All-sky search for continuous gravitational waves from isolated neutron stars
using Advanced LIGO O2 data
B. P. Abbott,
1
R. Abbott,
1
T. D. Abbott,
2
S. Abraham,
3
F. Acernese,
4, 5
K. Ackley,
6
C. Adams,
7
R. X. Adhikari,
1
V. B. Adya,
8, 9
C. Affeldt,
8, 9
M. Agathos,
10
K. Agatsuma,
11
N. Aggarwal,
12
O. D. Aguiar,
13
L. Aiello,
14, 15
A. Ain,
3
P. Ajith,
16
G. Allen,
17
A. Allocca,
18, 19
M. A. Aloy,
20
P. A. Altin,
21
A. Amato,
22
A. Ananyeva,
1
S. B. Anderson,
1
W. G. Anderson,
23
S. V. Angelova,
24
S. Antier,
25
S. Appert,
1
K. Arai,
1
M. C. Araya,
1
J. S. Areeda,
26
M. Ar`ene,
27
N. Arnaud,
25, 28
K. G. Arun,
29
S. Ascenzi,
30, 31
G. Ashton,
6
S. M. Aston,
7
P. Astone,
32
F. Aubin,
33
P. Aufmuth,
9
K. AultONeal,
34
C. Austin,
2
V. Avendano,
35
A. Avila-Alvarez,
26
S. Babak,
36, 27
P. Bacon,
27
F. Badaracco,
14, 15
M. K. M. Bader,
37
S. Bae,
38
P. T. Baker,
39
F. Baldaccini,
40, 41
G. Ballardin,
28
S. W. Ballmer,
42
S. Banagiri,
43
J. C. Barayoga,
1
S. E. Barclay,
44
B. C. Barish,
1
D. Barker,
45
K. Barkett,
46
S. Barnum,
12
F. Barone,
4, 5
B. Barr,
44
L. Barsotti,
12
M. Barsuglia,
27
D. Barta,
47
J. Bartlett,
45
I. Bartos,
48
R. Bassiri,
49
A. Basti,
18, 19
M. Bawaj,
50, 41
J. C. Bayley,
44
M. Bazzan,
51, 52
B. B ́ecsy,
53
M. Bejger,
27, 54
I. Belahcene,
25
A. S. Bell,
44
D. Beniwal,
55
B. K. Berger,
49
G. Bergmann,
8, 9
S. Bernuzzi,
56, 57
J. J. Bero,
58
C. P. L. Berry,
59
D. Bersanetti,
60
A. Bertolini,
37
J. Betzwieser,
7
R. Bhandare,
61
J. Bidler,
26
I. A. Bilenko,
62
S. A. Bilgili,
39
G. Billingsley,
1
J. Birch,
7
R. Birney,
24
O. Birnholtz,
58
S. Biscans,
1, 12
S. Biscoveanu,
6
A. Bisht,
9
M. Bitossi,
28, 19
M. A. Bizouard,
25
J. K. Blackburn,
1
C. D. Blair,
7
D. G. Blair,
63
R. M. Blair,
45
S. Bloemen,
64
N. Bode,
8, 9
M. Boer,
65
Y. Boetzel,
66
G. Bogaert,
65
F. Bondu,
67
E. Bonilla,
49
R. Bonnand,
33
P. Booker,
8, 9
B. A. Boom,
37
C. D. Booth,
68
R. Bork,
1
V. Boschi,
28
S. Bose,
69, 3
K. Bossie,
7
V. Bossilkov,
63
J. Bosveld,
63
Y. Bouffanais,
27
A. Bozzi,
28
C. Bradaschia,
19
P. R. Brady,
23
A. Bramley,
7
M. Branchesi,
14, 15
J. E. Brau,
70
T. Briant,
71
J. H. Briggs,
44
F. Brighenti,
72, 73
A. Brillet,
65
M. Brinkmann,
8, 9
V. Brisson,
25,
∗
P. Brockill,
23
A. F. Brooks,
1
D. D. Brown,
55
S. Brunett,
1
A. Buikema,
12
T. Bulik,
74
H. J. Bulten,
75, 37
A. Buonanno,
36, 76
D. Buskulic,
33
C. Buy,
27
R. L. Byer,
49
M. Cabero,
8, 9
L. Cadonati,
77
G. Cagnoli,
22, 78
C. Cahillane,
1
J. Calder ́on Bustillo,
6
T. A. Callister,
1
E. Calloni,
79, 5
J. B. Camp,
80
W. A. Campbell,
6
K. C. Cannon,
81
H. Cao,
55
J. Cao,
82
E. Capocasa,
27
F. Carbognani,
28
S. Caride,
83
M. F. Carney,
59
G. Carullo,
18
J. Casanueva Diaz,
19
C. Casentini,
30, 31
S. Caudill,
37
M. Cavagli`a,
84
F. Cavalier,
25
R. Cavalieri,
28
G. Cella,
19
P. Cerd ́a-Dur ́an,
20
G. Cerretani,
18, 19
E. Cesarini,
85, 31
O. Chaibi,
65
K. Chakravarti,
3
S. J. Chamberlin,
86
M. Chan,
44
S. Chao,
87
P. Charlton,
88
E. A. Chase,
59
E. Chassande-Mottin,
27
D. Chatterjee,
23
M. Chaturvedi,
61
B. D. Cheeseboro,
39
H. Y. Chen,
89
X. Chen,
63
Y. Chen,
46
H.-P. Cheng,
48
C. K. Cheong,
90
H. Y. Chia,
48
A. Chincarini,
60
A. Chiummo,
28
G. Cho,
91
H. S. Cho,
92
M. Cho,
76
N. Christensen,
65, 93
Q. Chu,
63
S. Chua,
71
K. W. Chung,
90
S. Chung,
63
G. Ciani,
51, 52
P. Ciecielag,
54
A. A. Ciobanu,
55
R. Ciolfi,
94, 95
F. Cipriano,
65
A. Cirone,
96, 60
F. Clara,
45
J. A. Clark,
77
P. Clearwater,
97
F. Cleva,
65
C. Cocchieri,
84
E. Coccia,
14, 15
P.-F. Cohadon,
71
D. Cohen,
25
R. Colgan,
98
M. Colleoni,
99
C. G. Collette,
100
C. Collins,
11
L. R. Cominsky,
101
M. Constancio Jr.,
13
L. Conti,
52
S. J. Cooper,
11
P. Corban,
7
T. R. Corbitt,
2
I. Cordero-Carri ́on,
102
K. R. Corley,
98
N. Cornish,
53
A. Corsi,
83
S. Cortese,
28
C. A. Costa,
13
R. Cotesta,
36
M. W. Coughlin,
1
S. B. Coughlin,
68, 59
J.-P. Coulon,
65
S. T. Countryman,
98
P. Couvares,
1
P. B. Covas,
99
E. E. Cowan,
77
D. M. Coward,
63
M. J. Cowart,
7
D. C. Coyne,
1
R. Coyne,
103
J. D. E. Creighton,
23
T. D. Creighton,
104
J. Cripe,
2
M. Croquette,
71
S. G. Crowder,
105
T. J. Cullen,
2
A. Cumming,
44
L. Cunningham,
44
