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.

We analyze the stellar kinematics of 39 dwarf early-type galaxies (dEs) in the Virgo Cluster. Based on the specific stellar angular momentum lambda(Re) and the ellipticity, we find 11 slow rotators and 28 fast rotators. The fast rotators in the outer parts of the Virgo Cluster rotate significantly faster than fast rotators in the inner parts of the cluster. Moreover, 10 out of the 11 slow rotators are located in the inner 3 degrees (D < 1 Mpc) of the cluster. The fast rotators contain subtle disk-like structures that are visible in high-pass filtered optical images, while the slow rotators do not exhibit these structures. In addition, two of the dEs have kinematically decoupled cores and four more have emission partially filling in the Balmer absorption lines. These properties suggest that Virgo Cluster dEs may have originated from late-type star-forming galaxies that were transformed by the environment after their infall into the cluster. The correlation between lambda(Re) and the clustercentric distance can be explained by a scenario where low luminosity star-forming galaxies fall into the cluster, their gas is rapidly removed by ram-pressure stripping, although some of it can be retained in their core, their star formation is quenched but their stellar kinematics are preserved. After a long time in the cluster and several passes through its center, the galaxies are heated up and transformed into slow rotating dEs.

We model the dynamics of dwarf early-type galaxies in the Virgo cluster when subject to a variety of environmental processes. We focus on how these processes imprint trends in the dynamical state (rotational versus pressure support as measured by the lambda(Re/2)* statistic) with projected distance from the cluster center, and compare these results to observational estimates. We find a large scatter in the gradient of lambda(Re/2)* with projected radius. A statistical analysis shows that models with no environmental effects produce gradients as steep as those observed in none of the 100 cluster realizations we consider, while in a model incorporating tidal stirring by the cluster potential 34% of realizations produce gradients as steep as that observed. Our results suggest that tidal stirring may be the cause of the observed radial dependence of dwarf early-type dynamics in galaxy clusters.

We present a simulation setup for studying the dynamical and chemical evolution of the intracluster medium (ICM) and analyze a sample of 12 galaxy clusters that are diverse both kinetically (pre-merger, merging, virialized) and in total mass (M-vir = 1.17 x 10(14) - 1.06 x 10(15) M-circle dot). We analyzed the metal mass fraction in the ICM as a function of redshift and discuss radial trends as well as projected 2D metallicity maps. The setup combines high mass resolution N-body simulations with the semi-analytical galaxy formation model GALACTICUS for consistent treatment of the subgrid physics (such as galactic winds and ram-pressure stripping) in the cosmological hydrodynamical simulations. The interface between GALACTICUS and the hydro simulation of the ICM with FLASH is discussed with respect to observations of star formation rate histories, radial star formation trends in galaxy clusters, and the metallicity at different redshifts. As a test for the robustness of the wind model, we compare three prescriptions from different approaches. For the wind model directly taken from GALACTICUS, we find mean ICM metallicities between 0.2-0.8 Z(circle dot) within the inner 1 Mpc at z = 0. The main contribution to the metal mass fraction comes from galactic winds. The outflows are efficiently mixed in the ICM, leading to a steady homogenization of metallicities until ram-pressure stripping becomes effective at low redshifts. We find a very peculiar and yet common drop in metal mass fractions within the inner similar to 200 kpc of the cool cores, which is due to a combination of wind suppression by outer pressure within our model and a lack of mixing after the formation of these dense regions.

We present the results of a Keck-ESI study of dwarf galaxies across a range of environment: the Perseus Cluster, the Virgo Cluster, the NGC 1407 group, and the NGC 1023 group. 18 dwarf ellipticals (dEs) are targeted for spectroscopy, three for the first time. We confirm cluster membership for one Virgo dE, and group membership for one dE in the NGC 1023 group, and one dE in the NGC 1407 group for the first time. Regardless of environment, the dEs follow the same size-magnitude and sigma-luminosity relation. Two of the Virgo dwarfs, VCC 1199 and VCC 1627, have among the highest central velocity dispersions (sigma(0) = 58.4 and 49.2 km s(-1)) measured for dwarfs of their luminosity (M-R approximate to -17). Given their small sizes (R-e < 300 pc) and large central velocity dispersions, we classify these two dwarfs as compact ellipticals (cEs) rather than dEs. Group dEs typically have higher mean dynamical-to-stellar mass ratios than the cluster dEs, with M-dyn/M-star = 5.1 +/- 0.6 for the group dwarfs, versus M-dyn/M-star = 2.2 +/- 0.5 for the cluster sample, which includes two cEs. We also search for trends in M-dyn/M-star versus distance from M87 for the Virgo Cluster population, and find no preference for dwarfs with high values of M-dyn/M-star to reside in the cluster outskirts dyn centre.