共查询到20条相似文献，搜索用时 15 毫秒
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D. L. Clements S. A. Eales A. C. Baker 《Monthly notices of the Royal Astronomical Society》1999,308(1):L11-L16
We present the results of colour selection of candidate high-redshift galaxies in Hubble Deep Field South (HDF-S) using the Lyman dropout scheme. The HDF-S data we discuss were taken in a number of different filters extending from the near-UV (F300W) to the infrared (F222M) in two different fields. This allows us to select candidates with redshifts from z ∼3 to z ∼12. We find 15 candidate z ∼3 objects (F300W dropouts), one candidate z ∼4 object (F450W dropout) and 16 candidate z ∼5 objects (F606W dropouts) in the ∼4.7‐arcmin2 WFPC-2 field, and four candidate z ∼6 objects (optical dropouts) and one candidate z ∼8 object (F110W dropout) in the 0.84-arcmin2 NICMOS-3 field. No F160W dropouts are found ( z ∼12). We compare our selection technique with existing data for Hubble Deep Field North (HDF-N) and discuss alternative interpretations of the objects. We conclude that there are a number of lower redshift interlopers in the selections, including one previously identified object, and reject those objects most likely to be foreground contaminants. Even after this we conclude that the F606W dropout list is likely to still contain substantial foreground contamination. The lack of candidate very-high-redshift UV-luminous galaxies supports earlier conclusions by Lanzetta et al. We discuss the morphologies and luminosity functions of the high-redshift objects, and their cosmological implications. 相似文献
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We use the Hubble Ultra Deep Field to study the galaxy luminosity–size ( M – R e ) distribution. With a careful analysis of selection effects due to both detection completeness and measurement reliability, we identify bias-free regions in the M – R e plane for a series of volume-limited samples. By comparison to a nearby survey also having well-defined selection limits, namely the Millennium Galaxy Catalogue, we present clear evidence for evolution in surface brightness since z ∼ 0.7 . Specifically, we demonstrate that the mean, rest-frame B -band 〈μ〉 e for galaxies in a sample spanning 8 mag in luminosity between M B =−22 and −14 mag increases by ∼1.0 mag arcsec−2 from z ∼ 0.1 to 0.7. We also highlight the importance of considering surface brightness-dependent measurement biases in addition to incompleteness biases. In particular, the increasing, systematic underestimation of Kron fluxes towards low surface brightnesses may cause diffuse, yet luminous, systems to be mistaken for faint, compact objects. 相似文献
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Elizabeth R. Stanway Richard G. McMahon Andrew J. Bunker 《Monthly notices of the Royal Astronomical Society》2005,359(3):1184-1192
We analyse near-infrared Hubble Space Telescope ( HST )/Near-Infrared Camera and Multi-Object Spectrometer F 110 W ( J ) and F 160 W ( H ) band photometry of a sample of 27 i '-drop candidate z ≃ 6 galaxies in the central region of the HST /Advanced Camera for Surveys Ultra Deep Field . The infrared colours of the 20 objects not affected by near neighbours are consistent with a high-redshift interpretation. This suggests that the low-redshift contamination of this i '-drop sample is smaller than that observed at brighter magnitudes, where values of 10–40 per cent have been reported. The J – H colours are consistent with a slope flat in fν ( fλ ∝λ−2 ) , as would be expected for an unreddened starburst. However, there is evidence for a marginally bluer spectral slope ( fλ ∝λ−2.2 ) , which is perhaps indicative of an extremely young starburst (∼10 Myr old) or a top heavy initial mass function and little dust. The low levels of contamination, median photometric redshift of z ∼ 6.0 and blue spectral slope, inferred using the near-infrared data, support the validity of the assumptions in our earlier work in estimating the star formation rates, and that the majority of the i -drop candidates galaxies lie at z ∼ 6 . 相似文献
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Robert G. Mann Seb Oliver Ruth Carballo Alberto Franceschini Michael Rowan-Robinson Alan F. Heavens Maria Kontizas David Elbaz Anastasios Dapergolas Evanghelos Kontizas Gian Luigi Granato Laura Silva Dimitra Rigopoulou J. Ignacio Gonzalez-Serrano Aprajita Verma Steve Serjeant reas Efstathiou Paul P. van der Werf 《Monthly notices of the Royal Astronomical Society》2002,332(3):549-574
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J. A. Peacock M. Rowan-Robinson A. W. Blain J. S. Dunlop A. Efstathiou D. H. Hughes T. Jenness R. J. Ivison A. Lawrence M. S. Longair R. G. Mann S. J. Oliver S. Serjeant 《Monthly notices of the Royal Astronomical Society》2000,318(2):535-546
We use an 850-μm SCUBA map of the Hubble Deep Field (HDF) to study the dust properties of optically-selected starburst galaxies at high redshift. The optical/infrared (IR) data in the HDF allow a photometric redshift to be estimated for each galaxy, together with an estimate of the visible star-formation rate. The 850-μm flux density of each source provides the complementary information: the amount of hidden, dust-enshrouded star formation activity. Although the 850-μm map does not allow detection of the majority of individual sources, we show that the galaxies with the highest UV star-formation rates are detected statistically, with a flux density of about S 850 =0.2 mJy for an apparent UV star-formation rate of 1 h −2 M⊙ yr−1 . This level of submillimetre output indicates that the total star-forming activity is on average a factor of approximately 6 times larger than the rate inferred from the UV output of these galaxies. The general population of optical starbursts is then predicted to contribute at least 25 per cent of the 850-μm background. We carry out a power-spectrum analysis of the map, which yields some evidence for angular clustering of the background source population, but at a level lower than that seen in Lyman-break galaxies. Together with other lines of argument, particularly from the NICMOS HDF data, this suggests that the 850-μm background originates over an extremely wide range of redshifts – perhaps 1≲ z ≲6. 相似文献
