18 research outputs found
Comprehensive Observations of the Bright and Energetic Type Iax SN 2012Z: Interpretation as a Chandrasekhar Mass White Dwarf Explosion
We present UV through NIR broad-band photometry, and optical and NIR
spectroscopy of Type Iax supernova 2012Z. The data set consists of both early
and late-time observations, including the first late phase NIR spectrum
obtained for a spectroscopically classified SN Iax. Simple model calculations
of its bolometric light curve suggest SN 2012Z produced ~0.3 M_sun of (56)Ni,
ejected about a Chandrasekhar mass of material, and had an explosion energy of
~10^51 erg, making it one of the brightest and most energetic SN Iax yet
observed. The late phase NIR spectrum of SN 2012Z is found to broadly resemble
similar epoch spectra of normal SNe Ia; however, like other SNe Iax,
corresponding visual-wavelength spectra differ substantially compared to all
supernova types. Constraints from the distribution of IMEs, e.g. silicon and
magnesium, indicate that the outer ejecta did not experience significant mixing
during or after burning, and the late phase NIR line profiles suggests most of
the (56)Ni is produced during high density burning. The various observational
properties of SN 2012Z are found to be consistent with the theoretical
expectations of a Chandrasekhar mass white dwarf progenitor that experiences a
pulsational delayed detonation, which produced several tenths of a solar mass
of (56)Ni during the deflagration burning phase and little (or no) (56)Ni
during the detonation phase. Within this scenario only a moderate amount of
Rayleigh-Taylor mixing occurs both during the deflagration and fallback phase
of the pulsation, and the layered structure of the IMEs is a product of the
subsequent denotation phase. The fact that the SNe Iax population does not
follow a tight brightness-decline relation similar to SNe Ia can then be
understood in the framework of variable amounts of mixing during pulsational
rebound and variable amounts of (56)Ni production during the early subsonic
phase of expansion.Comment: Submitted to A&A, manuscript includes response to referee's comments.
39 pages, including 16 figures, 9 table
Carnegie Supernova Project-II: Extending the Near-Infrared Hubble Diagram for Type Ia Supernovae to
The Carnegie Supernova Project-II (CSP-II) was an NSF-funded, four-year
program to obtain optical and near-infrared observations of a "Cosmology"
sample of Type Ia supernovae located in the smooth Hubble flow (). Light curves were also obtained of a "Physics"
sample composed of 90 nearby Type Ia supernovae at selected for
near-infrared spectroscopic time-series observations. The primary emphasis of
the CSP-II is to use the combination of optical and near-infrared photometry to
achieve a distance precision of better than 5%. In this paper, details of the
supernova sample, the observational strategy, and the characteristics of the
photometric data are provided. In a companion paper, the near-infrared
spectroscopy component of the project is presented.Comment: 43 pages, 10 figures, accepted for publication in PAS
ASAS-SN follow-up of IceCube high-energy neutrino alerts
We report on the search for optical counterparts to IceCube neutrino alerts
released between April 2016 and August 2021 with the All-Sky Automated Survey
for SuperNovae (ASAS-SN). Despite the discovery of a diffuse astrophysical
high-energy neutrino flux in 2013, the source of those neutrinos remains
largely unknown. Since 2016, IceCube has published likely-astrophysical
neutrinos as public realtime alerts. Through a combination of normal survey and
triggered target-of-opportunity observations, ASAS-SN obtained images within 1
hour of the neutrino detection for 20% (11) of all observable IceCube alerts
and within one day for another 57% (32). For all observable alerts, we obtained
images within at least two weeks from the neutrino alert. ASAS-SN provides the
only optical follow-up for about 17% of IceCube's neutrino alerts. We recover
the two previously claimed counterparts to neutrino alerts, the flaring-blazar
TXS 0506+056 and the tidal disruption event AT2019dsg. We investigate the light
curves of previously-detected transients in the alert footprints, but do not
identify any further candidate neutrino sources. We also analysed the optical
light curves of Fermi 4FGL sources coincident with high-energy neutrino alerts,
but do not identify any contemporaneous flaring activity. Finally, we derive
