A5005103694- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Optical Systems and Laser Technology
- Adaptive optics and wavefront sensing
- Neutrino Physics Research
- Geological and Geophysical Studies
- Astrophysics and Star Formation Studies
- Methane Hydrates and Related Phenomena
- Spectroscopy Techniques in Biomedical and Chemical Research
- SAS software applications and methods
- Calibration and Measurement Techniques
- Statistical and numerical algorithms
- Advanced Research in Systems and Signal Processing
University of Oklahoma
2019-2024
University of California, Berkeley
2016-2021
San Francisco State University
2017-2018
We carried out spectroscopic monitoring of 21 low-redshift Seyfert 1 galaxies using the Kast double spectrograph on 3-m Shane telescope at Lick Observatory from April 2016 to May 2017. Targeting active galactic nuclei (AGN) with luminosities {\lambda}L{\lambda} (5100 {\AA}) = 10^44 erg/s and predicted H{\beta} lags 20-30 days or black hole masses 10^7-10^8.5 Msun, our campaign probes luminosity-dependent trends in broad-line region (BLR) structure dynamics as well improve calibrations for...
We present the complete sample of stripped-envelope supernova (SN) spectra observed by Lick Observatory Supernova Search (LOSS) collaboration over last three decades: 888 302 SNe, 652 published here for first time, with 384 (of 92 SNe) having photometrically-determined phases. After correcting redshift and Milky Way dust reddening reevaluating spectroscopic classifications each SN, we construct mean major spectral subtypes (Types IIb, Ib, Ic) binned phase. compare measures line strengths...
We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part a larger multi-wavelength reverberation mapping campaign. The campaign spanned six months and achieved almost daily cadence with observations from five ground-based telescopes. H$\beta$ He II $\lambda$4686 broad emission-line light curves lag that 5100 $\AA$ continuum by $4.17^{+0.36}_{-0.36}$ days $0.79^{+0.35}_{-0.34}$ days, respectively. relative to 1158 ultraviolet curve measured Hubble Space...
We present BVRI and unfiltered light curves of 93 Type Ia supernovae (SNe Ia) from the Lick Observatory Supernova Search (LOSS) follow-up program conducted between 2005 2018. Our sample consists 78 spectroscopically normal SNe Ia, with remainder divided distinct subclasses (three SN 1991bg-like, three 1991T-like, four Iax, two peculiar, super-Chandrasekhar events), has a median redshift 0.0192. The in our have coverage 16 photometric epochs at cadence 5.4 days, first observed epoch is ~4.6...
ABSTRACT We present photometry and spectroscopy of the slowly evolving superluminous Type IIn supernova (SN) 2015da. SN 2015da is extraordinary for its very high peak luminosity, also sustaining a luminosity several years. Even at 8 yr after explosion, remains as luminous normal II-P. The total radiated energy integrated over this time period (with no bolometric correction) least $1.6 \times 10^{51}$ erg (or 1.6 FOE). Including mild correction, adding kinetic expanding cold dense shell...
In this work, BV RI light curves of 55 Type II supernovae (SNe II) from the Lick Observatory Supernova Search program obtained with Katzman Automatic Imaging Telescope and 1 m Nickel telescope 2006 to 2018 are presented. Additionally, more than 150 spectra gathered 3 Shane published. We conduct an analyse peak absolute magnitudes, decline rates, time durations different phases colour curves. Typically, our sampled a median cadence 5.5 days for total 5093 photometric points. average V-band...
We have modeled the velocity-resolved reverberation response of H\b{eta} broad emission line in nine Seyfert 1 galaxies from Lick Active Galactic Nucleus (AGN) Monitioring Project 2016 sample, drawing inferences on geometry and structure low-ionization broad-line region (BLR) mass central supermassive black hole. Overall, we find that BLR is generally a thick disk viewed at low to moderate inclination angles. combine our sample with prior studies investigate line-profile shape dependence,...
We investigate the relationship between AGN optical variability timescales, amplitudes, and supermassive black hole (SMBH) masses using homogeneous light curves from All-Sky Automated Survey for SuperNovae (ASAS-SN). fit a damped random walk (DRW) model to high-cadence, long-baseline ASAS-SN estimate characteristic timescale ($\tau_\text{DRW}$) amplitude ($\sigma$) 57 with precise SMBH mass measurements reverberation mapping dynamical methods. confirm significant correlation...
We present the multi-wavelength and environmental properties of 37 variability-selected active galactic nuclei (AGNs), including 30 low luminosity AGNs (LLAGNs), using a high cadence time-domain survey (ASAS-SN) from spectroscopic sample 1218 nearby bright galaxies. find that high-cadence surveys uniquely select LLAGNs do not necessarily satisfy other AGN selection methods, such as X-ray, mid-IR, or BPT methods. In our sample, 3% them pass mid-infrared color based selection, 18% X-ray 60%...
We present 637 low-redshift optical spectra collected by the Berkeley Supernova Ia Program (BSNIP) between 2009 and 2018, almost entirely with Kast double spectrograph on Shane 3~m telescope at Lick Observatory. describe our automated spectral classification scheme arrive a final set of 626 (of 242 objects) that are unambiguously classified as belonging to Type supernovae (SNe~Ia). Of these, 70 30 objects spectroscopically peculiar (i.e., not matching signatures "normal" SNe~Ia) 79 SNe~Ia...
