Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe SUrvey for Pulsars and Extragalactic Radio Bursts II: New FRB discoveries and their follow-up
76
0
0.0
(
0
)
Added by
Shivani Bhandari Miss
Publication date
2017
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
We report the discovery of four Fast Radio Bursts (FRBs) in the ongoing SUrvey for Pulsars and Extragalactic Radio Bursts (SUPERB) at the Parkes Radio Telescope: FRBs 150610, 151206, 151230 and 160102. Our real-time discoveries have enabled us to conduct extensive, rapid multi-messenger follow-up at 12 major facilities sensitive to radio, optical, X-ray, gamma-ray photons and neutrinos on time scales ranging from an hour to a few months post-burst. No counterparts to the FRBs were found and we provide upper limits on afterglow luminosities. None of the FRBs were seen to repeat. Formal fits to all FRBs show hints of scattering while their intrinsic widths are unresolved in time. FRB 151206 is at low Galactic latitude, FRB 151230 shows a sharp spectral cutoff, and FRB 160102 has the highest dispersion measure (DM = $2596.1pm0.3$ pc cm$^{-3}$) detected to date. Three of the FRBs have high dispersion measures (DM >$1500$ pc cm$^{-3}$), favouring a scenario where the DM is dominated by contributions from the Intergalactic Medium. The slope of the Parkes FRB source counts distribution with fluences $>2$ Jyms is $alpha=-2.2^{+0.6}_{-1.2}$ and still consistent with a Euclidean distribution ($alpha=-3/2$). We also find that the all-sky rate is $1.7^{+1.5}_{-0.9}times10^3$FRBs/($4pi$ sr)/day above $sim2$ Jyms and there is currently no strong evidence for a latitude-dependent FRB sky-rate.
rate research
Read More
We describe the Survey for Pulsars and Extragalactic Radio Bursts (SUPERB), an ongoing pulsar and fast transient survey using the Parkes radio telescope. SUPERB involves real-time acceleration searches for pulsars and single-pulse searches for pulsars and fast radio bursts. We report on the observational setup, data analysis, multi-wavelength/messenger connections, survey sensitivities to pulsars and fast radio bursts and the impact of radio frequency interference. We further report on the first 10 pulsars discovered in the project. Among these is PSR~J1306$-$40, a millisecond pulsar in a binary system where it appears to be eclipsed for a large fraction of the orbit. PSR~J1421$-$4407 is another binary millisecond pulsar; its orbital period is $30.7$ days. This orbital period is in a range where only highly eccentric binaries are known, and expected by theory; despite this its orbit has an eccentricity of $10^{-5}$.
We report the discovery of PSR~J2251$-$3711, a radio pulsar with a spin period of 12.1 seconds, the second longest currently known. Its timing parameters imply a characteristic age of 15 Myr, a surface magnetic field of $1.3 times 10^{13}$~G and a spin-down luminosity of $2.9 times 10^{29}~mathrm{erg~s}^{-1}$. Its dispersion measure of 12.12(1)~$mathrm{pc}~mathrm{cm}^{-3}$ leads to distance estimates of 0.5 and 1.3 kpc according to the NE2001 and YMW16 Galactic free electron density models, respectively. Some of its single pulses show an uninterrupted 180 degree sweep of the phase-resolved polarization position angle, with an S-shape reminiscent of the rotating vector model prediction. However, the fact that this sweep occurs at different phases from one pulse to another is remarkable and without straightforward explanation. Although PSR~J2251$-$3711 lies in the region of the $P-dot{P}$ parameter space occupied by the X-ray Isolated Neutron Stars (XINS), there is no evidence for an X-ray counterpart in our Swift XRT observation; this places a 99%-confidence upper bound on its unabsorbed bolometric thermal luminosity of $1.1 times 10^{31}~(d / 1~mathrm{kpc})^2~mathrm{erg/s}$ for an assumed temperature of 85 eV, where $d$ is the distance to the pulsar. Further observations are needed to determine whether it is a rotation-powered pulsar with a true age of at least several Myr, or a much younger object such as an XINS or a recently cooled magnetar. Extreme specimens like PSR J2251$-$3711 help bridge populations in the so-called neutron star zoo in an attempt to understand their origins and evolution.
