J/AJ/151/142 Five years of blazar observations with VERITAS (Archambault+, 2016)
Upper limits from five years of blazar observations with the VERITAS Cherenkov
telescopes.
Archambault S., Archer A., Benbow W., Bird R., Biteau J., Buchovecky M.,
Buckley J.H., Bugaev V., Byrum K., Cerruti M., Chen X., Ciupik L.,
Connolly M.P., Cui W., Eisch J.D., Errando M., Falcone A., Feng Q.,
Finley J.P., Fleischhack H., Fortin P., Fortson L., Furniss A.,
Gillanders G.H., Griffin S., Grube J., Gyuk G., Hutten M., Hakansson N.,
Hanna D., Holder J., Humensky T.B., Johnson C.A., Kaaret P., Kar P.,
Kelley-Hoskins N., Kertzman M., Kieda D., Krause M., Krennrich F.,
Kumar S., Lang M.J., Maier G., McArthur S., McCann A., Meagher K.,
Moriarty P., Mukherjee R., Nguyen T., Nieto D., O'Faolain de Bhroithe A.,
Ong R.A., Otte A.N., Park N., Perkins J.S., Pichel A., Pohl M., Popkow A.,
Pueschel E., Quinn J., Ragan K., Reynolds P.T., Richards G.T., Roache E.,
Rovero A.C., Santander M., Sembroski G.H., Shahinyan K., Smith A.W.,
Staszak D., Telezhinsky I., Tucci J.V., Tyler J., Vincent S., Wakely S.P.,
Weiner O.M., Weinstein A., Williams D.A., Zitzer B.,
(the the Veritas collaboration), Fumagalli M., Prochaska J.X.
<Astron. J., 151, 142-142 (2016)>
=2016AJ....151..142A 2016AJ....151..142A (SIMBAD/NED BibCode)
ADC_Keywords: BL Lac objects ; QSOs ; Gamma rays ; Redshifts ; Ephemerides ;
Spectra, optical
Keywords: BL Lacertae objects: general - galaxies: active -
γ rays: galaxies - radiation mechanisms: non-thermal
Abstract:
Between the beginning of its full-scale scientific operations in 2007
and 2012, the VERITAS Cherenkov telescope array observed more than
130 blazars; of these, 26 were detected as very-high-energy (VHE;
E>100 GeV) γ-ray sources. In this work, we present the analysis
results of a sample of 114 undetected objects. The observations
constitute a total live-time of ∼570 hr. The sample includes several
unidentified Fermi-Large Area Telescope (LAT) sources (located at high
Galactic latitude) as well as all the sources from the second
Fermi-LAT catalog (Nolan et al. 2012, J/ApJS/199/31) that are
contained within the field of view of the VERITAS observations. We
have also performed optical spectroscopy measurements in order to
estimate the redshift of some of these blazars that do not have
spectroscopic distance estimates. We present new optical spectra from
the Kast instrument on the Shane telescope at the Lick observatory for
18 blazars included in this work, which allowed for the successful
measurement or constraint on the redshift of four of them. For each of
the blazars included in our sample, we provide the flux upper limit in
the VERITAS energy band. We also study the properties of the
significance distributions and we present the result of a stacked
analysis of the data set, which shows a 4σ excess.
Description:
In this paper, we present the results of the analysis of most of the
non-detected blazars observed by VERITAS from 2007 (the beginning of
full-scale scientific operations) to 2012 August (before the upgrade
of the VERITAS array, see Kieda 2013arXiv1308.4849D 2013arXiv1308.4849D).
The VERITAS (Very Energetic Radiation Imaging Telescope Array System)
telescope array is composed of four IACTs of 12 m diameter each, located
at the Fred Lawrence Whipple Observatory, on the slopes of Mount Hopkins,
in southern Arizona (31°40'N, 110°57'W). Each telescope has a
segmented mirror that focuses light onto a camera composed of 499
photomultipliers located at the focal plane. The instrument FOV is
3.5°. For further details on the VERITAS instrument, see Holder et al.
