arXiv subjects

J. Jencson

Publications and source records attributed to J. Jencson.

At least 19 recordsLinked to original sources

arXiv2025

JWST Observations of SN 2023ixf II: The Panchromatic Evolution Between 250 and 720 Days After the Explosion

We present the nebular phase spectroscopic and photometric observations of the nearby hydrogen-rich core-collapse supernova (CC-SN) 2023ixf, obtained through our JWST programs. These observations, combined with ground-based optical and near-infrared spectra, cover +252.67 - 719.96 d, creating a comprehensive, panchromatic time-series dataset spanning 0.32 - 30$\mu$m. In this second paper of the series, we focus on identifying key spectral emission features and tracking their evolution through the nebular phase. The JWST data reveal hydrogen emission from the Balmer to Humphreys series, as well as prominent forbidden lines from Ne, Ar, Fe, Co, and Ni. NIRSpec observations display strong emission from the first overtone and fundamental bands of carbon monoxide, which weaken with time as the ejecta cools and dust emission dominates. The spectral energy distribution shows a clear infrared excess emerging by +252.67 d peaking around 10.0$\mu$m, with a secondary bump at 18.0$\mu$m developing by +719.96 d. We suggest that this evolution could arises from multiple warm dust components. In upcoming papers in this series, we will present detailed modeling of the molecular and dust properties. Overall, this dataset significantly advances our understanding of the mid-infrared properties of CC-SNe, providing an unprecedented view of their late-time line, molecule, and dust emission.

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arXiv2025

OpenUniverse2024: A shared, simulated view of the sky for the next generation of cosmological surveys

The OpenUniverse2024 simulation suite is a cross-collaboration effort to produce matched simulated imaging for multiple surveys as they would observe a common simulated sky. Both the simulated data and associated tools used to produce it are intended to uniquely enable a wide range of studies to maximize the science potential of the next generation of cosmological surveys. We have produced simulated imaging for approximately 70 deg$^2$ of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) Wide-Fast-Deep survey and the Nancy Grace Roman Space Telescope High-Latitude Wide-Area Survey, as well as overlapping versions of the ELAIS-S1 Deep-Drilling Field for LSST and the High-Latitude Time-Domain Survey for Roman. OpenUniverse2024 includes i) an early version of the updated extragalactic model called Diffsky, which substantially improves the realism of optical and infrared photometry of objects, compared to previous versions of these models; ii) updated transient models that extend through the wavelength range probed by Roman and Rubin; and iii) improved survey, telescope, and instrument realism based on up-to-date survey plans and known properties of the instruments. It is built on a new and updated suite of simulation tools that improves the ease of consistently simulating multiple observatories viewing the same sky. The approximately 400 TB of synthetic survey imaging and simulated universe catalogs are publicly available, and we preview some scientific uses of the simulations.

astro-ph.CO↗

arXiv2025

Discovery of a likely Type II SN at $z$=3.6 with JWST

Transient astronomy in the early, high-redshift (z > 3) Universe is an unexplored regime that offers the possibility of probing the first stars and the Epoch of Reionization. During Cycles 1 and 2 of the James Webb Space Telescope (JWST), the JWST Advanced Deep Extragalactic Survey (JADES) program enabled one of the first searches for transients in deep images (~30 AB mag) over a relatively wide area (25 arcmin^2). One transient, AT 2023adsv, was discovered with an F200W magnitude of 28.04 AB mag, and subsequent JWST observations revealed that the transient is a likely supernova (SN) in a host with z_spec = 3.613 +/- 0.001 and an inferred metallicity at the position of the SN of Z_* = 0.3 +/- 0.1 Z_{\odot}. At this redshift, the first detections in F115W and F150W show that AT 2023adsv had bright rest-frame ultraviolet flux at the time of discovery. The multi-band light curve of AT 2023adsv is best matched by a template of an SN IIP with a peak absolute magnitude of M_B ~ -18.3 AB mag. We find a good match to a 20 M_{\odot} red supergiant progenitor star with an explosion energy of 2.0x10^51 ergs, likely higher than normally observed in the local Universe, but consistent with SNe IIP drawn from local, lower metallicity environments. AT 2023adsv is the most distant photometrically classified SN IIP yet discovered with a spectroscopic redshift measurement, and may represent a global shift in SNe IIP properties as a function of redshift.