E. Cuoco,
28
T. Dal Canton,
80
G. D ́alya,
106
S. L. Danilishin,
8, 9
S. D’Antonio,
31
K. Danzmann,
9, 8
A. Dasgupta,
107
C. F. Da Silva Costa,
48
L. E. H. Datrier,
44
V. Dattilo,
28
I. Dave,
61
M. Davier,
25
D. Davis,
42
E. J. Daw,
108
D. DeBra,
49
M. Deenadayalan,
3
J. Degallaix,
22
M. De Laurentis,
79, 5
S. Del ́eglise,
71
W. Del Pozzo,
18, 19
L. M. DeMarchi,
59
N. Demos,
12
T. Dent,
8, 9, 109
R. De Pietri,
110, 57
J. Derby,
26
R. De Rosa,
79, 5
C. De Rossi,
22, 28
R. DeSalvo,
111
O. de Varona,
8, 9
S. Dhurandhar,
3
M. C. D ́ıaz,
104
T. Dietrich,
37
L. Di Fiore,
5
M. Di Giovanni,
112, 95
T. Di Girolamo,
79, 5
A. Di Lieto,
18, 19
B. Ding,
100
S. Di Pace,
113, 32
I. Di Palma,
113, 32
F. Di Renzo,
18, 19
A. Dmitriev,
11
Z. Doctor,
89
F. Donovan,
12
K. L. Dooley,
68, 84
S. Doravari,
8, 9
O. Dorosh,
114
I. Dorrington,
68
T. P. Downes,
23
M. Drago,
14, 15
J. C. Driggers,
45
Z. Du,
82
J.-G. Ducoin,
25
P. Dupej,
44
S. E. Dwyer,
45
P. J. Easter,
6
T. B. Edo,
108
M. C. Edwards,
93
A. Effler,
7
P. Ehrens,
1
J. Eichholz,
1
S. S. Eikenberry,
48
M. Eisenmann,
33
R. A. Eisenstein,
12
R. C. Essick,
89
H. Estelles,
99
D. Estevez,
33
Z. B. Etienne,
39
T. Etzel,
1
M. Evans,
12
T. M. Evans,
7
V. Fafone,
30, 31, 14
H. Fair,
42
S. Fairhurst,
68
X. Fan,
82
S. Farinon,
60
B. Farr,
70
W. M. Farr,
11
E. J. Fauchon-Jones,
68
M. Favata,
35
M. Fays,
108
M. Fazio,
115
C. Fee,
116
J. Feicht,
1
M. M. Fejer,
49
F. Feng,
27
A. Fernandez-Galiana,
12
I. Ferrante,
18, 19
E. C. Ferreira,
13
T. A. Ferreira,
13
F. Ferrini,
28
F. Fidecaro,
18, 19
I. Fiori,
28
D. Fiorucci,
27
M. Fishbach,
89
R. P. Fisher,
42, 117
J. M. Fishner,
12
M. Fitz-Axen,
43
R. Flaminio,
33, 118
M. Fletcher,
44
E. Flynn,
26
H. Fong,
119
J. A. Font,
20, 120
P. W. F. Forsyth,
21
J.-D. Fournier,
65
S. Frasca,
113, 32
F. Frasconi,
19
Z. Frei,
106
A. Freise,
11
R. Frey,
70
V. Frey,
25
P. Fritschel,
12
V. V. Frolov,
7
P. Fulda,
48
M. Fyffe,
7
H. A. Gabbard,
44
B. U. Gadre,
3
S. M. Gaebel,
11
J. R. Gair,
121
arXiv:1903.01901v2 [astro-ph.HE] 15 Mar 2019
2
L. Gammaitoni,
40
M. R. Ganija,
55
S. G. Gaonkar,
3
A. Garcia,
26
C. Garc ́ıa-Quir ́os,
99
F. Garufi,
79, 5
B. Gateley,
45
S. Gaudio,
34
G. Gaur,
122
V. Gayathri,
123
G. Gemme,
60
E. Genin,
28
A. Gennai,
19
D. George,
17
J. George,
61
L. Gergely,
124
V. Germain,
33
S. Ghonge,
77
Abhirup Ghosh,
16
Archisman Ghosh,
37
S. Ghosh,
23
B. Giacomazzo,
112, 95
J. A. Giaime,
2, 7
K. D. Giardina,
7
A. Giazotto,
19,
†
K. Gill,
34
G. Giordano,
4, 5
L. Glover,
111
P. Godwin,
86
E. Goetz,
45
R. Goetz,
48
B. Goncharov,
6
G. Gonz ́alez,
2
J. M. Gonzalez Castro,
18, 19
A. Gopakumar,
125
M. L. Gorodetsky,
62
S. E. Gossan,
1
M. Gosselin,
28
R. Gouaty,
33
A. Grado,
126, 5
C. Graef,
44
M. Granata,
22
A. Grant,
44
S. Gras,
12
P. Grassia,
1
C. Gray,
45
R. Gray,
44
G. Greco,
72, 73
A. C. Green,
11, 48
R. Green,
68
E. M. Gretarsson,
34
P. Groot,
64
H. Grote,
68
S. Grunewald,
36
P. Gruning,
25
G. M. Guidi,
72, 73
H. K. Gulati,
107
Y. Guo,
37
A. Gupta,
86
M. K. Gupta,
107
E. K. Gustafson,
1
R. Gustafson,
127
L. Haegel,
99
O. Halim,
15, 14
B. R. Hall,
69
E. D. Hall,
12
E. Z. Hamilton,
68
G. Hammond,
44
M. Haney,
66
M. M. Hanke,
8, 9
J. Hanks,
45
C. Hanna,
86
O. A. Hannuksela,
90
J. Hanson,
7
T. Hardwick,
2
K. Haris,
16
J. Harms,
14, 15
G. M. Harry,
128
I. W. Harry,
36
B. Haskell,
54
C.-J. Haster,
119
K. Haughian,
44
F. J. Hayes,
44
J. Healy,
58
A. Heidmann,
71
M. C. Heintze,
7
H. Heitmann,
65
P. Hello,
25
G. Hemming,
28
M. Hendry,
44
I. S. Heng,
44
J. Hennig,
8, 9
A. W. Heptonstall,
1
Francisco Hernandez Vivanco,
6
M. Heurs,
8, 9
S. Hild,
44
T. Hinderer,
129, 37, 130
D. Hoak,
28
S. Hochheim,
8, 9
D. Hofman,
22
A. M. Holgado,
17
N. A. Holland,
21
K. Holt,
7
D. E. Holz,
89
P. Hopkins,
68
C. Horst,
23
J. Hough,
44
S. Hourihane,
127
E. J. Howell,
63
C. G. Hoy,
68
A. Hreibi,
65
E. A. Huerta,
17
D. Huet,
25
B. Hughey,
34
M. Hulko,
1
S. Husa,
99
S. H. Huttner,
44
T. Huynh-Dinh,
7
B. Idzkowski,
74
A. Iess,
30, 31
C. Ingram,
55
R. Inta,
83
G. Intini,
113, 32
B. Irwin,
116
H. N. Isa,
44
J.-M. Isac,
71
M. Isi,
1
B. R. Iyer,
16
K. Izumi,
45
T. Jacqmin,
71
S. J. Jadhav,
131
K. Jani,
77
N. N. Janthalur,
