of 14
Comprehensive all-sky search for periodic gravitational waves
in the sixth science run LIGO data
B. P. Abbott,
1
R. Abbott,
1
T. D. Abbott,
2
M. R. Abernathy,
3
F. Acernese,
4,5
K. Ackley,
6
C. Adams,
7
T. Adams,
8
P. Addesso,
9
R. X. Adhikari,
1
V. B. Adya,
10
C. Affeldt,
10
M. Agathos,
11
K. Agatsuma,
11
N. Aggarwal,
12
O. D. Aguiar,
13
L. Aiello,
14,15
A. Ain,
16
P. Ajith,
17
B. Allen,
10,18,19
A. Allocca,
20,21
P. A. Altin,
22
S. B. Anderson,
1
W. G. Anderson,
18
K. Arai,
1
M. C. Araya,
1
C. C. Arceneaux,
23
J. S. Areeda,
24
N. Arnaud,
25
K. G. Arun,
26
S. Ascenzi,
27,15
G. Ashton,
28
M. Ast,
29
S. M. Aston,
7
P. Astone,
30
P. Aufmuth,
19
C. Aulbert,
10
S. Babak,
31
P. Bacon,
32
M. K. M. Bader,
11
P. T. Baker,
33
F. Baldaccini,
34,35
G. Ballardin,
36
S. W. Ballmer,
37
J. C. Barayoga,
1
S. E. Barclay,
38
B. C. Barish,
1
D. Barker,
39
F. Barone,
4,5
B. Barr,
38
L. Barsotti,
12
M. Barsuglia,
32
D. Barta,
40
J. Bartlett,
39
I. Bartos,
41
R. Bassiri,
42
A. Basti,
20,21
J. C. Batch,
39
C. Baune,
10
V. Bavigadda,
36
M. Bazzan,
43,44
M. Bejger,
45
A. S. Bell,
38
B. K. Berger,
1
G. Bergmann,
10
C. P. L. Berry,
46
D. Bersanetti,
47,48
A. Bertolini,
11
J. Betzwieser,
7
S. Bhagwat,
37
R. Bhandare,
49
I. A. Bilenko,
50
G. Billingsley,
1
J. Birch,
7
R. Birney,
51
S. Biscans,
12
A. Bisht,
10,19
M. Bitossi,
36
C. Biwer,
37
M. A. Bizouard,
25
J. K. Blackburn,
1
C. D. Blair,
52
D. G. Blair,
52
R. M. Blair,
39
S. Bloemen,
53
O. Bock,
10
M. Boer,
54
G. Bogaert,
54
C. Bogan,
10
A. Bohe,
31
C. Bond,
46
F. Bondu,
55
R. Bonnand,
8
B. A. Boom,
11
R. Bork,
1
V. Boschi,
20,21
S. Bose,
56,16
Y. Bouffanais,
32
A. Bozzi,
36
C. Bradaschia,
21
P. R. Brady,
18
V. B. Braginsky,
50
M. Branchesi,
57,58
J. E. Brau,
59
T. Briant,
60
A. Brillet,
54
M. Brinkmann,
10
V. Brisson,
25
P. Brockill,
18
J. E. Broida,
61
A. F. Brooks,
1
D. A. Brown,
37
D. D. Brown,
46
N. M. Brown,
12
S. Brunett,
1
C. C. Buchanan,
2
A. Buikema,
12
T. Bulik,
62
H. J. Bulten,
63,11
A. Buonanno,
31,64
D. Buskulic,
8
C. Buy,
32
R. L. Byer,
42
M. Cabero,
10
L. Cadonati,
65
G. Cagnoli,
66,67
C. Cahillane,
1
J. Calderón Bustillo,
65
T. Callister,
1
E. Calloni,
68,5
J. B. Camp,
69
K. C. Cannon,
70
J. Cao,
71
C. D. Capano,
10
E. Capocasa,
32
F. Carbognani,
36
S. Caride,
72
J. Casanueva Diaz,
25
C. Casentini,
27,15
S. Caudill,
18
M. Cavaglià,
23
F. Cavalier,
25
R. Cavalieri,
36
G. Cella,
21
C. B. Cepeda,
1
L. Cerboni Baiardi,
57,58
G. Cerretani,
20,21
E. Cesarini,
27,15
M. Chan,
38
S. Chao,
73
P. Charlton,
74
E. Chassande-Mottin,
32
B. D. Cheeseboro,
75
H. Y. Chen,
76
Y. Chen,
77
C. Cheng,
73
A. Chincarini,
48
A. Chiummo,
36
H. S. Cho,
78
M. Cho,
64
J. H. Chow,
22
N. Christensen,
61
Q. Chu,
52
S. Chua,
60
S. Chung,
52
G. Ciani,
6
F. Clara,
39
J. A. Clark,
65
F. Cleva,
54
E. Coccia,
27,14
P.-F. Cohadon,
60
A. Colla,
79,30
C. G. Collette,
80
L. Cominsky,
81
M. Constancio, Jr.,
13
A. Conte,
79,30
L. Conti,
44
D. Cook,
39
T. R. Corbitt,
2
N. Cornish,
33
A. Corsi,
72
S. Cortese,
36
C. A. Costa,
13
M. W. Coughlin,
61
S. B. Coughlin,
82
J.-P. Coulon,
54
S. T. Countryman,
41
P. Couvares,
1
E. E. Cowan,
65
D. M. Coward,
52
M. J. Cowart,
7
D. C. Coyne,
1
R. Coyne,
72
K. Craig,
38
J. D. E. Creighton,
18
T. Creighton,
87
J. Cripe,
2
S. G. Crowder,
83
A. Cumming,
38
L. Cunningham,
38
E. Cuoco,
36
T. Dal Canton,
10
S. L. Danilishin,
38
S. D
Antonio,
15
K. Danzmann,
19,10
N. S. Darman,
84
A. Dasgupta,