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arXiv2024

A study in scarlet -- I. Photometric properties of a sample of Intermediate Luminosity Red Transients

We investigate the photometric characteristics of a sample of Intermediate Luminosity Red Transients (ILRTs), a class of elusive objects with peak luminosity between that of classical novae and standard supernovae. We present the multi-wavelength photometric follow-up of four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, AT 2019ahd and AT 2019udc. Through the analysis and modelling of their spectral energy distribution and bolometric light curves we infer the physical parameters associated with these transients. All four objects display a single peaked light curve which ends in a linear decline in magnitudes at late phases. A flux excess with respect to a single black body emission is detected in the infrared domain for three objects in our sample, a few months after maximum. This feature, commonly found in ILRTs, is interpreted as a sign of dust formation. Mid infrared monitoring of NGC 300 2008OT-1 761 days after maximum allows us to infer the presence of $\sim$10$^{-3}$-10$^{-5}$ M$_{\odot}$ of dust, depending on the chemical composition and the grain size adopted. The late time decline of the bolometric light curves of the considered ILRTs is shallower than expected for $^{56}$Ni decay, hence requiring an additional powering mechanism. James Webb Space Telescope observations of AT 2019abn prove that the object has faded below its progenitor luminosity in the mid-infrared domain, five years after its peak. Together with the disappearance of NGC 300 2008OT-1 in Spitzer images seven years after its discovery, this supports the terminal explosion scenario for ILRTs. With a simple semi-analytical model we try to reproduce the observed bolometric light curves in the context of few M$_{\odot}$ of material ejected at few 10$^{3}$ km s$^{-1}$ and enshrouded in an optically thick circumstellar medium.

astro-ph.SR↗

arXiv2024

A study in scarlet -- II. Spectroscopic properties of a sample of Intermediate Luminosity Red Transients

We investigate the spectroscopic characteristics of Intermediate Luminosity Red Transients (ILRTs), a class of elusive objects with peak luminosity between that of classical novae and standard supernovae. We present the extensive optical and near-infrared (NIR) spectroscopic monitoring of four ILRTs, namely NGC 300 2008OT-1, AT 2019abn, AT 2019ahd and AT 2019udc. First we focus on the evolution of the most prominent spectral features observed in the low resolution spectra, then we discuss more in detail the high resolution spectrum collected for NGC 300 2008OT-1 with the Very Large Telescope equipped with UVES. Finally we analyse late time spectra of NGC 300 2008OT-1 and AT 2019ahd through comparisons with both synthetic and observed spectra. Balmer and Ca lines dominate the optical spectra, revealing the presence of slowly moving circumstellar medium (CSM) around the objects. The line luminosity of H$\alpha$, H$\beta$ and Ca II NIR triplet presents a double peaked evolution with time, possibly indicative of interaction between fast ejecta and the slow CSM. The high resolution spectrum of NGC 300 2008OT-1 reveals a complex circumstellar environment, with the transient being surrounded by a slow ($\sim$30 km s$^{-1}$) progenitor wind. At late epochs, optical spectra of NGC 300 2008OT-1 and AT 2019ahd show broad ($\sim$2500 km s$^{-1}$) emission features at $\sim$6170 A and $\sim$7000 A which are unprecedented for ILRTs. We find that these lines originate most likely from the blending of several narrow lines, possibly of iron-peak elements.

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arXiv2024

JWST NIRSpec+MIRI Observations of the nearby Type IIP supernova 2022acko

We present JWST spectral and photometric observations of the Type IIP supernova (SN) 2022acko at ~50 days past explosion. These data are the first JWST spectral observations of a core-collapse SN. We identify ~30 different H I features, other features associated with products produced from the CNO cycle, and s-process elements such as Sc II and Ba II. By combining the JWST spectra with ground-based optical and NIR spectra, we construct a full Spectral Energy Distribution from 0.4 to 25 microns and find that the JWST spectra are fully consistent with the simultaneous JWST photometry. The data lack signatures of CO formation and we estimate a limit on the CO mass of < 10^{-8} solar mass. We demonstrate how the CO fundamental band limits can be used to probe underlying physics during stellar evolution, explosion, and the environment. The observations indicate little mixing between the H envelope and C/O core in the ejecta and show no evidence of dust. The data presented here set a critical baseline for future JWST observations, where possible molecular and dust formation may be seen.