(2006APh....25..391H 2006APh....25..391H) and Holder (2011ICRC...12..137H 2011ICRC...12..137H). The VERITAS
observations here have an average length of 20 minutes (referred to as
a run), before switching targets or wobble directions.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 112 184 List of Sources Observed by VERITAS
table2.dat 112 43 List of Known VHE Sources Observed but Not
Detected by VERITAS in 2007-2012
table3.dat 102 21 List of 2FGL Sources in the VERITAS Field of
View of Sources Listed in Tables 1 and 2
table4.dat 95 82 Analysis Results and Flux Upper Limits for
the Non-detected AGNs Observed by VERITAS
table5.dat 95 11 Results and Upper Limits for the Known VHE
Sources
table6.dat 95 21 Results and Upper Limits for the 2FGL Sources
in the VERITAS Field of View
table7.dat 80 28 Blazars Observed at the Lick Observatory using
the Shane 3 m Kast Spectrograph
--------------------------------------------------------------------------------
See also:
III/175 : Optical spectroscopy of radio sources (Stickel+, 1989-94)
IX/15 : Einstein EMSS Survey (Gioia+ 1990, Stocke+ 1991)
VII/158 : Revised and Updated Catalog of Quasi-stellar Objects (Hewitt+ 1993)
VIII/34 : Parkes Half-Jansky Flat-Spectrum Sample (Drinkwater + 1997)
IX/32 : ROSAT Bright Survey (Fischer+, 1998-2000)
J/MNRAS/277/1477 : A catalogue of BL Lacertae objects (Padovani+ 1995)
J/A+A/323/739 : ROSAT detected quasars. II. (Brinkmann+ 1997)
J/ApJ/525/127 : RGB sample of BL Lacertae objects
(Laurent-Muehleisen+, 1999)
J/ApJS/126/133 : The FIRST bright quasar survey. II. (White+, 2000)
J/ApJS/129/435 : NORAS galaxy cluster survey. I. (Bohringer+, 2000)
J/ApJS/129/547 : RBSC-NVSS sample. I. (Bauer+, 2000)
J/ApJS/150/181 : Redshifts of 110 radio-loud AGNs (Eracleous+, 2004)
J/A+A/434/385 : X-ray/radio data of high energy peaked BL Lacs
(Giommi+, 2005)
J/ApJ/626/95 : Gamma-ray blazar candidates (Sowards-Emmerd+, 2005)
J/A+A/445/441 : SED of BL Lacertae objects (Nieppola+, 2006)
J/A+A/470/787 : High energy peaked BL Lacs optical spectros.
(Piranomonte+, 2007)
J/A+A/472/699 : ROXA: multi-frequency large sample of blazars
(Turriziani+, 2007)
J/ApJ/667/673 : FIRST-2MASS red quasar survey (Glikman+, 2007)
J/ApJS/175/97 : CGRaBS: survey of γ-ray blazar candidates
(Healey+, 2008)
J/AJ/139/390 : Optically selected BL Lac objects from SDSS-DR7
(Plotkin+, 2010)
J/ApJ/709/1407 : SED of the Fermi blazars (Li+, 2010)
J/ApJ/716/30 : SED of Fermi bright blazars (Abdo+, 2010)
J/ApJS/188/405 : Fermi-LAT first source catalog (1FGL) (Abdo+, 2010)
J/ApJ/742/27 : 15GHz and jet properties of MOJAVE blazars (Lister+, 2011)
J/MNRAS/416/2840 : The 2M++ galaxy redshift catalogue (Lavaux+, 2011)
J/A+A/538/A26 : BL Lac objects beyond z=1.3 (Rau+, 2012)
J/A+A/541/A160 : Planck + X/γ observations of blazars (Giommi+, 2012)