85
C. F. Da Silva Costa,
6
V. Dattilo,
36
I. Dave,
49
M. Davier,
25
G. S. Davies,
38
E. J. Daw,
86
R. Day,
36
S. De,
37
D. DeBra,
42
G. Debreczeni,
40
J. Degallaix,
66
M. De Laurentis,
68,5
S. Deléglise,
60
W. Del Pozzo,
46
T. Denker,
10
T. Dent,
10
V. Dergachev,
1
R. De Rosa,
68,5
R. T. DeRosa,
7
R. DeSalvo,
9
R. C. Devine,
75
S. Dhurandhar,
16
M. C. Díaz,
87
L. Di Fiore,
5
M. Di Giovanni,
88,89
T. Di Girolamo,
68,5
A. Di Lieto,
20,21
S. Di Pace,
79,30
I. Di Palma,
31,79,30
A. Di Virgilio,
21
V. Dolique,
66
F. Donovan,
12
K. L. Dooley,
23
S. Doravari,
10
R. Douglas,
38
T. P. Downes,
18
M. Drago,
10
R. W. P. Drever,
1
J. C. Driggers,
39
M. Ducrot,
8
S. E. Dwyer,
39
T. B. Edo,
86
M. C. Edwards,
61
A. Effler,
7
H.-B. Eggenstein,
10
P. Ehrens,
1
J. Eichholz,
6,1
S. S. Eikenberry,
6
W. Engels,
77
R. C. Essick,
12
T. Etzel,
1
M. Evans,
12
T. M. Evans,
7
R. Everett,
90
M. Factourovich,
41
V. Fafone,
27,15
H. Fair,
37
S. Fairhurst,
91
X. Fan,
71
Q. Fang,
52
S. Farinon,
48
B. Farr,
76
W. M. Farr,
46
M. Favata,
92
M. Fays,
91
H. Fehrmann,
10
M. M. Fejer,
42
E. Fenyvesi,
93
I. Ferrante,
20,21
E. C. Ferreira,
13
F. Ferrini,
36
F. Fidecaro,
20,21
I. Fiori,
36
D. Fiorucci,
32
R. P. Fisher,
37
R. Flaminio,
66,94
M. Fletcher,
38
J.-D. Fournier,
54
S. Frasca,
79,30
F. Frasconi,
21
Z. Frei,
93
A. Freise,
46
R. Frey,
59
V. Frey,
25
P. Fritschel,
12
V. V. Frolov,
7
P. Fulda,
6
M. Fyffe,
7
H. A. G. Gabbard,
23
J. R. Gair,
95
L. Gammaitoni,
34
S. G. Gaonkar,
16
F. Garufi,
68,5
G. Gaur,
96,85
N. Gehrels,
69
G. Gemme,
48
P. Geng,
87
E. Genin,
36
A. Gennai,
21
J. George,
49
L. Gergely,
97
V. Germain,
8
Abhirup Ghosh,
17
Archisman Ghosh,
17
S. Ghosh,
53,11
J. A. Giaime,
2,7
K. D. Giardina,
7
A. Giazotto,
21
K. Gill,
98
A. Glaefke,
38
E. Goetz,
39
R. Goetz,
6
L. Gondan,
93
G. González,
2
J. M. Gonzalez Castro,
20,21
A. Gopakumar,
99
N. A. Gordon,
38
M. L. Gorodetsky,
50
S. E. Gossan,
1
M. Gosselin,
36
R. Gouaty,
8
A. Grado,
100,5
C. Graef,
38
P. B. Graff,
64
M. Granata,
66
A. Grant,
38
S. Gras,
12
C. Gray,
39
G. Greco,
57,58
A. C. Green,
46
P. Groot,
53
H. Grote,
10
S. Grunewald,
31
G. M. Guidi,
57,58
X. Guo,
71
A. Gupta,
16
M. K. Gupta,
85
K. E. Gushwa,
1
E. K. Gustafson,
1
R. Gustafson,
101
J. J. Hacker,
24
B. R. Hall,
56
E. D. Hall,
1
G. Hammond,
38
M. Haney,
99
M. M. Hanke,
10
J. Hanks,
39
C. Hanna,
90
M. D. Hannam,
91
J. Hanson,
7
T. Hardwick,
2
J. Harms,
57,58
G. M. Harry,
3
I. W. Harry,
31
M. J. Hart,
38
M. T. Hartman,
6
C.-J. Haster,
46
K. Haughian,
38
A. Heidmann,
60
M. C. Heintze,
7
H. Heitmann,
54
P. Hello,
25
G. Hemming,
36
M. Hendry,
38
I. S. Heng,
38
J. Hennig,
38
J. Henry,
102
A. W. Heptonstall,
1
M. Heurs,
10,19
S. Hild,
38
D. Hoak,
36
D. Hofman,
66
K. Holt,
7
D. E. Holz,
76
P. Hopkins,
91
J. Hough,
38
E. A. Houston,
38
E. J. Howell,
52
Y. M. Hu,
10
S. Huang,
73
E. A. Huerta,
103
D. Huet,
25
B. Hughey,
98
S. Husa,
104
S. H. Huttner,
38
T. Huynh-Dinh,
7
N. Indik,
10
D. R. Ingram,
39
R. Inta,
72
H. N. Isa,
38
J.-M. Isac,
60
M. Isi,
1
T. Isogai,
12
B. R. Iyer,
17
K. Izumi,
39
T. Jacqmin,
60
H. Jang,
78
K. Jani,
65
P. Jaranowski,
105
S. Jawahar,
106
L. Jian,
52
F. Jiménez-Forteza,
104
W. W. Johnson,
2
D. I. Jones,
28
R. Jones,
38
R. J. G. Jonker,
11
L. Ju,
52
K. Haris,
107
C. V. Kalaghatgi,
91
V. Kalogera,
82
S. Kandhasamy,
23
G. Kang,
78
J. B. Kanner,
1
PHYSICAL REVIEW D
94,
042002 (2016)
2470-0010
=
2016
=
94(4)
=
042002(14)
042002-1
