分类： 天文学 >> 天文学 提交时间： 2023-02-19
C. R. Bom
J. Annis
A. Garcia
A. Palmese
N. Sherman
M. Soares-Santos
L. Santana-Silva
R. Morgan
K. Bechtol
T. Davis
H. T. Diehl
S. S. Allam
T. G. Bachmann
B. M. O. Fraga
J. Garcıa-Bellido
M. S. S. Gill
K. Herner
C. D. Kilpatrick
M. Makler
F. Olivares E.
摘要： We address the problem of optimally identifying all kilonovae detected via gravitational wave emission in the upcoming LIGO/Virgo/KAGRA Collaboration observing run, O4, which is expected to be sensitive to a factor of $\sim 7$ more Binary Neutron Stars alerts than previously. Electromagnetic follow-up of all but the brightest of these new events will require $>1$ meter telescopes, for which limited time is available. We present an optimized observing strategy for the Dark Energy Camera during O4. We base our study on simulations of gravitational wave events expected for O4 and wide-prior kilonova simulations. We derive the detectabilities of events for realistic observing conditions. We optimize our strategy for confirming a kilonova while minimizing telescope time. For a wide range of kilonova parameters, corresponding to a fainter kilonova compared to GW170817/AT2017gfo we find that, with this optimal strategy, the discovery probability for electromagnetic counterparts with the Dark Energy Camera is $\sim 80\%$ at the nominal binary neutron star gravitational wave detection limit for the next LVK observing run (190 Mpc), which corresponds to a $\sim 30\%$ improvement compared to the strategy adopted during the previous observing run. For more distant events ($\sim 330$ Mpc), we reach a $\sim 60\%$ probability of detection, a factor of $\sim 2$ increase. For a brighter kilonova model dominated by the blue component that reproduces the observations of GW170817/AT2017gfo, we find that we can reach $\sim 90\%$ probability of detection out to 330 Mpc, representing an increase of $\sim 20 \%$, while also reducing the total telescope time required to follow-up events by $\sim 20\%$.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
P. D. Aleo
K. Malanchev
S. Sharief
D. O. Jones
G. Narayan
R. J. Foley
V. A. Villar
C. R. Angus
V. F. Baldassare
M. J. Bustamante-Rosell
D. Chatterjee
C. Cold
D. A. Coulter
K. W. Davis
S. Dhawan
M. R. Drout
A. Engel
K. D. French
A. Gagliano
C. Gall
摘要： We present the Young Supernova Experiment Data Release 1 (YSE DR1), comprised of processed multi-color Pan-STARRS1 (PS1) griz and Zwicky Transient Facility (ZTF) gr photometry of 1975 transients with host-galaxy associations, redshifts, spectroscopic/photometric classifications, and additional data products from 2019 November 24 to 2021 December 20. YSE DR1 spans discoveries and observations from young and fast-rising supernovae (SNe) to transients that persist for over a year, with a redshift distribution reaching z~0.5. We present relative SN rates from YSE's magnitude- and volume-limited surveys, which are consistent with previously published values within estimated uncertainties for untargeted surveys. We combine YSE and ZTF data, and create multi-survey SN simulations to train the ParSNIP and SuperRAENN photometric classification algorithms; when validating our ParSNIP classifier on 472 spectroscopically classified YSE DR1 SNe, we achieve 82% accuracy across three SN classes (SNe Ia, II, Ib/Ic) and 90% accuracy across two SN classes (SNe Ia, core-collapse SNe). Our classifier performs particularly well on SNe Ia, with high (>90%) individual completeness and purity, which will help build an anchor photometric SNe Ia sample for cosmology. We then use our photometric classifier to characterize our photometric sample of 1483 SNe, labeling 1048 (~71%) SNe Ia, 339 (~23%) SNe II, and 96 (~6%) SNe Ib/Ic. YSE DR1 provides a training ground for building discovery, anomaly detection, and classification algorithms, performing cosmological analyses, understanding the nature of red and rare transients, exploring tidal disruption events and nuclear variability, and preparing for the forthcoming Vera C. Rubin Observatory Legacy Survey of Space and Time.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
D. A. Coulter
D. O. Jones
P. McGill
R. J. Foley
P. D. Aleo
M. J. Bustamante-Rosell
D. Chatterjee
K. W. Davis
C. Dickinson
A. Engel
A. Gagliano
W. V. Jacobson-Galán
C. D. Kilpatrick
J. Kutcka
X. K. Le Saux
Y. -C. Pan
P. J. Quiñonez
C. Rojas-Bravo
M. R. Siebert
K. Taggart
摘要： The modern study of astrophysical transients has been transformed by an exponentially growing volume of data. Within the last decade, the transient discovery rate has increased by a factor of ~20, with associated survey data, archival data, and metadata also increasing with the number of discoveries. To manage the data at this increased rate, we require new tools. Here we present YSE-PZ, a transient survey management platform that ingests multiple live streams of transient discovery alerts, identifies the host galaxies of those transients, downloads coincident archival data, and retrieves photometry and spectra from ongoing surveys. YSE-PZ also presents a user with a range of tools to make and support timely and informed transient follow-up decisions. Those subsequent observations enhance transient science and can reveal physics only accessible with rapid follow-up observations. Rather than automating out human interaction, YSE-PZ focuses on accelerating and enhancing human decision making, a role we describe as empowering the human-in-the-loop. Finally, YSE-PZ is built to be flexibly used and deployed; YSE-PZ can support multiple, simultaneous, and independent transient collaborations through group-level data permissions, allowing a user to view the data associated with the union of all groups in which they are a member. YSE-PZ can be used as a local instance installed via Docker or deployed as a service hosted in the cloud. We provide YSE-PZ as an open-source tool for the community.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
