Astrometric accuracy of snapshot fast radio burst localisations with ASKAP

Abstract The recent increase in well-localised fast radio bursts (FRBs) has facilitated in-depth studies of global FRB host properties, the source circumburst medium, and the potential impacts of these environments on the burst properties. The Australian Square Kilometre Array Pathfinder (ASKAP) has localised 11 FRBs with sub-arcsecond to arcsecond precision, leading to sub-galaxy localisation regions in some cases and those covering much of the host galaxy in others. The method used to astrometrically register the FRB image frame for ASKAP, in order to align it with images taken at other wavelengths, is currently limited by the brightness of continuum sources detected in the short-duration (‘snapshot’) voltage data captured by the Commensal Real-Time ASKAP Fast Transients (CRAFT) software correlator, which are used to correct for any frame offsets due to imperfect calibration solutions and estimate the accuracy of any required correction. In this paper, we use dedicated observations of bright, compact radio sources in the low- and mid-frequency bands observable by ASKAP to investigate the typical astrometric accuracy of the positions obtained using this so-called ‘snapshot’ technique. Having captured these data with both the CRAFT software and ASKAP hardware correlators, we also compare the offset distributions obtained from both data products to estimate a typical offset between the image frames resulting from the differing processing paths, laying the groundwork for future use of the longer duration, higher signal-to-noise ratio (S/N) data recorded by the hardware correlator. We find typical offsets between the two frames of ${\sim}0.6$ and ${\sim}0.3$ arcsec in the low- and mid-band data, respectively, for both RA and Dec. We also find reasonable agreement between our offset distributions and those of the published FRBs. We detect only a weak dependence in positional offset on the relative separation in time and elevation between target and calibrator scans, with the trends being more pronounced in the low-band data and in Dec. Conversely, the offsets show a clear dependence on frequency in the low band, which we compare to the frequency-dependent Dec. offsets found in FRB 200430. In addition, we present a refined methodology for estimating the overall astrometric accuracy of CRAFT FRBs.

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High Signal-to-Noise Ratio Mid-Infrared Quasar Spectral Templates

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314004153 ◽

2013 ◽

Vol 9 (S304) ◽

pp. 315-318

Author(s):

Allison R. Hill ◽

S. C. Gallagher ◽

R. P. Deo ◽

E. Peeters ◽

Gordon T. Richards

Keyword(s):

Star Formation ◽

Signal To Noise Ratio ◽

Host Galaxy ◽

High Signal ◽

Host Galaxies ◽

Signal To Noise ◽

Mid Infrared ◽

High Ionization ◽

Noise Ratio ◽

Luminous Objects

AbstractMid-infrared (MIR) quasar spectra exhibit a suite of emission features including high ionization coronal lines from the narrow line region (NLR) illuminated by the ionizing continuum, and hot dust features from grains, as well as polycyclic aromatic hydrocarbons (PAH) features from star formation in the host galaxy. Few features are detected in most spectra because of typically low signal-to-noise ratio (S/N) data. By generating spectral composites in three different luminosity bins from over 180 Spitzer Ifnfrared Spectrograph (IRS) observations, we boost the S/N and reveal important features in the complex spectra. We detect high-ionization, forbidden emission lines in all templates, PAH features in all but the most luminous objects, and broad silicate and graphite features in emission whose strength increases relative to the continuum with luminosity. We find that the intrinsic quasar spectrum for all luminosity templates is consistent, and the differences in the spectra can be explained by host galaxy contamination in the lower luminosity templates. We also posit that star formation may be active in most quasar host galaxies, but the spectral features of star formation are only detectable if the quasar is faint.

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A fast radio burst source at a complex magnetised site in a barred galaxy

10.21203/rs.3.rs-1059119/v1 ◽

2021 ◽

Author(s):

K.J. Lee ◽

Heng Xu ◽

J.R. Niu ◽

P. Chen ◽

Weiwei Zhu ◽

...

