event_selection

Events of the chosen catalogs whose median source-frame masses, luminosity distance and effective spin χ_eff fall in given ranges, and/or that belong to a class of sources: neutron stars, the lower mass gap, hierarchical-merger candidates. Every bound is optional.

# heavy binaries within 2 Gpc
gwtc_analysis event_selection --catalogs ALL --m1-min 50 --dl-max 2000

# potential neutron-star companions
gwtc_analysis event_selection --catalogs ALL --m2-max 3

Option	Selects on
--m1-min, --m1-max	primary mass, source frame (M☉)
--m2-min, --m2-max	secondary mass, source frame (M☉)
--dl-min, --dl-max	luminosity distance (Mpc)
--chi-eff-min, --chi-eff-max	effective spin χ_eff
--preset	a class of sources: neutron-stars, mass-gap, hierarchical

The selection is written to --out-selection (TSV). It uses the GWOSC confident lists; for analyses that need the marginal candidates as well, see Known issues.

Examples

The mode writes the selection as a TSV (--out-selection, one row per event) and, with --out-plot, a PNG of the selected events among all the events of the catalogs. The TSV gives, for each event, the median source-frame masses, the luminosity distance and the redshift. The redshift is not measured: GWOSC infers it from the luminosity distance for the Planck 2015 cosmology, and the source-frame masses are the detector-frame ones divided by 1 + z, so the table shows which redshift they rely on.

Heavy binaries within 2 Gpc

gwtc_analysis event_selection --catalogs ALL --m1-min 50 --dl-max 2000 --out-plot selection.png

Heavy binaries within 2 Gpc; the TSV (event_selection.tsv) lists:

event_id	catalog_key	mass_1_source	mass_2_source	luminosity_distance	redshift
GW191109_010717-v1	GWTC-3	65.0	47.0	1290	0.25
GW240519_012815-v1	GWTC-5	65.0	39.0	1740	0.32
GW241127_061008-v1	GWTC-5	63.8	20.8	1080	0.21
GW241225_082815-v1	GWTC-5	55.7	42.2	1880	0.34

The 4 selected events (orange) among the 290 events of GWTC-1 to GWTC-5 with masses and distance; the dashed lines are the bounds m₁ ≥ 50 M☉ and D_L ≤ 2000 Mpc.

Potential neutron-star companions

gwtc_analysis event_selection --catalogs ALL --m2-max 3 --out-plot selection.png

event_id	catalog_key	mass_1_source	mass_2_source	luminosity_distance	redshift
GW191219_163120-v1	GWTC-3	31.1	1.17	550	0.11
GW170817-v3	GWTC-1	1.46	1.27	40	0.01
GW190425_081805-v3	GWTC-2.1	2.1	1.3	150	0.03
GW230529_181500-v2	GWTC-4	3.66	1.42	203	0.04
GW200115_042309-v2	GWTC-3	5.9	1.44	290	0.06
GW230518_125908-v1	GWTC-4	8.17	1.45	236	0.05
GW190917_114630-v1	GWTC-2.1	9.7	2.1	720	0.15
GW190814_211039-v3	GWTC-2.1	23.3	2.6	230	0.05
GW200210_092254-v1	GWTC-3	24.1	2.83	940	0.19

Nine events: the two binary neutron stars (GW170817, GW190425), neutron star–black hole binaries, and binaries whose lighter component lies between 2.5 and 3 M☉, at the edge of the neutron-star range (GW190814, GW200210).

The selected events lie below m₂ = 3 M☉ (dashed line), well apart from the binary black holes; they are also among the nearest events (right).

GW200105_162426, an NSBH, is absent: GWOSC lists it only as a marginal candidate (Known issues).

Presets: classes of sources

--preset selects a class of sources; the cuts (--m1-min, --chi-eff-max, …) apply on top of it. The GWOSC values are medians: a median inside a range is not a probability of being in it, so each preset adds the 90% intervals and a *_confident flag that requires the whole interval in the range.

Preset	Selects	Parameters	Added columns
neutron-stars	a component below the maximum neutron-star mass (median)	--ns-max-mass (3 M☉, the binary types of catalog_statistics)	class (BNS, NSBH), mass_2_source_hi90, m2_below_ns_max_90
mass-gap	a component in the lower mass gap between neutron stars and black holes (median)	--mass-gap (3 5 M☉)	gap_component, gap_confident, the 90% intervals of both masses
hierarchical	a primary in the pair-instability gap, or χ_eff < 0 at 90%	--pisn-gap-min (50 M☉)	pisn_gap, pisn_gap_confident, negative_chi_eff, χ_eff and its interval

Neutron stars

gwtc_analysis event_selection --catalogs ALL --preset neutron-stars --out-plot ns.png

The nine events of the m₂ < 3 M☉ example above, classified: two BNS (GW170817, GW190425) and seven NSBH candidates. Only GW190917 and GW200210 have a 90% upper bound of m₂ above 3 M☉. GW190814 (m₂ = 2.6 M☉, 90% below 2.7) passes the mass cut, but whether its companion is the heaviest neutron star or the lightest black hole is open: a mass alone cannot tell.

The lower mass gap

gwtc_analysis event_selection --catalogs ALL --preset mass-gap --out-plot gap.png

Few compact objects have been seen between the heaviest neutron stars and the lightest black holes, at about 3–5 M☉. One event has a median there: GW230529_181500, whose primary has 3.66 M☉ (90%: 2.45–4.48), so not confidently inside the gap (LVK 2024 [45]). GW190814's companion (2.6 M☉) lies just below the gap with the default bounds; --mass-gap 2.5 5 includes it.

Hierarchical-merger candidates

gwtc_analysis event_selection --catalogs ALL --preset hierarchical --out-plot hierarchical.png

Stellar evolution should not form black holes in the pair-instability gap, from about 50 to 130 M☉ (the lower edge is uncertain, 45–65 M☉ in the literature): such a black hole is more likely the remnant of an earlier merger, in a dense star cluster or an AGN disk. Remnants of mergers spin with χ ≈ 0.7 in random directions, so a negative χ_eff, spins anti-aligned with the orbit, is another sign of dynamical assembly.

The preset selects 54 events of GWTC-1 to GWTC-5. 19 of them have their whole 90% interval of m₁ above 50 M☉; the heaviest are GW231123_135430 (137 M☉, 90% above 119), GW190426_190642 and GW190521_030229 (98 M☉). Two have χ_eff < 0 at 90%: GW241110_124123 (χ_eff = −0.31, a 16 M☉ primary: selected by its spin alone) and GW241127_061008. Spin magnitudes of the components are not in the GWOSC lists; they are read from the PE samples with parameters_estimation.

The shaded areas are the pair-instability gap (m₁ ≥ 50 M☉) and negative χ_eff.

All options: CLI reference.