Faint Blue Galaxies Research Articles

Galaxy Dark Matter: Galaxy-Galaxy Lensing in the Hubble Deep Field

In this Letter we present calibrated observations of the average mass of galaxies with 22 < I < 25 in the Hubble Deep Field. We measure the mean mass profile using the statistical gravitational lens distortion of faint blue background galaxies, based on 2221 foreground-background pairs. The observed weak lensing distortion is calibrated via full three-dimensional simulations and other Hubble Space Telescope data on a foreground cluster of known mass.

The Inferred Redshift Distribution of the Faint Blue Galaxy Excess

We infer the redshift distribution of the faint blue galaxy excess (FBE) at mB = 23.5 by subtracting the predicted distribution of giant/normal galaxies from the observed N(z) distribution for all types. This is possible because of the recent deep Hubble Space Telescope (HST) WFPC2 morphological number counts that have convincingly demonstrated that little evolution of the giant population is seen to mB = 26.0. The mean redshift of the FBE at mB = 23.5 is found to be zFBE = 0.40 ± 0.07 with upper and lower quartiles defined by z0.75 = 0.58 ± 0.05 and z0.25 = 0.28 ± 0.05, respectively. We compare this inferred FBE N(z) distribution to the predictions from three generic faint galaxy models: dwarf dominated (no-evolution), pure luminosity evolution, and evolving dwarfs. The inferred FBE N(z) distribution strongly supports a hybrid evolving dwarf-rich model wherein a large population of dwarfs present at z = 0.5 has subsequently faded to obscurity. The total integrated number density of dwarfs (down to MB = -11) is estimated to be a factor of 20 times greater than that of E-Sc galaxies and the estimated fading to be 1.0 < Δm < 1.4 mag. Thus, the dwarf population is estimated to be responsible for ~30% of the luminosity density locally, rising to ~57% at z = 0.5.

The Cosmological Constant and Statistical Lensing of Giant Arcs

Using a singular isothermal sphere model for the matter distribution of foreground clusters of galaxies, we study the statistics of giant ares in flat cosmologies with and without a cosmological constant. We find that the relative number of arcs predicted within z = 1 in a universe with {OMEGA}_0_ = 0.3 and λ_0_ = {DELTA}/(3H_0_^2^) = 0.7 is a factor of ~2 greater than that predicted in the Einstein-de Sitter universe ({OMEGA}_0_ = 1, λ_0_ = 0). For a luminosity-dependent evolution model of the number density of background galaxies that accounts for the overdensity of faint blue galaxies at z_s_ ~ 0.4, the Einstein-de Sitter cosmological model predicts that ~5% of clusters of galaxies with X-ray luminosity L_x_ &gt; 2 x 10^44^ ergs s^-1^ should have giant arcs, with length-to-width ratio greater than 10. This is a factor of ~4 lower than the observed fraction in the gravitational-lensing survey of distant X-ray-selected Einstein Extended Medium-Sensitivity Survey clusters of galaxies, indicating a significant deviation of the matter distribution of clusters of galaxies from simple isothermal spheres and/or the presence of a significant cosmological constant. It will be profitable to further study the constraints on the cosmological constant from giant arcs with more realistic cluster models.

K-baml photometry of spectroscopic redshift survey objects

We present K -band photometry of the objects in the spectroscopic redshift survey of Colless et al. The absolute K magnitudes of the objects are inconsistent with the no-evolution or pure luminosity evolution models, regardless of model normalization, showing an excess of intrinsically faint galaxies at intermediate redshifts (z ~O.4) with very blue colours. Many of these faint blue galaxies do not have strong emission lines, and it is argued that unidentified galaxies in faint redshift surveys could also be at intermediate redshift. It is argued that the excess faint blue galaxies seen in the B -band number counts at intermediate magnitudes and redshifts are a population of dwarf galaxies undergoing, or seen shortly following, a starburst in which supernova-driven winds blowout the gas of the galaxy, quenching the star formation and eliminating the emission lines.