J/ApJ/748/49 : Optical spectroscopy of 1LAC broad-line blazars
(Shaw+, 2012)
J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)
J/ApJ/764/135 : Spectroscopic redshifts of BL Lac objects (Shaw+, 2013)
J/A+A/570/A126 : XShooter spectrum of 4 BL Lacs (Landoni+, 2014)
J/ApJ/780/73 : Redshifts of BL Lac objects from Fermi (Ajello+, 2014)
J/ApJ/833/117 : VERITAS gamma-ray TeV LCs of 6 blazars (Turley+, 2016)
Byte-by-byte Description of file: table1.dat table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 21 A21 --- Name Simbad source name
23- 24 I2 h RAh Simbad Hour of Right Ascension (J2000)
26- 27 I2 min RAm Simbad Minute of Right Ascension (J2000)
29- 32 F4.1 s RAs Simbad Second of Right Ascension (J2000)
34 A1 --- DE- Simbad Sign of the Declination (J2000)
35- 36 I2 deg DEd Simbad Degree of Declination (J2000)
38- 39 I2 arcmin DEm Simbad Arcminute of Declination (J2000)
41- 42 I2 arcsec DEs Simbad Arcsecond of Declination (J2000)
44 A1 --- l_z [>] Limit flag on z
45- 50 F6.4 --- z [0.028/1.28]? Redshift
51 A1 --- u_z [:] Uncertainty flag on z
52 A1 --- n_z [u] Note on z (u=Unconstrained redshift)
(only in table 1)
54- 55 I2 --- r_z [1/53]? Reference for z (G1)
57- 60 A4 --- Type Blazar classification (G2)
61 A1 --- n_Type [?] Note on Type (?=Blazar of unknown type)
(only in table 1)
63- 68 A6 --- r_Type Reference for Type (only in table 1) (G3)
70- 73 F4.1 h Exp [0.3/36]? VERITAS dead-time corrected exposure
(1)
75- 76 I2 deg theta [3/49]? Average zenith angle of VERITAS
observation θzenith
78- 93 A16 --- MJD Modified Julian Date(s) of VERITAS observation
and on which basis the source was selected as a
very-high-energy (VHE) candidate (JD-2450000)
95-104 A10 --- Ref Source selection reference(s) (2)
106-112 A7 --- Detec VHE detection reference(s) (only in table 2) (3)
--------------------------------------------------------------------------------
Note (1): The exposure values are all corrected for dead time, and represent
the effective live-time of VERITAS observations.
Note (2): Reference as follows:
1FGL = Abdo et al. (2010, J/ApJS/188/405);
2FGL = Nolan et al. (2012, J/ApJS/199/31);
B97 = Brinkmann et al. (1997, J/A+A/323/739);
CG02 = Costamante & Ghisellini (2002A&A...384...56C 2002A&A...384...56C);
C07 = Costamante (2007Ap&SS.309..487C 2007Ap&SS.309..487C);
F04 = Falcone et al. (2004ApJ...613..710F 2004ApJ...613..710F);
M01 = Mukherjee (2001AIPC..558..324M 2001AIPC..558..324M);
N06 = Nieppola et al. (2006, J/A+A/445/441);
ROXA = Turriziani et al. (2007, J/A+A/472/699);
S96 = Stecker et al. (1996ApJ...473L..75S 1996ApJ...473L..75S);
SHBL = Giommi et al. (2005, J/A+A/434/385);
P00 = Perlman (2000AIPC..515...53P 2000AIPC..515...53P);
P02 = Padovani et al. (2002ApJ...581..895P 2002ApJ...581..895P);
ToO = Target of Opportunity.
