Pulsars at low radio frequencies Vlad Kondratiev (ASTRON) Science - - PowerPoint PPT Presentation
Pulsars at low radio frequencies Vlad Kondratiev (ASTRON) Science at Low Frequencies III Caltech, Pasadena, CA Dec 9, 2016 Renaissance of low radio frequencies DE601 IPS array LOFAR SKA Low NenuFAR Ooty RT LWA DKR- MWA UTR-2
Science at Low Frequencies III — Caltech, Pasadena, CA — Dec 9, 2016
NenuFAR DE601 LOFAR LWA MWA IPS array Ooty RT BSA DKR- 1000 GURT UTR-2 URAN-3 SKA Low VLA uGMRT
▶ mostly transit instruments ▶ limited BW and/or Pol ▶ full tracking (rise-set) ▶ large BW
huge → Δf/f
▶ dual pols
→ Surveys
➤ Complete PSR samples
stellar evolution studies →
➤ Compact systems
GR tests →
➤ Many more MSPs
GW detection →
➤ Many other interesting and exotic systems
→ formation/evolution studies
▶ large FoV
faster →
▶ good for steep-spectra sources ▶ easy localization of the promising candidates with
multiple TABs in single follow-up observation
▶ precursors for SKA-Low pulsar survey(s) ▶ dispersion and scattering are more pronounced ▶ low-freq
Tsys is higher, but … →
▶ can do larger dwell times
FRBs, RRATs →
▶ much larger data volume ▶ much more processing (more DM trials) ▶ more RFI?
▶ large FoV
faster →
▶ good for steep-spectra sources ▶ easy localization of the promising candidates with
multiple TABs in single follow-up observation
▶ precursors for SKA-Low pulsar survey(s) ▶ dispersion and scattering are more pronounced ▶ low-freq
Tsys is higher, but … →
▶ can do larger dwell times
FRBs, RRATs →
▶ much larger data volume ▶ much more processing (more DM trials) ▶ more RFI?
✔ LOTAAS (survey for pulsars and fast transients with LOFAR) ✔ LNCC (LWA Northern Celestial Cap, irregular observations) ✔ MWA (planned in the near future)
GBNCC SKA1-Low LOTAAS
(coherent beams)
frequency (MHz) 350 135 200 data rate (x GBNCC) 1 25 ~50 – 100 field of view (sq. deg.) 0.25 10 1 number of beams 1 219 500 dwell time (min) 2 60 10 sensitivity (x GBNCC): instantaneous 1 0.4 9 cumulative 1 2 20
LOTAAS team: Jason Hessels, Ben Stappers, Vlad Kondratiev, Sotiris Sanidas, Sally Cooper, Daniele Michilli, Chia Min Tan, Cees Bassa, Ziggy Pleunis, Joeri van Leeuwen +LOFAR PWG
incoherent beams), ~ 30 sq.
TABs) for each SAP, ~9 sq. deg. total per pointing
towards known pulsars
1 SAP TABs (4 rings) 1 survey pointing in red 4 survey pointings are shown in total
Northern hemisphere with incoherent beams (651 pointings needed)
hemisphere with TABs
Cartesius – Dutch national supercomputer 55M core-hours allocated
Nov 11, 2016; Pass A – complete; Pass B – 61%)
3 hrs/beam on 24-core node
(20M+ cands, 50M+ SP cands)
classifier, Lyon+15
Cartesius – Dutch national supercomputer 55M hours allocated
Nov 11, 2016; Pass A – complete; Pass B – 61%)
3 hrs/beam on 24-core node
(20M+ cands, 50M+ SP cands)
classifier, Lyon+15
so far! (as of Dec 7, 2016)
(2 more not-yet confirmed)
20 hrs of observing
per 150 sq. deg. – at the moment somewhat lower than predicted
Lovell telescope at 1.4 GHz
Pass B
Pleunis
▸ Fermi Unid targeted
searches
▸ First MSP discovered
at < 300 MHz
▸ Steep spectrum as
many other MSPs ( < –2.6) α
Cooper
DM = 6.5 pc/cc d = 0.5 kpc
Michilli
➤ Spectra (turnover, GHz-peaked spectra) ➤ Polarization ➤ Profile evolution ➤ Moding, drifting subpulses, giant pulses, etc.
(see also posters by Bradley Meyers & Franz Kirsten)
Hassall et al. 2012
➤ Spectra (turnover, GHz-peaked spectra) ➤ Polarization ➤ Profile evolution ➤ Moding, drifting subpulses, giant pulses, etc.
(see also posters by Bradley Meyers & Franz Kirsten)
Log (Flux density) Log (frequency)
? ~ να
Carousel model (Rankin et al. 2006)
Also next talks in this session
Bilous et al. 2016
→ 194 Northern sources, δ > 8˚ → outside Galactic plane, |b| > 3˚ → not in Globular clusters → good coordinates, position errors < 130˝
split in 32 → −256 chan
(1 observation) Observations Kondratiev et al. 2016 → Exploratory observations and preparation for pulsar timing → Cycle 0 (most), Cycle 1-2 (some) → Full Core → HBA, 110−188 MHz LBA, 15−93 MHz → 400 subs → Complex-voltage data → Δt = 5.12 µs → Typically 20 min (LBA − 1 hour) Spectra work
many more data (!): → total number of HBA obs = 1508; (LBA obs = 18)
Bilous et al. 2016
Kondratiev et al. 2016 (best single observation)
Bilous et al. 2016
Preliminary
Kondratiev et al., in prep.
20 bright pulsars combining HBA polarization data with higher frequencies magnetospheric birefringence cannot be a sole explanation of
scattering can mimic Faraday rotation leading to phase- dependent RMs (but much smaller variation than at 1400 MHz) Noutsos et al. 2015
Hermsen et al. 2013, Science
Hermsen et al. 2013, Science
Bilous et al. 2014
LOFAR+Arecibo+LWA Mereghetti et al. 2016
➤ DM / RM / scattering (see also poster by Veronica Dike) ➤ Scintillation studies ➤ Solar wind, CMEs (talk by Greg Taylor) ➤ Space weather
input to high-freq timing → (DM chromaticity?)
Geyer et al., to be submitted Verbiest et al., in prep. Sobey et al., in prep. Howard et al. 2016
LWA
spectrum sources and transients. Will pave the road for the SKA-Low
view to study pulsar emission mechanism and ISM
monitoring