Faint Blue Galaxies and the Epoch of Dwarf Galaxy Formation

view Abstract Citations (160) References (101) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Faint Blue Galaxies and the Epoch of Dwarf Galaxy Formation Babul, Arif ; Ferguson, Henry C. Abstract Several independent lines of reasoning, both theoretical and observational, suggest that the very faint (B ≳ 24) galaxies seen in deep images of the sky are small low-mass galaxies that experienced a short starburst at redshifts 0.5 ≲ z ≲ 1 and have since faded into low-luminosity, low surface brightness (LSB) objects. We examine this hypothesis in detail in order to determine whether a model incorporating such dwarfs can account for the observed wavelength-dependent number counts, as well as redshift, color, and size distributions. Low-mass galaxies generically arise in large numbers in hierarchical clustering scenarios with realistic initial conditions. Generally, these galaxies are expected to form at high redshifts. Babul & Rees have argued that the formation epoch of these galaxies is, in fact, delayed until z ≲ 1 due to the photoionization of the gas by the metagalactic UV radiation at high redshifts. We combine these two elements, along with simple heuristic assumptions regarding star formation histories and efficiency, to construct our bursting dwarf model. The slope and the normalization of the mass function of the dwarf galaxies are derived from the initial conditions and are not adjusted to fit the data. We further augment the model with a phenomenological prescription for the formation and evolution of the locally observed population of galaxies (E, S0, Sab, Sbc, and Sdm types). We use spectral synthesis and Monte Carlo methods to generate realistic model galaxy catalogs for comparison with observations. We find that for reasonable choices of the star formation histories for the dwarf galaxies, the model results are in very good agreement with the results of the deep galaxy surveys. Such a dwarf-dominated model is also qualitatively supported by recent studies of faint galaxy gravitational lensing and clustering, by galaxy size distributions measured with the Hubble Space Telescope, and by the evidence for very modest evolution in regular galaxy properties out to z = 1. We also discuss various tests of the model based on some generic predictions. For example, the model predicts that the number counts in the K band ought to begin rising more steeply at magnitudes fainter than KAB ≍ 24-25. The model also predicts that the local field luminosity function (LF) ought to exhibit a steep upturn at magnitudes fainter than MB ≍ -16. The detection of the latter, however, depends sensitively on the selection criteria used to construct a galaxy catalog. We also consider the possibility of detecting the LSB remnants at low redshifts. Publication: The Astrophysical Journal Pub Date: February 1996 DOI: 10.1086/176795 arXiv: arXiv:astro-ph/9508156 Bibcode: 1996ApJ...458..100B Keywords: GALAXIES: FORMATION; GALAXIES: LUMINOSITY FUNCTION; MASS FUNCTION; GALAXIES: PHOTOMETRY; Astrophysics E-Print: 44 pages, compressed, uuencoded postscript (no figures), Accepted by ApJ, Complete preprint (with figures) available from: ftp://almuhit.physics.nyu.edu/babul/Faint_Blue_Galaxies/ full text sources arXiv | ADS |

The HST Medium Deep Survey: Galaxy Morphology at High Redshift

With HST and WFPC2, galaxies in the Medium Deep Survey can be reliably classified to magnitudesI814≲ 22.0 in the F814W band, at a mean redshift. The main result is the relatively high proportion (~40%) of objects which are in some way irregular or anomalous, and which are of relevance in understanding the origin of the familiar excess population of faint galaxies. These diverse objects include compact galaxies, apparently interacting pairs, galaxies with superluminous starforming regions and diffuse low surface brightness galaxies of various forms. The ‘irregulars’ and ‘peculiar’ galaxies contribute most of the excess counts in the I-band at our limiting magnitude, and may explain the ‘faint blue galaxy’ problem.

Supernova Rates

Extragalactic supernova rates are reviewed. The main uncertainties in calculated rates are due to (1) the influence of the (still poorly known) luminosity function of supernova of a given type on “control times”, to (2) uncertain corrections for possible inclination - dependent bias in supernova discovery probabilities, and (3) interstellar absorption. The total supernova rate in late-type galaxies is found to be ∼ 2(H0/75)2 supernovae (SNe) per century per 1010LB(ʘ) This is consistent with the rate of 3 SNe per century that is derived from the historical data on Galactic supernovae. It is, however, a source of some concern that none of the three Galactic SNe expected to have occurred during the last century was actually observed!The expansion velocities of SNe Ia are found to correlate strongly with parent galaxy Hubble type. This relation is in the sense that low expansion velocities are only observed for those SNe Ia that occur in early-type galaxies. This suggests that V(exp) correlates with the ages of SNe Ia progenitors. It is speculated that the progenitors of a few SNe Ia with high V(exp) values in E and S0 galaxies were formed during recent starbursts.SNe Ia rates appear to be enhanced in post-starburst galaxies. It is suggested that supernova rates might be quite high in the recently discovered population of faint blue galaxies at intermediate redshifts.