131
P. Jaranowski,
132
A. C. Jenkins,
133
J. Jiang,
48
D. S. Johnson,
17
A. W. Jones,
11
D. I. Jones,
134
R. Jones,
44
R. J. G. Jonker,
37
L. Ju,
63
J. Junker,
8, 9
C. V. Kalaghatgi,
68
V. Kalogera,
59
B. Kamai,
1
S. Kandhasamy,
84
G. Kang,
38
J. B. Kanner,
1
S. J. Kapadia,
23
S. Karki,
70
K. S. Karvinen,
8, 9
R. Kashyap,
16
M. Kasprzack,
1
S. Katsanevas,
28
E. Katsavounidis,
12
W. Katzman,
7
S. Kaufer,
9
K. Kawabe,
45
N. V. Keerthana,
3
F. K ́ef ́elian,
65
D. Keitel,
44
R. Kennedy,
108
J. S. Key,
135
F. Y. Khalili,
62
H. Khan,
26
I. Khan,
14, 31
S. Khan,
8, 9
Z. Khan,
107
E. A. Khazanov,
136
M. Khursheed,
61
N. Kijbunchoo,
21
Chunglee Kim,
137
J. C. Kim,
138
K. Kim,
90
W. Kim,
55
W. S. Kim,
139
Y.-M. Kim,
140
C. Kimball,
59
E. J. King,
55
P. J. King,
45
M. Kinley-Hanlon,
128
R. Kirchhoff,
8, 9
J. S. Kissel,
45
L. Kleybolte,
141
J. H. Klika,
23
S. Klimenko,
48
T. D. Knowles,
39
P. Koch,
8, 9
S. M. Koehlenbeck,
8, 9
G. Koekoek,
37, 142
S. Koley,
37
V. Kondrashov,
1
A. Kontos,
12
N. Koper,
8, 9
M. Korobko,
141
W. Z. Korth,
1
I. Kowalska,
74
D. B. Kozak,
1
V. Kringel,
8, 9
N. Krishnendu,
29
A. Kr ́olak,
114, 143
G. Kuehn,
8, 9
A. Kumar,
131
P. Kumar,
144
R. Kumar,
107
S. Kumar,
16
L. Kuo,
87
A. Kutynia,
114
S. Kwang,
23
B. D. Lackey,
36
K. H. Lai,
90
T. L. Lam,
90
M. Landry,
45
B. B. Lane,
12
R. N. Lang,
145
J. Lange,
58
B. Lantz,
49
R. K. Lanza,
12
A. Lartaux-Vollard,
25
P. D. Lasky,
6
M. Laxen,
7
A. Lazzarini,
1
C. Lazzaro,
52
P. Leaci,
113, 32
S. Leavey,
8, 9
Y. K. Lecoeuche,
45
C. H. Lee,
92
H. K. Lee,
146
H. M. Lee,
147
H. W. Lee,
138
J. Lee,
91
K. Lee,
44
J. Lehmann,
8, 9
A. Lenon,
39
N. Leroy,
25
N. Letendre,
33
Y. Levin,
6, 98
J. Leviton,
127
J. Li,
82
K. J. L. Li,
90
T. G. F. Li,
90
X. Li,
46
F. Lin,
6
F. Linde,
37
S. D. Linker,
111
T. B. Littenberg,
148
J. Liu,
63
X. Liu,
23
R. K. L. Lo,
90, 1
N. A. Lockerbie,
24
L. T. London,
68
A. Longo,
149, 150
M. Lorenzini,
14, 15
V. Loriette,
151
M. Lormand,
7
G. Losurdo,
19
J. D. Lough,
8, 9
C. O. Lousto,
58
G. Lovelace,
26
M. E. Lower,
152
H. L ̈uck,
9, 8
D. Lumaca,
30, 31
A. P. Lundgren,
153
R. Lynch,
12
Y. Ma,
46
R. Macas,
68
S. Macfoy,
24
M. MacInnis,
12
D. M. Macleod,
68
A. Macquet,
65
F. Maga ̃na-Sandoval,
42
L. Maga ̃na Zertuche,
84
R. M. Magee,
86
E. Majorana,
32
I. Maksimovic,
151
A. Malik,
61
N. Man,
65
V. Mandic,
43
V. Mangano,
44
G. L. Mansell,
45, 12
M. Manske,
23, 21
M. Mantovani,
28
F. Marchesoni,
50, 41
F. Marion,
33
S. M ́arka,
98
Z. M ́arka,
98
C. Markakis,
10, 17
A. S. Markosyan,
49
A. Markowitz,
1
E. Maros,
1
A. Marquina,
102
S. Marsat,
36
F. Martelli,
72, 73
I. W. Martin,
44
R. M. Martin,
35
D. V. Martynov,
11
K. Mason,
12
E. Massera,
108
A. Masserot,
33
T. J. Massinger,
1
M. Masso-Reid,
44
S. Mastrogiovanni,
113, 32
A. Matas,
43, 36
F. Matichard,
1, 12
L. Matone,
98
N. Mavalvala,
12
N. Mazumder,
69
J. J. McCann,
63
R. McCarthy,
45
D. E. McClelland,
21
S. McCormick,
7
L. McCuller,
12
S. C. McGuire,
154
J. McIver,
1
D. J. McManus,
21
T. McRae,
21
S. T. McWilliams,
39
D. Meacher,
86
G. D. Meadors,
6
M. Mehmet,
8, 9
A. K. Mehta,
16
J. Meidam,
37
A. Melatos,
97
G. Mendell,
45
R. A. Mercer,
23
L. Mereni,
22
E. L. Merilh,
45
M. Merzougui,
65
S. Meshkov,
1
C. Messenger,
44
C. Messick,
86
R. Metzdorff,
71
P. M. Meyers,
97
H. Miao,
11
C. Michel,
22
H. Middleton,
97
E. E. Mikhailov,
155
L. Milano,
79, 5
A. L. Miller,
48
A. Miller,
113, 32
M. Millhouse,
53
J. C. Mills,
68
M. C. Milovich-Goff,
111
O. Minazzoli,
65, 156
Y. Minenkov,
31
A. Mishkin,
48
C. Mishra,
157
T. Mistry,
108
S. Mitra,
3
V. P. Mitrofanov,
62
G. Mitselmakher,
48
R. Mittleman,
12
G. Mo,
93
D. Moffa,
116
K. Mogushi,
84
S. R. P. Mohapatra,
12
M. Montani,
72, 73
C. J. Moore,
10
D. Moraru,
45
G. Moreno,
45
S. Morisaki,
81
B. Mours,
33
C. M. Mow-Lowry,
11
Arunava Mukherjee,
8, 9
D. Mukherjee,
23
S. Mukherjee,
104
N. Mukund,
3
A. Mullavey,
7
J. Munch,
55
E. A. Mu ̃niz,
42
M. Muratore,
34
P. G. Murray,
44
I. Nardecchia,
30, 31
L. Naticchioni,
113, 32
R. K. Nayak,
158
J. Neilson,
111
G. Nelemans,
64, 37
T. J. N. Nelson,
7
3
M. Nery,
8, 9
A. Neunzert,
127
K. Y. Ng,
12
S. Ng,
55
P. Nguyen,
70
D. Nichols,
129, 37