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arXiv2022

The Hydrogen-Poor Superluminous Supernovae from the Zwicky Transient Facility Phase-I Survey: I. Light Curves and Measurements

During the Zwicky Transient Facility (ZTF) Phase-I operation, 78 hydrogen-poor superluminous supernovae (SLSNe-I) were discovered in less than three years, making up the largest sample from a single survey. This paper (Paper I) presents the data, including the optical/ultraviolet light curves and classification spectra, while Paper II in this series will focus on the detailed analysis of the light curves and modeling. Our photometry is primarily taken by the ZTF in the $g,r,i$ bands, and with additional data from other ground-based facilities and Swift. The events of our sample cover a redshift range of $z = 0.06 - 0.67$, with a median and $1σ$ error (16\% and 84\% percentiles) $z_{\rm med} = 0.265^{+0.143}_{-0.135}$. The peak luminosity covers $-22.8\,{\rm mag} \leq M_{g,\rm peak} \leq -19.8$\,mag, with a median value of $-21.48^{+1.13}_{-0.61}$\,mag. Their light curves evolve slowly with the mean rest-frame rise time of $t_{\rm rise} = 41.9\pm17.8$\,days. The luminosity and time scale distributions suggest that low luminosity SLSNe-I with peak luminosity $\sim -20$\,mag or extremely fast rising events ($<10$\,days) exist but are rare. We confirm previous findings that slowly rising SLSNe-I also tend to fade slowly. The rest-frame color and temperature evolution show large scatters, suggesting that the SLSN-I population may have diverse spectral energy distributions. The peak rest-frame color shows a moderate correlation with the peak absolute magnitude, i.e. brighter SLSNe-I tend to have bluer colors. With optical and ultraviolet photometry, we construct bolometric luminosity and derive a bolometric correction relation generally applicable for converting $g,r$-band photometry to bolometric luminosity for SLSNe-I.

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arXiv2022

A Kilonova Following a Long-Duration Gamma-Ray Burst at 350 Mpc

Here, we report the discovery of a kilonova associated with the nearby (350 Mpc) minute-duration GRB 211211A. In tandem with deep optical limits that rule out the presence of an accompanying supernova to $M_I > -13$ mag at 17.7 days post-burst, the identification of a kilonova confirms that this burst's progenitor was a compact object merger. While the spectrally softer tail in GRB 211211A's gamma-ray light curve is reminiscent of previous extended emission short GRBs (EE-SGRBs), its prompt, bright spikes last $\gtrsim 12$ s, separating it from past EE-SGRBs. GRB 211211A's kilonova has a similar luminosity, duration and color to AT2017gfo, the kilonova found in association with the gravitational wave (GW)-detected binary neutron star (BNS) merger GW170817. We find that the merger ejected $\approx 0.04 M_{\odot}$ of r-process-rich material, and is consistent with the merger of two neutron stars (NSs) with masses close to the canonical $1.4 M_{\odot}$. This discovery implies that GRBs with long, complex light curves can be spawned from compact object merger events and that a population of kilonovae following GRBs with durations $\gg 2$ s should be accounted for in calculations of the NS merger r-process contribution and rate. At 350 Mpc, the current network of GW interferometers at design sensitivity would have detected the merger precipitating GRB 211211A, had it been operating at the time of the event. Further searches for GW signals coincident with long GRBs are therefore a promising route for future multi-messenger astronomy.

astro-ph.HE↗

arXiv2022

PGIR 20eid (SN2020qmp): A Type IIP Supernova at 15.6 Mpc discovered by the Palomar Gattini-IR survey

We present a detailed analysis of SN 2020qmp, a nearby type IIP core-collapse supernova (CCSN), discovered by the Palomar Gattini-IR (PGIR) survey in the galaxy UGC07125. We illustrate how the multiwavelength study of this event helps our general understanding of stellar progenitors and circumstellar medium (CSM) interactions in CCSNe. We also highlight the importance of near-infrared (NIR) surveys for early detections of SNe in dusty environments. SN 2020qmp displays characteristic hydrogen lines in its optical spectra, as well as a plateau in its optical LC, hallmarks of a type IIP SN. We do not detect linear polarization during the plateau phase, with a 3 sigma upper limit of 0.78%. Through hydrodynamical LC modeling and an analysis of its nebular spectra, we estimate a progenitor mass of around 11 solar masses, and an explosion energy of around 0.8e51 erg. We find that the spectral energy distribution cannot be explained by a simple CSM interaction model, assuming a constant shock velocity and steady mass-loss rate, and the excess X-ray luminosity compared with the synchrotron radio luminosity suggests deviations from equipartition. Finally, we demonstrate the advantages of NIR surveys over optical surveys for the detection of dust-obscured CCSNe in the local universe. Specifically, our simulations show that the Wide-Field Infrared Transient Explorer will detect about 14 more CCSNe out of 75 expected in its footprint within 40 Mpc, over five years than an optical survey equivalent to the Zwicky Transient Facility would detect. We have determined or constrained the main properties of SN 2020qmp and of its progenitor, highlighting the value of multiwavelength follow-up observations of nearby CCSNe. We have also shown that forthcoming NIR surveys will finally enable us to do a nearly complete census of CCSNe in the local universe.