constraints on the luminosity functions of neutrino sources for a range of
assumed evolution models
The Carnegie Supernova Project II. The shock wave revealed through the fog: The strongly interacting Type IIn SN 2013L
We present ultra-violet to mid-infrared observations of the long-lasting Type
IIn supernova (SN) 2013L obtained by the Carnegie Supernova Project II
(CSP-II). The spectra of SN 2013L are dominated by H emission features
characterized by three components attributed to different regions. A unique
feature of this Type IIn SN is that the blue shifted line profile is dominated
by the macroscopic velocity of the expanding shock wave of the SN. We are
therefore able to trace the evolution of the shock velocity in the dense and
partially opaque circumstellar medium (CSM), from at +48
d, decreasing as to after a year. We perform
spectral modeling of both the broad- and intermediate-velocity components of
the H line profile. The high-velocity component is consistent with
emission from a radially thin, spherical shell located behind the expanding
shock with emission wings broadened by electron scattering. We propose that the
intermediate component originates from pre-ionized gas from the unshocked dense
CSM with the same velocity as the narrow component, , but
also broadened by electron scattering. The spectral energy distributions (SEDs)
of SN 2013L after +132 d are well reproduced by a two-component black-body (BB)
model. The circumstellar-interaction model of the bolometric light curve
reveals a mass-loss rate history with large values () over the 25 - 40 years before explosion. The drop
in the light curve at days and presence of electron scattering wings
at late epochs indicate an anisotropic CSM. The mass-loss rate values and the
unshocked CSM velocity are consistent with the characteristics of a massive
star, such as a luminous blue variable (LBV) undergoing strong eruptions,
similar to Carina.Comment: Replaced after language editor corrections, accepted for publication
on Astronomy and Astrophysics, 43 pages, 29 figures. Abstract abridge
The carbon-rich type Ic supernova 2016adj in the iconic dust lane of Centaurus A: signatures of interaction with circumstellar hydrogen?
We present a comprehensive data set of supernova (SN) 2016adj located within
the central dust lane of Centaurus A. SN 2016adj is significantly reddened and
after correcting the peak apparent -band magnitude ()
for Milky Way reddening and our inferred host-galaxy reddening parameters
(i.e., and ), we estimate
it reached a peak absolute magnitude of . Detailed inspection of
the optical/NIR spectroscopic time-series reveals a carbon-rich SN Ic and not a
SN Ib/IIb as previously suggested in the literature. The NIR spectra shows
prevalent carbon-monoxide formation occurring already by +41 days past -band
maximum, which is days earlier than previously reported in the
literature for this object. Interestingly around two months past maximum, the
NIR spectrum of SN~2016adj begins to exhibit H features, with a +97~d medium
resolution spectrum revealing both Paschen and Bracket lines with absorption
minima of km/s, full-width-half-maximum emission velocities of
km/s, and emission line ratios consistent with a dense emission
region. We speculate these attributes are due to circumstellar interaction
(CSI) between the rapidly expanding SN ejecta and a H-rich shell of material
formed during the pre-SN phase. A bolometric light curve is constructed and a
semi-analytical model fit suggests the supernova synthesized 0.5 solar masses
of Ni and ejected 4.2 solar masses of material, though these values
should be approached with caution given the large uncertainties associated with
the adopted reddening parameters, possible CSI contamination, and known light
echo emission. Finally, inspection of Hubble Space Telescope archival data
yielded no progenitor detection.Comment: Submitted to A&A, comments are welcom
Carnegie Supernova Project-I and -II: Measurements of using Cepheid, TRGB, and SBF Distance Calibration to Type Ia Supernovae
We present an analysis of Type Ia Supernovae (SNe~Ia) from both the Carnegie
Supernova Project~I (CSP-I) and II (CSP-II), and extend the Hubble diagram from
the optical to the near-infrared wavelengths (). We calculate the
Hubble constant, , using various distance calibrators: Cepheids, Tip of
the Red Giant Branch (TRGB), and Surface Brightness Fluctuations (SBF).
