Observing the signature of accretion from the intergalactic medium (IGM) on to galaxies at z similar to 3 requires the detection of faint (L << L*) galaxies embedded in a filamentary matrix of low-density (rho < 100 <(rho)over bar>), metal-poor gas (Z similar to 10(-2.5) Z(circle dot)) coherent over hundreds of kpc. We study the gaseous environment of three Ly alpha emitters (LAEs) at z = 2.7 - 2.8, found to be aligned in projection with a background QSO over similar to 250 kpc along the slit of a long-slit spectrum. The lack of detection of the LAEs in deep continuum images and the low inferred Ly alpha luminosities show the LAEs to be intrinsically faint, low-mass galaxies (L less than or similar to 0.1L*, M-star less than or similar to 0.1M*). An echelle spectrum of the QSO reveals strong Ly alpha absorption within +/- 200 km s(-1) from the LAEs. Our absorption line analysis leads to HI column densities in the range of logN(H I)/cm(-2) = 16-18. Associated absorption from ionic metal species CIV and Si IV constrains the gas metallicities to similar to 0.01 solar if the gas is optically thin, and possibly as low as similar to 0.001 solar if the gas is optically thick, assuming photoionization equilibrium. While the inferred metallicities are at least a factor of 10 lower than expected metallicities in the interstellar medium (ISM) of these LAEs, they are consistent with the observed chemical enrichment level in the IGM at the same epoch. Total metal abundances and kinematic arguments suggest that these faint galaxies have not been able to affect the properties of their surrounding gas. The projected spatial alignment of the LAEs, together with the kinematic quiescence and correspondence between the LAEs and absorbing gas in velocity space, suggests that these observations probe a possible filamentary structure. Taken together with the blue-dominant Ly alpha emission line profile of one of the objects, the evidence suggests that the absorbing gas is part of an accretion stream of low-metallicity gas in the IGM.

We identify a strong Ly? damping wing profile in the spectrum of the quasar P183+05 at z=6.4386. Given the detection of several narrow metal absorption lines at z=6.40392, the most likely explanation for the absorption profile is that it is due to a damped Ly? system. However, in order to match the data a contribution of an intergalactic medium 5%?38% neutral or additional weaker absorbers near the quasar is also required. The absorption system presented here is the most distant damped Ly? system currently known. We estimate an H i column density of 10(20.680.25) cm(?2), metallicity [O/H] = ?2.92 0.32, and relative chemical abundances of a system consistent with a low-mass galaxy during the first Gyr of the universe. This object is among the most metal-poor damped Ly? systems known and, even though it is observed only ?850 Myr after the big bang, its relative abundances do not show signatures of chemical enrichment by Population III stars.

We report the Subaru Hyper Suprime-Cam (HSC) discovery of two Ly alpha blobs (LABs), dubbed z70-1 and z49-1 at z = 6.965 and z = 4.888, respectively, that are Ly alpha emitters with a bright (log Lly alpha/[crg s(-1)] > 43.4 and and spatially extended Ly alpha emission, and present the photometric and spectroscopic properties of a total of seven LABs: the two new LABs and five previously known LABs at z = 5.7-6.6. The z70-1 LAB shows extended Ly alpha emission with a scale length of 1.4 +/- 0.2 kpc, about three times larger than the UV continuum emission, making z70-1 the most distant LAB identified to date. All of the seven LABs, except z49-1, exhibit no active galactic nucleus (AGN) signatures such as X-ray emission, N v lambda 1240 emission, or Ly alpha line broadening, while z49-1 has a strong C iv lambda 1548 emission line indicating an AGN on the basis of the UV-line ratio diagnostics. We carefully model the point-spread functions of the HSC images and conduct two-component exponential profile fitting to the extended Ly alpha emission of the LABs. The Ly alpha scale lengths of the core (star-forming region) and halo components are r(c) = 0.6-1.2 kpc and r(h) = 2.0-13.8 kpc, respectively. The relations between the scale lengths and galaxy properties (Ly alpha luminosity L-Ly alpha, Ly alpha rest-frame equivalent width EW0, and UV continuum magnitude M-UV) of our LABs are similar to those of Ly alpha halos (LAHs) identified around star-forming galaxies found previously by the Very Large Telescope/MUSE at similar redshifts, suggesting that our LABs are likely the bright version of high-z LAHs.