We present the results of an extensive observational campaign on nearby Type Ibn SN 2015G, including data from radio through ultraviolet wavelengths. 2015G was asymmetric, showing late-time nebular lines redshifted by ~1000 km/s. It shared many features with prototypical In 2006jc, extremely strong He I emssion and a blue pseudocontinuum. The young showed narrow P-Cygni profiles I, but never in its evolution did it show any signature hydrogen - arguing for dense, ionized, hydrogen-free...
Outbursts on young stars are usually interpreted as accretion bursts caused by instabilities in the disk or star-disk connection. However, some protostellar outbursts may not fit into this framework. In paper, we analyze optical and near-infrared spectra photometry to characterize 2015 outburst of probable star ASASSN-15qi. The $\sim 3.5$ mag brightening $V$ band was sudden, with an unresolved rise time less than one day. decayed exponentially 1 for 6 days then gradually back pre-outburst...
The Type~Ia supernova (SN~Ia) 2016coj in NGC 4125 (redshift $z=0.004523$) was discovered by the Lick Observatory Supernova Search 4.9 days after fitted first-light time (FFLT; 11.1 before $B$-band maximum). Our first detection (pre-discovery) is merely $0.6\pm0.5$ day FFLT, making SN one of earliest known detections a Ia. A spectrum taken only 3.7 hr discovery (5.0 FFLT) and classified as normal We performed high-quality photometry, low- high-resolution spectroscopy, spectropolarimetry,...
We present BVRI and unfiltered Clear light curves of 70 stripped-envelope supernovae (SESNe), observed between 2003 2020, from the Lick Observatory Supernova Search (LOSS) follow-up program. Our SESN sample consists 19 spectroscopically normal SNe~Ib, two peculiar SNe Ib, six SN Ibn, 14 Ic, one ten Ic-BL, 15 IIb, ambiguous IIb/Ib/c, superluminous SNe. photometry has (on a per-SN basis) mean coverage 81 photometric points (median 58 points) cadence 3.6d 1.2d). From our full sample, subset 38...
Photometric and spectroscopic analyses of the intermediate-luminosity Type Ib supernova (SN) 2015ap heavily reddened SN~2016bau are discussed. properties two SNe, such as colour evolution, bolometric luminosity, photospheric radius, temperature, velocity also constrained. The ejecta mass, synthesised nickel kinetic energy calculated from their light-curve analysis. We model compare spectra SN~2015ap at various stages evolution. P~Cygni profiles lines present in used to determine evolution...
Abstract Low luminosity active galactic nuclei (LLAGN) probe accretion physics in the low Eddington regime can provide additional clues about galaxy evolution. AGN variability is ubiquitous and thus provides a reliable tool for finding AGN. We analyze All-Sky Automated Survey SuperNovae light curves of 1218 galaxies with g < 14 mag Sloan Digital Sky spectra search find 37 objects that are both variable have AGN-like structure functions, which 3% sample. The majority selected LLAGN ratios...
Abstract Gamma-ray burst (GRB) 150910A was detected by Swift/Burst Alert Telescope (BAT), and then rapidly observed Swift/XRT, Swift/Ultraviolet-Optical Telescope, ground-based telescopes. We report Lick Observatory spectroscopic photometric observations of GRB 150910A, we investigate the physical origins both optical X-ray afterglows, incorporating data obtained with BAT XRT. The light curves show that jet-emission episode lasts ∼360 s a sharp pulse from to XRT (Episode I). In Episode II,...
ABSTRACT We present optical and ultraviolet photometry, as well spectra, for the type II supernova (SN) 2015bf. Our observations cover phases from ∼2 to ∼200 d after explosion. The first spectrum is characterized by a blue continuum with blackbody temperature of ∼24 000 K flash-ionized emission lines. After about 1 week, spectra SN 2015bf evolve like those regular II. From luminosity narrow component H α, we deduce that mass-loss rate larger than ${\sim}3.7\times 10^{-3}\, {\rm M_\odot \,...
We present photometry, spectra, and spectropolarimetry of supernova (SN) 2014ab, obtained through $\sim 200$ days after peak brightness. SN 2014ab was a luminous Type IIn ($M_V < -19.14$ mag) discovered brightness near the nucleus its host galaxy, VV 306c. Prediscovery upper limits constrain time explosion to within 200 prior discovery. While declined by 1$ mag over course our observations, observed spectrum remained remarkably unchanged. Spectra exhibit an asymmetric emission-line...
We present photometry and spectroscopy of the slowly evolving superluminous Type IIn SN2015da. SN2015da is extraordinary for its very high peak luminosity, also sustaining a luminosity several years. Even at 8\,yr after explosion, remains as luminous normal SNII-P. The total radiated energy integrated over this time period (with no bolometric correction) least 1.6 FOE. Including mild correction, adding kinetic expanding cold dense shell swept-up circumstellar material (CSM), accounting...
We analyze the optical power spectral density (PSD) for 22 active galactic nuclei (AGN) with measured X-ray PSDs using light curves from All-Sky Automated Survey SuperNovae (ASAS-SN) and Transiting Exoplanet Satellite (TESS). The joint PSD is over up to six orders of magnitude in frequency space timescales minutes a decade. fit either damped random walk (DRW) or broken law model constrain break frequency. For power-law fits PSDs, we find high-frequency timescale which proportional both black...