Combining all methods of calibrations, we derive $\rm H_0=71.76 \pm 0.58 \
(stat) \pm 1.19 \ (sys) \ km \ s^{-1} \ Mpc^{-1}B\rm
H_0=73.22 \pm 0.68 \ (stat) \pm 1.28 \ (sys) \ km \ s^{-1} \ Mpc^{-1}H1.2\sim 1.3 \rm \ km \
s^{-1} \ Mpc^{-1}H_0H_0H_0Y0.12\pm0.01\sigma_{int}$). We revisit SN~Ia Hubble residual-host mass correlations and
recover previous results that these correlations do not change significantly
between the optical and the near-infrared wavelengths. Finally, SNe~Ia that
explode beyond 10 kpc from their host centers exhibit smaller dispersion in
their luminosity, confirming our earlier findings. Reduced effect of dust in
the outskirt of hosts may be responsible for this effect.Comment: Revised calculations are made. Will be resubmitted to Ap
The Most Rapidly Declining Type I Supernova 2019bkc/ATLAS19dqr
We report observations of the hydrogen-deficient supernova (SN) 2019bkc/ATLAS19dqr. With B- and r-band decline between peak and 10 days post peak of Dm10 (B) = 5.24. 0.07 mag and Dm10 (r) = 3.85. 0.10 mag, respectively, SN.2019bkc is the most rapidly declining SN I discovered so far. While its closest matches are the rapidly declining SN.2005ek and SN. 2010X, the light curves and spectra of SN.2019bkc show some unprecedented characteristics. SN.2019bkc appears "hostless," with no identifiable host galaxy near its location, although it may be associated with the galaxy cluster MKW1 at z.=.0.02. We evaluate a number of existing models of fast-evolving SNe, and we find that none of them can satisfactorily explain all aspects of SN.2019bkc observations
Hubble space telescope reveals spectacular light echoes associated with the stripped-envelope supernova 2016adj in the iconic dust lane of Centaurus A
We present a multiband sequence of Hubble Space Telescope images documenting the emergence and evolution of multiple light echoes (LEs) linked to the stripped-envelope supernova (SN) 2016adj located in the central dust lane of Centaurus A. Following point-spread function subtraction, we identify the earliest LE emission associated with an SN at only +34 days past the epoch of the B-band maximum. Additional HST images extending through +578 days cover the evolution of LE1 taking the form of a ring, while images taken on +1991 days reveal not only LE1 but also segments of a new inner LE ring (LE2) as well as two additional outer LE rings (LE3 and LE4). Adopting the single-scattering formalism, the angular radii of the LEs suggest they originate from discrete dust sheets in the foreground of the SN. This information, combined with measurements of color and optical depth of the scattering surfaces, informs a scenario with multiple sheets of clumpy dust characterized by a varying degree of holes. In this case, the larger the LE's angular radii, the farther in the foreground of the SN its dust sheet is located. However, an exception to this is LE2, which is formed by a dust sheet located in closer proximity to the SN than the dust sheets producing LE1, LE3, and LE4. The delayed appearance of LE2 can be attributed to its dust sheet having a significant hole along the line of sight between the SN and Earth.This research is funded by grants from the Independent Research Fund Denmark (8021-00170B) and the Villum FONDEN (28021). M.F. is supported by a Royal Society—Science Foundation Ireland University Research Fellowship. L.G. acknowledges financial support from the MCIU AEI 10.13039/501100011033 PID2020-115253GA-I00 HOSTFLOWS project, the 2019 Ramón y Cajal program RYC2019-027683-I, the PIE project 20215AT016, and the program CEX2020-001058-M. Data presented in the paper were made with the NASA/ESA Hubble Space Telescope under program ID: 11360 (PI O'Connell), 14115 (PI Van Dyk), 14487 (PI Sugerman), 14700 (PI Sugerman), and 16179 (PI Filippenko). Images were retrieved from the archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. Support for S.S.L. via programs 14487 and 14700 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127.Peer reviewe