Keyword(s):

Optical Observations ◽

Host Galaxy ◽

Radio Bursts ◽

Radio Waves ◽

Galactocentric Distance ◽

Burst Source ◽

Radiation Mechanism ◽

Circular Polarisation ◽

Rotation Measure ◽

Fast Radio Burst

Abstract Fast radio bursts (FRBs) are highly dispersed radio bursts prevailing in the universe. The recent detection of FRB~200428 from a Galactic magnetar suggested that at least some FRBs originate from magnetars, but it is unclear whether the majority of cosmological FRBs, especially the actively repeating ones, are produced from the magnetar channel. Here we report the detection of 1863 polarised bursts from the repeating source FRB~20201124A during a dedicated radio observational campaign of Five-hundred-meter Aperture Spherical radio Telescope (FAST). The large sample of radio bursts detected in 88 hr over 54 days indicate a significant, irregular, short-time variation of the Faraday rotation measure (RM) of the source during the first 36 days, followed by a constant RM during the later 18 days. Significant circular polarisation up to 75\% was observed in a good fraction of bursts. Evidence suggests that some low-level circular polarisation originates from the conversion from linear polarisation during the propagation of the radio waves, but an intrinsic radiation mechanism is required to produce the higher degree of circular polarisation. All of these features provide evidence for a more complicated, dynamically evolving, magnetised immediate environment around this FRB source. Its host galaxy was previously known. Our optical observations reveal that it is a Milky-Way-sized, metal-rich, barred-spiral galaxy at redshift z=0.09795+-0.00003, with the FRB residing in a low stellar density, interarm region at an intermediate galactocentric distance, an environment not directly expected for a young magnetar formed during an extreme explosion of a massive star.

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Astrometry of Millijansky Sources Using A Phase Reference VLBI Technique

Symposium - International Astronomical Union ◽

10.1017/s0074180900134850 ◽

1988 ◽

Vol 129 ◽

pp. 323-324

Author(s):

Jean-François Lestrade ◽

Alan E. E. Rogers ◽

Arthur E. Niell ◽

Robert A. Preston

Keyword(s):

Signal To Noise Ratio ◽

Coherence Time ◽

Reference Source ◽

Radio Sources ◽

Hydrogen Maser ◽

Signal To Noise ◽

Strong Source ◽

Vlbi Data ◽

Noise Ratio ◽

Radio Stars

Atmospheric fluctuations and hydrogen maser clock instabilities limit the coherence time (Tcoh) and hence the signal-to-noise ratio of VLBI data , to a few minutes at GHz frequencies. However, Tcoh can be increased up to many hours if a phase reference is established throughout the experiment by using a strong source observed alternatively with the program source. Weak celestial radio sources with flux densities in the milliJansky range at centimeter wavelengths, such as radio stars, fast pulsars and faint components of extragalactic sources, can then be reliably detected by this VLBI technique, simultaneously providing accurate astrometry relative to the reference source.

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The performance and calibration of the CRAFT fly’s eye fast radio burst survey

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2019.1 ◽

2019 ◽

Vol 36 ◽

Cited By ~ 11

Author(s):

C. W. James ◽

K. W. Bannister ◽

J.-P. Macquart ◽

R. D. Ekers ◽

S. Oslowski ◽

...

Keyword(s):

Radio Burst ◽

Phased Array ◽

Radio Frequency Interference ◽

Radio Bursts ◽

System Noise ◽

Fast Transients ◽

Fast Radio Burst ◽

Power Law Index ◽

Phased Array Feeds ◽

Best Fit

AbstractThe Commensal Real-time Australian Square Kilometre Array Pathfinder Fast Transients survey is the first extensive astronomical survey using phased array feeds. Since January 2017, it has been searching for fast radio bursts in fly’s eye mode. Here, we present a calculation of the sensitivity and total exposure of the survey that detected the first 20 of these bursts, using the pulsars B1641-45 and B0833-45 as calibrators. The beamshape, antenna-dependent system noise, and the effects of radio-frequency interference and fluctuations during commissioning are quantified. Effective survey exposures and sensitivities are calculated as a function of the source counts distribution. Statistical ‘stat’ and systematics ‘sys’ effects are treated separately. The implied fast radio burst rate is significantly lower than the 37 sky−1 day−1 calculated using nominal exposures and sensitivities for this same sample by Shannon et al. (2018). At the Euclidean (best-fit) power-law index of −1.5 (−2.2), the rate is $12.7_{-2.2}^{+3.3}$ (sys) ± 3.6 (stat) sky−1 day−1 ( $20.7_{-1.7}^{+2.1}$ (sys) ± 2.8 (stat) sky−1 day−1) above a threshold of 56.6 ± 6.6(sys) Jy ms (40.4 ± 1.2(sys) Jy ms). This strongly suggests that these calculations be performed for other FRB-hunting experiments, allowing meaningful comparisons to be made between them.