We report the first detection of multiphase gas within a quiescent galaxy beyond z approximate to 0. The observations use the brighter image of doubly lensed QSO HE 0047-1756 to probe the interstellar medium (ISM) of the massive (M-star approximate to 10(11) M-circle dot) elliptical lens galaxy at z(gal) = 0.408. Using Hubble Space Telescope's Cosmic Origins Spectrograph (COS), we obtain a medium-resolution FUV spectrum of the lensed QSO and identify numerous absorption features from H-2 in the lens ISM at projected distance d = 4.6 kpc. The H-2 column density is log N(H-2)/cm(-2) 17.8(-0.3)(+0.1) with a molecular gas fraction of f(H2) = 2%-5% , roughly consistent with some local quiescent galaxies. The new COS spectrum also reveals kinematically complex absorption features from highly ionized species O VI and N V with column densities log N(O VI) cm(-2) = 15.2 +/- 0.1 and log N(N V) cm(-2) = 14.6 +/- 0.1, among the highest known in external galaxies. Assuming the high-ionization absorption features originate in a transient warm (T similar to 105 K) phase undergoing radiative cooling from a hot halo surrounding the galaxy, we infer a mass accretion rate of similar to 0.5-1.5 M-circle dot yr(-1). The lack of star formation in the lens suggests that the bulk of this flow is returned to the hot halo, implying a heating rate of similar to 1048 erg yr(-1). Continuous heating from evolved stellar populations (primarily SNe Ia but also winds from AGB stars) may suffice to prevent a large accumulation of cold gas in the ISM, even in the absence of strong feedback from an active nucleus.

The nearby Type Ia supernova (SN Ia) SN 2011fe in M101 (cz = 241 km s(-1)) provides a unique opportunity to study the early evolution of a "normal" SN Ia, its compositional structure, and its elusive progenitor system. We present 18 high signal-to-noise spectra of SN 2011fe during its first month beginning 1.2 days post-explosion and with an average cadence of 1.8 days. This gives a clear picture of how various line-forming species are distributed within the outer layers of the ejecta, including that of unburned material (C+O). We follow the evolution of C II absorption features until they diminish near maximum light, showing overlapping regions of burned and unburned material between ejection velocities of 10,000 and 16,000 km s(-1). This supports the notion that incomplete burning, in addition to progenitor scenarios, is a relevant source of spectroscopic diversity among SNe Ia. The observed evolution of the highlyDoppler-shifted OI lambda 7774 absorption features detected within 5 days post-explosion indicates the presence of OI with expansion velocities from 11,500 to 21,000 km s(-1). The fact that some OI is present above C II suggests that SN 2011fe may have had an appreciable amount of unburned oxygen within the outer layers of the ejecta.

Current time domain facilities are finding several hundreds of transient astronomical events a year. The discovery rate is expected to increase in the future as soon as new surveys such as the Zwicky Transient Facility (ZTF) and the Large Synoptic Sky Survey (LSST) come online. Presently, the rate at which transients are classified is approximately one order or magnitude lower than the discovery rate, leading to an increasing "follow-up drought". Existing telescopes with moderate aperture can help address this deficit when equipped with spectrographs optimized for spectral classification. Here, we provide an overview of the design, operations and first results of the Spectral Energy Distribution Machine (SEDM), operating on the Palomar 60-inch telescope (P60). The instrument is optimized for classification and high observing efficiency. It combines a low-resolution (R similar to 100) integral field unit (IFU) spectrograph with "Rainbow Camera" (RC), a multi-band field acquisition camera which also serves as multi-band (ugri) photometer. The SEDM was commissioned during the operation of the intermediate Palomar Transient Factory (iPTF) and has already lived up to its promise. The success of the SEDM demonstrates the value of spectrographs optimized for spectral classification.