© 2016 American Physical Society
S. J. Kapadia,
10
S. Karki,
59
K. S. Karvinen,
10
M. Kasprzack,
36,2
E. Katsavounidis,
12
W. Katzman,
7
S. Kaufer,
19
T. Kaur,
52
K. Kawabe,
39
F. Kéfélian,
54
M. S. Kehl,
108
D. Keitel,
104
D. B. Kelley,
37
W. Kells,
1
R. Kennedy,
86
J. S. Key,
87
F. Y. Khalili,
50
I. Khan,
14
S. Khan,
91
Z. Khan,
85
E. A. Khazanov,
109
N. Kijbunchoo,
39
Chi-Woong Kim,
78
Chunglee Kim,
78
J. Kim,
110
K. Kim,
111
N. Kim,
42
W. Kim,
112
Y.-M. Kim,
110
S. J. Kimbrell,
65
E. J. King,
112
P. J. King,
39
J. S. Kissel,
39
B. Klein,
82
L. Kleybolte,
29
S. Klimenko,
6
S. M. Koehlenbeck,
10
S. Koley,
11
V. Kondrashov,
1
A. Kontos,
12
M. Korobko,
29
W. Z. Korth,
1
I. Kowalska,
62
D. B. Kozak,
1
V. Kringel,
10
B. Krishnan,
10
A. Królak,
113,114
C. Krueger,
19
G. Kuehn,
10
P. Kumar,
108
R. Kumar,
85
L. Kuo,
73
A. Kutynia,
113
B. D. Lackey,
37
M. Landry,
39
J. Lange,
102
B. Lantz,
42
P. D. Lasky,
115
M. Laxen,
7
A. Lazzarini,
1
C. Lazzaro,
44
P. Leaci,
79,30
S. Leavey,
38
E. O. Lebigot,
32,71
C. H. Lee,
110
H. K. Lee,
111
H. M. Lee,
116
K. Lee,
38
A. Lenon,
37
M. Leonardi,
88,89
J. R. Leong,
10
N. Leroy,
25
N. Letendre,
8
Y. Levin,
115
J. B. Lewis,
1
T. G. F. Li,
117
A. Libson,
12
T. B. Littenberg,
118
N. A. Lockerbie,
106
A. L. Lombardi,
119
L. T. London,
91
J. E. Lord,
37
M. Lorenzini,
14,15
V. Loriette,
120
M. Lormand,
7
G. Losurdo,
58
J. D. Lough,
10,19
H. Lück,
19,10
A. P. Lundgren,
10
R. Lynch,
12
Y. Ma,
52
B. Machenschalk,
10
M. MacInnis,
12
D. M. Macleod,
2
F. Magaña-Sandoval,
37
L. Magaña Zertuche,
37
R. M. Magee,
56
E. Majorana,
30
I. Maksimovic,
120
V. Malvezzi,
27,15
N. Man,
54
I. Mandel,
46
V. Mandic,
83
V. Mangano,
38
G. L. Mansell,
22
M. Manske,
18
M. Mantovani,
36
F. Marchesoni,
121,35
F. Marion,
8
S. Márka,
41
Z. Márka,
41
A. S. Markosyan,
42
E. Maros,
1
F. Martelli,
57,58
L. Martellini,
54
I. W. Martin,
38
D. V. Martynov,
12
J. N. Marx,
1
K. Mason,
12
A. Masserot,
8
T. J. Massinger,
37
M. Masso-Reid,
38
S. Mastrogiovanni,
79,30
F. Matichard,
12
L. Matone,
41
N. Mavalvala,
12
N. Mazumder,
56
R. McCarthy,
39
D. E. McClelland,
22
S. McCormick,
7
S. C. McGuire,
122
G. McIntyre,
1
J. McIver,
1
D. J. McManus,
22
T. McRae,
22
S. T. McWilliams,
75
D. Meacher,
90
G. D. Meadors,
31,10
J. Meidam,
11
A. Melatos,
84
G. Mendell,
39
R. A. Mercer,
18
E. L. Merilh,
39
M. Merzougui,
54
S. Meshkov,
1
C. Messenger,
38
C. Messick,
90
R. Metzdorff,
60
P. M. Meyers,
83
F. Mezzani,
30,79
H. Miao,
46
C. Michel,
66
H. Middleton,
46
E. E. Mikhailov,
123
L. Milano,
68,5
A. L. Miller,
6,79,30
A. Miller,
82
B. B. Miller,
82
J. Miller,
12
M. Millhouse,
33
Y. Minenkov,
15
J. Ming,
31
S. Mirshekari,
124
C. Mishra,
17
S. Mitra,
16
V. P. Mitrofanov,
50
G. Mitselmakher,
6
R. Mittleman,
12
A. Moggi,
21
M. Mohan,
36
S. R. P. Mohapatra,
12
M. Montani,
57,58
B. C. Moore,
92
C. J. Moore,
125
D. Moraru,
39
G. Moreno,
39
S. R. Morriss,
87
K. Mossavi,
10
B. Mours,
8
C. M. Mow-Lowry,
46
G. Mueller,
6
A. W. Muir,
91
Arunava Mukherjee,
17
D. Mukherjee,
18
S. Mukherjee,
87
N. Mukund,
16
A. Mullavey,
7
J. Munch,
112
D. J. Murphy,
41
P. G. Murray,
38
A. Mytidis,
6
I. Nardecchia,
27,15
L. Naticchioni,
79,30
R. K. Nayak,
126
K. Nedkova,
119
G. Nelemans,
53,11
T. J. N. Nelson,
7
M. Neri,
47,48
A. Neunzert,
101
G. Newton,
38
T. T. Nguyen,
22
A. B. Nielsen,
10
S. Nissanke,
53,11
A. Nitz,
10
F. Nocera,
36
D. Nolting,
7
M. E. N. Normandin,
87
L. K. Nuttall,
