIJASS data and of measuring their H i parameters. The properties of the resulting H i‐selected sample of galaxies are described. Of the 222 sources so far confirmed, 170 (77 per cent) are clearly associated with a previously catalogued galaxy. A further 23 sources (10 per cent) lie close (within 6 arcmin) to a previously catalogued galaxy for which no previous redshift exists. A further 29 sources (13 per cent) do not appear to be associated with any previously catalogued galaxy. The distributions of peak flux, integrated flux, H i mass and cz are discussed. We show, using the HIJASS data, that H i self‐absorption is a significant, but often overlooked, effect in galaxies with large inclination angles to the line of sight. Properly accounting for it could increase the derived H i mass density of the local Universe by at least 25 per cent. The effect that this will have on the shape of the H i mass function will depend on how self‐absorption affects galaxies of different morphological types and H i masses. We also show that galaxies with small inclinations to the line of sight may also be excluded from H i‐selected samples, since many such galaxies will have observed velocity widths that are too narrow for them to be distinguished from narrow‐band radio‐frequency interference. This effect will become progressively more serious for galaxies with smaller intrinsic velocity widths. If, as we might expect, galaxies with smaller intrinsic velocity widths have smaller H i masses, then compensating for this effect could significantly steepen the faint‐end slope of the derived H i mass function.

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Section: Introductionmentioning

confidence: 94%

First results from the H i Jodrell All Sky Survey: inclination-dependent selection effects in a 21-cm blind survey

Lang

Boyce

Kilborn

et al. 2003

Monthly Notices of the Royal Astronomical Society

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“…The APM catalogue magnitudes are calibrated for unresolved (stellar) objects only (see Bunclark & Irwin 1984), so we supplemented these with total magnitudes for the galaxies measured by direct analysis of the digitized plate data. These magnitudes were obtained by fitting exponentials to the APM galaxy surface brightness profiles (see Phillipps et al 1987; Morshidi‐Esslinger, Davies & Smith 1999) across the surface brightness range 22.7 to 25.7 B mag arcsec −2 (i.e. between the possibly saturated inner parts of the images and the sky‐noise‐dominated outer parts).…”

Section: The Fornax Cluster Spectroscopic Surveymentioning

confidence: 99%

The Fornax Cluster Spectroscopic Survey: a sample of confirmed cluster dwarfs

Deady

Boyce

Phillipps

et al. 2002

Monthly Notices of the Royal Astronomical Society

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The Fornax Cluster Spectroscopic Survey (FCSS) project utilizes the Two‐degree Field (2dF) multi‐object spectrograph on the Anglo‐Australian Telescope (AAT). Its aim is to obtain spectra for a complete sample of all 14 000 objects with 16.5 ≤bj≤ 19.7 irrespective of their morphology in a 12 deg2 area centred on the Fornax cluster. A sample of 24 Fornax cluster members has been identified from the first 2dF field (3.1 deg2 in area) to be completed. This is the first complete sample of cluster objects of known distance with well‐defined selection limits. Nineteen of the galaxies (with −15.8 < MB < −12.7) appear to be conventional dwarf elliptical (dE) or dwarf S0 (dS0) galaxies. The other five objects (with −13.6 < MB < −11.3) are those galaxies which were described recently by Drinkwater et al. and labelled ‘ultracompact dwarfs’ (UCDs). A major result is that the conventional dwarfs all have scale sizes α≳ 3 arcsec (≃300 pc). This apparent minimum scale size implies an equivalent minimum luminosity for a dwarf of a given surface brightness. This produces a limit on their distribution in the magnitude–surface brightness plane, such that we do not observe dEs with high surface brightnesses but faint absolute magnitudes. Above this observed minimum scale size of 3 arcsec, the dEs and dS0s fill the whole area of the magnitude–surface brightness plane sampled by our selection limits. The observed correlation between magnitude and surface brightness noted by several recent studies of brighter galaxies is not seen with our fainter cluster sample. A comparison of our results with the Fornax Cluster Catalog (FCC) of Ferguson illustrates that attempts to determine cluster membership solely on the basis of observed morphology can produce significant errors. The FCC identified 17 of the 24 FCSS sample (i.e. 71 per cent) as being ‘cluster’ members, in particular missing all five of the UCDs. The FCC also suffers from significant contamination: within the FCSS's field and selection limits, 23 per cent of those objects described as cluster members by the FCC are shown by the FCSS to be background objects.

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“…Caldwell 1987;Ferguson & Sandage 1988;Ferguson 1989;Phillipps et al 1987;Kambas et al 2000;Hilker et al 2003). This is because spectroscopic surveys have not had the depth needed to obtain velocities for dE candidates fainter than about µ V,0 23 mag/arcsec 2 (e.g.…”

Section: Introductionmentioning

confidence: 99%

The early-type dwarf galaxy population of the Fornax cluster

Mieske¹,

Hilker²,

Infante³

et al. 2006

A&A

147

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Aims. We analyse the photometric properties of the early-type Fornax cluster dwarf-galaxy population (M V > −17 mag), based on a wide-field imaging study of the central cluster area in V and I bandpasses. We used the instrument/telescope combination IMACS/Magellan at Las Campanas Observatory, providing much larger light-collecting area and better image resolution than previous wide-field imaging surveys. Methods. We created a fiducial sample of Fornax cluster dwarf ellipticals (dEs) in the following three steps. (1) To verify cluster membership, we measured I-band surface brightness fluctuations (SBF) distances to candidate dEs known from previous surveys.(2) We re-assessed morphological classifications for those candidate dEs that are too faint for SBF detection. (3) We searched for new candidate dEs in the size-luminosity regime close to the resolution limit of previous surveys. Results.(1) We confirm cluster membership for 28 candidate dEs in the range −16.6 < M V < −10.1 mag by means of SBF measurement. We find no SBF background galaxy. (2) Of 51 other candidate dEs in the range −13.2 < M V < −8.6 mag, 2/3 are confirmed as probable cluster members by morphological re-assessment, while 1/3 are re-classified as probable background objects. (3) We find 12 new dE candidates in the range −12.3 < M V < −8.8 mag, two of which are directly confirmed via SBF measurement. The resulting fiducial dE sample follows a well-defined surface brightness-magnitude relation, showing that Fornax dEs are about 40% larger than Local Group dEs. The sample also defines a colour-magnitude relation that appears slightly shallower than that of Local Group dEs. The early-type dwarf galaxy luminosity function in Fornax has a very flat faint end slope α −1.1 ± 0.1. We discuss these findings in the context of structure-formation theories. Conclusions. The SBF method is a very powerful tool to help constrain the faint end of the galaxy luminosity function in nearby galaxy clusters. For the Fornax cluster, morphological cluster memberships -if performed at sufficient resolution -are very reliable.

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The surface brightness of 1550 galaxies in Fornax: automated galaxy surface photometry - II

Cited by 32 publications

References 0 publications

First results from the H i Jodrell All Sky Survey: inclination-dependent selection effects in a 21-cm blind survey

First results from the H i Jodrell All Sky Survey: inclination-dependent selection effects in a 21-cm blind survey

The Fornax Cluster Spectroscopic Survey: a sample of confirmed cluster dwarfs

The early-type dwarf galaxy population of the Fornax cluster

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