2009A&A...504..525S


Query : 2009A&A...504..525S

2009A&A...504..525S - Astronomy and Astrophysics, volume 504, 525-530 (2009/9-3)

Optical and infrared observations of the Crab pulsar and its nearby knot.

SANDBERG A. and SOLLERMAN J.

Abstract (from CDS):

We study the spectral energy distribution (SED) of the Crab Pulsar and its nearby knot in the optical and in the infrared (IR) regime. We want to investigate how the contribution from the knot affects the pulsar SED in that regime, and examine the evidence for synchrotron self-absorption in the IR. We also draw the attention to the predicted secular decrease in luminosity of the Crab Pulsar, and attempt to investigate this with CCD observations. We present high-quality UBVRIz, as well as adaptive optics JHKsL' photometry, achieved under excellent conditions with the FORS1 and NAOS/CONICA instruments at the VLT. We combine these data with re-analyzed archival Spitzer Space Telescope data to construct a SED for the pulsar, and quantify the contamination from the knot. We have also gathered optical imaging data from 1988 to 2008 from several telescopes in order to examine the predicted secular decrease in luminosity. For the Crab Pulsar SED we find a spectral slope of αν=0.27±0.03 in the optical/near-IR regime, when we exclude the contribution from the knot. For the knot itself, we find a much redder slope of αν=-1.3±0.1. Our best estimate of the average decrease in luminosity for the pulsar is 2.9±1.6mmag per year. We have demonstrated the importance of the nearby knot in precision measurements of the Crab Pulsar SED, in particular in the near-IR. We have scrutinized the evidence for the traditional view of a synchrotron self-absorption roll-over in the infrared, and find that these claims are unfounded. We also find evidence for a secular decrease in the optical light for the Crab Pulsar, in agreement with current pulsar spin-down models. However, although our measurements of the decrease significantly improve on previous investigations, the detection is still tentative. We finally point to future observations that can improve the situation significantly.

Abstract Copyright:

Journal keyword(s): pulsars: individual: The Crab Pulsar - stars: pulsars: general - radiation mechanisms: non-thermal

CDS comments: Table 4, fig.4 : the stars are 2MASS objects.

Simbad objects: 13

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Number of rows : 13
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 2MASS J05342822+2200307 * 05 34 28.2313400789 +22 00 30.745060434 18.13 17.93 17.07 16.51 15.97 ~ 1 0
2 2MASS J05342840+2201387 * 05 34 28.4072078463 +22 01 38.774613813 18.43 17.74 16.36 15.59 15.36 ~ 1 0
3 2MASS J05343187+2201161 * 05 34 31.8813888368 +22 01 16.184078309 18.42 18.29 17.40 16.82 16.26 ~ 1 0
4 V* CM Tau Psr 05 34 31.93830 +22 00 52.1758           ~ 4966 1
5 M 1 SNR 05 34 31.94 +22 00 52.2           ~ 5816 4
6 2MASS J05343217+2200560 * 05 34 32.1827037086 +22 00 56.002461158 16.80 16.64 15.79 15.25 14.74 ~ 2 0
7 2MASS J05343342+2200584 * 05 34 33.4273270014 +22 00 58.491305842 17.80 17.49 16.51 15.92 15.36 ~ 1 0
8 2MASS J05343561+2200372 * 05 34 35.6228943437 +22 00 37.240748858 16.56 16.29 15.37 14.78 14.22 ~ 1 0
9 2MASS J05343759+2201222 * 05 34 37.5954759119 +22 01 22.246763318 18.74 18.32 17.16 16.48 15.86 ~ 1 0
10 2MASS J05343821+2200486 * 05 34 38.2195956894 +22 00 48.691057362 18.45 17.23 15.64 14.80 14.07 ~ 1 0
11 GD 71 WD* 05 52 27.6197286025 +15 53 13.228639956 11.675 12.783 13.032 13.169 13.337 DA1.5 353 0
12 PN G219.2+07.5 PN 07 29 58.4752157301 -02 06 37.599190864 11.749 12.830 13.017 13.076 13.164 sdO 67 0
13 * alf Lyr dS* 18 36 56.33635 +38 47 01.2802 0.03 0.03 0.03 0.07 0.10 A0Va 2565 0

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2021.12.09-16:11:44

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