37
J. Oberling,
39
E. Ochsner,
18
J. O
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127
E. Oelker,
12
G. H. Ogin,
128
J. J. Oh,
129
S. H. Oh,
129
F. Ohme,
91
M. Oliver,
104
P. Oppermann,
10
Richard J. Oram,
7
B. O
Reilly,
7
R. O
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102
D. J. Ottaway,
112
H. Overmier,
7
B. J. Owen,
72
A. Pai,
107
S. A. Pai,
49
J. R. Palamos,
59
O. Palashov,
109
C. Palomba,
30
A. Pal-Singh,
29
H. Pan,
73
C. Pankow,
82
F. Pannarale,
91
B. C. Pant,
49
F. Paoletti,
36,21
A. Paoli,
36
M. A. Papa,
31,18,10
H. R. Paris,
42
W. Parker,
7
D. Pascucci,
38
A. Pasqualetti,
36
R. Passaquieti,
20,21
D. Passuello,
21
B. Patricelli,
20,21
Z. Patrick,
42
B. L. Pearlstone,
38
M. Pedraza,
1
R. Pedurand,
66,130
L. Pekowsky,
37
A. Pele,
7
S. Penn,
131
A. Perreca,
1
L. M. Perri,
82
M. Phelps,
38
O. J. Piccinni,
79,30
M. Pichot,
54
F. Piergiovanni,
57,58
V. Pierro,
9
G. Pillant,
36
L. Pinard,
66
I. M. Pinto,
9
M. Pitkin,
38
M. Poe,
18
R. Poggiani,
20,21
P. Popolizio,
36
A. Post,
10
J. Powell,
38
J. Prasad,
16
V. Predoi,
91
T. Prestegard,
83
L. R. Price,
1
M. Prijatelj,
10,36
M. Principe,
9
S. Privitera,
31
R. Prix,
10
G. A. Prodi,
88,89
L. Prokhorov,
50
O. Puncken,
10
M. Punturo,
35
P. Puppo,
30
M. Pürrer,
31
H. Qi,
18
J. Qin,
52
S. Qiu,
115
V. Quetschke,
87
E. A. Quintero,
1
R. Quitzow-James,
59
F. J. Raab,
39
D. S. Rabeling,
22
H. Radkins,
39
P. Raffai,
93
S. Raja,
49
C. Rajan,
49
M. Rakhmanov,
87
P. Rapagnani,
79,30
V. Raymond,
31
M. Razzano,
20,21
V. Re,
27
J. Read,
24
C. M. Reed,
39
T. Regimbau,
54
L. Rei,
48
S. Reid,
51
D. H. Reitze,
1,6
H. Rew,
123
S. D. Reyes,
37
F. Ricci,
79,30
K. Riles,
101
M. Rizzo,
102
N. A. Robertson,
1,38
R. Robie,
38
F. Robinet,
25
A. Rocchi,
15
L. Rolland,
8
J. G. Rollins,
1
V. J. Roma,
59
J. D. Romano,
87
R. Romano,
4,5
G. Romanov,
123
J. H. Romie,
7
D. Rosi
ń
ska,
132,45
S. Rowan,
38
A. Rüdiger,
10
P. Ruggi,
36
K. Ryan,
39
S. Sachdev,
1
T. Sadecki,
39
L. Sadeghian,
18
M. Sakellariadou,
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L. Salconi,
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M. Saleem,
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F. Salemi,
10
A. Samajdar,
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L. Sammut,
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E. J. Sanchez,
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V. Sandberg,
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B. Sandeen,
82
J. R. Sanders,
37
B. Sassolas,
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37
O. E. S. Sauter,
101
R. L. Savage,
39
A. Sawadsky,
19
P. Schale,
59
R. Schilling,
10
,*
J. Schmidt,
10
P. Schmidt,
1,77
R. Schnabel,
29
R. M. S. Schofield,
59
A. Schönbeck,
29
E. Schreiber,
10
D. Schuette,
10,19
B. F. Schutz,
91,31
J. Scott,
38
S. M. Scott,
22
D. Sellers,
7
A. S. Sengupta,
96
D. Sentenac,
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V. Sequino,
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A. Sergeev,
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Y. Setyawati,
53,11
D. A. Shaddock,
22
T. Shaffer,
39
M. S. Shahriar,
82
M. Shaltev,
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65
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87
K. A. Strain,
38
N. Straniero,
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57,58
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,*
B. P. ABBOTT
et al.