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A single fast radio burst localized to a massive galaxy at cosmological distance

Science ◽

10.1126/science.aaw5903 ◽

2019 ◽

Vol 365 (6453) ◽

pp. 565-570 ◽

Cited By ~ 126

Author(s):

K. W. Bannister ◽

A. T. Deller ◽

C. Phillips ◽

J.-P. Macquart ◽

J. X. Prochaska ◽

...

Keyword(s):

Column Density ◽

Single Pulse ◽

Line Of Sight ◽

Host Galaxy ◽

Radio Bursts ◽

Positional Accuracy ◽

Radio Emissions ◽

Individual Host ◽

Fast Radio Burst ◽

Massive Galaxy

Fast radio bursts (FRBs) are brief radio emissions from distant astronomical sources. Some are known to repeat, but most are single bursts. Nonrepeating FRB observations have had insufficient positional accuracy to localize them to an individual host galaxy. We report the interferometric localization of the single-pulse FRB 180924 to a position 4 kiloparsecs from the center of a luminous galaxy at redshift 0.3214. The burst has not been observed to repeat. The properties of the burst and its host are markedly different from those of the only other accurately localized FRB source. The integrated electron column density along the line of sight closely matches models of the intergalactic medium, indicating that some FRBs are clean probes of the baryonic component of the cosmic web.

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First Prompt Optical Observations of Nearest Fast Radio Burst new New Astromomical Method

10.21203/rs.3.rs-97780/v1 ◽

2020 ◽

Author(s):

Vladimir Lipunov ◽

V. Kornilov ◽

E. Gorbovskoy ◽

Kirill Zhirkov ◽

Aristarkh Chasovnikov ◽

...

Keyword(s):

Radio Burst ◽

Gamma Ray ◽

The Other ◽

New Method ◽

Optical Observations ◽

Host Galaxy ◽

Radio Range ◽

Fast Transients ◽

Fast Radio Burst ◽

The Universe

Abstract With the discovery of gamma ray bursts1,2, it became clear that our Universe flickers with superfast catastrophic events, sometimes lasting for a thousandths of a second. These ultra-fast transients - the peculiar one-day butterflies of the Universe - shine so brightly that they are noticed even on the other end of the Universe and, moreover, by very small telescopes. But in the radio range, the sky remained silent until the beginning of the 21st century. Only in 2007, radio astronomers analyzing archival observations of the Parkes Radio Telescope first encountered fast transients 3,4 . About a hundred such sources have already been discovered. We report the first optical observation of the closest radio burster FRB 180916.J0158+655-8 synchronously with a radio burst. In total, we obtained about 155,093 images at MASTER Global Robotic Net9*. In the course of our observations, we found a new method for detecting objects deep below the noise level. In addition, using the new method, we found the excess of photons in the FRB direction at a level of 23 m associated with the emission of the host galaxy.

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Commensal discovery of four fast radio bursts during Parkes Pulsar Timing Array observations

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1751 ◽

2019 ◽

Vol 488 (1) ◽

pp. 868-875 ◽

Cited By ~ 19

Author(s):

S Osłowski ◽

R M Shannon ◽

V Ravi ◽

J F Kaczmarek ◽

S Zhang ◽

...

Keyword(s):

Radio Telescope ◽

Spectral Properties ◽

Signal To Noise Ratio ◽

Radio Bursts ◽

Signal To Noise ◽

Fundamental Physics ◽

Millisecond Pulsars ◽

Pulsar Timing ◽

Physics Experiments ◽

Pulsar Timing Array

ABSTRACT The Parkes Pulsar Timing Array (PPTA) project monitors two dozen millisecond pulsars (MSPs) in order to undertake a variety of fundamental physics experiments using the Parkes 64-m radio telescope. Since 2017 June, we have been undertaking commensal searches for fast radio bursts (FRBs) during the MSP observations. Here, we report the discovery of four FRBs (171209, 180309, 180311, and 180714). The detected events include an FRB with the highest signal-to-noise ratio ever detected at the Parkes Observatory, which exhibits unusual spectral properties. All four FRBs are highly polarized. We discuss the future of commensal searches for FRBs at Parkes.

