Table 3: Enhancement factors $q_{{\rm Model}~x/ {\rm Model}~y} = f_{i,{\rm Model}~x}/f_{i,{\rm Model}~y}$ for different line transitions.
Ratio H¹³CO⁺ 3-2 H¹³CO⁺ 4-3 H¹³CO⁺ 8-7

q_1/0 1 1 4

q_2/0 1 1 2

q_3/0 1 2 10

q_4/0 2 4 43

q_5/0 2 4 36

q_6/0 2 4 38

q_2/1 1 1 1

q_3/1 1 2 3

q_4/1 2 4 11

q_5/1 2 4 9

q_6/1 2 4 10

Ratio HCS⁺ 6-5 HCS⁺ 8-7 HCS⁺ 10-9

q_1/0 1 3 8

q_2/0 1 1 2

q_3/0 3 7 19

q_4/0 17 61 169

q_5/0 14 51 141

q_6/0 13 49 138

q_2/1 1 0.5 0.2

q_3/1 2 2 2

q_4/1 12 21 20

q_5/1 10 18 17

q_6/1 10 17 16

The values represent the ratios of the integrated line fluxes $f = \int T_{{\rm mb}} {\rm d}V$ .
The Models are described in Table 1 in Sect. 4.

**Table 3:** Enhancement factors $q_{{\rm Model}~x/ {\rm Model}~y} = f_{i,{\rm Model}~x}/f_{i,{\rm Model}~y}$ for different line transitions.
Ratio	H¹³CO⁺ 3-2	H¹³CO⁺ 4-3	H¹³CO⁺ 8-7
q_1/0	1	1	4
q_2/0	1	1	2
q_3/0	1	2	10
q_4/0	2	4	43
q_5/0	2	4	36
q_6/0	2	4	38
q_2/1	1	1	1
q_3/1	1	2	3
q_4/1	2	4	11
q_5/1	2	4	9
q_6/1	2	4	10
Ratio	HCS⁺ 6-5	HCS⁺ 8-7	HCS⁺ 10-9
q_1/0	1	3	8
q_2/0	1	1	2
q_3/0	3	7	19
q_4/0	17	61	169
q_5/0	14	51	141
q_6/0	13	49	138
q_2/1	1	0.5	0.2
q_3/1	2	2	2
q_4/1	12	21	20
q_5/1	10	18	17
q_6/1	10	17	16

Source LaTeX | All tables | In the text

	1 Introduction
	2 Model
	3 X-ray induced chemistry
	4 Results and discussion
	5 X-ray tracers
	6 AFGL 2591 models
	7 Calculated emission lines
	8 Conclusion
	References
	Online Material
	Appendix A: Initial chemical abundances
	Appendix B: Electron recombination and charge transfer reactions
	Appendix C: Influence of $T{_{{\rm X}}}$ and $N{_{{\rm H,in}}}$
	Appendix D: Influence of an outer FUV field and cosmic rays
	Appendix E: Comparison to observations