Note (3): Reference as follows:
1 = Aleksic et al. (2015MNRAS.446..217A 2015MNRAS.446..217A);
2 = Aharonian et al. (2008A&A...481L.103A 2008A&A...481L.103A);
3 = Mirzoyan (2014ATel.5768....1M 2014ATel.5768....1M);
4 = Mirzoyan (2014ATel.6062....1M 2014ATel.6062....1M);
5a = Aleksic et al. (2011ApJ...730L...8A 2011ApJ...730L...8A);
5b = Holder (2014ATel.5981....1H 2014ATel.5981....1H);
6a = Albert et al. (2008Sci...320.1752A 2008Sci...320.1752A);
6b = Aleksic et al. (2014A&A...567A..41A 2014A&A...567A..41A);
7a = Abramowski et al. (2013A&A...554A.107H 2013A&A...554A.107H);
7b = Aleksic et al. (2014A&A...569A..46A 2014A&A...569A..46A);
8 = Cortina (2013ATel.5080....1C 2013ATel.5080....1C);
9 = Aleksic et al. (2014A&A...572A.121A 2014A&A...572A.121A);
10 = Holder (2014ATel.6849....1H 2014ATel.6849....1H);
11 = Aleksic et al. (2012A&A...539A.118A 2012A&A...539A.118A).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- Name Source name (2FGL JHHMM.m+DDMM)
19- 39 A21 --- CName Counterpart name
41- 42 I2 h RAh Hour of Right Ascension (J2000) (1)
44- 45 I2 min RAm Minute of Right Ascension (J2000) (1)
47- 50 F4.1 s RAs Second of Right Ascension (J2000) (1)
52 A1 --- DE- Sign of the Declination (J2000) (1)
53- 54 I2 deg DEd Degree of Declination (J2000) (1)
56- 57 I2 arcmin DEm Arcminute of Declination (J2000) (1)
59- 60 I2 arcsec DEs Arcsecond of Declination (J2000) (1)
62 A1 --- l_z [>] Limit flag on z
63- 67 F5.3 --- z [0.37/2.06]? Redshift
68 A1 --- n_z [u] Note on z (u=Unconstrained redshift)
70- 71 I2 --- r_z [6/53]? Reference for z (G1)
73- 76 A4 --- Type Blazar classification (G2)
77 A1 --- n_Type [?] Note on Type (?=Blazar of unknown type)
79- 80 I2 --- r_Type [29/48]? Reference for Type (G3)
82-102 A21 --- FOV Source name (from table 1 and 2) in the field
of view of this 2FGL source
--------------------------------------------------------------------------------
Note (1): Coordinates are provided for the counterpart. If the Fermi-LAT source
is not associated with any lower-energy blazar, coordinates from
the 2FGL catalog are given instead.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat table5.dat table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 21 A21 --- Name Source name
23- 27 F5.2 --- sigma [-1.98/3.49] Source significance
(in σ units)
29- 32 I4 --- CntON [32/7515] Number of ON (source) counts
34- 38 I5 --- CntOFF [190/64132] Number of OFF (background)
counts
40- 45 F6.4 --- alpha [0.037/0.267] Ratio of the ON over OFF
region size α
47- 51 F5.3 TeV Eth [0.138/0.501] Threshold energy of the
analysis Eth
53- 57 F5.3 TeV Edec [0.226/0.829] Decorrelation energy
Edec (1)
59- 64 F6.2 10-12/cm2/s/TeV UL-Edec [1.6/102] Differential flux upper limit
at Edec
66- 69 F4.1 Crab UL-Eth [0.9/17.4] Integral flux upper limit
(above Eth) (2)
71- 77 E7.5 --- UL/Phi1 ? Ratio between the VERITAS differential
upper limit and the extrapolation of
the Fermi-LAT detection (ΦHE,
evaluated at Edec)
79- 85 E7.5 --- UL/Phi2 ? Ratio between the VERITAS differential
upper limit and the extrapolation of
the Fermi-LAT detection (ΦHE,
evaluated at Edec)
87- 91 F5.3 --- z1 [0.086/1.05]? Redshift associated
to UL/Phi1
93- 95 F3.1 --- z2 [0.5]? Redshift associated to UL/Phi2
--------------------------------------------------------------------------------
Note (1): The energy at which the upper limit on the very-high-energy (VHE) flux
estimate depends the least on the spectral index.
