J/ApJ/895/49 Optical spectrum of ZTF18abvkwla and its host galaxy (Ho+, 2020)
The Koala: A Fast Blue Optical Transient with Luminous Radio Emission from a
Starburst Dwarf Galaxy at.
Ho A.Y.Q., Perley D.A., Kulkarni S.R., Dong D.Z.J., De K., Chandra P.,
Andreoni I., Bellm E.C., Burdge K.B., Coughlin M., Dekany R., Feeney M.,
Frederiks D.D., Fremling C., Golkhou V.Z., Graham M.J., Hale D., Helou G.,
Horesh A., Kasliwal M.M., Laher R.R., Masci F.J., Miller A.A., Porter M.,
Ridnaia A., Rusholme B., Shupe D.L., Soumagnac M.T., Svinkin D.S.
<Astrophys. J., 895, 49 (2020)>
=2020ApJ...895...49H 2020ApJ...895...49H
ADC_Keywords: Galaxies; Spectra, optical
Keywords: Radio transient sources ; High energy astrophysics ; Supernovae ;
Core-collapse supernovae ; Jets ; Sky surveys
Abstract:
We present ZTF18abvkwla (the "Koala"), a fast blue optical transient
discovered in the Zwicky Transient Facility (ZTF) One-Day Cadence
(1DC) Survey. ZTF18abvkwla has a number of features in common with the
groundbreaking transient AT2018cow: blue colors at peak (g-r~-0.5mag),
a short rise time from half-max of under two days, a decay time to
half-max of only three days, a high optical luminosity
(Mg.peak~-20.6mag), a hot (≳40000K) featureless spectrum at peak
light, and a luminous radio counterpart. At late times
(Δ>80days), the radio luminosity of ZTF18abvkwla
(νLν≳1040erg/s at 10GHz, observer-frame) is most similar to
that of long-duration gamma-ray bursts (GRBs). The host galaxy is a
dwarf starburst galaxy (M∼5x108M☉, SFR∼7M☉/yr) that is
moderately metal-enriched (log[O/H]∼8.5), similar to the hosts of GRBs
and superluminous supernovae. As in AT2018cow, the radio and optical
emission in ZTF18abvkwla likely arise from two separate components:
the radio from fast- moving ejecta (Γβc>0.38c) and the
optical from shock-interaction with confined dense material
(<0.07M☉ in ∼1015cm). Compiling transients in the literature
with trise<5days and Mpeak←20mag, we find that a significant
number are engine-powered, and suggest that the high peak optical
luminosity is directly related to the presence of this engine. From 18
months of the 1DC survey, we find that transients in this
rise-luminosity phase space are at least two to three orders of
magnitude less common than CC SNe. Finally, we discuss strategies for
identifying such events with future facilities like the Large Synoptic
Survey Telescope, as well as prospects for detecting accompanying
X-ray and radio emission.
Description:
We obtained a spectrum of ZTF18abvkwla using the Double Beam
Spectrograph (DBSP) on the 200inch Hale telescope at Palomar
Observatory. We used the D55 dichroic, a slit width of 1.5arcseconds,
the 600/4000 blue grating, and the 316/7500 red grating.
We obtained a spectrum of the host galaxy of ZTF18abvkwla using the
Low Resolution Imaging Spectrometer on the Keck I 10m telescope, with
the 400/3400 grism in the blue camera and the 400/8500 grating in the
red camera.
Objects:
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RA (2000) DE Designation(s)
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02 00 15.19 +16 47 57.3 ZTF18abvkwla = ZTF18abvkwla
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig5.dat 21 4657 Spectrum of ZTF18abvkwla at the peak of the g-band
optical light curve
fig6.dat 35 5132 Spectrum of the host galaxy of ZTF18abvkwla
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See also:
J/ApJ/720/1513 : The afterglows of Swift-era GRBs. I. (Kann+, 2010)
J/other/Nat/463.513 : Radio observations of SN 2009bb (Soderberg+, 2010)
J/ApJ/759/107 : Core-collapse SNe and host galaxies (Kelly+, 2012)
J/ApJ/794/23 : Pan-STARRS1 transients optical photometry (Drout+, 2014)
J/ApJ/781/37 : Multi-band photometry of GRB 130427A (Perley+, 2014)
J/ApJS/211/13 : The second Fermi/GBM GRB catalog (4yr) (von Kienlin+, 2014)
J/A+A/581/A125 : UV/Optical/NIR spectroscopy GRB hosts (Kruehler+, 2015)
J/ApJ/819/35 : Light curves of four transients from PTF & SNLS (Arcavi+,2016)
J/ApJ/830/13 : Host-galaxy NUV-NIR data 32 superluminous SNe (Perley+, 2016)
J/ApJ/851/107 : iPTF 16asu photometry follow-up (Whitesides+, 2017)
J/A+A/617/A122 : GRB 111209A GROND and UVOT light curves (Kann+, 2018)
J/ApJ/887/169 : UV-Opt light curves of the type Ic SN 2018gep (Ho+, 2019)
J/ApJ/886/152 : ZTF early observations of Type Ia SNe. I. LCs (Yao+, 2019)
Byte-by-byte Description of file: fig5.dat
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Bytes Format Units Label Explanations
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1- 9 F9.3 0.1nm Wave [3400/10501] Observed wavelength; Angstroms
11- 21 E11.4 cW/m2/nm Flux [-4.6e-17/3.9e-16] Observed flux; erg/s/cm2/A
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Byte-by-byte Description of file: fig6.dat
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Bytes Format Units Label Explanations
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1- 10 F10.4 0.1nm Wave [3070/10308] Observed wavelength; Angstroms
12- 23 E12.4 cW/m2/nm Flux [-6.6e-17/5.7e-16] Observed flux; erg/s/cm2/A
25- 35 E11.4 cW/m2/nm e_Flux [1.4e-18/1.1e-16] Uncertainty in Flux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 20-Sep-2021