J/ApJS/209/14 The Swift/BAT hard X-ray transient monitor (Krimm+, 2013)
The Swift/BAT hard X-ray transient monitor.
Krimm H.A., Holland S.T., Corbet R.H.D., Pearlman A.B., Romano P.,
Kennea J.A., Bloom J.S., Barthelmy S.D., Baumgartner W.H., Cummings J.R.,
Gehrels N., Lien A.Y., Markwardt C.B., Palmer D.M., Sakamoto T.,
Stamatikos M., Ukwatta T.N.
<Astrophys. J. Suppl. Ser., 209, 14 (2013)>
=2013ApJS..209...14K 2013ApJS..209...14K
ADC_Keywords: X-ray sources ; Surveys ; Binaries, X-ray ; Active gal. nuclei
Mission_Name: Swift
Keywords: black hole physics - pulsars: general - surveys - X-rays: binaries -
X-rays: general
Abstract:
The Swift/Burst Alert Telescope (BAT) hard X-ray transient monitor
provides near real-time coverage of the X-ray sky in the energy range
15-50 keV. The BAT observes 88% of the sky each day with a detection
sensitivity of 5.3 mCrab for a full-day observation and a time
resolution as fine as 64s. The three main purposes of the monitor are
(1) the discovery of new transient X-ray sources, (2) the detection of
outbursts or other changes in the flux of known X-ray sources, and (3)
the generation of light curves of more than 900 sources spanning over
eight years. The primary interface for the BAT transient monitor is a
public Web site. Between 2005 February 12 and 2013 April 30, 245
sources have been detected in the monitor, 146 of them persistent and
99 detected only in outburst. Among these sources, 17 were previously
unknown and were discovered in the transient monitor. In this paper,
we discuss the methodology and the data processing and filtering for
the BAT transient monitor and review its sensitivity and exposure. We
provide a summary of the source detections and classify them according
to the variability of their light curves. Finally, we review all new
BAT monitor discoveries. For the new sources that are previously
unpublished, we present basic data analysis and interpretations.
Description:
The Swift/BAT hard X-ray transient monitor has provided a continuous
historical record of the variations in 15-50keV X-ray flux of several
hundred astrophysical hard X-ray sources from 2005 February 12 to the
present time (2013 April 30), and its function is expected to continue
as long as the Swift/BAT telescope is operational. In total, 245 X-ray
sources are considered to have been detected in the BAT monitor during
this period. A source is considered detected if it meets one of three
criteria. The first two are systematized: either the mean rate M is
≥3mCrab or the peak rate P7 is >30mCrab and ≥7σ. Simple
application of these two criteria finds 223 sources. An additional 22
sources were reported to be in outburst either by Swift/BAT or by
another group and then subsequently confirmed through detection in the
BAT monitor. The detected sources are divided according to their
variability, V, excess variance, Fvar, and M into four categories:
outburst, flaring, steady, and variable. A subset of the variable
sources are further classified as periodic.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 110 245 Sources detected in the BAT transient monitor
table6.dat 108 17 Localizations of Swift/BAT discovered transients
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See also:
J/ApJS/207/19 : Hard X-ray from Swift-BAT 2004-2010 (Baumgartner+, 2013)
J/ApJS/201/34 : Swift-INTEGRAL X-ray (SIX) survey (Bottacini+, 2012)
J/A+A/545/A101 : Spectra of 29 Swift/BAT optical counterparts (Parisi+, 2012)
J/ApJ/740/87 : Chandra observations of radio transients (Croft+, 2011)
J/ApJ/739/57 : Ultra hard X-ray AGNs in the Swift/BAT survey (Koss+, 2011)
J/ApJS/186/378 : Hard X-ray survey from Swift-BAT 2004-2006 (Tueller+, 2010)
J/A+A/524/A64 : The 54-month Palermo BAT-survey catalogue (Cusumano+, 2010)
J/A+A/520/A47 : Blazars in the Swift-BAT hard X-ray sky (Maselli+, 2010)
J/A+A/510/A48 : Palermo Swift-BAT Hard X-ray Catalogue (Cusumano+, 2010)
J/ApJ/673/96 : BAT X-ray Survey - III (Ajello+, 2008)
J/A+A/462/1081 : BVRIJHK light curves of 4U 0115+63/V635 Cas (Reig+, 2007)
J/ApJ/643/356 : Transient X-ray sources in M31 (Williams+, 2006)
J/A+A/407/1039 : X-ray power spectra of Cygnus X-1 (Pottschmidt+, 2003)
J/PAZh/26/27 : Cyg X-1 (V1357) variability in 1995-1996 (Karitskaya+, 2000)
http://swift.gsfc.nasa.gov/results/transients : Swift/BAT Hard X-ray
Transient Monitor home page
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 23 A23 --- Name Source name
25 A1 --- n_Name [n] n: discovered transient
27- 33 F7.3 deg RAdeg Right ascension in decimal degrees (J2000)
35- 41 F7.3 deg DEdeg Declination in decimal degrees (J2000)
43- 56 A14 --- OType Source type (XRB, HMXB, LMXB, Sy, etc)
58- 67 A10 --- Class Classification (Flaring, Outburst, Periodic,
Steady or Variable)
69 A1 --- f_Class [e] e: source detected by hand (1)
71- 76 F6.1 mCrab M [-0.5/1226] The mean flux (M) in the
17-52kev band
78- 83 F6.1 mCrab P7 [0/5266] The peak count rate (P7) in
the 15-50keV band (2)
85- 91 F7.2 --- V [0.7/1357] Scaled variability index (3)
93-100 F8.3 --- Fvar [-5/1113] Normalized excess variance Fvar (4)
102-110 F9.5 --- e_Fvar [0.0002/193] Error on excess variance
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Note (1): A review of the Astronomer's Telegrams finds that there are 22
additional sources that are not in the list of the 223 selected
sources, but which had significant outbursts during the transient
monitor era. These were found either by integrating monitor results
over periods of longer than a day, by an on board BAT trigger (usually
for a short-duration event), or from an outburst report on the source
from another instrument such as RXTE/PCA, Fermi/LAT, or MAXI. Seven of
these sources are new Swift/BAT discoveries, which are discussed in
Section 4.2 (See also table 6).
