GRB110715A: Multifrequency study of the first gamma-ray burst observed with ALMA

GRB 110715A had a bright afterglow that was obscured by a high Galactic extinction. We discovered the submillimetre counterpart with APEX and followed it in radio with ATCA for over 2 months. Additional submillimetre observations were performed with ALMA as a test of the ToO procedures during commissioning. UV, optical and NIR observations were performed with UVOT/Swift and GROND at the 2.2 m telescope in La Silla and X-ray data was obtained by XRT/Swift. The dataset is complemented with spectroscopic data from the X-shooter spectrograph at the VLT. From a broadband model we derive a peculiar density profile in the environment of the progenitor, with a discontinuity that produces a break in the light curve at ∼ 1 day after the burst onset. The absorption features present in the intermediate resolution optical/nIR spectra reveal a redshift of 0.8224 and a host galaxy environment with low ionisation and no velocity components beyond 30 km s−1 . These preliminary results will be published elsewhere

Dust content of Virgo star-forming dwarf galaxies

We investigate the dust properties of a small sample of Virgo cluster dwarf galaxies drawn from the science demonstration phase data set of the Herschel Virgo Cluster Survey (HeViCS). These galaxies have low metallicities (7.8 < 12 + log(O/H) < 8.3) and star formation rates less than or similar to 0.1 M-circle dot yr(-1). We measure the spectral energy distribution (SED) from 100 to 500 mu m and derive dust temperatures and masses. The SEDs are fitted by a cool component with T less than or similar to 20 K, implying dust masses around 10(5) M-circle dot and dust-to-gas ratios (D) within the range 10(-3)-10(-2)

Dust in cluster dwarf elliptical galaxies

Based on single cross-scan data of the Herschel Virgo Cluster Survey, we report the first detections of dust in cluster early-type dwarf galaxies: VCC 209, VCC 781 and VCC 951. All three galaxies have dust masses M-d approximate to 10(5) - 10(6) M-circle dot and average dust temperatures approximate to 16-20 K. Since these three early-type dwarfs reside in densely crowded regions close to the center of the Virgo cluster, and several HI-detected dwarfs in the outskirts of Virgo were not detected by Herschel (implying a dust content < 10(4) M-circle dot), this might imply that dust in dwarfs is more closely related to the molecular gas, which is more centrally peaked in a galaxy's potential well and therefore, not easily removed by any stripping mechanism. We conclude that the removal of interstellar dust from these early-type dwarfs appears to be less efficient than the removal of the HI gas