The Opacity of Galactic Disks and Faint Blue Galaxy Number Counts

The Opacity of Galactic Disks and Faint Blue Galaxy Number Counts

Low Surface Brightness Galaxies and the Field Galaxy Luminosity Function

We have developed a catalog of local low surface brightness galaxies (LSBGs) which is selected by objective criteria. We present here a luminosity function (LF) for LSBGs based on that catalog. This LF includes the effects of the completeness corrections to the LSBG catalog, and includes only galaxies with surface brightnesses (22.25 ≤ μB(0) ≤ 24.5) fainter than those included in the CfA Redshift Survey (see Marzke et al. 1994, AJ 108, 437). The best-fitting Schechter function has parameters α = –1.42, M∗B = −18.34, and Φ∗ = 0.0036 h3 Mpc–3 mag–1. Thus, surveys which do not take account of the observational selection bias imposed by surface brightness are missing a substantial fraction of the local galaxies, but, this missed fraction is not large enough to explain the counts of faint blue galaxies observed at moderate redshift.

Faint Field Galaxy Counts, Colors, and Redshifts

This paper aims to provide the non-specialist a brief overview and major highlights in the rapidly changing research area of faint field galaxy evolution. Special emphasis is given to number counts, colors, and redshifts more recent than 1992 and their interpretation, both conventional and exotic. We close with previews of new directions that exploit sizes and velocity widths to explore the nature of faint blue galaxies, a puzzle that has defied solution for 15 years. The mystery continues.

The Effects of Starbursts and Low Surface Brightness Galaxies on Faint Galaxy Models

We present models predicting the magnitude, redshift, and color distributions of field galaxies. We explore whether a fading starburst scenario can account for the observations of faint blue galaxies. We marginally rule out a starburst scenario with a local initial mass function (IMF) because the models predict too many nearby faint galaxies that are not observed. A burst model with a truncated IMF reproduces the counts and redshift distributions well but produces too blue a population. We show that surface brightness selection has a significant effect on the distributions. In particular, adding a population of low-surface brightness galaxies, known to exist locally, can explain the counts for B<SUB>J</SUB> &lt; 23. They do not, however, account for the steepness of the counts at fainter magnitudes. Finally, we show that the colors of galaxies in a K-band-selected sample are too blue to be consistent with a constant star formation rate, passive-evolution model.

The Contribution of Late-Type/Irregulars to the Faint Galaxy Counts from Hubble Space Telescope Medium-Deep Survey Images

We present a complete morphologically classified sample of 144 faint field galaxies from the HST Medium Deep Survey with 20.0 < I <22.0 mag. We compare the global properties of the ellipticals, early and late-type spirals, and find a non-negligible fraction (13/144) of compact blue [(V-I) < 1.0 mag] systems with $r^{1/4}$-profiles. We give the differential galaxy number counts for ellipticals and early-type spirals independently, and find that the data are consistent with no-evolution predictions based on conventional flat Schechter luminosity functions (LF's) and a standard cosmology. Conversely, late-type/Irregulars show a steeply rising differential number count with slope $(\frac{\delta log N}{\delta m}) = 0.64\pm 0.1$. No-evolution models based on the Loveday et al. (1992) and Marzke et al. (1994b) {\it local} luminosity functions under-predict the late-type/Irregular counts by 1.0 and 0.5 dex, respectively, at I = 21.75 mag. Examination of the Irregulars alone shows that $\sim 50$% appear inert and the remainder have multiple cores. If the inert galaxies represent a non-evolving late-type population, then a Loveday-like LF ($\alpha\simeq -1.0$) is ruled out for these types, and a LF with a steep faint-end ($\alpha\simeq -1.5$) is suggested. If multiple core structure indicates recent star-formation, then the observed excess of faint blue field galaxies is likely due to {\it evolutionary} processes acting on a {\it steep} field LF for late-type/Irregulars. The evolutionary mechanism is unclear, but 60% of the multiple-core Irregulars show close companions. To reconcile a Marzke-like LF with the faint redshift surveys, this evolution must be preferentially occurring in the brightest late-type galaxies with z > 0.5 at I = 21.75 mag.