astro-ph.HE↗

arXiv2021

Enormous explosion energy of Type IIP SN 2017gmr with bipolar Ni-56 ejecta

The unusual Type IIP SN 2017gmr is revisited in order to pinpoint the origin of its anomalous features, including the peculiar light curve after about 100 days. The hydrodynamic modelling suggests the enormous explosion energy of about 10^52 erg. We find that the light curve with the prolonged plateau/tail transition can be reproduced either in the model with a high hydrogen abundance in the inner ejecta and a large amount of radioactive Ni-56, or in the model with an additional central energy source associated with the fallback/magnetar interaction in the propeller regime. The asymmetry of the late H-alpha emission and the reported linear polarization are reproduced by the model of the bipolar Ni-56 ejecta. The similar bipolar structure of the oxygen distribution is responsible for the two-horn structure of the [O I] 6360, 6364 A emission. The bipolar Ni-56 structure along with the high explosion energy are indicative of the magneto-rotational explosion. We identify narrow high-velocity absorption features in H-alpha and He I 10830 A lines with their origin in the fragmented cold dense shell formed due to the outer ejecta deceleration in a confined circumstellar shell.

astro-ph.HE↗

arXiv2021

The luminous red nova variety: AT 2020hat and AT 2020kog

We present the results of our monitoring campaigns of the luminous red novae (LRNe) AT 2020hat in NGC 5068 and AT 2020kog in NGC 6106. The two objects were imaged (and detected) before their discovery by routine survey operations. They show a general trend of slow luminosity rise, lasting at least a few months. The subsequent major LRN outbursts were extensively followed in photometry and spectroscopy. The light curves present an initial short-duration peak, followed by a redder plateau phase. AT 2020kog is a moderately luminous event peaking at ~7 x 10^40 erg/s, while AT 2020hat is almost one order of magnitude fainter than AT 2020kog, although it is still more luminous than V838 Mon. In analogy with other LRNe, the spectra of AT 2020kog change significantly with time. They resemble those of type IIn supernovae at early phases, then they become similar to those of K-type stars during the plateau, and to M-type stars at very late phases. In contrast, AT 2020hat already shows a redder continuum at early epochs, and its spectrum shows the late appearance of molecular bands. A moderate-resolution spectrum of AT 2020hat taken at +37 d after maximum shows a forest of narrow P Cygni lines of metals with velocities of 180 km/s, along with an Halpha emission with a full-width at half-maximum velocity of 250 km/s. For AT 2020hat, a robust constraint on its quiescent progenitor is provided by archival images of the Hubble Space Telescope. The progenitor is clearly detected as a mid-K type star, with an absolute magnitude of MF606W = -3.33+-0.09 mag and a colour of F606W-F814W = 1.14+-0.05 mag, which are inconsistent with the expectations from a massive star that could later produce a core-collapse supernova. Although quite peculiar, the two objects nicely match the progenitor versus light curve absolute magnitude correlations discussed in the literature.

astro-ph.SR↗

arXiv2020

Supernova 2018cuf: A Type IIP supernova with a slow fall from plateau

We present multi-band photometry and spectroscopy of SN 2018cuf, a Type IIP ("P" for plateau) supernova (SN) discovered by the Distance Less Than 40 Mpc survey (DLT40) within 24 hours of explosion. SN 2018cuf appears to be a typical Type IIP SN, with an absolute $V$-band magnitude of $-$16.73 $\pm$ 0.32 at maximum and a decline rate of 0.21 $\pm$ 0.05 mag/50d during the plateau phase. The distance of the object is constrained to be 41.8 $\pm$ 5.7 Mpc by using the expanding photosphere method. We use spectroscopic and photometric observations from the first year after the explosion to constrain the progenitor of SN 2018cuf using both hydrodynamic light curve modelling and late-time spectroscopic modelling. The progenitor of SN 2018cuf was most likely a red supergiant of about 14.5 $\rm M_{\odot}$ that produced 0.04 $\pm$ 0.01 $\rm M_{\odot}$ $\rm ^{56}Ni$ during the explosion. We also found $\sim$ 0.07 $\rm M_{\odot}$ of circumstellar material (CSM) around the progenitor is needed to fit the early light curves, where the CSM may originate from pre-supernova outbursts. During the plateau phase, high velocity features at $\rm \sim 11000\ km~s^{-1}$ are detected both in the optical and near-infrared spectra, supporting the possibility that the ejecta were interacting with some CSM. A very shallow slope during the post-plateau phase is also observed and it is likely due to a low degree of nickel mixing or the relatively high nickel mass in the SN.