PHYSICAL REVIEW D
94,
042002 (2016)
042002-2
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1
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A. Zadro
ż
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113
L. Zangrando,
44
M. Zanolin,
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44
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1
M. Zhang,
123
Y. Zhang,
102
C. Zhao,
52
M. Zhou,
82
Z. Zhou,
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M. E. Zucker,
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S. E. Zuraw,
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and J. Zweizig
1
(LIGO Scientific Collaboration and Virgo Collaboration)
1
LIGO, California Institute of Technology, Pasadena, California 91125, USA
2
Louisiana State University, Baton Rouge, Louisiana 70803, USA
3
American University, Washington, D.C. 20016, USA
4
Università di Salerno, Fisciano, I-84084 Salerno, Italy
5
INFN, Sezione di Napoli, Complesso Universitario di Monte S.Angelo, I-80126 Napoli, Italy
6
University of Florida, Gainesville, Florida 32611, USA
7
LIGO Livingston Observatory, Livingston, Louisiana 70754, USA
8
Laboratoire d
Annecy-le-Vieux de Physique des Particules (LAPP), Université Savoie Mont Blanc,
CNRS/IN2P3, F-74941 Annecy-le-Vieux, France
9
University of Sannio at Benevento, I-82100 Benevento, Italy
and INFN, Sezione di Napoli, I-80100 Napoli, Italy
10
Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik, D-30167 Hannover, Germany
11
Nikhef, Science Park, 1098 XG Amsterdam, The Netherlands
12
LIGO, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
13
Instituto Nacional de Pesquisas Espaciais, 12227-010 São José dos Campos, São Paulo, Brazil
14
INFN, Gran Sasso Science Institute, I-67100 L
Aquila, Italy
15
INFN, Sezione di Roma Tor Vergata, I-00133 Roma, Italy
16
Inter-University Centre for Astronomy and Astrophysics, Pune 411007, India
17
International Centre for Theoretical Sciences, Tata Institute of Fundamental Research,
Bangalore 560012, India
18
University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA
19
Leibniz Universität Hannover, D-30167 Hannover, Germany
20
Università di Pisa, I-56127 Pisa, Italy
21
INFN, Sezione di Pisa, I-56127 Pisa, Italy
22
Australian National University, Canberra, Australian Capital Territory 0200, Australia
23
The University of Mississippi, University, Mississippi 38677, USA
24
California State University Fullerton, Fullerton, California 92831, USA
25
LAL, Univ. Paris-Sud, CNRS/IN2P3, Université Paris-Saclay, Orsay, France
26
Chennai Mathematical Institute, Chennai 603103, India
27
Università di Roma Tor Vergata, I-00133 Roma, Italy
28
University of Southampton, Southampton SO17 1BJ, United Kingdom
29
Universität Hamburg, D-22761 Hamburg, Germany
30
INFN, Sezione di Roma, I-00185 Roma, Italy
31
Albert-Einstein-Institut, Max-Planck-Institut für Gravitationsphysik, D-14476 Potsdam-Golm, Germany
32
APC, AstroParticule et Cosmologie, Université Paris Diderot, CNRS/IN2P3, CEA/Irfu,
Observatoire de Paris, Sorbonne Paris Cité, F-75205 Paris Cedex 13, France
33
Montana State University, Bozeman, Montana 59717, USA
34
Università di Perugia, I-06123 Perugia, Italy
35
INFN, Sezione di Perugia, I-06123 Perugia, Italy
36
European Gravitational Observatory (EGO), I-56021 Cascina, Pisa, Italy
37
Syracuse University, Syracuse, New York 13244, USA
38
SUPA, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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...
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39
LIGO Hanford Observatory, Richland, Washington 99352, USA
40
Wigner RCP, RMKI, H-1121 Budapest, Konkoly Thege Miklós út 29-33, Hungary
41
Columbia University, New York, New York 10027, USA
42
Stanford University, Stanford, California 94305, USA
43
Università di Padova, Dipartimento di Fisica e Astronomia, I-35131 Padova, Italy
44
INFN, Sezione di Padova, I-35131 Padova, Italy
45
CAMK-PAN, 00-716 Warsaw, Poland
46
University of Birmingham, Birmingham B15 2TT, United Kingdom
47
Università degli Studi di Genova, I-16146 Genova, Italy
48
INFN, Sezione di Genova, I-16146 Genova, Italy
49
RRCAT, Indore, MP 452013, India
50
Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia
51
SUPA, University of the West of Scotland, Paisley PA1 2BE, United Kingdom
52
University of Western Australia, Crawley, Western Australia 6009, Australia
53
Department of Astrophysics/IMAPP, Radboud University Nijmegen,
P.O. Box 9010, 6500 GL Nijmegen, The Netherlands
54
Artemis, Université Côte d
Azur, CNRS, Observatoire Côte d
Azur, CS 34229, Nice cedex 4, France
55
Institut de Physique de Rennes, CNRS, Université de Rennes 1, F-35042 Rennes, France
56
Washington State University, Pullman, Washington 99164, USA
57
Università degli Studi di Urbino
Carlo Bo,
I-61029 Urbino, Italy
58
INFN, Sezione di Firenze, I-50019 Sesto Fiorentino, Firenze, Italy
59
University of Oregon, Eugene, Oregon 97403, USA
60
Laboratoire Kastler Brossel, UPMC-Sorbonne Universités, CNRS, ENS-PSL Research University,
Collège de France, F-75005 Paris, France
61
Carleton College, Northfield, Minnesota 55057, USA
62
Astronomical Observatory Warsaw University, 00-478 Warsaw, Poland
63
VU University Amsterdam, 1081 HV Amsterdam, The Netherlands
64
University of Maryland, College Park, Maryland 20742, USA
65
Center for Relativistic Astrophysics and School of Physics, Georgia Institute of Technology,