High-cadence transient surveys are able to capture supernovae closer to their first light than ever before. Applying analytical models to such early emission, we can constrain the progenitor stars' properties. In this paper, we present observations of SN 2018fif (ZTF 18abokyfk). The supernova was discovered close to first light and monitored by the Zwicky Transient Facility (ZTF) and the Neil Gehrels Swift Observatory. Early spectroscopic observations suggest that the progenitor of SN 2018fif was surrounded by relatively small amounts of circumstellar material compared to all previous cases. This particularity, coupled with the high-cadence multiple-band coverage, makes it a good candidate to investigate using shock-cooling models. We employ the SOPRANOS code, an implementation of the model by Sapir & Waxman and its extension to early times by Morag et al. Compared with previous implementations, SOPRANOS has the advantage of including a careful account of the limited temporal validity domain of the shock-cooling model as well as allowing usage of the entirety of the early UV data. We find that the progenitor of SN 2018fif was a large red supergiant with a radius of R = 744.0(-128.0)(+183.0) R-circle dot and an ejected mass of M-ej = 9.3(-5.8)(+0.4) M-circle dot. Our model also gives information on the explosion epoch, the progenitor's inner structure, the shock velocity, and the extinction. The distribution of radii is double-peaked, with smaller radii corresponding to lower values of the extinction, earlier recombination times, and a better match to the early UV data. If these correlations persist in future objects, denser spectroscopic monitoring constraining the time of recombination, as well as accurate UV observations (e.g., with ULTRASAT), will help break the extinction/radius degeneracy and independently determine both.

We present a spectrophotometric survey of 2522 extragalactic globular clusters (GCs) around 12 early-type galaxies, nine of which have not been published previously. Combining space-based and multicolour wide-field ground-based imaging, with spectra from the Keck/DEep Imaging Multi-Object Spectrograph (DEIMOS) instrument, we obtain an average of 160 GC radial velocities per galaxy, with a high-velocity precision of similar to 15 km s(-1) per GC. After studying the photometric properties of the GC systems, such as their spatial and colour distributions, we focus on the kinematics of metal-poor (blue) and metal-rich (red) GC subpopulations to an average distance of similar to 8 effective radii from the galaxy centre.

We compare predictions of cooled masses and cooling rates from three stripped-down semi-analytic models (SAMs) of galaxy formation with the results of N-body+Smoothed Particle Hydrodynamics (SPH) simulations with gas particle mass of 3.9 x 10(6) h(-1) M-aS (TM), where radiative cooling of a gas of primordial composition is implemented. We also run a simulation where cooling is switched on at redshift similar to 2, in order to test cooling models in a regime in which their approximations are expected to be valid. We confirm that cooling models implemented in SAMs are able to predict the amount of cooled mass at z = 0 to within similar to 20 per cent. However, some relevant discrepancies are found. (i) When the contribution from poorly resolved haloes is subtracted out, SAMs tend to underpredict by similar to 30 per cent the mass that cools in the infall-dominated regime. (ii) At large halo masses, SAMs tend to overpredict cooling rates, though the numerical result may be affected by the use of a standard version of SPH. (iii) As found in our previous work, cooling rates are found to be significantly affected by model details: simulations disfavour models with large cores and with quenching of cooling at major mergers. (iv) When cooling is switched on at z similar to 2, cold gas accumulates very quickly in the simulated haloes. This accumulation is reproduced by SAMs with varying degrees of accuracy.

A robust prediction of Lambda CDM cosmology is the halo circular velocity function (CVF), a dynamical cousin of the halo mass function. The correspondence between theoretical and observed CVFs is uncertain, however: cluster galaxies are reported to exhibit a power-law CVF consistent with N-body simulations, but that of the field is distinctly Schechter-like, flattened compared to Lambda CDM expectations at circular velocities v(c) less than or similar to 200 km s(-1). Groups offer a powerful probe of the role environment plays in this discrepancy as they bridge the field and clusters. Here, we construct the CVF for a large, mass- and multiplicity-complete sample of group galaxies from the Sloan Digital Sky Survey. Using independent photometric vc estimators, we find no transition from field to Lambda CDM-shaped CVF above v(c) = 50 km s-1 as a function of group halo mass. All groups with 12.4 less than or similar to log M-halo/M-circle dot less than or similar to 15.1 (Local Group analogs to rich clusters) display similar Schechter-like CVFs marginally suppressed at low v(c) compared to that of the field. Conversely, some agreement with N-body results emerges for samples saturated with late-type galaxies, with isolated late-types displaying a CVF similar in shape to Lambda CDM predictions. We conclude that the flattening of the low-v(c) slope in groups is due to their depressed late-type fractions-environment affecting the CVF only to the extent that it correlates with this quantity-and that previous cluster analyses may suffer from interloper contamination. These results serve as useful benchmarks for cosmological simulations of galaxy formation.