astro-ph.HE↗

arXiv2020

Helium-rich Superluminous Supernovae From the Zwicky Transient Facility

Helium is expected to be present in the ejecta of some hydrogen-poor superluminous supernovae (SLSN-I). However, so far only one event, PTF10hgi has been identified with He features in its photospheric spectra (Quimby et al. 2018). We present the discovery of a new He-rich SLSN-I, ZTF19aawfbtg (SN2019hge) at $z=0.0866$. This event has more than 10 optical spectra at phases from $-41$ to $+103$\,days relative to the peak, most of which match well with that of PTF10hgi. Confirmation comes from a near-IR spectrum taken at $+34$ days, revealing He I features with P-Cygni profiles at 1.083 and 2.058$μ$m. Using the optical spectra of PTF10hgi and SN2019hge as templates, we examine 70 SLSN-I discovered by ZTF in the first two years of operation and found additional five SLSN-I with distinct He-features. The excitation of He\,I atoms in normal core collapse supernovae requires non-thermal radiation, as proposed by previous studies. These He-rich events can not be explained by traditional $^{56}$Ni mixing model because of their blue spectra, high peak luminosity and slow rising time scales. Magnetar models offer a possible solution since pulsar winds naturally generate high energy particles as sources of non-thermal excitation. An alternative model is ejecta interaction with H-poor CSM which may be supported by the observed light curve undulations. These six SLSN-Ib appear to have relatively low-peak luminosities (rest-frame $M_g = -20.06\pm0.16$ mag).

astro-ph.SR↗

arXiv2017

A tale of two transients: GW170104 and GRB170105A

We present multi-wavelength follow-up campaigns by the AstroSat-CZTI and GROWTH collaborations to search for an electromagnetic counterpart to the gravitational wave event GW170104. At the time of the GW170104 trigger, the AstroSat CZTI field-of-view covered 50.3\% of the sky localization. We do not detect any hard X-ray (>100 keV) signal at this time, and place an upper limit of $\approx 4.5 \times 10^{-7}~{\rm erg~cm}^{-2}{\rm~s}^{-1}$ for a 1\,s timescale. Separately, the ATLAS survey reported a rapidly fading optical source dubbed ATLAS17aeu in the error circle of GW170104. Our panchromatic investigation of ATLAS17aeu shows that it is the afterglow of an unrelated long, soft GRB~170105A, with only a fortuitous spatial coincidence with GW170104. We then discuss the properties of this transient in the context of standard long GRB afterglow models.

astro-ph.HE↗

arXiv2017

Far-Ultraviolet to Near-Infrared Spectroscopy of A Nearby Hydrogen Poor Superluminous Supernova Gaia16apd

We report the first maximum-light far-Ultraviolet to near-infrared spectra (1000A - 1.62um, rest) of a H-poor superluminous supernova, Gaia16apd. At z=0.1018, it is one of the closest and the UV brightest such events, with 17.4 (AB) magnitude in Swift UV band (1928A) at -11days pre-maximum. Assuming an exponential form, we derived the rise time of 33days and the peak bolometric luminosity of 3x10^{44}ergs^-1. At maximum light, the estimated photospheric temperature and velocity are 17,000K and 14,000kms^-1 respectively. The inferred radiative and kinetic energy are roughly 1x10^{51} and 2x10^{52}erg. Gaia16apd is extremely UV luminous, emitting 50% of its total luminosity at 1000 - 2500A. Compared to the UV spectra (normalized at 3100A) of well studied SN1992A (Ia), SN2011fe(Ia), SN1999em (IIP) and SN1993J (IIb), it has orders of magnitude more far-UV emission. This excess is interpreted primarily as a result of weaker metal line blanketing due to much lower abundance of iron-group elements in the outer ejecta. Because these elements originate either from the natal metallicity of the star, or have been newly produced, our observation provides direct evidence that little of these freshly synthesized material, including 56Ni, was mixed into the outer ejecta, and the progenitor metallicity is likely sub-solar. This disfavors Pair-Instability Supernova (PISN) models with Helium core masses >=90Msun, where substantial 56Ni material is produced. Higher photospheric temperature of Gaia16apd than that of normal SNe may also contribute to the observed far-UV excess. We find some indication that UV luminous SLSNe-I like Gaia16apd could be common. Using the UV spectra, we show that WFIRST could detect SLSNe-I out to redshift of 8.

