Alexei V. FILIPPENKO

In this contribution, we achieve the primary goal of the active galactic nucleus (AGN) STORM campaign by recovering velocity–delay maps for the prominent broad emission lines (Lyα, C iv, He ii, and Hβ) in the spectrum of NGC 5548. These are the most detailed velocity–delay maps ever obtained for an AGN, providing unprecedented information on the geometry, ionization structure, and kinematics of the broad-line region. Virial envelopes enclosing the emission-line responses show that the reverberating gas is bound to the black hole. A stratified ionization structure is evident. The He ii response inside 5–10 lt-day has a broad single-peaked velocity profile. The Lyα, C iv, and Hβ responses extend from inside 2 to outside 20 lt-day, with double peaks at±2500 km s− 1 in the 10–20 lt-day delay range. An incomplete ellipse in the velocity–delay plane is evident in Hβ. We interpret the maps in terms of a Keplerian disk with …

Gamma-ray burst (GRB) 150910A was detected by Swift/Burst Alert Telescope (BAT), and then rapidly observed by Swift/XRT, Swift/Ultraviolet-Optical Telescope, and ground-based telescopes. We report Lick Observatory spectroscopic and photometric observations of GRB 150910A, and we investigate the physical origins of both the optical and X-ray afterglows, incorporating data obtained with BAT and XRT. The light curves show that the jet-emission episode lasts∼ 360 s with a sharp pulse from BAT to XRT (Episode I). In Episode II, the optical emission has a smooth onset bump followed by a normal decay (α R, 2≈− 1.36), as predicted in the standard external shock model, while the X-ray emission exhibits a plateau (α X, 1≈− 0.36) followed by a steep decay (α X, 2≈− 2.12). The light curves show obvious chromatic behavior with an excess in the X-ray flux. Our results suggest that GRB 150910A is an unusual …

The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, observed the 90% region of the gravitational-wave event S200128d (GCN 26906) detected by LIGO/Virgo. More than one thousand galaxies were selected from the Glade catalog V1. 0 (Dalya et al., 2018, MNRAS, 479, 2374; http://aquarius. elte. hu/glade/) according to their priority score. KAIT observed 100 of them based on their priority scores and elevation visibility, with each clear-filter exposure time being 60 s. The first image was taken at 02: 32: 19, Jan. 28th UT, about 12.0 minutes after the trigger, and the last image at 10: 19: 35 UT. Our typical limiting mag is 19.0. No viable counterparts were identified and the analysis is ongoing. A full list of galaxies observed by KAIT is given below. GladeID UT (Jan28) RA_J2000 Dec_J2000-----------------------------------------------G0696216 02: 32: 19 01: 17: 45.1378-25: 50: 21.1524 …

We report the search results in the BAT data within T0+/-100 s of the LVC event S200219ac (LIGO/VIRGO Collaboration GCN Circ. 27130), where T0 is the LVC trigger time (2020-02-19T09: 44: 15.195 UTC). The center of the BAT field of view (FOV) at T0 is RA= 342.701 deg, DEC=-59.111 deg, and the roll angle is 346.271 deg. The BAT FOV (> 10% partial coding) covers 47.80% of the integrated LVC localization probability, and 47.45% of the galaxy convolved probability (Evans et al. 2016). Note that the sensitivity in the BAT FOV changes with the partial coding fraction. Please see the BAT FOV figure in the summary page (link below) for the specific location of the LVC region relative to the BAT FOV. Within T0+/-100 s, no significant detections (signal-to-noise ratio>~ 5 sigma) are found in the BAT raw light curves with time bins of 64 ms, 1 s, and 1.6 s. Also, there is no significant signal in BAT around the time of the …

We present details on the observing strategy, data-processing techniques, and spectroscopic targeting algorithms for the first three years of operation for the Dark Energy Survey Supernova Program (DES-SN). This five-year program using the Dark Energy Camera mounted on the 4 m Blanco telescope in Chile was designed to discover and follow supernovae (SNe) Ia over a wide redshift range (0.05< z< 1.2) to measure the equation-of-state parameter of dark energy. We describe the SN program in full: strategy, observations, data reduction, spectroscopic follow-up observations, and classification. From three seasons of data, we have discovered 12,015 likely SNe, 308 of which have been spectroscopically confirmed, including 251 SNe Ia over a redshift range of 0.017< z< 0.85. We determine the effective spectroscopic selection function for our sample and use it to investigate the redshift-dependent bias on the …

Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) are crucial for constraining the properties of their progenitor systems. Theoretical studies predicted that the UV spectra, which probe the outermost layers of an SN, should be sensitive to the metal content of the progenitor. Using the largest SN Ia UV (λ < 2900 Å) spectroscopic sample obtained from Neil Gehrels Swift Observatory, we investigate the dependence of UV spectra on metallicity. For the first time, our results reveal a correlation (∼2σ) between SN Ia UV flux and host-galaxy metallicities, with SNe in more metal-rich galaxies (which are likely to have higher progenitor metallicities) having lower UV flux level. We find that this metallicity effect is only significant at short wavelengths (λ ≲ 2700 Å), which agrees well with the theoretical predictions. We produce UV spectral templates for SNe Ia at peak brightness. With our sample, we could …

MCA-1B (also called UIT003) is a luminous hot star in the western outskirts of M33, classified over 20 yr ago with a spectral type of Ofpe/WN9 and identified then as a candidate luminous blue variable (LBV). Palomar Transient Factory data reveal that this star brightened in 2010, with a light curve resembling that of the classic LBV star AF And in M31. Other Ofpe/WN9 stars have erupted as LBVs, but MCA-1B was unusual because it remained hot. It showed a WN-type spectrum throughout its eruption, whereas LBVs usually get much cooler. MCA-1B showed an almost four-fold increase in bolometric luminosity and a doubling of its radius, but its temperature stayed ≳29 kK. As it faded, it shifted to even hotter temperatures, exhibiting a WN7/WN8-type spectrum, and doubling its wind speed. MCA-1B is reminiscent of some supernova impostors, and its location resembles the isolated environment of SN 2009ip. It is …

Unlike ordinary supernovae (SNe), some of which are hydrogen and helium deficient (called Type Ic SNe), broad-lined Type Ic SNe (SNe Ic-bl) are very energetic events, and only SNe Ic-bl are coincident with long-duration gamma-ray bursts (GRBs). Understanding the progenitors of SN Ic-bl explosions versus those of their SN Ic cousins is key to understanding the SN–GRB relationship and jet production in massive stars. Here we present the largest existing set of host galaxy spectra of 28 SNe Ic and 14 SNe Ic-bl, all discovered by the same galaxy-untargeted survey, namely, the Palomar Transient Factory (PTF). We carefully measure their gas-phase metallicities, stellar masses (M*), and star formation rates (SFRs). We further reanalyze the hosts of 10 literature SN–GRBs using the same methods and compare them to our PTF SN hosts with the goal of constraining their progenitors from their local environments …