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Fast Radio Transients: From Pulsars to Fast Radio Bursts

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318002156 ◽

2017 ◽

Vol 14 (S339) ◽

pp. 27-32

Author(s):

B. W. Stappers ◽

M. Caleb ◽

L. N. Driessen

Keyword(s):

Real Time ◽

Time Scales ◽

Radio Burst ◽

Host Galaxy ◽

Radio Bursts ◽

Recent Developments ◽

New Instrumentation ◽

Fast Radio Burst ◽

Radio Transients ◽

Archived Data

AbstractThe radio sky is full of transients, their time-scales ranging from nanoseconds to decades. Recent developments in technology sensitivity and computing capabilities have opened up the short end of that range, and are revealing a plethora of new phenomenologies. Studies of radio transients were previously restricted to analyses of archived data, but are now including real-time analyses. We focus here on Fast Radio Bursts, discuss and compare the properties of the population, and describe what is to date the only known repeating Fast Radio Burst and its host galaxy. We also review what will be possible with the new instrumentation coming online.

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Calculation of velocity dispersion of the nearby galaxies using different stellar template libraries

Serbian Astronomical Journal ◽

10.2298/saj1080057l ◽

2010 ◽

pp. 57-69

Author(s):

Ana Lalovic

Keyword(s):

Reasonable Agreement ◽

Velocity Dispersion ◽

Signal To Noise Ratio ◽

Sloan Digital Sky Survey ◽

Signal To Noise ◽

Method Of Calculation ◽

Sky Survey ◽

Best Fitting ◽

Nearby Galaxies ◽

Spectral Libraries

We present the central velocity dispersion measurements of the nearby galaxies from the Sloan Digital Sky Survey (SDSS). Using the sample from the paper by Ho et al. 2009, we have selected 23 galaxies for which we calculate the velocity dispersion. We have used the Penalized Pixel-Fitting code (Cappellari and Emsellem2004) to measure the velocity dispersion throughout the four chosen spectral regions: (3800,4568)?A, (4568,5336)?A, (5336,6104) and (6104,6872)?A. In all these regions, we have separately calculated dispersions and corresponding errors. We found that the measured values may vary with the change of spectral region, but, if weighted properly with the measure of the goodness of the fit, the final results will be shifted coloser to those for the best fitting regions. We have also tested how the use of different spectral libraries (Miles, Valdes and Elodie databases) influences measurements and we showed that they do not affect measurements much. However, Elodie stellar library introduces the smallest errors in the velocity dispersion and it is the most stable throughout all four spectral regions. For these reasons it should be used preferentially when dealing with the SDSS spectra. We compare the results with the above mentioned paper and find a reasonable agreement. The agreement with the dispersions available in the HyperLeda database is very poor. The best agreement is obtained with SDSS measurements. We believe that our measurements are useful since SDSS velocity dispersions measurements are not available for many galaxies and the method of calculation of the velocity dispersion outlined in this work enables calculation of velocity dispersion for any galaxy. Of course, spectra with signal-to-noise ratio below 20 should be taken with caution.

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Fast radio burst dispersion measures and rotation measures and the origin of intergalactic magnetic fields

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2033 ◽

2019 ◽

Vol 488 (3) ◽

pp. 4220-4238 ◽

Cited By ~ 7

Author(s):

S Hackstein ◽

M Brüggen ◽

F Vazza ◽

B M Gaensler ◽

V Heesen

Keyword(s):

Magnetic Fields ◽

Radio Burst ◽

Milky Way ◽

Intergalactic Medium ◽

Local Environment ◽

Distribution Functions ◽

Host Galaxy ◽

Radio Bursts ◽

Dispersion Measures ◽

Fast Radio Burst

ABSTRACT We investigate the possibility of measuring intergalactic magnetic fields using the dispersion measures and rotation measures of fast radio bursts. With Bayesian methods, we produce probability density functions for values of these measures. We distinguish between contributions from the intergalactic medium, the host galaxy, and the local environment of the progenitor. To this end, we use constrained, magnetohydrodynamic simulations of the local Universe to compute lines-of-sight integrals from the position of the Milky Way. In particular, we differentiate between predominantly astrophysical and primordial origins of magnetic fields in the intergalactic medium. We test different possible types of host galaxies and probe different distribution functions of fast radio burst progenitor locations inside the host galaxy. Under the assumption that fast radio bursts are produced by magnetars, we use analytic predictions to account for the contribution of the local environment. We find that less than 100 fast radio bursts from magnetars in stellar-wind environments hosted by starburst dwarf galaxies at redshift z ≳ 0.5 suffice to discriminate between predominantly primordial and astrophysical origins of intergalactic magnetic fields. However, this requires the contribution of the Milky Way to be removed with a precision of ≈1 rad m−2. We show the potential existence of a subset of fast radio bursts whose rotation measures carry information on the strength of the intergalactic magnetic field and its origins.

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