astro-ph.SR↗

arXiv2017

Spitzer observations of SN 2014J and properties of mid-IR emission in Type Ia supernovae

SN 2014J in M82 is the closest Type Ia supernova (SN Ia) in decades. The proximity allows for detailed studies of supernova physics and provides insights into the circumstellar and interstellar environment. In this work we analyze Spitzer mid-IR data of SN 2014J in the 3.6 and 4.5 μm wavelength range, together with several other nearby and well-studied SNe Ia. We compile the first composite mid-IR light-curve templates from our sample of SNe~Ia, spanning the range from before peak brightness well into the nebular phase. Our observations indicate that SNe Ia form a very homogeneous class of objects at these wavelengths. Using the low-reddening supernovae for comparison, we constrain possible thermal emission from circumstellar dust around the highly reddened SN 2014J. We also study SNe 2006X and 2007le, where the presence of matter in the circumstellar environment has been suggested. No significant mid-IR excess is detected, allowing us to place upper limits on the amount of pre-existing dust in the circumstellar environment. For SN 2014J, $M_{dust} < 10^{-5}$ M$_{\odot}$ within $r_{dust} \sim 10^{17}$ cm, which is insufficient to account for the observed extinction. Similar limits are obtained for SNe 2006X and 2007le.

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arXiv2016

Common Envelope ejection for a Luminous Red Nova in M101

We present the results of optical, near-infrared, and mid-infrared observations of M101 OT2015-1 (PSN J14021678+5426205), a luminous red transient in the Pinwheel galaxy (M101), spanning a total of 16 years. The lightcurve showed two distinct peaks with absolute magnitudes $M_r\leq-12.4$ and $M_r \simeq-12$, on 2014 November 11 and 2015 February 17, respectively. The spectral energy distributions during the second maximum show a cool outburst temperature of $\approx$3700 K and low expansion velocities ($\approx-$300 \kms) for the H I, Ca II, Ba II and K I lines. From archival data spanning 15 to 8 years before the outburst, we find a single source consistent with the optically discovered transient which we attribute to being the progenitor; it has properties consistent with being an F-type yellow supergiant with $L$~$\sim$~8.7~$\times\ 10^4$ \Lsun, $T_{\rm{eff}}\approx$7000~K and an estimated mass of $\rm{M1}= 18\pm 1$ \Msun. This star has likely just finished the H burning phase in the core, started expanding, and is now crossing the Hertzsprung gap. Based on the combination of observed properties, we argue that the progenitor is a binary system, with the more evolved system overfilling the Roche lobe. Comparison with binary evolution models suggests that the outburst was an extremely rare phenomenon, likely associated with the ejection of the common envelope. The initial mass of the binary progenitor system fills the gap between the merger candidates V838 Mon (5$-$10 \Msun) and NGC~4490-OT~(30~\Msun).

astro-ph.SR↗

arXiv2016

A Fast Radio Burst Host Galaxy

In recent years, millisecond duration radio signals originating from distant galaxies appear to have been discovered in the so-called Fast Radio Bursts. These signals are dispersed according to a precise physical law and this dispersion is a key observable quantity which, in tandem with a redshift measurement, can be used for fundamental physical investigations. While every fast radio burst has a dispersion measurement, none before now have had a redshift measurement, due to the difficulty in pinpointing their celestial coordinates. Here we present the discovery of a fast radio burst and the identification of a fading radio transient lasting $\sim 6$ days after the event, which we use to identify the host galaxy; we measure the galaxy's redshift to be $z=0.492\pm0.008$. The dispersion measure and redshift, in combination, provide a direct measurement of the cosmic density of ionised baryons in the intergalactic medium of $Ω_{\mathrm{IGM}}=4.9 \pm 1.3\%$, in agreement with the expectation from WMAP, and including all of the so-called "missing baryons". The $\sim6$-day transient is largely consistent with a short gamma-ray burst radio afterglow, and its existence and timescale do not support progenitor models such as giant pulses from pulsars, and supernovae. This contrasts with the interpretation of another recently discovered fast radio burst, suggesting there are at least two classes of bursts.

astro-ph.HE↗