J/ApJ/784/154 A survey for Hα pulsar bow shocks (Brownsberger+, 2014)
A survey for Hα pulsar bow shocks.
Brownsberger S., Romani R.W.
<Astrophys. J., 784, 154 (2014)>
=2014ApJ...784..154B 2014ApJ...784..154B (SIMBAD/NED BibCode)
ADC_Keywords: Pulsars ; Gamma rays ; Photometry, H-alpha ; Stars, distances ;
Extinction
Keywords: gamma rays: stars -
pulsars: individual: PSR J2030+4415, PSR J1509-5850 - shock waves
Abstract:
We report on a survey for Hα bow shock emission around nearby
γ-detected energetic pulsars. This survey adds three
Balmer-dominated neutron star bow shocks to the six previously
confirmed examples. In addition to the shock around Fermi pulsar PSR
J1741-2054, we now report Hα structures around two additional
γ-ray pulsars, PSR J2030+4415 and PSR J1509-5850. These are the
first known examples of Hα nebulae with pre-ionization halos.
With new measurements, we show that a simple analytic model can
account for the angular size and flux of the bow shocks' apices. The
latter, in particular, provides a new pulsar probe and indicates large
moments of inertia and smaller distances than previously assumed in
several cases. In particular, we show that the re-measured PSR
J0437-4715 shock flux implies I=(1.7±0.2)x1045/(f_H I_sin i)g cm2.
We also derive a distance d∼0.72 kpc for the γ-ray only
pulsar PSR J2030+4415 and revised distances for PSRs J1959+2048 (1.4 kpc)
and J2555+6535 (∼1 kpc), smaller than the conventional DM-estimated
values. Finally, we report upper limits for 94 additional LAT pulsars.
An estimate of the survey sensitivity indicates that for a warm
neutral medium filling factor φWNM∼0.3 there should be a total
of approximately nine Hα bow shocks in our LAT-targeted survey;
given that seven such objects are now known, a much larger φWNM
seems problematic.
Description:
Our pulsar Hα campaign was pursued during a series of WIYN and SOAR
observations, allocated through the joint Fermi/NOAO program to study
the counterparts of LAT pulsar, blazar, and unidentified sources. The
PWN data reported here came from portions of five observing runs, covering
both the Northern and Southern hemispheres. For all Hα images we used
the WIYN W012 (λ=6566 Å, ΔλFWHM=16 Å) narrow band
Hα filter, kindly loaned to SOAR for the two southern campaigns.
To help distinguish poorly resolved Hα sources near the pulsars from
stars, we also obtained, when possible, matching continuum observations
using the W014 (λ=6562 Å, ΔλFWHM=378 Å) wide
Hα filter or a Sloan Digital Sky Survey (SDSS) r'(λ=6163 Å,
ΔλFWHM=1518 Å) broad band filter.
Objects:
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RA (ICRS) DE Designation(s)
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20 30 55 +44 11.9 PSR J2030+4415 = 1FGL J2030.9+4411
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 92 95 Pulsars with Flux Upper Limits
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See also:
VII/189 : Catalog of Pulsars (Taylor+ 1995)
J/MNRAS/273/411 : Multifrequency fluxes of 280 pulsars (Lorimer+ 1995)
J/MNRAS/405/2243 : GMOS/WIYN spectroscopic catalogue (Trichas+, 2010)
J/MNRAS/424/2832 : Pulsars in γ-ray sources (Lee+, 2012)
J/ApJS/208/17 : 2nd Fermi LAT cat. of gamma-ray pulsars (2PC) (Abdo+, 2013)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Pulsar name
12- 15 I4 s Exp W012 exposure time
17 A1 --- Tel [GSW] Telescope/camera flag (1)
19- 22 F4.1 10-5cm-2/s fobs5 Measured Hα flux limit at fixed
scale (2)
24- 28 F5.2 kpc Dist Distance
30 A1 --- Code [DGKOP] Distance type code (3)
32- 35 F4.2 mag AR Estimated R band extinction
37- 41 F5.1 km/s pVel Adopted perpendicular velocity
43- 49 F7.2 --- Spin Spindown power (dE34/dt)
51- 57 F7.2 10-5cm-2/s fmod5 Expected flux for the WNM model
59 A1 --- l_Ratio [>] Limit flag on Ratio
60- 65 F6.3 --- Ratio Ratio of observed limit to model flux at
the model angular scales (4)
67- 71 F5.2 arcsec Thetamod Model angular scale
73 A1 --- l_ThetaI [<>] Limit flag on ThetaI
74- 78 F5.2 arcsec ThetaI ? Ionization angular scale
80- 83 F4.2 cm-3 nWNM Model local WNM density at
the pulsar Z (5)
85- 88 F4.2 --- Phi Model local WNM fill factor at
the pulsar Z (5)
90- 92 F3.1 --- Flg [0/1]? Detectability flag (6)
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Note (1): Flag as follows:
G = SOAR/GHTS;
S = SOAR/SOI;
W = WIYN/MiMo.
Note (2): Hα flux upper limit for J2030+4415 template at θa=0.9''
scale in units of 10-5 cm-2/s.
Note (3): Distance type codes are from 2PC (Abdo et al. 2013, J/ApJS/208/17).
Code as follows:
D = DM;
G = Gamma-ray (Equation (16));
K = Kinematic;
O = Other;
P = Parallax.
Note (4): Ratio = fobs-5(scaled to θmod)/fmod-5.
Note (5): For each pulsar we use the distance and plane height Z=d*sin(b) to
compute the local WNM density and filling factor (Equation (20))
Note (6): Flag as follows:
0.0 = When known parameters imply no Hα bow shock;
1.0 = when pVel>100 km/s;
0.6 = Otherwise.
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History:
From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 02-Jun-2017