Note (2): Provided in Crab units, following Hillas et al. 1998ApJ...503..744H 1998ApJ...503..744H.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 21 A21 --- Name Target name (1)
23- 33 A11 "date" Date UT Observation date
35- 38 I4 d MJD [5421/6958] Modified Julian Date of observation
(JD-2450000)
40- 43 I4 s ExpTime [900/5400] Exposure time
45- 49 F5.1 --- S/Nblue [0.4/111]? Average signal-to-noise per pixel
for the blue side CCD, between 3500 and
5400Å
50- 52 A3 --- n_S/Nblue [n/a ] Note on S/Nblue (n/a=not analyzed)
54- 58 F5.1 --- S/Nred [4.3/229] Average signal-to-noise per pixel for
the red side CCD, between 5700 and 6800Å
60- 69 A10 --- Star Standard star name
71 A1 --- l_z [>] Limit flag on z
72- 76 F5.3 --- z [0.23/0.267]? Redshift
78- 80 F3.1 --- Fig [2.1/2.6]? Figure number corresponding in the
paper, if applicable (2)
--------------------------------------------------------------------------------
Note (1): See tables 1 and 2 for coordinates.
Note (2): Several targets have spectra from multiple nights. Only one spectrum
per target is shown in the corresponding figure.
--------------------------------------------------------------------------------
Global notes:
Note (G1): Reference as follows:
1 = Fischer et al. (1998, Cat. IX/32);
2 = Rau et al. (2012, J/A+A/538/A26);
3 = Laurent-Muehleisen et al. (1998ApJS..118..127L 1998ApJS..118..127L);
4 = Perlman et al. (1996ApJS..104..251P 1996ApJS..104..251P);
5 = Lawrence et al. (1986AJ.....91..494L 1986AJ.....91..494L);
6 = Shaw et al. (2013, J/ApJ/764/135);
7 = Meisner & Romani (2010ApJ...712...14M 2010ApJ...712...14M);
8 = Marcha et al. (1996MNRAS.281..425M 1996MNRAS.281..425M);
9 = Bohringer et al. (2000, J/ApJS/129/435);
10 = Sbarufatti et al. (2005AJ....129..559S 2005AJ....129..559S);
11 = Cohen et al. (1987ApJ...318..577C 1987ApJ...318..577C);
12 = This work;
13 = Piranomonte et al. (2007, Cat. J/A+A/470/787);
14 = Bauer et al. (2000, J/ApJS/129/547);
15 = Lavaux & Hudson (2011, J/MNRAS/416/2840);
16 = Carswell et al. (1974ApJ...190L.101C 1974ApJ...190L.101C);
17 = Falomo (1991AJ....102.1991F 1991AJ....102.1991F);
18 = Osterbrock & Dahari (1983ApJ...273..478O 1983ApJ...273..478O);
19 = Stickel et al. (1989, Cat. III/175);
20 = Plotkin et al. (2010, J/AJ/139/390);
21 = Nilsson et al. (2003A&A...400...95N 2003A&A...400...95N);
22 = Stocke et al. (1991, Cat. IX/15);
23 = Cao et al. (1999A&AS..135..243C 1999A&AS..135..243C);
24 = Sbarufatti et al. (2009ATel.2123....1S 2009ATel.2123....1S);
25 = Burbidge et al. (1977ApJS...33..113B 1977ApJS...33..113B);
26 = White et al. (2000, J/ApJS/126/133);
27 = Padovani & Giommi (1995, J/MNRAS/277/1477);
28 = Sandrinelli et al. (2013AJ....146..163S 2013AJ....146..163S);
29 = Jannuzi et al. (1993ApJS...85..265J 1993ApJS...85..265J);
30 = Henstock et al. (1997MNRAS.290..380H 1997MNRAS.290..380H);
31 = Shaw et al. (2009ApJ...704..477S 2009ApJ...704..477S);
32 = Eracleous & Halpern (2004, J/ApJS/150/181);
33 = Stickel et al. (1988A&A...191L..16S 1988A&A...191L..16S);
34 = Sbarufatti et al. (2006AJ....132....1S 2006AJ....132....1S);