We have been conducting the GMRT High Resolution Southern Sky (GHRSS) survey for the last four years and have discovered 18 pulsars to date. The GHRSS survey is an off-Galactic-plane survey at 322 MHz in a region of the sky (declination range -40 degrees to -54 degrees) complementary to other ongoing low-frequency surveys. In this paper we report the discovery of three pulsars, PSRs J1239-48, J1516-43 and J1726-52. We also present timing solutions for three pulsars previously discovered with the GHRSS survey: PSR J2144-5237, a millisecond pulsar with a period P=5 ms in a 10 day orbit around a < 0.18 Msun companion; PSR J1516-43, a mildly recycled P=36 ms pulsar in a 228 day orbit with a companion of mass ~0.4 Msun; and the P=320 ms PSR J0514-4408 which we show is a source of pulsed $gamma$-ray emission. We also report radio polarimetric observations of three of the GHRSS discoveries, PSRs J0418-4154, J0514-4408 and J2144-5237.
We report the follow-up of 10 pulsars discovered by the Five-hundred-meter Aperture Spherical radio-Telescope (FAST) during its commissioning. The pulsars were discovered at a frequency of 500-MHz using the ultra-wide-band (UWB) receiver in drift-scan mode, as part of the Commensal Radio Astronomy FAST Survey (CRAFTS). We carried out the timing campaign with the 100-m Effelsberg radio-telescope at L-band around 1.36 GHz. Along with 11 FAST pulsars previously reported, FAST seems to be uncovering a population of older pulsars, bordering and/or even across the pulsar death-lines. We report here two sources with notable characteristics. PSR J1951$+$4724 is a young and energetic pulsar with nearly 100% of linearly polarized flux density and visible up to an observing frequency of 8 GHz. PSR J2338+4818, a mildly recycled pulsar in a 95.2-d orbit with a Carbon-Oxygen white dwarf (WD) companion of $gtrsim 1rm{M}_{odot}$, based on estimates from the mass function. This system is the widest WD binary with the most massive companion known to-date. Conspicuous discrepancy was found between estimations based on NE2001 and YMW16 electron density models, which can be attributed to under-representation of pulsars in the sky region between Galactic longitudes $70^o<l<100^o$. This work represents one of the early CRAFTS results, which start to show potential to substantially enrich the pulsar sample and refine the Galactic electron density model.
We report on the results of multi-wavelength follow-up observations with Gemini, VLA, and ATCA, to search for a host galaxy and any persistent radio emission associated with FRB 180309. This FRB is among the most luminous FRB detections to date, with a luminosity of $> 8.7times 10^{32}$ erg Hz$^{-1}$ at the dispersion-based redshift upper limit of 0.32. We used the high-significance detection of FRB 180309 with the Parkes Telescope and a beam model of the Parkes Multibeam Receiver to improve the localization of the FRB to a region spanning approximately $sim2times2$. We aimed to seek bright galaxies within this region to determine the strongest candidates as the originator of this highly luminous FRB. We identified optical sources within the localization region above our r-band magnitude limit of 24.27, fourteen of which have photometric redshifts whose fitted mean is consistent with the redshift upper limit ($z < 0.32$) of our FRB. Two of these galaxies are coincident with marginally detected persistent radio sources of flux density 24.3$mu$Jy beam$^{-1}$ and 22.1$mu$Jy beam$^{-1}$ respectively. Our redshift-dependent limit on the luminosity of any associated persistent radio source is comparable to the luminosity limits for other localized FRBs. We analyze several properties of the candidate hosts we identified, including chance association probability, redshift, and presence of radio emission, however it remains possible that any of these galaxies could be the host of this FRB. Follow-up spectroscopy on these objects to explore their H$alpha$ emission and ionization contents, as well as to obtain more precisely measured redshifts, may be able to isolate a single host for this luminous FRB.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