Atlanta, Georgia 30332, USA
66
Laboratoire des Matériaux Avancés (LMA), CNRS/IN2P3, F-69622 Villeurbanne, France
67
Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France
68
Università di Napoli
Federico II,
Complesso Universitario di Monte S.Angelo, I-80126 Napoli, Italy
69
NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
70
RESCEU, University of Tokyo, Tokyo 113-0033, Japan
71
Tsinghua University, Beijing 100084, China
72
Texas Tech University, Lubbock, Texas 79409, USA
73
National Tsing Hua University, Hsinchu City, 30013 Taiwan, Republic of China
74
Charles Sturt University, Wagga Wagga, New South Wales 2678, Australia
75
West Virginia University, Morgantown, West Virginia 26506, USA
76
University of Chicago, Chicago, Illinois 60637, USA
77
Caltech CaRT, Pasadena, California 91125, USA
78
Korea Institute of Science and Technology Information, Daejeon 305-806, Korea
79
Università di Roma
La Sapienza,
I-00185 Roma, Italy
80
University of Brussels, Brussels 1050, Belgium
81
Sonoma State University, Rohnert Park, California 94928, USA
82
Center for Interdisciplinary Exploration & Research in Astrophysics (CIERA), Northwestern University,
Evanston, Illinois 60208, USA
83
University of Minnesota, Minneapolis, Minnesota 55455, USA
84
The University of Melbourne, Parkville, Victoria 3010, Australia
85
Institute for Plasma Research, Bhat, Gandhinagar 382428, India
86
The University of Sheffield, Sheffield S10 2TN, United Kingdom
87
The University of Texas Rio Grande Valley, Brownsville, Texas 78520, USA
88
Università di Trento, Dipartimento di Fisica, I-38123 Povo, Trento, Italy
89
INFN, Trento Institute for Fundamental Physics and Applications, I-38123 Povo, Trento, Italy
90
The Pennsylvania State University, University Park, Pennsylvania 16802, USA
91
Cardiff University, Cardiff CF24 3AA, United Kingdom
92
Montclair State University, Montclair, New Jersey 07043, USA
93
MTA Eötvös University,
Lendulet
Astrophysics Research Group, Budapest 1117, Hungary
B. P. ABBOTT
et al.
PHYSICAL REVIEW D
94,
042002 (2016)
042002-4
94
National Astronomical Observatory of Japan,
2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
95
School of Mathematics, University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
96
Indian Institute of Technology, Gandhinagar, Ahmedabad, Gujarat 382424, India
97
University of Szeged, Dóm tér 9, Szeged 6720, Hungary
98
Embry-Riddle Aeronautical University, Prescott, Arizona 86301, USA
99
Tata Institute of Fundamental Research, Mumbai 400005, India
100
INAF, Osservatorio Astronomico di Capodimonte, I-80131 Napoli, Italy
101
University of Michigan, Ann Arbor, Michigan 48109, USA
102
Rochester Institute of Technology, Rochester, New York 14623, USA
103
NCSA, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
104
Universitat de les Illes Balears, IAC3
IEEC, E-07122 Palma de Mallorca, Spain
105
University of Bia
ł
ystok, 15-424 Bia
ł
ystok, Poland
106
SUPA, University of Strathclyde, Glasgow G1 1XQ, United Kingdom
107
IISER-TVM, CET Campus, Trivandrum, Kerala 695016, India
108
Canadian Institute for Theoretical Astrophysics, University of Toronto,
Toronto, Ontario M5S 3H8, Canada
109
Institute of Applied Physics, Nizhny Novgorod 603950, Russia
110
Pusan National University, Busan 609-735, Korea
111
Hanyang University, Seoul 133-791, Korea
112
University of Adelaide, Adelaide, South Australia 5005, Australia
113
NCBJ, 05-400
Ś
wierk-Otwock, Poland
114
IM-PAN, 00-956 Warsaw, Poland
115
Monash University, Victoria 3800, Australia
116
Seoul National University, Seoul 151-742, Korea
117
The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
118
University of Alabama in Huntsville, Huntsville, Alabama 35899, USA
119
University of Massachusetts-Amherst, Amherst, Massachusetts 01003, USA
120
ESPCI, CNRS, F-75005 Paris, France
121
Università di Camerino, Dipartimento di Fisica, I-62032 Camerino, Italy
122
Southern University and A&M College, Baton Rouge, Louisiana 70813, USA
123
College of William and Mary, Williamsburg, Virginia 23187, USA
124
Instituto de Física Teórica, University Estadual Paulista/ICTP
South American Institute for Fundamental Research, São Paulo, SP 01140-070, Brazil
125
University of Cambridge, Cambridge CB2 1TN, United Kingdom
126
IISER-Kolkata, Mohanpur, West Bengal 741252, India
127
Rutherford Appleton Laboratory, HSIC, Chilton, Didcot, Oxon OX11 0QX, United Kingdom
128
Whitman College, 345 Boyer Avenue, Walla Walla, Washington 99362, USA
129
National Institute for Mathematical Sciences, Daejeon 305-390, Korea
130
Université de Lyon, F-69361 Lyon, France
131
Hobart and William Smith Colleges, Geneva, New York 14456, USA
132
Janusz Gil Institute of Astronomy, University of Zielona Góra, 65-265 Zielona Góra, Poland
133
King
s College London, University of London, London WC2R 2LS, United Kingdom
134
Andrews University, Berrien Springs, Michigan 49104, USA
135
Università di Siena, I-53100 Siena, Italy
136
Trinity University, San Antonio, Texas 78212, USA
137
University of Washington, Seattle, Washington 98195, USA
138
Kenyon College, Gambier, Ohio 43022, USA
139
Abilene Christian University, Abilene, Texas 79699, USA
(Received 14 May 2016; published 15 August 2016)
We report on a comprehensive all-sky search for periodic gravitational waves in the frequency band
100
1500 Hz and with a frequency time derivative in the range of
½
1
.