35 = Smith et al. (1976PASP...88..621S 1976PASP...88..621S);
36 = Falomo & Kotilainen (1999A&A...352...85F 1999A&A...352...85F);
37 = Private communication from Perlman, see Falomo & Kotilainen
(1999A&A...352...85F 1999A&A...352...85F);
38 = Bade et al. (1994A&A...286..381B 1994A&A...286..381B);
39 = Burbidge & Kinman (1966ApJ...145..654B 1966ApJ...145..654B);
40 = Marziani et al. (1996ApJS..104...37M 1996ApJS..104...37M);
41 = Thompson et al. (1990PASP..102.1235T 1990PASP..102.1235T);
42 = Landoni et al. (2014, J/A+A/570/A126);
43 = Aleksic et al. (2014A&A...572A.121A 2014A&A...572A.121A);
44 = Shaw et al. (2012, J/ApJ/748/49);
45 = Kraus & Gearhart (1975AJ.....80....1K 1975AJ.....80....1K);
46 = Halpern et al. (1986ApJ...302..711H 1986ApJ...302..711H);
47 = Plotkin et al. (2010, J/AJ/139/390);
48 = Healey et al. (2008, J/ApJS/175/97);
49 = Hewitt & Burbidge (1993, Cat. VII/158);
50 = White et al. (1988ApJ...327..561W 1988ApJ...327..561W);
51 = Glikman et al. (2007, J/ApJ/667/673);
52 = Afanas'Ev et al. (2005, 2005ARep...49..374A 2005ARep...49..374A);
53 = Sowards-Emmerd et al. (2005, J/ApJ/626/95).
Note (G2): Classification as follows:
FSRQ = Flat-spectrum radio-quasar;
HBL = High-frequency-peaked BL Lac object;
IBL = Intermediate-frequency-peaked BL Lac object;
LBL = Low-frequency-peaked BL Lac object;
NLS1 = Narrow-line Seyfert-1 galaxy;
Sy1 = Seyfert-1 galaxy.
Note (G3): Reference as follows:
29 = Shaw et al. (2012, J/ApJ/748/49);
30 = Kraus & Gearhart (1975AJ.....80....1K 1975AJ.....80....1K);
31 = Ghisellini et al. (2011MNRAS.411..901G 2011MNRAS.411..901G);
32 = Hewitt & Burbidge (1993, Cat. VII/158);
33 = Plotkin et al. (2010, J/AJ/139/390);
34 = Glikman et al. (2007, J/ApJ/667/673);
35 = Afanas'Ev et al. (2005, 2005ARep...49..374A 2005ARep...49..374A);
36 = Maselli et al. (2010A&A...512A..74M 2010A&A...512A..74M);
37 = Laurent-Muehleisen et al. (1999, J/ApJ/525/127);
38 = Giommi et al. (2012, J/A+A/541/A160);
39 = Chandra et al. (2012ApJ...746...92C 2012ApJ...746...92C);
40 = Ackermann et al. (2012ApJ...751..159A 2012ApJ...751..159A);
41 = Nieppola et al. (2006, J/A+A/445/441);
42 = Abdo et al. (2009ApJ...707L.142A 2009ApJ...707L.142A);
43 = Massaro et al. (2012ApJ...750..138M 2012ApJ...750..138M);
44 = Rani et al. (2011MNRAS.417.1881R 2011MNRAS.417.1881R);
45 = Osterbrock & Dahari (1983ApJ...273..478O 1983ApJ...273..478O);
46 = Impey & Neugebauer (1988AJ.....95..307I 1988AJ.....95..307I);
47 = Cornwell et al. (1986JApA....7..119C 1986JApA....7..119C);
48 = Ajello et al. (2014, J/ApJ/780/73);
49 = Massaro et al. (2003A&A...399...33M 2003A&A...399...33M);
50 = Padovani et al. (2002ApJ...581..895P 2002ApJ...581..895P);
51 = Komossa et al. (2006AJ....132..531K 2006AJ....132..531K);
52 = Li et al. (2010, J/ApJ/709/1407);
53 = Drinkwater et al. (1997, Cat. VIII/34);
54 = Abdo et al. (2010, J/ApJ/716/30);
55 = Lister et al. (2011, J/ApJ/742/27);
56 = Smith et al. (1976PASP...88..621S 1976PASP...88..621S).
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 04-Apr-2018