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M. Magliocchetti S. J. Maddox 《Monthly notices of the Royal Astronomical Society》1999,306(4):988-993
We present a correlation function analysis for the catalogue of photometric redshifts obtained from the Hubble Deep Field image by Fernandez-Soto, Lanzetta & Yahil. By dividing the catalogue into redshift bins of width Δ z =0.4 we measured the angular correlation function w ( θ ) as a function of redshift up to z ∼4.8. From these measurements we derive the trend of the correlation length r 0 . We find that r 0 ( z ) is roughly constant with look-back time up to z ≃2, and then increases to higher values at z ≳2.4. We estimate the values of r 0 , assuming ξ ( r , z )=[ r r 0 ( z )]− γ , γ =1.8 and various geometries. For Ω0 =1 we find r 0 ( z =3)≃7.00±4.87 h −1 Mpc, in good agreement with the values obtained from analysis of the Lyman break galaxies. 相似文献
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We present a quantitative study of the classification of Extremely Red Objects (EROs). The analysis is based on the multi-band spatial-and ground-based observa-tions (HST/ACS-BViz, HST/NICMOS-JH, VLT-JHK) in the Hubble Ultra Deep Field (UDF). Over a total sky area of 5.50 arcmin2 in the UDF, we select 24 EROs with the color criterion (i-K)vega 3.9, corresponding to (I-K)vega 4.0, down to KVega = 22. We develop four methods to classify EROs into Old passively evolving Galaxies (OGs) and Dusty star-forming Galaxies (DGs), including (i-K) vs. (J-K) color diagram,spectral energy distribution fitting method, Spitzer MIPS 24μm image matching, and nonparametric measure of galaxy morphology, and found that the classification results from these methods agree well. Using these four classification methods, we classify our EROs sample into 60Gs and 8 DGs to KVega < 20.5, and 80Gs and 16 DGs to KVega < 22, respectively. The fraction of DGs increases from 8/14 at KVega < 20.5to 16/24 at Kvega < 22. To study the morphology of galaxies with its wavelength, we measure the central concentration and the Gini coefficient for the 24 EROs in our sample in HST/ACS-i, z and HST/NICMOS-J, H bands. We find that the morphological param-eters of galaxies in our sample depend on the wavelength of observation, which suggests that caution is necessary when comparing single wavelength band images of galaxies at a variety of redshifts. 相似文献
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Seb Oliver Robert G. Mann Ruth Carballo Alberto Franceschini Michael Rowan-Robinson Maria Kontizas Anastasios Dapergolas Evanghelos Kontizas Aprajita Verma David Elbaz Gian Luigi Granato Laura Silva Dimitra Rigopoulou J. Ignacio Gonzalez-Serrano Steve Serjeant reas Efstathiou Paul P. van der Werf 《Monthly notices of the Royal Astronomical Society》2002,332(3):536-548
We present results from a deep mid-infrared survey of the Hubble Deep Field South (HDF-S) region performed at 6.7 and 15 μm with the ISOCAM instrument on board the Infrared Space Observatory ( ISO ). The final map in each band was constructed by the co-addition of four independent rasters, registered using bright sources securely detected in all rasters, with the absolute astrometry being defined by a radio source detected at both 6.7 and 15 μm. We sought detections of bright sources in a circular region of radius 2.5 arcmin at the centre of each map, in a manner that simulations indicated would produce highly reliable and complete source catalogues using simple selection criteria. Merging source lists in the two bands yielded a catalogue of 35 distinct sources, which we calibrated photometrically using photospheric models of late-type stars detected in our data. We present extragalactic source count results in both bands, and discuss the constraints that they impose on models of galaxy evolution, given the volume of space sampled by this galaxy population. 相似文献
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Giulia Rodighiero Alberto Franceschini Giovanni Fasano 《Monthly notices of the Royal Astronomical Society》2001,324(2):491-497
We have extended our previous analysis of morphologically selected elliptical and S0 galaxies in the Hubble Deep Field (HDF) North to include Hubble Space Telescope ( HST ) data in the HDF South and the HDFS–NICMOS areas. Our final sample amounts to 69 E/S0 galaxies with K <20.15 over an area of 11 arcmin2 . Although a moderately small number over a modest sky area, this sample benefits from the best imaging and photometric data available on high-redshift galaxies. Multi-waveband photometry allows us to estimate with good accuracy the redshifts for the majority of these galaxies, which lack a spectroscopic measure. We confirm our previous findings that massive E/S0s tend to disappear from flux-limited samples at z >1.4. This adds to the evidence that the rest-frame colours and spectral energy distributions (SEDs) of the numerous objects found at 0.8< z <1.2 are inconsistent with a very high redshift of formation for the bulk of stars, while they are more consistent with protracted (either continuous or episodic) star formation down to z ≤1. These results based on high-quality imaging on a small field can be complemented with data from colour-selected extremely red objects (EROs) on much larger sky areas: our claimed demise of E/S0s going from z =1 to z =1.5 is paralleled by a similarly fast decrease in the areal density of EROs when the colour limit is changed from ( R − K )=5 to ( R − K )=6 (corresponding to z ≃1 and z ≃1.3 respectively). Altogether, the redshift interval from 1 to 2 seems to correspond to a very active phase for the assembly of massive E/S0 galaxies in the field, and also probably one where a substantial fraction of their stars are formed. 相似文献