BINARY X-RAY PULSARS IN THE MAGELLANIC CLOUDS

(thanks to my grad student Helen for producing these illustrations – please acknowledge her if you borrow them….)

The figure below shows the location of many of the SMC pulsars systems (against a backdrop of an HI map of Stanimirovic et al., 1999). The pulse periods in seconds are shown.

And here is a similar plot for the LMC pulsars (using the HI map of Kim et al, 1998)

TABLE OF PULSARS

A list of all known SMC X-ray pulsars may be found in Coe & Kirk (2015). The tables from that paper may be found here in Excel format: Table 2& 3 combined, Table 4. I will try to keep these tables up to date.

To minimise confusion arising from long, similar source names we advocate using the SXP names in the future. This identity is created simply from the acronym SXP (Small magellanic cloud X-ray Pulsar – see Coe et al 2005, MNRAS 356, 502) followed by the pulse period in seconds to three significant figures. Similarly we use LXP for those in the Large Magellanic Cloud and they are listed below:

Short ID	RA (2000)	Dec (2000)	Full or alternative name
LXP0.07	05 35 40.8	-66 51 54	A0538-66, RX J0535.6-6651
LXP4.10	05 02 51.7	-66 26 26.5	RX J0502.9-6626, CAL E
LXP4.40	05 41 27	-69 01 24	IGRJ05414-6858 ATel 2704
LXP8.03	05 20 29.7	-69 31 55	RX J0520.5-6932 ATel 5673
LXP13.5	05 32 48	-66 22 14	LMC X-4
LXP13.7	05 31 12	-66 0707.9	EXO053109-6609.2
LXP27.2	05 13 28.3	-65 47 18.9	Swift J0513.4-6547
LXP28.8	05 30 41.9	-66 54 29	Swift J053041.9-665426, ATels 3751, 3753
LXP38.55	05 00 46.1	-70 44 37.4	IGRJ05007-7047
LXP61.6	05 41 34.3	-68 25 48.3	XMMU J054134.7-682550
LXP69.5	05 29 48	-65 56 50.9	RX J0529.8-6556
LXP91.1	05 44 06.3	-71 00 50	RX J0544.1-7100,1SAX J0544.1-710
LXP169	05 07 55.4	-68 25 06	Eclipsing system (Maggi et al 2013)
LXP187	04 51 06.8	-69 48 02.9	Swift J045106.8-694803, [M2002] 9775 (Klus et al 2013)
LXP272	05 30 11.0	-65 51 22.0	XMMU J053011.2-655122
LXP956	05 12 59	-68 26 38	3XMMJ051259.8−682640

The major discovery that the pulsar period distribution in the SMC (and elsewhere) appears to be bimodal (see figure below) and that this may have major evolutionary consequences is presented in our Nature paper (Knigge, Coe & Podsiadlowski Nature 2011 479, 372) and the supplementary material.

The second major discovery was the evidence that not all the systems are simply spinning faster, most are in spin equilibrium, or very close to it. Hence we suggest that ~50% of the neutron stars in these systems have magnetic field strengths in excess of the critical quantum limit (see Klus et al 2014 for the full discussion):

---

Malcolm Coe