Faint blue galaxies as a probe of the X-ray background at high redshift

We present a formalism describing the physical content of cross-correlation functions between a diffuse background and a population of discrete sources. The formalism is used to interpret cross-correlation signals between the unresolved X-ray background and a galaxy population resolved to high redshift in another spectral band. Specifically, we apply it to the so-called faint blue galaxy population and constrain their X-ray emissivity and clustering properties. A model is presented which satisfies the recently measured constraints on all 3 correlation functions (galaxy/galaxy, background/background and galaxy/background). This model predicts that faint galaxies in the magnitude range B=18-23 (cvering redshifts $z \lsim 0.5$) make up $\sim 22 \%$ of the X-ray background in the 0.5-2 keV band. At the mean redshift of the galaxy sample, $\bar z=0.26$, the comoving volume emissivity is $\rho_X \sim 6-9 \times 10^{38}h$ ergs s$^{-1}$Mpc$^{-3}$ . When extrapolated to fainter magnitudes, the faint blue galaxy population can account for most of the residual background at soft energy. We show how the measurement of the angular and zero-lag cross-correlation functions between increasingly faint galaxies and the X-ray background can allow us to map the X-ray emissivity as a function of redshift.

Spectrophotometric Properties of Merging Galaxies

view Abstract Citations (116) References (56) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectrophotometric Properties of Merging Galaxies Liu, Charles T. ; Kennicutt, Robert C., Jr. Abstract We present quantitative analysis of long-slit spectrophotometry of 40 merging and strongly interacting galaxy systems, in the wavelength range 3650-7100 Å. Along with optically selected objects, the sample includes 10 ultraluminous IRAS galaxies with ongoing merger activity. The mergers exhibit a very large range of spectral properties, ranging from completely evolved stellar populations to emission-line dominated starbursts and absorption-line dominated poststarburst systems. The spectral types are correlated with the morphological types of the merging galaxies, as best as they can be inferred. The sample has much higher mean star-formation rates than isolated galaxies, as measured by Hα + [N II] line emission. The distribution of [0 II] equivalent widths in the sample is very different from that of local field galaxies, but does resemble the EW([O II]) distribution for faint blue field galaxies studied in deep redshift surveys. The far-infrared (FIR) luminosities and L(FIR)/L(B) ratios of the optically selected subsample are substantially higher than that of field galaxies as a whole. The ultraluminous IRAS mergers have distinctly higher L(FIR) and L(FIR)/L(B), but are similar to the optically selected mergers at optical wavelengths; on the average, their optical continuum colors are actually somewhat bluer than the optical subsample, indicating the presence of a global, young stellar population along with heavily dust-enshrouded nuclei. The frequency of the appearance of Seyfert nuclei and LINERs in the sample is also discussed. A considerable fraction of the mergers exhibit spectra with anomalously strong Balmer absorption, when compared to nearby normal galaxies. Many of these systems have spectra resembling those of distant "E + A" galaxies. A quantitative comparison of the Balmer absorption-dominated mergers with several E + A galaxies at high redshift shows that they are indeed similar and suggests that the two kinds of galaxies may be the same class of objects. Publication: The Astrophysical Journal Pub Date: September 1995 DOI: 10.1086/176165 Bibcode: 1995ApJ...450..547L Keywords: GALAXIES: INTERACTIONS; GALAXIES: STELLAR CONTENT; INFRARED: GALAXIES full text sources ADS | data products NED (60) SIMBAD (58)

The Lens Parallax Method: Determining Redshifts of Faint Blue Galaxies through Gravitational Lensing

view Abstract Citations (47) References (44) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Lens Parallax Method: Determining Redshifts of Faint Blue Galaxies through Gravitational Lensing Bartelmann, Matthias ; Narayan, Ramesh Abstract We propose a new technique, which we call the lens parallax method, to determine simultaneously the redshift distribution of the faint blue galaxies and the mass distributions of foreground clusters of galaxies. The method is based on gravitational lensing and makes use of the following: (1) the amplitude of lensing-induced distortions of background galaxies increases with redshift; (2) the surface brightnesses of galaxies decrease steeply with redshift The distortions of galaxy images due to lensing are thus expected to be inversely correlated with surface brightness, allowing us to obtain relative distances to galaxies as a function of surface brightness. If the redshifts of the brightest galaxies are measured, then the relative distance scale can be converted to mean galaxy redshifts as a function of surface brightness. Further, by comparing the angular sizes of lensed galaxies with those of similar galaxies in empty control fields, it is possible to break the so-called mass sheet degeneracy inherent to cluster mass reconstruction techniques that are based purely on image ellipticities. This allows an unambiguous determination of the surface density of a lensing cluster. We describe an iterative algorithm based on these ideas and present numerical simulations which show that the proposed techniques are feasible with a sample of ≈10 rich clusters at moderate redshifts ∼0.3-0.4 and an equal number of control fields. The numerical tests show that the method can be used to determine the redshifts of galaxies with an accuracy of Δz ≈ 0.1-0.2 at z ∼1-1.7, and to measure the masses of lensing clusters to about 5% accuracy. Publication: The Astrophysical Journal Pub Date: September 1995 DOI: 10.1086/176200 arXiv: arXiv:astro-ph/9504086 Bibcode: 1995ApJ...451...60B Keywords: COSMOLOGY: GRAVITATIONAL LENSING; COSMOLOGY: OBSERVATIONS; GALAXIES: CLUSTERS: GENERAL; GALAXIES: DISTANCES AND REDSHIFTS; Astrophysics E-Print: 31 pages, uuencoded compressed postscript file containing 10 figures, to be published in the Sep. 20 issue of ApJ full text sources arXiv | ADS | data products SIMBAD (3)

