A digital correlator upgrade for the Arcminute MicroKelvin Imager

Hickish, J.; Razavi-Ghods, Nima; Perrott, Y. C.; Titterington, D.; Carey, S. H.; Scott, Paul F.; Grainge, Keith; Scaife, Anna M. M.; Alexander, Paul; Saunders, Richard D. E.; Crofts, Mike; Javid, Kamran; Rumsey, C.; Jin, Terry Z.; Ely, John; Shaw, Clive; Northrop, I.; Pooley, G. G.; D'Alessandro, R.; Doherty, Peter; Willatt, Greg P.

doi:10.1093/mnras/sty074

Cited by 71 publications

(50 citation statements)

References 23 publications

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“…MAXI J1820+070 was observed in the radio with the Arcminute Microkelvin Imager Large Array (AMI-LA Zwart et al 2008;Hickish et al 2018) at a central frequency of 15.5 GHz, across a 5 GHz bandwidth consisting of 4096 channels. A total of 183 observations were made between 2018 March and 2018 December, with observation lengths between 1 hr and 8 hr.…”

Section: Ami-lamentioning

confidence: 99%

A Rapid Change in X-Ray Variability and a Jet Ejection in the Black Hole Transient MAXI J1820+070

Homan

Bright

Motta

et al. 2020

ApJL

108

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We present Neutron Star Interior Composition Explorer X-ray and Arcminute Microkelvin Imager Large Array radio observations of a rapid hard-to-soft state transition in the black hole X-ray transient MAXI J1820+070. During the transition from the hard state to the soft state a switch between two particular types of quasiperiodic oscillations (QPOs) was seen in the X-ray power density spectra, from type-C to type-B, along with a drop in the strength of the broadband X-ray variability and a brief flare in the 7-12 keV band. Soon after this switch (∼1.5-2.5 hr) a strong radio flare was observed that corresponded to the launch of superluminal ejecta. Although hints of a connection between QPO transitions and radio flares have been seen in other black hole X-ray transients, our observations constitute the strongest observational evidence to date for a link between the appearance of type-B QPOs and the launch of discrete jet ejections. are usually recognized: the hard state, which shows strong rapid (subsecond) X-ray variability and a spectrum dominated by Comptonized power-law emission, and the soft state, in which rapid X-ray variability is weak and where a thermal disk blackbody component dominates the spectrum. The transitions between these two spectral states, during which sources are often classified as being in an intermediate state, are accompanied by strong evolution of the X-ray variability properties. As a source starts the transition from the hard state to the soft state, strong (type-C) low-frequency quasi-periodic oscillations (QPOs) are usually present in the power density spectra (see Wijnands et al. 1999;Remillard et al. 2002;Casella et al. 2005, for the various low-frequency QPO types). Their frequencies increase from ∼0.01 Hz to ∼10 Hz as the spectrum softens. At some point during the transition the type-C QPOs and arXiv:2003.01012v1 [astro-ph.HE]

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Section: Ami-lamentioning

confidence: 99%

A Rapid Change in X-Ray Variability and a Jet Ejection in the Black Hole Transient MAXI J1820+070

Homan

Bright

Motta

et al. 2020

ApJL

108

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“…We also obtained three epochs of observations with the AMI large array (AMI-LA; Zwart et al 2008;Hickish et al 2018), on UT 2018Sept 12, 2018Sept 23, and 2018 Oct 20. AMI-LA is a radio interferometer comprised of eight, 12.8 m diameter that extends from 18 m up to 110 m in length and operates with a 5 GHz bandwidth around a central frequency of 15.5 GHz.…”

Section: Search For Pre-discovery Emissionmentioning

confidence: 99%

Evidence for Late-stage Eruptive Mass Loss in the Progenitor to SN2018gep, a Broad-lined Ic Supernova: Pre-explosion Emission and a Rapidly Rising Luminous Transient

