G. Hosseinzadeh
A5041269121- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Superconducting Materials and Applications
- Astro and Planetary Science
- Particle Detector Development and Performance
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Advanced Data Processing Techniques
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Gravity Measurements
- Neutrino Physics Research
- Radiation Dose and Imaging
- Geological and Geophysical Studies
- Medical Imaging Techniques and Applications
- Advanced X-ray and CT Imaging
- Methane Hydrates and Related Phenomena
- Advanced Power Generation Technologies
- Water Quality Monitoring and Analysis
- Historical Astronomy and Related Studies
- Calibration and Measurement Techniques
- Advanced Research in Systems and Signal Processing
University of California, San Diego
2025
University of Arizona
2022-2024
Las Cumbres Observatory Global Telescope Network
2015-2023
University of California, Santa Barbara
2015-2023
Center for Astrophysics Harvard & Smithsonian
2018-2023
The NSF AI Institute for Artificial Intelligence and Fundamental Interactions
2021
Community Farm Alliance
2021
Harvard University Press
2020
Abstract The Astropy Project supports and fosters the development of open-source openly developed Python packages that provide commonly needed functionality to astronomical community. A key element is core package astropy , which serves as foundation for more specialized projects packages. In this article, we summarize features in recent major release, version 5.0, updates on Project. We then discuss supporting a broader ecosystem interoperable packages, including connections with several...
Abstract The Astropy Project supports and fosters the development of open-source openly developed Python packages that provide commonly needed functionality to astronomical community. A key element is core package astropy , which serves as foundation for more specialized projects packages. In this article, we an overview organization project summarize features in package, recent major release, version 2.0. We then describe infrastructure designed facilitate support a broader ecosystem...
High-quality collections of Type II supernova (SN) light curves are scarce because they evolve for hundreds days, making follow-up observations time consuming and often extending over multiple observing seasons. In these difficulties, the diversity SNe is not fully understood. Here we present ultraviolet optical photometry 12 monitored by Las Cumbres Observatory Global Telescope Network during 2013 to 2014, compare them with previously studied having well-sampled curves. We explore SN...
Abstract We present the discovery of Type II supernova SN 2023ixf in M101 and follow-up photometric spectroscopic observations, respectively, first month week its evolution. Our was made within a day estimated light, following light curve is characterized by rapid rise (≈5 days) to luminous peak ( M V ≈ − 18.2 mag) plateau 17.6 extending 30 days with fast decline rate ≈0.03 mag −1 . During rising phase, U color shows blueward evolution, followed redward evolution phase. Prominent flash...
Abstract We present the optical spectroscopic evolution of SN 2023ixf seen in subnight cadence spectra from 1.18 to 15 days after explosion. identify high-ionization emission features, signatures interaction with material surrounding progenitor star, that fade over first 7 days, rapid between observed within same night. compare lines and their relative strength those other supernovae early interaction, finding a close match 2020pni 2017ahn spectrum 2014G at later epochs. To physically...
We analyze pre-explosion near- and mid-infrared (IR) imaging of the site SN 2023ixf in nearby spiral galaxy M101 characterize candidate progenitor star. The star displays compelling evidence variability with a possible period $\approx$1000 days an amplitude $\Delta m \approx 0.6$ mag extensive monitoring Spitzer Space Telescope since 2004, likely indicative radial pulsations. Variability consistent this is also seen near-IR $J$ $K_{s}$ bands between 2010 2023, up to just 10 before explosion....
Abstract We present the densely sampled early light curve of Type II supernova (SN) 2023ixf, first observed within hours explosion in nearby Pinwheel Galaxy (Messier 101; 6.7 Mpc). Comparing these data to recently updated models shock-cooling emission, we find that progenitor likely had a radius 410 ± 10 R ⊙ . Our estimate is model dependent but consistent with red supergiant. These provide good fit starting about 1 day after explosion, despite fact classification spectrum shows signatures...
Abstract We present a series of high-resolution echelle spectra SN 2023ixf in M101, obtained nightly during the first week or so after discovery using PEPSI on Large Binocular Telescope. Na i D absorption these indicates host reddening E ( B − V ) = 0.031 mag and systemic velocity +7 km s −1 relative to average redshift M101. Dramatic changes are seen strength shape strong emission lines emitted by circumstellar material (CSM), including He ii λ 4686, C iv λλ 5801,5811, H α , N 7109,7123. In...
Abstract We present ultraviolet/optical/near-infrared observations and modeling of Type II supernovae (SNe II) whose early time ( δ t < 2 days) spectra show transient, narrow emission lines from shock ionization confined r 10 15 cm) circumstellar material (CSM). The observed electron-scattering broadened line profiles (i.e., IIn-like) H i , He i/ii C iv N iii/iv/v the CSM persist on a characteristic timescale IIn ) that marks transition to lower-density emergence Doppler-broadened...
We present observations of SN 2015bn (= PS15ae = CSS141223-113342+004332 MLS150211-113342+004333), a Type I superluminous supernova (SLSN) at redshift $z=0.1136$. As well as being one the closest SLSNe yet discovered, it is intrinsically brighter ($M_U\approx-23.1$) and in fainter galaxy ($M_B\approx-16.0$) than other $z\sim0.1$. used this opportunity to collect most extensive dataset for any SLSN date, including densely-sampled spectroscopy photometry, from UV NIR, spanning $-$50 +250 days...
