Lyman-alpha emission galaxies at a redshift of z = 5.7 in the FORS Deep Field

We present the results of a search for Lyman-alpha emission galaxies at z~ 5.7 in the FORS Deep Field. The objective of this study is to improve the faint end of the luminosity function of high-redshift Lyman-alpha emitting galaxies and to derive properties of intrinsically faint Lyman-alpha emission galaxies in the young universe. Using FORS2 at the ESO VLT and a set of special interference filters, we identified candidates for high-redshift Lyman-alpha galaxies. We then used FORS2 in spectroscopic mode to verify the identifications and to study their spectral properties. The narrow-band photometry resulted in the detection of 15 likely Lyman-alpha emission galaxies. Spectra with an adequate exposure time could be obtained for eight galaxies. In all these cases the presence of Lyman-alpha emission at z = 5.7 was confirmed spectroscopically. The line fluxes of the 15 candidates range between 3 and 16 * 10^-21 Wm^-2, which corresponds to star-formation rates not corrected for dust between 1 and 5 Msun/yr. The luminosity function derived for our photometrically identified objects extends the published luminosity functions of intrinsically brighter Lyman-alpha galaxies. With this technique the study of high-redshift Lyman-alpha emission galaxies can be extended to low intrinsic luminosities.Comment: 9 pages, 17 figures. Accepted by A&A. PDF version with higher resolution figures here: http://www.lsw.uni-heidelberg.de/users/jheidt/fdf/pubs/fdflae5_7_110406.pd

Maintaining Personal Resiliency: Lessons Learned from Evangelical Protestant Clergy

Despite the prominence of clergy in providing human services, and the work-related stressors they experience, clergy health and coping responses have rarely been the focus of psychological research. We report two studies. In the first, we evaluated responses of 398 senior pastors to three open-ended questions regarding personal coping, structural support for their work, and remediation efforts in times of distress. In the second study, Christian mental health professionals and Christian education professionals identified Protestant Christian clergy who exemplify emotional and spiritual health. Twenty-six participated in individual 30-minute interviews. Respondents emphasized the importance of being intentional in maintaining balance in life and developing healthy relationships. They also value a vital spiritual life, emphasizing both their sense of calling into ministry the importance of spiritual disciplines, and an ongoing awareness of God's grace. We suggest ways that Christian mental health professionals can support pastors in preventive and remedial roles. </jats:p

Effects of deposit-feeding bivalve (Macomona liliana) density on intertidal sediment stability

Effects of macrofaunal feeding and bioturbation on intertidal sediment stability (u*crit) were investigated by manipulating density (0-3 x ambient) of the facultative deposit-feeding wedge shell (Macomona liliana) on the Tuapiro sandflat in Tauranga Harbour, New Zealand. Sediment stability increased up to 200% with decreasing M. liliana density and this was correlated with greater sediment microalgal biomass and mucilage content. The change in stability occurred despite homogeneity of grain size amongst experimental treatments, highlighting the importance of macrofaunal-microbial relationships in determining estuarine sediment erodibility

The X-ray emission lines in GRB afterglows: the evidence for the two-component jet model

Recently, X-ray emission lines have been observed in X-ray afterglows of several $\gamma$-ray bursts. It is a major breakthrough for understanding the nature of the progenitors. It is proposed that the X-ray emission lines can be well explained by the Geometry-Dominated models, but in these models the illuminating angle is much larger than that of the collimated jet of the $\gamma$-ray bursts(GRBs). For GRB 011211, we obtain the illuminating angle is about $\theta\sim45^{\circ}$, while the angle of GRB jet is only $3.6^{\circ}$, so we propose that the outflow of the GRBs with emission lines should have two distinct components. The wide component illuminates the reprocessing material, and produces the emission lines, while the narrow one produces the $\gamma$-ray bursts. The observations show that the energy for producing the emission lines is higher than that of the GRBs. In this case, when the wide component dominates the afterglows, a bump will appear in the GRBs afterglows. For GRB 011211, the emergence time of the bump is less than 0.05 days after the GRB, it is obviously too early for the observation to catch it. With the presence of the X-ray emission lines there should also be a bright emission component between the UV and the soft X-rays. These features can be tested by the $Swift$ satellite in the near future.Comment: 10 pags, 1 figure, ChJAA in pres