S. Nissanke,
129, 37
F. Nocera,
28
C. North,
68
L. K. Nuttall,
153
M. Obergaulinger,
20
J. Oberling,
45
B. D. O’Brien,
48
G. D. O’Dea,
111
G. H. Ogin,
159
J. J. Oh,
139
S. H. Oh,
139
F. Ohme,
8, 9
H. Ohta,
81
M. A. Okada,
13
M. Oliver,
99
P. Oppermann,
8, 9
Richard J. Oram,
7
B. O’Reilly,
7
R. G. Ormiston,
43
L. F. Ortega,
48
R. O’Shaughnessy,
58
S. Ossokine,
36
D. J. Ottaway,
55
H. Overmier,
7
B. J. Owen,
83
A. E. Pace,
86
G. Pagano,
18, 19
M. A. Page,
63
A. Pai,
123
S. A. Pai,
61
J. R. Palamos,
70
O. Palashov,
136
C. Palomba,
32
A. Pal-Singh,
141
Huang-Wei Pan,
87
B. Pang,
46
P. T. H. Pang,
90
C. Pankow,
59
F. Pannarale,
113, 32
B. C. Pant,
61
F. Paoletti,
19
A. Paoli,
28
A. Parida,
3
W. Parker,
7, 154
D. Pascucci,
44
A. Pasqualetti,
28
R. Passaquieti,
18, 19
D. Passuello,
19
M. Patil,
143
B. Patricelli,
18, 19
B. L. Pearlstone,
44
C. Pedersen,
68
M. Pedraza,
1
R. Pedurand,
22, 160
A. Pele,
7
S. Penn,
161
C. J. Perez,
45
A. Perreca,
112, 95
H. P. Pfeiffer,
36, 119
M. Phelps,
8, 9
K. S. Phukon,
3
O. J. Piccinni,
113, 32
M. Pichot,
65
F. Piergiovanni,
72, 73
G. Pillant,
28
L. Pinard,
22
M. Pirello,
45
M. Pitkin,
44
R. Poggiani,
18, 19
D. Y. T. Pong,
90
S. Ponrathnam,
3
P. Popolizio,
28
E. K. Porter,
27
J. Powell,
152
A. K. Prajapati,
107
J. Prasad,
3
K. Prasai,
49
R. Prasanna,
131
G. Pratten,
99
T. Prestegard,
23
S. Privitera,
36
G. A. Prodi,
112, 95
L. G. Prokhorov,
62
O. Puncken,
8, 9
M. Punturo,
41
P. Puppo,
32
M. P ̈urrer,
36
H. Qi,
23
V. Quetschke,
104
P. J. Quinonez,
34
E. A. Quintero,
1
R. Quitzow-James,
70
F. J. Raab,
45
H. Radkins,
45
N. Radulescu,
65
P. Raffai,
106
S. Raja,
61
C. Rajan,
61
B. Rajbhandari,
83
M. Rakhmanov,
104
K. E. Ramirez,
104
A. Ramos-Buades,
99
Javed Rana,
3
K. Rao,
59
P. Rapagnani,
113, 32
V. Raymond,
68
M. Razzano,
18, 19
J. Read,
26
T. Regimbau,
33
L. Rei,
60
S. Reid,
24
D. H. Reitze,
1, 48
W. Ren,
17
F. Ricci,
113, 32
C. J. Richardson,
34
J. W. Richardson,
1
P. M. Ricker,
17
K. Riles,
127
M. Rizzo,
59
N. A. Robertson,
1, 44
R. Robie,
44
F. Robinet,
25
A. Rocchi,
31
L. Rolland,
33
J. G. Rollins,
1
V. J. Roma,
70
M. Romanelli,
67
R. Romano,
4, 5
C. L. Romel,
45
J. H. Romie,
7
K. Rose,
116
D. Rosi ́nska,
162, 54
S. G. Rosofsky,
17
M. P. Ross,
163
S. Rowan,
44
A. R ̈udiger,
8, 9,
‡
P. Ruggi,
28
G. Rutins,
164
K. Ryan,
45
S. Sachdev,
1
T. Sadecki,
45
M. Sakellariadou,
133
L. Salconi,
28
M. Saleem,
29
A. Samajdar,
37
L. Sammut,
6
E. J. Sanchez,
1
L. E. Sanchez,
1
N. Sanchis-Gual,
20
V. Sandberg,
45
J. R. Sanders,
42
K. A. Santiago,
35
N. Sarin,
6
B. Sassolas,
22
P. R. Saulson,
42
O. Sauter,
127
R. L. Savage,
45
P. Schale,
70
M. Scheel,
46
J. Scheuer,
59
P. Schmidt,
64
R. Schnabel,
141
R. M. S. Schofield,
70
A. Sch ̈onbeck,
141
E. Schreiber,
8, 9
B. W. Schulte,
8, 9
B. F. Schutz,
68
S. G. Schwalbe,
34
J. Scott,
44
S. M. Scott,
21
E. Seidel,
17
D. Sellers,
7
A. S. Sengupta,
165
N. Sennett,
36
D. Sentenac,
28
V. Sequino,
30, 31, 14
A. Sergeev,
136
Y. Setyawati,
8, 9
D. A. Shaddock,
21
T. Shaffer,
45
M. S. Shahriar,
59
M. B. Shaner,
111
L. Shao,
36
P. Sharma,
61
P. Shawhan,
76
H. Shen,
17
R. Shink,
166
D. H. Shoemaker,
12
D. M. Shoemaker,
77
S. ShyamSundar,
61
K. Siellez,
77
M. Sieniawska,
54
D. Sigg,
45
A. D. Silva,
13
L. P. Singer,
80
N. Singh,
74
A. Singhal,
14, 32
A. M. Sintes,
99
S. Sitmukhambetov,
104
V. Skliris,
68
B. J. J. Slagmolen,
21
T. J. Slaven-Blair,
63
J. R. Smith,
26
R. J. E. Smith,
6
S. Somala,
167
E. J. Son,
139
B. Sorazu,
44
F. Sorrentino,
60
T. Souradeep,
3
E. Sowell,
83
A. P. Spencer,
44
A. K. Srivastava,
107
V. Srivastava,
42
K. Staats,
59
C. Stachie,
65
M. Standke,
8, 9
D. A. Steer,
27
M. Steinke,
8, 9
J. Steinlechner,
141, 44
S. Steinlechner,
141
D. Steinmeyer,
8, 9
S. P. Stevenson,
152
D. Stocks,
49
R. Stone,
104
D. J. Stops,
11
K. A. Strain,
44
G. Stratta,
72, 73
S. E. Strigin,
62
A. Strunk,
45
R. Sturani,
168
A. L. Stuver,
169
V. Sudhir,
12
T. Z. Summerscales,
170
L. Sun,
1
S. Sunil,
107
J. Suresh,
3
P. J. Sutton,
68
B. L. Swinkels,
37
M. J. Szczepa ́nczyk,
34
M. Tacca,
37
S. C. Tait,
44
C. Talbot,
6
D. Talukder,
70
D. B. Tanner,
48
M. T ́apai,
124
A. Taracchini,
36
J. D. Tasson,
93