Identification of faint radio sources with optically luminous interacting disk galaxies

THE question of when galaxies and stars started to form in the early Universe is one of the most fundamental in cosmology. Faint radio sources (with fluxes of a few microjanskys or less) may be these early galaxies; radio surveys have shown them to be increasingly common as fainter levels are reached1-7, suggesting that they are an important constituent of the early Universe. Many of these sources were identified with faint blue galaxies—some of which have peculiar morphology (perhaps arising from inter actions) 1,8-10 or with galaxies hosting enhanced star formation activity10-12, but lack of optical resolution has made the nature of these identifications rather uncertain. Here we present the results of a very deep radio survey, obtained with the Very Large Array, of a field imaged with the Wide Field Camera on the Hubble Space Telescope. We find that most of the microjansky sources are indeed faint blue galaxies, with light profiles resembling disk galaxies. More than half of these galaxies occur in pairs or small groups, compared to fewer than ten per cent of nearby galaxies. We conclude that the microjansky sources are luminous disk galaxies, in a starburst (or post-starburst) phase that was triggered by interactions or mergers. Only a few show evidence for an active nucleus2,13,14, which is the other possible power source for the emission.

Measurement of the Mass Profile of Abell 1689

In this letter we present calibrated mass and light profiles of the rich cluster of galaxies Abell 1689 out to 1 $h^{-1}$ Mpc from the center. The high surface density of faint blue galaxies at high redshift, selected by their low surface brightness, are unique tools for mapping the projected mass distribution of foreground mass concentrations. The systematic gravitational lens distortions of $10^4$ of these background galaxies in 15\arcmin\ fields reveal detailed mass profiles for intervening clusters of galaxies, and are a direct measure of the growth of mass inhomogeneity. The mass is measured directly, avoiding uncertainties encountered in velocity or X-ray derived mass estimates. Mass in the rich cluster Abell 1689 follows smoothed light, outside 100 h$^{-1}$ kpc, with a rest-frame V band mass-to-light ratio of $400 \pm 60$ $h^{-1} (M/L_V)_\odot$. Near the cluster center, mass appears to be more smoothly distributed than light. Out to a radius of 1 $h^{-1}$ Mpc the total mass follows a steeper than isothermal profile. Comparing with preliminary high resolution N-body clustering simulations for various cosmogonies on these scales, these data are incompatible with hot dark matter, a poor fit to most mixed dark matter models, and favor open or $\Lambda > 0$ cold dark matter. Substructure is seen in both the mass and the light, but detailed correspondence is erased on scales less than 100 $h^{-1}$ kpc.

Ly-alpha forests and cooling outflow from dwarf galaxies

We propose that cooling outflows from star-forming dwarf galaxies that are spatially correlated with but unbound to bright galaxies may account for the low column QSO Ly$\alpha$ forests, providing an explanation for both the heavy elements recently detected in them and the large sizes associated with them. Thus, we suggest that structure formations in the early universe on scales where matters collapse gravitationally and the gas forms stars are responsible for the Ly$\alpha$ forests (cf. the mini-halo model). Supernovae shock the interstellar gas to high temperature, and the resulting gas outflows from the dwarfs owing to their shallow potential wells. The gas cools radiatively as the radiative cooling time shortens because of adiabatic expansion. Subsequent thermal instability results in condensation of clouds. The clouds inherit the kinetic energy of the flow and coast to large distances, providing regions of the absorbing gas with sizes of up to hundreds of kpc. We calculate the Ly$\alpha$ absorption line profiles and the neutral column distribution, and show that they are consistent with observations. We suggest that the Ly$\alpha$ forests are caused by the faint blue galaxies found in the deep extragalactic surveys.