A. Pastorello
G. Valerin
M. Fraser
A. Reguitti
N. Elias-Rosa
A. V. Filippenko
C. Rojas-Bravo
L. Tartaglia
T. M. Reynolds
S. Valenti
J. E. Andrews
C. Ashall
K. A. Bostroem
T. G. Brink
J. Burke
Y. -Z. Cai
E. Cappellaro
D. A. Coulter
R. Dastidar
K. W. Davis
摘要： We present photometric and spectroscopic data on three extragalactic luminous red novae (LRNe): AT2018bwo, AT2021afy, and AT2021blu. AT2018bwo was discovered in NGC45 (at 6.8 Mpc) a few weeks after the outburst onset. During the monitoring period, the transient reached a peak luminosity of 10^40 erg/s. AT2021afy, hosted by UGC10043 (49.2 Mpc), showed a double-peaked light curve, with the two peaks reaching a similar luminosity of 2.1(+-0.6)x10^41 erg/s. For AT2021blu in UGC5829, (8.6 Mpc), the pre-outburst phase was well-monitored by several photometric surveys, and the object showed a slow luminosity rise before the outburst. The light curve of AT2021blu was sampled with an unprecedented cadence until the object disappeared behind the Sun, and it was then recovered at late phases. The light curve of AT2021blu shows a double peak, with a prominent early maximum reaching a luminosity of 6.5x10^40 erg/s, which is half of that of AT2021afy. The spectra of AT2021afy and AT2021blu display the expected evolution for LRNe: a blue continuum dominated by prominent Balmer lines in emission during the first peak, and a redder continuum consistent with that of a K-type star with narrow absorption metal lines during the second, broad maximum. The spectra of AT2018bwo are markedly different, with a very red continuum dominated by broad molecular features in absorption. As these spectra closely resemble those of LRNe after the second peak, AT2018bwo was probably discovered at the very late evolutionary stages. This would explain its fast evolution and the spectral properties compatible with that of an M-type star. From the analysis of deep frames of the LRN sites years before the outburst, and considerations of the light curves, the quiescent progenitor systems of the three LRNe were likely massive, with primaries ranging from 13Mo for AT2018bwo, to 13-18Mo for AT2021blu, and over 40Mo for AT2021afy.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
K. W. Davis
K. Taggart
S. Tinyanont
R. J. Foley
V. A. Villar
L. Izzo
C. R. Angus
M. J. Bustamante-Rosell
D. A. Coulter
N. Earl
D. Farias
J. Hjorth
M. E. Huber
D. O. Jones
P. L. Kelly
C. D. Kilpatrick
D. Langeroodi
H. -Y. Miao
C. M. Pellegrino
E. Ramirez-Ruiz
摘要： We present optical and near-infrared (NIR) observations of the Type Icn supernova (SN Icn) 2022ann, the fifth member of its newly identified class of SNe. Its early optical spectra are dominated by narrow carbon and oxygen P-Cygni features with absorption velocities of 800 km/s; slower than other SNe Icn and indicative of interaction with a dense, H/He-poor circumstellar medium (CSM) that is outflowing slower than a typical Wolf-Rayet wind velocity of $>$1000 km/s. We identify helium in NIR spectra obtained two weeks after maximum and in optical spectra at three weeks, demonstrating that the CSM is not fully devoid of helium. We never detect broad spectral features from SN ejecta, including in spectra extending to the nebular phase, a unique characteristic among SNe~Icn. Compared to other SNe Icn, SN 2022ann has a low luminosity, with a peak o-band absolute magnitude of -17.7, and evolves slowly. We model the bolometric light curve and find it is well-described by 1.7 M_Sun of SN ejecta interacting with 0.2 M_sun of CSM. We place an upper limit of 0.04 M_Sun of Ni56 synthesized in the explosion. The host galaxy is a dwarf galaxy with a stellar mass of 10^7.34 M_Sun (implied metallicity of log(Z/Z_Sun) $\approx$ 0.10) and integrated star-formation rate of log(SFR) = -2.20 M_sun/yr; both lower than 97\% of the galaxies observed to produce core-collapse supernovae, although consistent with star-forming galaxies on the galaxy Main Sequence. The low CSM velocity, nickel and ejecta masses, and likely low-metallicity environment disfavour a single Wolf-Rayet progenitor star. Instead, a binary companion star is likely required to adequately strip the progenitor before explosion and produce a low-velocity outflow. The low CSM velocity may be indicative of the outer Lagrangian points in the stellar binary progenitor, rather than from the escape velocity of a single Wolf-Rayet-like massive star.
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