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We present new results on the evolution of the cosmic star formation rate as a function of stellar mass in the Subaru/XMM-Newton Deep Survey-Ultra Deep Survey field. We make use of narrow-band-selected emission line galaxies in four redshift slices between z = 1.46 and 0.63, and compute stellar masses by fitting a series of templates to recreate each galaxy's star formation history. We determine mass-binned luminosity functions in each redshift slice, and derive the star formation rate density (ρSFR) as a function of mass using the [OIII] or [OII] emission lines. We calculate dust extinction and metallicity as a function of stellar mass, and investigate the effect of these corrections on the shape of the overall ρSFR(M).We find that both these corrections are crucial for determining the shape of the ρSFR(M), and its evolution with redshift. The fully corrected ρSFR(M) is a relatively flat distribution, with the normalization moving towards lower values of ρSFR with increasing cosmic time/decreasing redshift, and requiring star formation to be truncated across all masses studied here. The peak of ρSFR(M) is found in the 1010.5 ๏ <1011.0 mass bin at z=1.46. In the lower redshift slices, the location of the peak is less certain; however, low-mass galaxies in the range 107.0 < M๏ < 108.0 play an important part in the overall ρSFR(M) out to at least z ~ 1.2. [ABSTRACT FROM AUTHOR]

We present a spectroscopic test confirming the potential of narrow-band optical imaging as a method for detecting star-forming satellites around nearby galaxies. To date the efficiency of such methods, and particularly the fraction of false detections resulting from its use, has not been tested. In this paper we use optical spectroscopy to verify the nature of objects that are apparently emission-line satellites, taken from imaging presented elsewhere. Observations of 12 probable satellites around 11 host galaxies are presented and used to compare the recession velocities of the host and satellite. This test confirms, in all cases, that there is a genuine line emission, that the detected line is Hα and that the satellites have similar recession velocities to their hosts with a maximum difference of ∼250 km s, consistent with their being gravitationally bound companions. We conclude that the spectroscopy has confirmed that narrow-band imaging through Hα filters is a reliable method for detecting genuine, star-forming satellites with low contamination from galaxies seen in projection along the line of sight. [ABSTRACT FROM AUTHOR]

We produce and analyse u-band ( nm) luminosity functions (LFs) for the red and blue populations of galaxies using data from the Sloan Digital Sky Survey (SDSS) u-band Galaxy Survey ( uGS) and Deep Evolutionary Exploratory Probe 2 (DEEP2) survey. From a spectroscopic sample of 41 575 SDSS uGS galaxies and 24 561 DEEP2 galaxies, we produce colour magnitude diagrams and make use of the colour bimodality of galaxies to separate red and blue populations. LFs for eight redshift slices in the range are determined using the method and fitted with Schechter functions showing that there is significant evolution in , with a brightening of 1.4 mag for the combined population. The integration of the Schechter functions yields the evolution in the u-band luminosity density (LD) out to . By parametrizing the evolution as , we find that for the combined populations and for the blue population. By removing the contribution of the old stellar population to the u-band LD and correcting for dust attenuation, we estimate the evolution in the star formation rate (SFR) of the Universe to be . Discrepancies between our result and higher evolution rates measured using the infrared and far-UV can be reconciled by considering possibilities such as an underestimated dust correction at high redshifts or evolution in the stellar initial mass function. [ABSTRACT FROM AUTHOR]

ABSTRACT We have imaged a sample of 20 spiral galaxies in Hα and in the near-infrared K band (2.2 μm), in order to determine the location and strength of star formation in these objects with respect to perturbations in the old stellar population. We have found that star formation rates are significantly enhanced in the vicinity of K -band arms. We have also found that this enhancement in star formation rate in arm regions correlates well with a quantity that measures the relative strengths of shocks in arms. Assuming that the K -band light is dominated by emission from the old stellar population, this shows that density waves trigger star formation in the vicinity of spiral arms. [ABSTRACT FROM AUTHOR]