R. Taylor,
1
R. Tenorio,
99
F. Thies,
8, 9
M. Thomas,
7
P. Thomas,
45
S. R. Thondapu,
61
K. A. Thorne,
7
E. Thrane,
6
Shubhanshu Tiwari,
112, 95
Srishti Tiwari,
125
V. Tiwari,
68
K. Toland,
44
M. Tonelli,
18, 19
Z. Tornasi,
44
A. Torres-Forn ́e,
171
C. I. Torrie,
1
D. T ̈oyr ̈a,
11
F. Travasso,
28, 41
G. Traylor,
7
M. C. Tringali,
74
A. Trovato,
27
L. Trozzo,
172, 19
R. Trudeau,
1
K. W. Tsang,
37
M. Tse,
12
R. Tso,
46
L. Tsukada,
81
D. Tsuna,
81
D. Tuyenbayev,
104
K. Ueno,
81
D. Ugolini,
173
C. S. Unnikrishnan,
125
A. L. Urban,
2
S. A. Usman,
68
H. Vahlbruch,
9
G. Vajente,
1
G. Valdes,
2
N. van Bakel,
37
M. van Beuzekom,
37
J. F. J. van den Brand,
75, 37
C. Van Den Broeck,
37, 174
D. C. Vander-Hyde,
42
J. V. van Heijningen,
63
L. van der Schaaf,
37
A. A. van Veggel,
44
M. Vardaro,
51, 52
V. Varma,
46
S. Vass,
1
M. Vas ́uth,
47
A. Vecchio,
11
G. Vedovato,
52
J. Veitch,
44
P. J. Veitch,
55
K. Venkateswara,
163
G. Venugopalan,
1
D. Verkindt,
33
F. Vetrano,
72, 73
A. Vicer ́e,
72, 73
A. D. Viets,
23
D. J. Vine,
164
J.-Y. Vinet,
65
S. Vitale,
12
T. Vo,
42
H. Vocca,
40, 41
C. Vorvick,
45
S. P. Vyatchanin,
62
A. R. Wade,
1
L. E. Wade,
116
M. Wade,
116
R. Walet,
37
M. Walker,
26
L. Wallace,
1
S. Walsh,
23
G. Wang,
14, 19
H. Wang,
11
J. Z. Wang,
127
W. H. Wang,
104
Y. F. Wang,
90
R. L. Ward,
21
Z. A. Warden,
34
J. Warner,
45
M. Was,
33
J. Watchi,
100
B. Weaver,
45
L.-W. Wei,
8, 9
M. Weinert,
8, 9
A. J. Weinstein,
1
R. Weiss,
12
G. Weldon,
127
F. Wellmann,
8, 9
L. Wen,
63
E. K. Wessel,
17
P. Weßels,
8, 9
J. W. Westhouse,
34
K. Wette,
21
J. T. Whelan,
58
B. F. Whiting,
48
C. Whittle,
12
D. M. Wilken,
8, 9
D. Williams,
44
A. R. Williamson,
129, 37
J. L. Willis,
1
B. Willke,
8, 9
M. H. Wimmer,
8, 9
W. Winkler,
8, 9
C. C. Wipf,
1
H. Wittel,
8, 9
G. Woan,
44
J. Woehler,
8, 9
J. K. Wofford,
58
J. Worden,
45
J. L. Wright,
44
D. S. Wu,
8, 9
D. M. Wysocki,
58
L. Xiao,
1
H. Yamamoto,
1
C. C. Yancey,
76
L. Yang,
115
M. J. Yap,
21
M. Yazback,
48
D. W. Yeeles,
68
Hang Yu,
12
Haocun Yu,
12
S. H. R. Yuen,
90
4
M. Yvert,
33
A. K. Zadro ̇zny,
104, 114
M. Zanolin,
34
T. Zelenova,
28
J.-P. Zendri,
52
M. Zevin,
59
J. Zhang,
63
L. Zhang,
1
T. Zhang,
44
C. Zhao,
63
M. Zhou,
59
Z. Zhou,
59
X. J. Zhu,
6
M. E. Zucker,
1, 12
and J. Zweizig
1
(The LIGO Scientific Collaboration and the Virgo Collaboration)
A. Pisarski
132
1
LIGO, California Institute of Technology, Pasadena, CA 91125, USA
2
Louisiana State University, Baton Rouge, LA 70803, USA
3
Inter-University Centre for Astronomy and Astrophysics, Pune 411007, India
4
Universit`a di Salerno, Fisciano, I-84084 Salerno, Italy
5
INFN, Sezione di Napoli, Complesso Universitario di Monte S.Angelo, I-80126 Napoli, Italy
6
OzGrav, School of Physics & Astronomy, Monash University, Clayton 3800, Victoria, Australia
7
LIGO Livingston Observatory, Livingston, LA 70754, USA
8
Max Planck Institute for Gravitational Physics (Albert Einstein Institute), D-30167 Hannover, Germany
9
Leibniz Universit ̈at Hannover, D-30167 Hannover, Germany
10
University of Cambridge, Cambridge CB2 1TN, United Kingdom
11
University of Birmingham, Birmingham B15 2TT, United Kingdom
12
LIGO, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
13
Instituto Nacional de Pesquisas Espaciais, 12227-010 S ̃ao Jos ́e dos Campos, S ̃ao Paulo, Brazil
14
Gran Sasso Science Institute (GSSI), I-67100 L’Aquila, Italy
15
INFN, Laboratori Nazionali del Gran Sasso, I-67100 Assergi, Italy
16
International Centre for Theoretical Sciences, Tata Institute of Fundamental Research, Bengaluru 560089, India
17
NCSA, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
18
Universit`a di Pisa, I-56127 Pisa, Italy
19
INFN, Sezione di Pisa, I-56127 Pisa, Italy
20
Departamento de Astronom ́ıa y Astrof ́ısica, Universitat de Val`encia, E-46100 Burjassot, Val`encia, Spain
21
OzGrav, Australian National University, Canberra, Australian Capital Territory 0200, Australia
22
Laboratoire des Mat ́eriaux Avanc ́es (LMA), CNRS/IN2P3, F-69622 Villeurbanne, France
23
University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
24
SUPA, University of Strathclyde, Glasgow G1 1XQ, United Kingdom