We present the spectroscopic evolution of AT 2017gfo, optical counterpart first binary neutron star (BNS) merger detected by LIGO and Virgo, GW170817. While models have long predicted that a BNS could produce kilonova (KN), we not been able to definitively test these until now. From one day four days after merger, took five spectra 2017gfo before it faded away, which was possible because at distance only 39.5 Mpc in galaxy NGC 4993. The evolve from blue ($\sim6400$K) red ($\sim3500$K) over...
We present very early, high-cadence photometric observations of the nearby Type Ia SN 2017cbv. The light curve is unique in that it has a blue bump during first five days U, B, and g bands, which clearly resolved given our cadence 5.7 hr time span. model as combination early shocking supernova ejecta against nondegenerate companion star plus standard component. Our best-fit suggests presence subgiant 56 solar radii from exploding white dwarf, although this number highly model-dependent....
Abstract We present Chandra and Very Large Array observations of GW170817 at ∼521–743 days post-merger, a homogeneous analysis the entire data set. find that late-time nonthermal emission follows expected evolution an off-axis relativistic jet, with steep temporal decay <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>F</mml:mi> </mml:mrow> <mml:mi>ν</mml:mi> </mml:msub> <mml:mo>∝</mml:mo> <mml:msup> <mml:mi>t</mml:mi>...
We present observations and analysis of 18 stripped-envelope supernovae observed during 2013–2018. This sample consists five H/He-rich SNe, six H-poor/He-rich three narrow lined SNe Ic, four broad Ic. The peak luminosity characteristic time-scales the bolometric light curves are calculated, modelled to derive 56Ni ejecta masses (MNi Mej). Additionally, temperature evolution spectral line velocity each SN examined. Analysis [O i] in nebular phase eight suggests their progenitors had initial...
We present an implementation of the Gehrels et al. (2016) galaxy-targeted strategy for gravitational-wave (GW) follow-up using Las Cumbres Observatory global network telescopes. use Galaxy List Advanced Detector Era (GLADE) galaxy catalog, which we show is complete (with respect to a Schechter function) out ~300 Mpc galaxies brighter than median function luminosity. prioritization algorithm select with highest chance containing counterpart given their luminosity, position, and distance...
We present observations of two new hydrogen-poor superluminous supernovae (SLSN-I), iPTF15esb and iPTF16bad, showing late-time H-alpha emission with line luminosities (1-3)e+41 erg/s velocity widths (4000-6000) km/s. Including the previously published iPTF13ehe, this makes up a total three such events to date. iPTF13ehe is one most luminous slowest evolving SLSNe-I, whereas other are less fast decliners. interpret as result ejecta running into neutral H-shell located at radius ~ 1.0e+16cm....
We present two hydrogen-rich superluminous supernovae (SLSNe), namely SN2013hx and PS15br. These objects, together with SN2008es are the only SLSNe showing a distinct, broad Halpha feature during photospheric phase also do not show any sign of strong interaction between fast-moving ejecta circumstellar shells in their early spectra. Despite PS15br peak luminosity is fainter than other spectrophotometric evolution similar to different supernova space. group all them as II hence distinct from...
We present nebular-phase imaging and spectroscopy for the hydrogen-poor superluminous supernova SN 2015bn, at redshift z=0.1136, spanning +250-400 d after maximum light. The light curve exhibits a steepening in decline rate from 1.4 mag/(100 d) to 1.7 d), suggestive of significant decrease opacity. This change is accompanied by transition blue continuum superposed with photospheric absorption lines nebular spectrum dominated emission oxygen, calcium magnesium. There are no obvious signatures...
We present multi-wavelength observations of the tidal disruption event (TDE) iPTF15af, discovered by intermediate Palomar Transient Factory (iPTF) survey at redshift $z=0.07897$. The optical and ultraviolet (UV) light curves transient show a slow decay over five months, in agreement with previous optically TDEs. It also has comparable black-body peak luminosity $L_{\rm{peak}} \approx 1.5 \times 10^{44}$ erg/s. inferred temperature from UV data shows value (3$-$5) $\times 10^4$ K. is not...
At 66 Mpc, AT2019qiz is the closest optical tidal disruption event (TDE) to date, with a luminosity intermediate between bulk of population and iPTF16fnl. Its proximity allowed very early detection triggering multiwavelength spectroscopic follow-up well before maximum light. The velocity dispersion host galaxy fits TDE light curve indicate black hole mass $\approx 10^6$ M$_\odot$, disrupting star 1$ M$_\odot$. Comprehensive UV, X-ray data shows that emission dominated by an outflow,...
Abstract On 2019 April 25.346 and 26.640 UT the Laser Interferometer Gravitational-Wave Observatory (LIGO) Virgo gravitational-wave (GW) observatory announced detection of first candidate events in Observing Run 3 that contained at least one neutron star (NS). S190425z is a likely binary (BNS) merger d L = 156 ± 41 Mpc, while S190426c possibly NS–black hole (BH) ever detected, 377 100 although with marginal statistical significance. Here we report our optical follow-up observations for both...