18
;
þ
1
.
00

×
10
8
Hz
=
s. Such a
signal could be produced by a nearby spinning and slightly nonaxisymmetric isolated neutron star in our
galaxy. This search uses the data from the initial LIGO sixth science run and covers a larger parameter
space with respect to any past search. A
Loosely Coherent
detection pipeline was applied to follow up weak
outliers in both Gaussian (95% recovery rate) and non-Gaussian (75% recovery rate) bands. No
gravitational wave signals were observed, and upper limits were placed on their strength. Our smallest
*
Deceased
COMPREHENSIVE ALL-SKY SEARCH FOR PERIODIC
...
PHYSICAL REVIEW D
94,
042002 (2016)
042002-5
upper limit on worst-case (linearly polarized) strain amplitude
h
0
is
9
.
7
×
10
25
near 169 Hz, while at the
high end of our frequency range we achieve a worst-case upper limit of
5
.
5
×
10
24
. Both cases refer to all
sky locations and entire range of frequency derivative values.
DOI:
10.1103/PhysRevD.94.042002
I. INTRODUCTION
In this paper we report the results of a comprehensive
all-sky search for continuous, nearly monochromatic
gravitational waves in data from LIGO
s sixth science
(S6) run. The search covered frequencies from 100 Hz
through 1500 Hz and frequency derivatives from
1
.
18
×
10
8
Hz
=
s through
1
.
00
×
10
8
Hz
=
s.
A number of searches for periodic gravitational waves
have been carried out previously in LIGO data
[1
10]
,
including coherent searches for gravitational radiation from
known radio and X-ray pulsars. An Einstein@Home search
running on the BOINC infrastructure
[11]
has performed
blind all-sky searches on S4 and S5 data
[12
14]
.
The results in this paper were produced with the
PowerFlux search program. It was first described in
[1]
together with two other semicoherent search pipelines
(Hough, Stackslide). The sensitivities of all three methods
were compared, with PowerFlux showing better results in
frequency bands lacking severe spectral artifacts. A sub-
sequent article
[3]
based on the data from the S5 run featured
improved upper limits and a systematic outlier follow-up
search based on the
Loosely Coherent
algorithm
[15]
.
The analysis of the data set from the sixth science run
described in this paper has several distinguishing features
from previously published results:
(i) A number of upgrades to the detector were made
in order to field-test the technology for Advanced
LIGO interferometers. This resulted in a factor of
about two improvement in intrinsic noise level at
high frequencies compared to previously published
results
[3]
.
(ii) The higher sensitivity allowed us to use less data
while still improving upper limits in high frequency
bands by 25% over previously published results.
This smaller data set allowed covering larger param-
eter space, and comprehensive exploration of high
frequency data.
(iii) This search improved on previous analyses by par-
titioningthedata in
1
month chunks andlooking for
signals in any contiguous sequence of these chunks.
This enables detections of signals that conform to
ideal signal model over only part of the data. Such
signals could arise because of a glitch, or because of
influence of a long-period companion object.
(iv) The upgrades to the detector, while improving
sensitivity on average, introduced a large number
of detector artifacts, with 20% of frequency range
contaminated by non-Gaussian noise. We addressed
this issue by developing a new
universal statistic
[16]
that provides correct upper limits regardless of
the noise distribution of the underlying data, while
still showing close to optimal performance for
Gaussian data.
We have observed no evidence of gravitational radiation
and have established the most sensitive upper limits to date
in the frequency band 100
1500 Hz. Our smallest 95%
confidence level upper limit on worst-case (linearly polar-
ized) strain amplitude
h
0
is
9
.
7
×
10
25
near 169 Hz, while
at the high end of our frequency range we achieve a worst-
case upper limit of
5
.
5
×
10
24
. Both cases refer to all sky
locations and entire range of frequency derivative values.
II. LIGO INTERFEROMETERS AND
S6 SCIENCE RUN
The LIGO gravitational wave network consists of two
observatories, one in Hanford, Washington and the other in
Livingston, Louisiana, separated by a 3000 km baseline.
During the S6 run each site housed one suspended
interferometer with 4 km long arms.
While the sixth science run spanned a
15
months
period of data acquisition, this analysis used only data from
GPS 951534120 (2010 Mar 02 03:01:45 UTC) through
GPS 971619922 (2010 Oct 20 14:25:07 UTC), for which
strain sensitivity was best. Since interferometers sporadi-
cally fall out of operation (
lose lock
) due to environ-
mental or instrumental disturbances or for scheduled
maintenance periods, the data set was not contiguous.
The Hanford interferometer H1 had a duty factor of 53%,
while the Livingston interferometer L1 had a duty factor of
51%. The strain sensitivity was not uniform, exhibiting a
50%
daily variation from anthropogenic activity as well
as gradual improvement toward the end of the run
[17,18]
.
Nonstationarity of noise was especially severe at
frequencies below 100 Hz, and since the average detector
sensitivity for such frequencies was not significantly better
than that observed in the longer S5 run
[3]
, this search was
restricted to frequencies above 100 Hz.
A detailed description of the instruments and data can be
found in
[19]
.
III. THE SEARCH FOR CONTINUOUS
GRAVITATIONAL RADIATION
A. Overview
In this paper we assume a classical model of a spinning
neutron star with a rotating quadrupole moment that
B. P. ABBOTT
et al.
PHYSICAL REVIEW D
94,
042002 (2016)
042002-6
produces circularly polarized gravitational radiation along
the rotation axis and linearly polarized radiation in the
directions perpendicular to the rotation axis. The linear
polarization is the worst case as such signals contribute the
smallest amount of power to the detector.