25
LAL, Univ. Paris-Sud, CNRS/IN2P3, Universit ́e Paris-Saclay, F-91898 Orsay, France
26
California State University Fullerton, Fullerton, CA 92831, USA
27
APC, AstroParticule et Cosmologie, Universit ́e Paris Diderot,
CNRS/IN2P3, CEA/Irfu, Observatoire de Paris,
Sorbonne Paris Cit ́e, F-75205 Paris Cedex 13, France
28
European Gravitational Observatory (EGO), I-56021 Cascina, Pisa, Italy
29
Chennai Mathematical Institute, Chennai 603103, India
30
Universit`a di Roma Tor Vergata, I-00133 Roma, Italy
31
INFN, Sezione di Roma Tor Vergata, I-00133 Roma, Italy
32
INFN, Sezione di Roma, I-00185 Roma, Italy
33
Laboratoire d’Annecy de Physique des Particules (LAPP), Univ. Grenoble Alpes,
Universit ́e Savoie Mont Blanc, CNRS/IN2P3, F-74941 Annecy, France
34
Embry-Riddle Aeronautical University, Prescott, AZ 86301, USA
35
Montclair State University, Montclair, NJ 07043, USA
36
Max Planck Institute for Gravitational Physics (Albert Einstein Institute), D-14476 Potsdam-Golm, Germany
37
Nikhef, Science Park 105, 1098 XG Amsterdam, The Netherlands
38
Korea Institute of Science and Technology Information, Daejeon 34141, South Korea
39
West Virginia University, Morgantown, WV 26506, USA
40
Universit`a di Perugia, I-06123 Perugia, Italy
41
INFN, Sezione di Perugia, I-06123 Perugia, Italy
42
Syracuse University, Syracuse, NY 13244, USA
43
University of Minnesota, Minneapolis, MN 55455, USA
44
SUPA, University of Glasgow, Glasgow G12 8QQ, United Kingdom
45
LIGO Hanford Observatory, Richland, WA 99352, USA
46
Caltech CaRT, Pasadena, CA 91125, USA
47
Wigner RCP, RMKI, H-1121 Budapest, Konkoly Thege Mikl ́os ́ut 29-33, Hungary
48
University of Florida, Gainesville, FL 32611, USA
49
Stanford University, Stanford, CA 94305, USA
50
Universit`a di Camerino, Dipartimento di Fisica, I-62032 Camerino, Italy
51
Universit`a di Padova, Dipartimento di Fisica e Astronomia, I-35131 Padova, Italy
52
INFN, Sezione di Padova, I-35131 Padova, Italy
53
Montana State University, Bozeman, MT 59717, USA
54
Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, 00-716, Warsaw, Poland
5
55
OzGrav, University of Adelaide, Adelaide, South Australia 5005, Australia
56
Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universit ̈at Jena, D-07743 Jena, Germany
57
INFN, Sezione di Milano Bicocca, Gruppo Collegato di Parma, I-43124 Parma, Italy
58
Rochester Institute of Technology, Rochester, NY 14623, USA
59
Center for Interdisciplinary Exploration & Research in Astrophysics (CIERA),
Northwestern University, Evanston, IL 60208, USA
60
INFN, Sezione di Genova, I-16146 Genova, Italy
61
RRCAT, Indore, Madhya Pradesh 452013, India
62
Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia
63
OzGrav, University of Western Australia, Crawley, Western Australia 6009, Australia
64
Department of Astrophysics/IMAPP, Radboud University Nijmegen,
P.O. Box 9010, 6500 GL Nijmegen, The Netherlands
65
Artemis, Universit ́e Cˆote d’Azur, Observatoire Cˆote d’Azur,
CNRS, CS 34229, F-06304 Nice Cedex 4, France
66
Physik-Institut, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
67
Univ Rennes, CNRS, Institut FOTON - UMR6082, F-3500 Rennes, France
68
Cardiff University, Cardiff CF24 3AA, United Kingdom
69
Washington State University, Pullman, WA 99164, USA
70
University of Oregon, Eugene, OR 97403, USA
71
Laboratoire Kastler Brossel, Sorbonne Universit ́e, CNRS,
ENS-Universit ́e PSL, Coll`ege de France, F-75005 Paris, France
72
Universit`a degli Studi di Urbino ’Carlo Bo,’ I-61029 Urbino, Italy
73
INFN, Sezione di Firenze, I-50019 Sesto Fiorentino, Firenze, Italy
74
Astronomical Observatory Warsaw University, 00-478 Warsaw, Poland
75
VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
76
University of Maryland, College Park, MD 20742, USA
77
School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
78
Universit ́e Claude Bernard Lyon 1, F-69622 Villeurbanne, France
79
Universit`a di Napoli ’Federico II,’ Complesso Universitario di Monte S.Angelo, I-80126 Napoli, Italy
80
NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
81
RESCEU, University of Tokyo, Tokyo, 113-0033, Japan.