Goldstein

Schulze

et al. 2019

ApJ

106

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We present detailed observations of ZTF18abukavn (SN2018gep), discovered in high-cadence data from the Zwicky Transient Facility as a rapidly rising (1.4 ± 0.1 mag/hr) and luminous (M g,peak = −20 mag) transient. It is spectroscopically classified as a broad-lined stripped-envelope supernova (Ic-BL SN). The high peak luminosity (L bol 3×10 44 erg s −1 ), the short rise time (t rise = 3 day in g-band), and the blue colors at peak (g −r ∼ −0.4) all resemble the high-redshift Ic-BL iPTF16asu, as well as several other unclassified fast transients. The early discovery of SN2018gep (within an hour of shock breakout) enabled an intensive spectroscopic campaign, including the highest-temperature (T eff 40, 000K) arXiv:1904.11009v4 [astro-ph.HE] 1 Dec 2019 2 spectra of a stripped-envelope SN. A retrospective search revealed luminous (M g ∼ M r ≈ −14 mag) emission in the days to weeks before explosion, the first definitive detection of precursor emission for a Ic-BL. We find a limit on the isotropic gamma-ray energy release E γ,iso < 4.9 × 10 48 erg, a limit on X-ray emission L X < 10 40 erg s −1 , and a limit on radio emission νL ν 10 37 erg s −1 . Taken together, we find that the early (< 10 day) data are best explained by shock breakout in a massive shell of dense circumstellar material (0.02 M ) at large radii (3 × 10 14 cm) that was ejected in eruptive pre-explosion mass-loss episodes. The late-time (> 10 day) light curve requires an additional energy source, which could be the radioactive decay of Ni-56.

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“…We observed iPTF 16hgs with the Arcminute Mi-croKelvin Imager Large Array (AMI-LA; Zwart et al 2008;Hickish et al 2018) radio telescope. The data have 4096 frequency channels across a 5 GHz bandwidth between 13-18 GHz.…”

Section: Ami Observationsmentioning

confidence: 99%

iPTF 16hgs: A Double-peaked Ca-rich Gap Transient in a Metal-poor, Star-forming Dwarf Galaxy

Kasliwal

Cantwell

et al. 2018

ApJ

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Calcium rich gap transients represent an intriguing new class of faint and fast evolving supernovae that exhibit strong [Ca II] emission in their nebular phase spectra. In this paper, we present the discovery and follow-up observations of iPTF 16hgs -an intermediate luminosity and fast evolving transient that exhibited a double peaked light curve. Exhibiting a typical Type Ib spectrum in the photospheric phase and an early transition to a [Ca II] dominated nebular phase, we show that iPTF 16hgs shows properties consistent with the class of Ca-rich gap transients, with two interesting exceptions. First, while the second peak of the light curve is similar to other Ca-rich gap transients (suggesting M ej ≈ 0.4 M and peak luminosity ≈ 3 × 10 41 ergs s −1 ), we show that the first blue and fast declining (over ≈ 2 days) peak is unique to this source. Second, with Integral Field Unit observations of the host galaxy, we find that iPTF 16hgs occurred in the outskirts (projected offset of ≈ 6 kpc ≈ 1.9 R eff ) of a low metallicity (≈ 0.4 Z ), star forming, dwarf spiral galaxy. Using deep late-time VLA and uGMRT observations, we place stringent limits on the local environment of the source, ruling out a large parameter space of circumstellar densities and mass loss environments of the progenitor. If iPTF 16hgs shares explosion physics with the class of Ca-rich gap transients, we suggest that the presence of the first peak can be explained by enhanced mixing of 0.01 M of 56 Ni into the outer layers the ejecta, reminiscent of some models of He-shell detonations on WDs. On the other hand, if iPTF 16hgs is physically unrelated to the class, the first peak is consistent with shock cooling emission (of an envelope with a mass of ≈ 0.08 M and radius of ≈ 13 R ) associated with a core-collapse explosion of a highly stripped massive star in a close binary system.

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A digital correlator upgrade for the Arcminute MicroKelvin Imager

Cited by 71 publications

References 23 publications

A Rapid Change in X-Ray Variability and a Jet Ejection in the Black Hole Transient MAXI J1820+070

A Rapid Change in X-Ray Variability and a Jet Ejection in the Black Hole Transient MAXI J1820+070

Evidence for Late-stage Eruptive Mass Loss in the Progenitor to SN2018gep, a Broad-lined Ic Supernova: Pre-explosion Emission and a Rapidly Rising Luminous Transient

iPTF 16hgs: A Double-peaked Ca-rich Gap Transient in a Metal-poor, Star-forming Dwarf Galaxy

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