Note (2): The peak count rate for days when the source was found at ≥7σ
significance. In this band, 1mCrab corresponds to 0.22ct/cm2/ks.
Note (3): V is defined as [Σ(Fi-Fav)2/vari]/(N-1) (Eq.1) where
vari represents the total variance σi2+σi,syst2.
Note (4): Fvar is defined as
Fvar2=[Σ(Fi-Fav)2/((N-1)-vari/N)]/Fav2 (Eq.2) where
vari represents the total variance σi2+σi,syst2.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Swift Swift source (JHHMM.m+DDMM)
14- 23 F10.6 deg RAdeg Right ascension in decimal degrees (J2000)
25- 26 I2 h RAh Hour of right ascension (J2000)
28- 29 I2 min RAm Minute of right ascension (J2000)
31- 36 F6.3 s RAs Second of right ascension (J2000)
38- 47 F10.6 deg DEdeg Declination in decimal degrees (J2000)
49 A1 --- DE- Sign of declination (J2000)
50- 51 I2 deg DEd Degree of declination (J2000)
53- 54 I2 arcmin DEm Arcminute of declination (J2000)
56- 60 F5.2 arcsec DEs Arcsecond of declination (J2000)
62- 65 F4.2 arcsec Err [0.01/3.5] Error radius, 90% confidence level
67 A1 --- f_Err Flag on Err (1)
69- 78 F10.6 deg GLON Galactic longitude
80- 89 F10.6 deg GLAT Galactic latitude
91-102 A12 --- Inst Instrument (2)
104-108 A5 --- Ref Reference(s) (3)
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Note (1): Flag as follows:
c = The larger dimension of the elliptical error region quoted by Miller-Jones
& Sivakoff (2012ATel.4394....1M 2012ATel.4394....1M).
d = Error radius for Swift J1816.7-1613; J. Halpern (2011, private
communication).
Note (2): Telescope that provided the best position measurement.
Note (3): References as follows:
1 = Greiner et al. 2009ATel.2013....1G 2009ATel.2013....1G
2 = Berger & Chornock 2011ATel.3469....1B 2011ATel.3469....1B
3 = Krimm et al. 2011ATel.3138....1K 2011ATel.3138....1K
4 = Krimm et al. 2011ApJ...735..104K 2011ApJ...735..104K
5 = Krimm et al. 2009ATel.2300....1K 2009ATel.2300....1K
6 = This work
7 = Krimm et al. 2013ATel.4789....1K 2013ATel.4789....1K
8 = Miller-Jones & Sivakoff 2012ATel.4394....1M 2012ATel.4394....1M
9 = Rau et al. 2013ATel.4904....1R 2013ATel.4904....1R
10 = Krimm et al. 2007ApJ...668L.147K 2007ApJ...668L.147K
11 = Halpern & Gotthelf 2008ATel.1457....1H 2008ATel.1457....1H
12 = Greiner et al. 2011ATel.3687....1G 2011ATel.3687....1G
13 = Markwardt et al. 2008ATel.1716....1M 2008ATel.1716....1M
14 = Krimm et al. 2011ATel.3169....1K 2011ATel.3169....1K
15 = Rau et al. 2012ATel.4144....1R 2012ATel.4144....1R
16 = Cenko & Ofek 2012ATel.4146....1C 2012ATel.4146....1C
17 = Krimm et al. 2012ATel.4049....1K 2012ATel.4049....1K
18 = Cenko et al. 2012ApJ...753...77C 2012ApJ...753...77C
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 22-Nov-2013