82
Tsinghua University, Beijing 100084, China
83
Texas Tech University, Lubbock, TX 79409, USA
84
The University of Mississippi, University, MS 38677, USA
85
Museo Storico della Fisica e Centro Studi e Ricerche “Enrico Fermi”,
I-00184 Roma, Italyrico Fermi, I-00184 Roma, Italy
86
The Pennsylvania State University, University Park, PA 16802, USA
87
National Tsing Hua University, Hsinchu City, 30013 Taiwan, Republic of China
88
Charles Sturt University, Wagga Wagga, New South Wales 2678, Australia
89
University of Chicago, Chicago, IL 60637, USA
90
The Chinese University of Hong Kong, Shatin, NT, Hong Kong
91
Seoul National University, Seoul 08826, South Korea
92
Pusan National University, Busan 46241, South Korea
93
Carleton College, Northfield, MN 55057, USA
94
INAF, Osservatorio Astronomico di Padova, I-35122 Padova, Italy
95
INFN, Trento Institute for Fundamental Physics and Applications, I-38123 Povo, Trento, Italy
96
Dipartimento di Fisica, Universit`a degli Studi di Genova, I-16146 Genova, Italy
97
OzGrav, University of Melbourne, Parkville, Victoria 3010, Australia
98
Columbia University, New York, NY 10027, USA
99
Universitat de les Illes Balears, IAC3—IEEC, E-07122 Palma de Mallorca, Spain
100
Universit ́e Libre de Bruxelles, Brussels 1050, Belgium
101
Sonoma State University, Rohnert Park, CA 94928, USA
102
Departamento de Matem ́aticas, Universitat de Val`encia, E-46100 Burjassot, Val`encia, Spain
103
University of Rhode Island, Kingston, RI 02881, USA
104
The University of Texas Rio Grande Valley, Brownsville, TX 78520, USA
105
Bellevue College, Bellevue, WA 98007, USA
106
MTA-ELTE Astrophysics Research Group, Institute of Physics, E ̈otv ̈os University, Budapest 1117, Hungary
107
Institute for Plasma Research, Bhat, Gandhinagar 382428, India
108
The University of Sheffield, Sheffield S10 2TN, United Kingdom
109
IGFAE, Campus Sur, Universidade de Santiago de Compostela, 15782 Spain
110
Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Universit`a di Parma, I-43124 Parma, Italy
111
California State University, Los Angeles, 5151 State University Dr, Los Angeles, CA 90032, USA
112
Universit`a di Trento, Dipartimento di Fisica, I-38123 Povo, Trento, Italy
113
Universit`a di Roma ’La Sapienza,’ I-00185 Roma, Italy
6
114
NCBJ, 05-400
́
Swierk-Otwock, Poland
115
Colorado State University, Fort Collins, CO 80523, USA
116
Kenyon College, Gambier, OH 43022, USA
117
Christopher Newport University, Newport News, VA 23606, USA
118
National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
119
Canadian Institute for Theoretical Astrophysics,
University of Toronto, Toronto, Ontario M5S 3H8, Canada
120
Observatori Astron`omic, Universitat de Val`encia, E-46980 Paterna, Val`encia, Spain
121
School of Mathematics, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
122
Institute Of Advanced Research, Gandhinagar 382426, India
123
Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
124
University of Szeged, D ́om t ́er 9, Szeged 6720, Hungary
125
Tata Institute of Fundamental Research, Mumbai 400005, India
126
INAF, Osservatorio Astronomico di Capodimonte, I-80131, Napoli, Italy
127
University of Michigan, Ann Arbor, MI 48109, USA
128
American University, Washington, D.C. 20016, USA
129
GRAPPA, Anton Pannekoek Institute for Astronomy and Institute of High-Energy Physics,
University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
130
Delta Institute for Theoretical Physics, Science Park 904, 1090 GL Amsterdam, The Netherlands
131
Directorate of Construction, Services & Estate Management, Mumbai 400094 India
132
University of Bia lystok, 15-424 Bia lystok, Poland
133
King’s College London, University of London, London WC2R 2LS, United Kingdom
134
University of Southampton, Southampton SO17 1BJ, United Kingdom
135
University of Washington Bothell, Bothell, WA 98011, USA
136
Institute of Applied Physics, Nizhny Novgorod, 603950, Russia
137
Ewha Womans University, Seoul 03760, South Korea
138
Inje University Gimhae, South Gyeongsang 50834, South Korea
139
National Institute for Mathematical Sciences, Daejeon 34047, South Korea
140
Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
141
Universit ̈at Hamburg, D-22761 Hamburg, Germany
142
Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
143
Institute of Mathematics, Polish Academy of Sciences, 00656 Warsaw, Poland
144
Cornell University, Ithaca, NY 14850, USA
145
Hillsdale College, Hillsdale, MI 49242, USA
146
Hanyang University, Seoul 04763, South Korea
147
Korea Astronomy and Space Science Institute, Daejeon 34055, South Korea
148
NASA Marshall Space Flight Center, Huntsville, AL 35811, USA
149
Dipartimento di Matematica e Fisica, Universit`a degli Studi Roma Tre, I-00146 Roma, Italy
150
INFN, Sezione di Roma Tre, I-00146 Roma, Italy
151
ESPCI, CNRS, F-75005 Paris, France
152
OzGrav, Swinburne University of Technology, Hawthorn VIC 3122, Australia
153
University of Portsmouth, Portsmouth, PO1 3FX, United Kingdom
154
Southern University and A&M College, Baton Rouge, LA 70813, USA
155
College of William and Mary, Williamsburg, VA 23187, USA
156
Centre Scientifique de Monaco, 8 quai Antoine Ier, MC-98000, Monaco
157
Indian Institute of Technology Madras, Chennai 600036, India
158
IISER-Kolkata, Mohanpur, West Bengal 741252, India
159
Whitman College, 345 Boyer Avenue, Walla Walla, WA 99362 USA
160
Universit ́e de Lyon, F-69361 Lyon, France
161
Hobart and William Smith Colleges, Geneva, NY 14456, USA
162
Janusz Gil Institute of Astronomy, University of Zielona G ́ora, 65-265 Zielona G ́ora, Poland
163
University of Washington, Seattle, WA 98195, USA
164
SUPA, University of the West of Scotland, Paisley PA1 2BE, United Kingdom
165
Indian Institute of Technology, Gandhinagar Ahmedabad Gujarat 382424, India
166
Universit ́e de Montr ́eal/Polytechnique, Montreal, Quebec H3T 1J4, Canada
167
Indian Institute of Technology Hyderabad, Sangareddy, Khandi, Telangana 502285, India
168
International Institute of Physics, Universidade Federal do Rio Grande do Norte, Natal RN 59078-970, Brazil
