The recently initiated Arecibo Legacy Fast ALFA (ALFALFA) survey aims to map $7000 deg 2 of the high Galactic latitude sky visible from Arecibo, providing a H i line spectral database covering the redshift range between À1600 and 18,000 km s À1 with $5 km s À1 resolution. Exploiting Arecibo's large collecting area and small beam size, ALFALFA is specifically designed to probe the faint end of the H i mass function in the local universe and will provide a census of H i in the surveyed sky area to faint flux limits, making it especially useful in synergy with wide-area surveys conducted at other wavelengths. ALFALFA will also provide the basis for studies of the dynamics of galaxies within the Local Supercluster and nearby superclusters, allow measurement of the H i diameter function, and enable a first wide-area blind search for local H i tidal features, H i absorbers at z < 0:06, and OH megamasers in the redshift range 0:16 < z < 0:25. Although completion of the survey will require some 5 years, public access to the ALFALFA data and data products will be provided in a timely manner, thus allowing its application for studies beyond those targeted by the ALFALFA collaboration. ALFALFA adopts a two-pass, minimum intrusion, drift scan observing technique that samples the same region of sky at two separate epochs to aid in the discrimination of cosmic signals from noise and terrestrial interference. Survey simulations, which take into account large-scale structure in the mass distribution and incorporate experience with the ALFA system gained from tests conducted during its commissioning phase, suggest that ALFALFA will detect on the order of 20,000 extragalactic H i line sources out to z $ 0:06, including several hundred with H i masses M H i < 10 7:5 M .

The GALEX Arecibo SDSS Survey (GASS) is a large targeted survey that started at Arecibo in March 2008. GASS is designed to measure the neutral hydrogen content of ~1000 massive galaxies (with stellar mass Mstar > 10^10 Msun) at redshift 0.025

Brown dwarfs are classified as objects which are not massive enough to sustain nuclear fusion of hydrogen, and are distinguished from planets by their ability to burn deuterium. 1 Old (>10 Myr) brown dwarfs are expected to possess short-lived magnetic fields 2 and, since they no longer generate energy from collapse and accretion, weak radio and X-ray emitting coronae. Several efforts have been undertaken in the past to detect chromospheric activity from the brown dwarf LP944−20 at X-ray 1,3 and optical 4,5,6,7 wavelengths, but only recently an X-ray flare from this object was detected. 3 Here we report on the discovery of quiescent and flaring radio emission from this source, which represents the first detection of persistent radio emission from a brown dwarf, with luminosities that are several orders of magnitude larger than predicted from an empirical relation 8,9 between the X-ray and radio luminosities of many stellar types. We show in the context of synchrotron emission, that LP944−20 possesses an unusually weak magnetic field in comparison to active dwarf M stars, 10,11 which might explain the null results from previous optical and X-ray observations of this source, and the deviation from the empirical relations. This paper has been submitted to Nature. You are free to use the results here for the purpose of

We report new IRAM/PdBI, JCMT/SCUBA-2, and VLA observations of the ultraluminous quasar SDSSJ010013.02+280225.8 (hereafter, J0100+2802) at z=6.3, which hosts the most massive supermassive black hole (SMBH) of 1.24 × 10 10 M ⊙ known at z>6. We detect the [C II] 158µm fine structure line and molecular CO(6-5) line and continuum emission at 353 GHz, 260 GHz, and 3 GHz from this quasar. The CO(2-1) line and the underlying continuum at 32 GHz are also marginally detected. The [C II] and CO detections suggest active star formation and highly excited molecular gas in the quasar host galaxy. The redshift determined with the [C II] and CO lines shows a velocity offset of ∼ 1000 km s −1 from that measured with the quasar Mg II line. The CO (2-1) line luminosity provides direct constraint on the molecular gas mass which is about -2 -(1.0 ± 0.3) × 10 10 M ⊙ . We estimate the FIR luminosity to be (3.5 ± 0.7) × 10 12 L ⊙ , and the UV-to-FIR spectral energy distribution of J0100+2802 is consistent with the templates of the local optically luminous quasars. The derived [C II]-to-FIR luminosity ratio of J0100+2802 is 0.0010±0.0002, which is slightly higher than the values of the most FIR luminous quasars at z∼6. We investigate the constraint on the host galaxy dynamical mass of J0100+2802 based on the [C II] line spectrum. It is likely that this ultraluminous quasar lies above the local SMBHgalaxy mass relationship, unless we are viewing the system at a small inclination angle.

We report results from a program aimed at investigating the temperature of neutral gas in highredshift damped Lyman-α absorbers (DLAs). This involved (1) HI 21cm absorption studies of a large sample of DLAs towards radio-loud quasars, (2) very long baseline interferometric studies to measure the low-frequency quasar core fractions, and (3) optical/ultraviolet spectroscopy to determine DLA metallicities and the velocity widths of low-ionization metal lines.Including literature data, our sample consists of 37 DLAs with estimates of the harmonicmean spin temperature T s . We find a statistically significant (4σ) difference between the T s distributions in the high-z (z > 2.4) and low-z (z < 2.4) DLA samples. The high-z sample contains more systems with high spin temperature, T s 1000 K. The T s distributions in DLAs and the Galaxy are also significantly (≈ 6σ) different, with more high-T s sightlines in DLAs than in the Milky Way. The high T s values in the high-z DLAs of our sample arise due to low fractions of the cold neutral medium (CNM). Only two of 23 DLAs at z > 1.7 have T s values indicating CNM fractions > 20%, comparable to the median value (≈ 27%) in the Galaxy.We tested whether the HI column density measured towards the optical quasar might be systematically different from that towards the radio core by comparing the HI column densities inferred from HI 21cm emission studies at different spatial resolutions (≈ 15 pc −1 kpc) in the Large Magellanic Cloud. The high-resolution N HI values are, on average, larger than the smoothed ones for N HI > 10 21 cm −2 , but lower than the smoothed N HI estimates for N HI < 10 21 cm −2 . Since there are far more DLAs with low N HI values than high ones, the use of the optical N HI value for the radio sightline results in a statistical tendency to under-estimate DLA spin temperatures.For 29 DLAs with metallicity estimates, we confirm the presence of an anti-correlation between T s and metallicity [Z/H], at 3.5σ significance via a non-parametric Kendall-tau test. This result was obtained with the assumption that the DLA covering factor is equal to the core fraction. However, Monte Carlo simulations show that the significance of the result is only marginally decreased if the covering factor and the core fraction are uncorrelated, or if there is a random error in the inferred covering factor.We also find statistically significant evidence for redshift evolution in DLA spin temperatures even for the DLA sub-sample at z > 1. Since all DLAs at z > 1 have angular diameter distances comparable to or larger than those of their background quasars, they have similar efficiency in covering the quasars. We conclude that low covering factors in high-z DLAs cannot account for the observed redshift evolution in spin temperatures.