J/ApJ/605/759 Multifrequency obs. of radio pulse broadening (Bhat+, 2004)
Multifrequency observations of radio pulse broadening and constraints on
interstellar electron density microstructure.
Bhat N.D.R., Cordes J.M., Camilo F., Nice D.J., Lorimer D.R.
<Astrophys. J., 605, 759-783 (2004)>
=2004ApJ...605..759B 2004ApJ...605..759B
ADC_Keywords: Pulsars
Keywords: ISM: structure - methods: data analysis - pulsars: general -
radio continuum: general - scattering
Abstract:
We have made observations of 98 low Galactic latitude pulsars to
measure pulse broadening caused by multipath propagation through the
interstellar medium. Data were collected with the 305m Arecibo
telescope at four radio frequencies between 430 and 2380MHz. We used a
CLEAN-based algorithm to deconvolve interstellar pulse broadening from
the measured pulse shapes.
We employed two distinct pulse-broadening functions (PBFs): PBF1 is
appropriate for a thin screen of scattering material between the Earth
and a pulsar, while PBF2 is appropriate for scattering material
uniformly distributed along the line of sight from the Earth to a
pulsar.
We found that some observations were better fitted by PBF1 and some
by PBF2. Pulse-broadening times (τd) are derived from fits of
PBFs to the data and are compared with the predictions of a smoothed
model of the Galactic electron distribution. Several lines of sight
show excess broadening, which we model as clumps of high-density
scattering material.
Description:
The observations were made at the Arecibo Observatory. New data for 81
pulsars were obtained in several observing sessions from 2001 May to
2002 November. For the analysis in this paper we also use the data
collected by Lorimer, Camilo, & Xilouris (2002AJ....123.1750L 2002AJ....123.1750L) for 17
pulsars, yielding a total of 98 pulsars.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
position.dat 35 98 Pulsar positions (from Simbad)
table2.dat 107 179 New measurements of pulse-broadening times and
predictions from the electron density models
--------------------------------------------------------------------------------
See also:
http://www.atnf.csiro.au/research/pulsar/psrcat : ATNF Pulsar Catalogue
Byte-by-byte Description of file: position.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- PSR Pulsar identification
16- 17 I2 h RAh Right ascension (J2000.0)
19- 20 I2 min RAm Right ascension (J2000.0)
22- 25 F4.1 s RAs ? Right ascension (J2000.0)
27 A1 --- DE- Declination sign (J2000.0)
28- 29 I2 deg DEd Declination (J2000.0)
31- 32 I2 arcmin DEm Declination (J2000.0)
34- 35 I2 arcsec DEs ? Declination (J2000.0)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- PSR Pulsar identification
12 A1 --- n_PSR [mi] Type of pulse (1)
14 I1 --- Ref Reference to pulsar parameters (2)
15 A1 --- --- [,]
16- 19 I4 MHz RefFreq Frequency band of the survey that discovered
the pulsar
21- 27 F7.2 ms Per ? Pulse period
29- 33 F5.1 pc/cm3 DM ? Dispersion measure
35- 38 F4.1 deg GLON ? Galactic longitude
40- 43 F4.1 deg GLAT ? Galactic latitude
45- 48 I4 MHz Freq ? Observation frequency
50 A1 --- l_PBF1t Limit flag on PBF1t
51- 56 F6.2 ms PBF1t ? PBF1 broadening time
58 A1 --- f_PBF1t [bcde] Flag on PBF1t (3)
60- 63 F4.1 ms e_PBF1t ? Uncertainty in PBF1t
65- 68 F4.2 --- PBF1f ? PBF1 figure of merit
70 A1 --- l_PBF2t Limit flag on PBF2t
71- 76 F6.2 ms PBF2t ? PBF2 broadening time
78 A1 --- f_PBF2t [bcde] Flag on PBF2t (3)
80- 84 F5.2 ms e_PBF2t ? Uncertainty in PBF2t
86- 89 F4.2 --- PBF2f ? PBF2 figure of merit
91 A1 --- l_tc93 Much less than limit flag on tc93
92- 98 F7.3 ms tc93 ? Pulse broadening using the TC93 model
100 A1 --- l_ne2001 Much less than limit flag on ne2001
101-107 F7.3 ms ne2001 ? Pulse broadening using the NE2001 model
--------------------------------------------------------------------------------
Note (1): Flag on PSR as follows:
m = Main pulse
i = inter pulse
See also Fig. 1.
Note (2): Reference(s) to pulsar parameters as follows:
1 = ATNF pulsar catalog, available at
http://www.atnf.csiro.au/research/pulsar/psrcat
2 = Morris et al. (2002, Cat. J/MNRAS/335/275)
3 = Hobbs et al. (2004), in preparation
4 = Lorimer et al. (2002AJ....123.1750L 2002AJ....123.1750L)
5 = Kramer et al. (2003, Cat. J/MNRAS/342/1299)
Note that pulsars in (2), (3), and (5) (Parkes multibeam survey
discoveries), as well as in (4), are also available in (1)
Note (3): Flags as follows:
b = The PBF yields unphysical residuals from the deconvolution for
any realistic value of τd (see text).
c = Signal-to-noise ratio is too small to allow a meaningful fit to
the PBF.
d = τd is negligibly small.
e = The pulsar is not detected at this frequency.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
* 01-Dec-2005: Original version
* 28-Jul-2008: some positions corrected
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 07-May-2004