169
Villanova University, 800 Lancaster Ave, Villanova, PA 19085, USA
170
Andrews University, Berrien Springs, MI 49104, USA
171
Max Planck Institute for Gravitationalphysik (Albert Einstein Institute), D-14476 Potsdam-Golm, Germany
172
Universit`a di Siena, I-53100 Siena, Italy
173
Trinity University, San Antonio, TX 78212, USA
174
Van Swinderen Institute for Particle Physics and Gravity,
University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
7
We present results of an all-sky search for continuous gravitational waves (CWs), which can be
produced by fast spinning neutron stars with an asymmetry around their rotation axis, using data
from the second observing run of the Advanced LIGO detectors. Three different semi-coherent
methods are used to search in a gravitational-wave frequency band from 20 to 1922 Hz and a first
frequency derivative from
−
1
×
10
−
8
to 2
×
10
−
9
Hz/s. None of these searches has found clear
evidence for a CW signal, so upper limits on the gravitational-wave strain amplitude are calculated,
which for this broad range in parameter space are the most sensitive ever achieved.
I. INTRODUCTION
Eleven detections of gravitational waves from black
hole binaries and from a neutron star binary have been
reported in [1]. One of the characteristics of the signals
detected so far is that their duration ranges from a frac-
tion of second to tens of seconds in the detector sensitive
frequency band. Other mechanisms, however, can pro-
duce gravitational waves with longer durations, not yet
detected. In this paper we describe an all-sky search for
continuous gravitational waves (CWs), almost monochro-
matic signals which are present at the detectors during
all the observing time. The principal sources for CW
emission (see [2] for a review) are spinning neutron stars.
If a spinning neutron star (NS) has an asymmetry with
respect to its rotation axis, it will emit CWs at twice the
rotation frequency.
Fast-spinning neutron stars in the Milky Way can gen-
erate continuous gravitational waves via various pro-
cesses which produce an asymmetry.
Crustal distor-
tions from cooling or from binary accretion, or magnetic
field energy buried below the crust could lead to the
non-axisymmetry necessary for detectable emission. Re-
cently, some evidence for a limiting minimum ellipticity
was discussed in [3]. A comprehensive review of contin-
uous gravitational wave emission mechanisms from neu-
tron stars can be found in [4]. The detection of a CW,
possibly combined with electromagnetic observations of
the same source, could yield insight into the structure of
neutron stars and into the equation of state of matter
under extreme conditions.
Searches for continuous waves are usually split in three
different domains: targeted searches look for signals from
known pulsars [5–15]; directed searches look for signals
from known sky locations like the Galactic Center, su-
pernova remnants and low-mass X-ray binaries such as
Sco-X1 [16–26]; all-sky searches look for signals from un-
known sources [27–40]. Since all-sky searches need to
cover a large parameter space, they are the most com-
putationally expensive. For this reason, the most sensi-
tive coherent search methods (e.g. matched filtering for
the full observing run) cannot be used and semi-coherent
methods which split the full observation time in shorter
chunks need to be used.
∗
Deceased, February 2018.
†
Deceased, November 2017.
‡
Deceased, July 2018.
The interest in all-sky searches stems from the fact
that they inspect regions of parameter space that no
other searches look at. Although the targeted searches
are more sensitive, they are limited to search for known
pulsars which are in the sensitive frequency band of the
detectors, while all-sky searches look for neutron stars
with no electromagnetic counterpart, which could have
different or more extreme properties than the observed
pulsars.
In this paper we present the results of an all-sky search
of CWs by three different pipelines (
FrequencyHough
[41],
SkyHough
[42],
Time-Domain
F
-statistic
[43]) using O2
data from the Advanced LIGO detectors. Each pipeline
uses different data analysis methods and covers differ-
ent regions of the parameter space, although there ex-
ists some overlap between them. Overall, we search the
whole sky for gravitational wave frequencies from 20 to
1922 Hz (this number was chosen in order to avoid the
violin modes of the test masses found at higher frequen-
cies) and a first frequency derivative from
−
1
×
10
−
8
to
2
×
10
−
9
Hz/s. No detection has been made, and upper
limits on the gravitational wave amplitude are presented.
The outline of the paper is the following: in Section II,
we summarize the second observing run and give some
details about the data that is used; in Section III, we
describe the model of the signal that we want to detect;
in Section IV, we present the different pipelines which are
used; in Section V, we describe the results obtained by
each pipeline; in Section VI, we give some final remarks.
II. LIGO O2 OBSERVING RUN
The LIGO second observing run (called O2) started on
November 30 2016 and finished on August 25 2017. Dur-
ing this time, three different gravitational-wave detectors
of second generation were active and producing data: Ad-
vanced LIGO [44], consisting of two detectors with 4-km
arm lengths situated in Hanford, Washington (H1) and
Livingston, Louisiana (L1), and Advanced Virgo [45], a
3-km detector located in Cascina, Pisa. Advanced Virgo
first joined the run at the beginning of August 2017, with
less sensitivity than the LIGO detectors, so we have not
considered its data for the search described in this paper.
A representative noise curve from O2 for each LIGO
detector and a comparison to O1 is shown in Fig. 1. We
can observe an improvement of the amplitude spectral
density, and we can also observe that the spectra features
a number (greatly reduced as compared to O1) of narrow
lines and combs affecting several frequency bands, which