The strain signal template is assumed to be
h
ð
t
Þ¼
h
0

F
þ
ð
t;
α
0
;
δ
0
;
ψ
Þ
1
þ
cos
2
ð
ι
Þ
2
cos
ð
Φ
ð
t
ÞÞ
þ
F
×
ð
t;
α
0
;
δ
0
;
ψ
Þ
cos
ð
ι
Þ
sin
ð
Φ
ð
t
ÞÞ

;
ð
1
Þ
where
F
þ
and
F
×
characterize the detector responses to
signals with
þ
and
×
quadrupolar polarizations
[1
3]
,
the sky location is described by right ascension
α
0
and
declination
δ
0
, the inclination of the source rotation axis to
the line of sight is denoted
ι
, and the phase evolution of the
signal is given by the formula
Φ
ð
t
Þ¼
2
π
ð
f
source
·
ð
t
t
0
Þþ
f
ð
1
Þ
·
ð
t
t
0
Þ
2
=
2
Þþ
φ
;
ð
2
Þ
with
f
source
being the source frequency and
f
ð
1
Þ
denoting
the first frequency derivative (which, when negative, is
termed the
spindown
). We use
t
to denote the time in the
Solar System barycenter frame. The initial phase
φ
is
computed relative to reference time
t
0
. When expressed as a
function of local time of ground-based detectors Eq.
(2)
acquires sky-position-dependent Doppler shift terms. We
use
ψ
to denote the polarization angle of the projected
source rotation axis in the sky plane.
The search has two main components. First, the main
PowerFlux
algorithm
[1
3,20
22]
was run to establish
upper limits and produce lists of outliers with signal-to-
noise ratio (SNR) greater than 5. Next, the
Loosely
Coherent
detection pipeline
[3,15,23]
was used to reject
or confirm collected outliers.
Both algorithms calculate power for a bank of signal
model templates and compute upper limits and signal-to-
noise ratios for each template based on comparison to
templates with nearby frequencies and the same sky
location and spindown. The input time series is broken
into 50% overlapping 1800 s long segments which are
Hann windowed and Fourier transformed. The resulting
short Fourier transforms (SFTs) are arranged into an input
matrix with time and frequency dimensions. The power
calculation can be expressed as a bilinear form of the input
matrix
f
a
t;f
g
:
P
½
f
X
t
1
;t
2
a
t
1
;f
þ
δ
f
ð
t
1
Þ
a

t
2
;f
þ
δ
f
ð
t
2
Þ
K
t
1
;t
2
;f
ð
3
Þ
Here
δ
f
ð
t
Þ
denotes the detector frame frequency drift due to
the effects from both Doppler shifts and the first frequency
derivative. The sum is taken over all times
t
corresponding
to the midpoint of the short Fourier transform time interval.
The kernel
K
t
1
;t
2
;f
includes the contribution of time
dependent SFT weights, antenna response, signal polari-
zation parameters and relative phase terms
[15,23]
.
The main semi-coherent PowerFlux algorithm uses a
kernel with main diagonal terms only and is very fast.
The Loosely Coherent algorithms increase coherence time
while still allowing for controlled deviation in phase
[15]
.
This is done by more complicated kernels that increase
effective coherence length.
The effective coherence length is captured in a parameter
δ
, which describes the amount of phase drift that the kernel
allows between SFTs, with
δ
¼
0
corresponding to a fully
coherent case, and
δ
¼
2
π
corresponding to incoherent
power sums.
Depending on the terms used, the data from different
interferometers can be combined incoherently (such as in
stages 0 and 1, see Table
II
) or coherently (as used in stages
2, 3 and 4). The coherent combination is more computa-
tionally expensive but provides much better parameter
estimation.
The upper limits (Fig.
1
) are reported in terms of the
worst-case value of
h
0
(which applies to linear polarizations
with
ι
¼
π
=
2
) and for the most sensitive circular polariza-
tion (
ι
¼
0
or
π
). As described in the previous paper
[3]
, the
pipeline does retain some sensitivity, however, to non-
general-relativity GW polarization models, including a
longitudinal component, and to slow amplitude evolution.
The 95% confidence level upper limits (see Fig.
1
)
produced in the first stage are based on the overall noise
level and largest outlier in strain found for every template
in each 0.25 Hz band in the first stage of the pipeline. The
0.25 Hz bands are analyzed by separate instances of
PowerFlux
[3]
. A followup search for detection is carried
out for high-SNR outliers found in the first stage. Certain
frequency ranges (Table
I
) were excluded from the analysis
because of gross contamination by detector artifacts.
B. Universal statistics
The detector sensitivity upgrades introduced many
artifacts, so that in 20% of the sensitive frequency range
the noise follows non-Gaussian distributions which, in
addition, are unknown. As the particular non-Gaussian
distribution can vary widely depending on particular
detector artifacts, the ideal estimate based on full knowl-
edge of the distribution is not usually available. In the
previous analysis
[1
3]
, the frequency bands where the
noise distribution was non-Gaussian were not used to put
upper limits. However, in the present case this approach
would have resulted in excluding most of the frequency
bands below 400 Hz and many above 400 Hz; even though
the average strain sensitivity in many of these frequency
bands is better than in the past.
To make use of the entire spectrum, we used in this work
the
Universal statistic
algorithm
[16]
for establishing upper
limits. The algorithm is derived from the Markov inequality
COMPREHENSIVE ALL-SKY SEARCH FOR PERIODIC
...
PHYSICAL REVIEW D
94,
042002 (2016)
042002-7