The Contribution of Low Surface Brightness Galaxies to Faint Galaxy Counts

view Abstract Citations (80) References (90) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Contribution of Low Surface Brightness Galaxies to Faint Galaxy Counts Ferguson, Henry C. ; McGaugh, Stacy S. Abstract Recent observations have revealed a population of blue galaxies at intermediate redshift with a space density well in excess of expectations from the local luminosity function and standard cosmology. The colors and luminosities of these faint blue galaxies are similar to nearby low surface brightness (LSB) galaxies. Such galaxies are severely underrepresented in surveys used to define the local luminosity function, but could in principle be detected in deep surveys. If LSB galaxy density is high enough, the faint-galaxy counts could be explained without requiring rapid galaxy evolution. To explore the consequences of including LSB galaxies, we construct catalogs of simulated nonevolving galaxies drawn from a multivariate distribution of galaxy luminosities, central surface brightnesses, bulge/disk ratios, and spectral-energy distributions. We compare two models dominated by LSB galaxies to a "standard" nonevolving model. Model galaxies are convolved with seeing and selected in a manner that closely matches real surveys. For each model we compute the local Bj band luminosity function, H I mass function, number counts in the Bj, I, and K bands, redshift distributions and color distributions. We find it possible to include a large population of LSB galaxies and incorporate a steep faint-end slope of the luminosity function in our simulations without violating the constraints on the local field-galaxy luminosity function or the H I mass function. For q0 = 0.5, the most favorable model matches the counts to B = 23, but falls short of the observations at fainter magnitudes. The discrepancy at faint magnitudes is smaller in the I and K bands. The colors and redshift distributions remain roughly consistent with observations to B = 24. The most serious discrepancy with observations is in the distribution of re at faint magnitudes, suggesting that the model contains too many LSB galaxies. Nevertheless, the results suggest that LSB galaxies could be a significant contributor to faint-galaxy counts, reducing the need for such extreme models of galaxy evolution as rapid merging or bursting dwarf galaxies. We propose several tests to assess the contribution of LSB galaxies to faint galaxy counts and to differentiate models involving moderate galaxy evolution from models involving rapid merging or starbursts. Publication: The Astrophysical Journal Pub Date: February 1995 DOI: 10.1086/175289 arXiv: arXiv:astro-ph/9409071 Bibcode: 1995ApJ...440..470F Keywords: COSMOLOGY: OBSERVATIONS; GALAXIES: LUMINOSITY FUNCTION; MASS FUNCTION; GALAXIES: PHOTOMETRY; Astrophysics E-Print: 39p, uuencoded compressed postscript, 18/21 figs included, full paper from http://planxty.stsci.edu:1024/ ferguson/lsb/lsbpp_b.ps,STScI 874 full text sources arXiv | ADS | data products SIMBAD (2)

The clustering properties of faint galaxies

The two-point angular correlation function of galaxies, \wte, has been computed from a new survey of faint galaxies covering a 2 deg$^2$ area near the North Galactic Pole. This survey, which is complete to limiting magnitudes \jmag=24 and \fmag=23, samples angular scales as large as $1\degpoint5$. Faint galaxies are found to be more weakly clustered (by a factor of at least two) compared to galaxies observed locally. Clustering amplitudes are closer to model predictions in the red than in the blue. The weak clustering of faint galaxies cannot be explained by any plausible model of clustering evolution with redshift. However, one possible explanation of the clustering properties of intermediate redshift galaxies is that they resemble those of starburst galaxies and H II region galaxies, which are observed locally to possess weak clustering amplitudes. Our clustering amplitudes are also similar to those of nearby late-type galaxies, which are observed to be more weakly clustered than early-type galaxies A simple, self-consistent model is presented that predicts the fraction of galaxies in the ``excess'' population at intermediate redshifts, and correctly matches observed color distributions. The available data on the clustering properties of faint galaxies are consistent with this model if the ``excess'' population of faint blue galaxies is also the weakly clustered population. Evidence is presented that the power-law slope of the angular correlation function becomes shallower at fainter magnitudes. A similar effect is seen locally both for dwarf galaxies and for galaxies with late morphological type;