Prompt optical observations of GRB050319 with the Swift UVOT

The UVOT telescope on the Swift observatory has detected optical afterglow emission from GRB 050319. The flux declines with a power law slope of alpha = -0.57 between the start of observations some 230 seconds after the burst onset (90s after the burst trigger) until it faded below the sensitivity threshold of the instrument after ~5 x 10^4s. There is no evidence for the rapidly declining component in the early light curve that is seen at the same time in the X-ray band. The afterglow is not detected in UVOT shortward of the B-band, suggesting a redshift of about 3.5. The optical V-band emission lies on the extension of the X-ray spectrum, with an optical to X-ray slope of beta = -0.8. The relatively flat decay rate of the burst suggests that the central engine continues to inject energy into the fireball for as long as a few x 10^4s after the burst.Comment: 16 pages, 4 figures, accepted by Ap

X-ray Destruction of Dust Along the Line of Sight to Gamma-Ray Bursts

We show that if all gamma-ray bursts emit X-rays in a way similar to those observed by BeppoSax, much of the extinction along the line of sight in the host galaxy of the burst can be destroyed. Two mechanisms are principally responsible for dust destruction: grain heating and grain charging. The latter, which can lead to electrostatic stresses greater than the tensile strength of the grains, is often the more important. Grains may regularly be destroyed at distances as large as 100 parsecs. This dust destruction can permit us to see the UV/optical afterglow even when the burst is embedded deep within a highly-obscured region. Because the destruction rate depends on grain composition and size, it may be possible to observe the amount and wavelength-dependence of extinction change during the course of the burst and first few minutes of the afterglow. It may also be possible to detect interstellar absorption lines in the afterglow spectrum that would not exist but for the return of heavy elements to the gas phase.Comment: Accepted for publication in The Astrophysical Journal. Uses AASTeX. 31 pages, including a six-panel figur

SN 2009kf : a UV bright type IIP supernova discovered with Pan-STARRS 1 and GALEX

We present photometric and spectroscopic observations of a luminous type IIP Supernova 2009kf discovered by the Pan-STARRS 1 (PS1) survey and detected also by GALEX. The SN shows a plateau in its optical and bolometric light curves, lasting approximately 70 days in the rest frame, with absolute magnitude of M_V = -18.4 mag. The P-Cygni profiles of hydrogen indicate expansion velocities of 9000km/s at 61 days after discovery which is extremely high for a type IIP SN. SN 2009kf is also remarkably bright in the near-ultraviolet (NUV) and shows a slow evolution 10-20 days after optical discovery. The NUV and optical luminosity at these epochs can be modelled with a black-body with a hot effective temperature (T ~16,000 K) and a large radius (R ~1x10^{15} cm). The bright bolometric and NUV luminosity, the lightcurve peak and plateau duration, the high velocities and temperatures suggest that 2009kf is a type IIP SN powered by a larger than normal explosion energy. Recently discovered high-z SNe (0.7 < z < 2.3) have been assumed to be IIn SNe, with the bright UV luminosities due to the interaction of SN ejecta with a dense circumstellar medium (CSM). UV bright SNe similar to SN 2009kf could also account for these high-z events, and its absolute magnitude M_NUV = -21.5 +/- 0.5 mag suggests such SNe could be discovered out to z ~2.5 in the PS1 survey.Comment: Accepted for publication in APJ

Optical monitoring of the gravitationally lensed quasar Q2237+0305 from APO between June 1995 and January 1998

We present a data set of images of the gravitationally lensed quasar Q2237+0305, that was obtained at the Apache Point Observatory (APO) between June 1995 and January 1998. Although the images were taken under variable, often poor seeing conditions and with coarse pixel sampling, photometry is possible for the two brighter quasar images A and B with the help of exact quasar image positions from HST observations. We obtain a light curve with 73 data points for each of the images A and B. There is evidence for a long (>~ 100 day) brightness peak in image A in 1996 with an amplitude of about 0.4 to 0.5 mag (relative to 1995), which indicates that microlensing has been taking place in the lensing galaxy. Image B does not vary much over the course of the observation period. The long, smooth variation of the light curve is similar to the results from the OGLE monitoring of the system (Wozniak et al. 2000a).Comment: 8 pages, 5 figures; accepted for publication in A&