J/ApJ/765/L26 Swift/BAT ultra-hard X-ray data from GOALS LIRGs (Koss+, 2013)
Studying faint ultra-hard X-ray emission from AGN in GOALS LIRGs with
Swift/BAT.
Koss M., Mushotzky R., Baumgartner W., Veilleux S., Tueller J.,
Markwardt C., Casey C.M.
<Astrophys. J., 765, L26 (2013)>
=2013ApJ...765L..26K 2013ApJ...765L..26K
ADC_Keywords: Galaxies, IR ; Active gal. nuclei ; X-ray sources
Keywords: galaxies: active; X-rays: galaxies
Abstract:
We present the first analysis of the all-sky Swift Burst Alert
Telescope (BAT) ultra-hard X-ray (14-195keV) data for a targeted list
of objects. We find that the BAT data can be studied at
three-times-fainter limits than in previous blind detection catalogs
based on prior knowledge of source positions and using smaller energy
ranges for source detection. We determine the active galactic nucleus
(AGN) fraction in 134 nearby (z<0.05) luminous infrared galaxies
(LIRGs) from the GOALS sample. We find that LIRGs have a higher
detection frequency than galaxies matched in stellar mass and redshift
at 14-195keV and 24-35keV. In agreement with work at other
wavelengths, the AGN detection fraction increases strongly at high IR
luminosity with half of the high-luminosity LIRGs (50%, 6/12,
logLIR/L☉>11.8) detected. The BAT AGN classification shows 97%
(37/38) agreement with Chandra and XMM-Newton AGN classification using
hardness ratios or detection of an iron Kα line. This confirms
our statistical analysis and supports the use of the Swift/BAT all-sky
survey to study fainter populations of any category of sources in the
ultra-hard X-ray band. BAT AGNs in LIRGs tend to show higher column
densities with 40%±9% showing 14-195 keV/2-10 keV hardness flux
ratios suggestive of high or Compton-thick column densities
(logNH>24/cm2), compared to only 12%±5% of non-LIRG BAT AGNs. We
also find that using specific energy ranges of the BAT detector can
yield additional sources over total band detections with 24% (5/21) of
detections in LIRGs at 24-35keV not detected at 14-195keV.
Description:
We selected a sample of nearby luminous infrared galaxies (LIRGs)
(z<0.05) in the Earth's Northern Hemisphere (DEC>-25) from GOALS
(Armus et al. 2009PASP..121..559A 2009PASP..121..559A; Great Observatories All Sky LIRG
Survey) We recomputed GOALS IR luminosities based on SED fitting using
IRAS data and a model joining a modified, single dust temperature
graybody that approximates hot-dust emission from AGN heating.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 64 134 Properties of GOALS luminous infrared galaxies
(LIRGs)
--------------------------------------------------------------------------------
See also:
J/ApJS/206/1 : Mid-IR properties of GOALS nearby LIRGs (Stierwalt+, 2013)
J/ApJ/753/104 : AGN identifications from AKARI and Swift (Matsuta+, 2012)
J/ApJ/754/45 : IR properties of Swift/BAT X-ray AGNs (Ichikawa+, 2012)
J/ApJ/746/L22 : Dual AGNs in the nearby Universe (Koss+, 2012)
J/ApJ/739/57 : Ultra hard X-ray AGNs in the Swift/BAT survey (Koss+, 2011)
J/ApJ/728/58 : Swift-BAT survey of AGNs (Burlon+, 2011)
J/ApJS/186/378 : Hard X-ray survey from Swift-BAT 2004-2006 (Tueller+, 2010)
J/ApJ/720/555 : COLA. III. AGN in compact IR galaxies (Parra+, 2010)
J/ApJ/715/572 : GOALS UV and FIR properties (Howell+, 2010)
J/ApJ/701/587 : A deep HST imaging survey. II. QUEST QSOs (Veilleux+, 2009)
J/ApJ/633/L77 : SWIFT/BAT detections of AGN (Markwardt+, 2005)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 1 A1 --- Det Swift/BAT detection; (Y)es or (N)o
3- 18 A16 --- Name Galaxy name
20 A1 --- n_Name [ab] a=Mrk 231; b=Mrk 273
22- 26 F5.2 [Lsun] logLIR [10.6/12.5] log of 8-1000um IR luminosity (2)
28- 31 F4.1 --- SNR1 ? Signal-to-noise ratio in 14-195 keV band (3)
33- 36 F4.1 --- SNR2 ? Signal-to-noise ratio in 24-35 keV band
38 A1 --- l_logL [<] logL is an upper limit (4)
39- 43 F5.2 [10-7W] logL [41/44] Log 14-195 keV X-ray luminosity; erg/s
45- 48 F4.2 [10-7W] e_logL ? Lower 1σ limit uncertainty in logL
50- 53 F4.2 [10-7W] E_logL ? Upper 1σ limit uncertainty in logL
55- 57 I3 --- HRUX ? Ultra hard X-ray hardness ratio
(HRUX =(14-195keV)/(2-10keV))
58 A1 --- u_HRUX [?] no available high quality measurements
60 A1 --- NeV [Y] Presence of [NeV] (14.3um) from Petric et
al. (2011ApJ...730...28P 2011ApJ...730...28P)?
62- 64 A3 --- Ref Reference for 2-10 keV X-ray data (5)
--------------------------------------------------------------------------------
Note (2): IR luminosity (L8-1000 microns > 1e11 Lsun) based on SED fitting
Casey 2012MNRAS.425.3094C 2012MNRAS.425.3094C using data from IRAS.
Note (3): Defined as the background-subtracted source count rate divided by
local background standard deviation.
Note (4): Lower limits were calculated at 3σ, using an X-ray power law
of Γ=1.9, and Galactic extinction, consistent with the mean
14-195 power law for Seyfert 2s in the BAT sample
(Winter et al. 2009ApJ...690.1322W 2009ApJ...690.1322W).
Note (5): Reference as follows:
G08 = Greenhill et al. (2008ApJ...686L..13G 2008ApJ...686L..13G);
I11 = Iwasawa et al. (2011A&A...529A.106I 2011A&A...529A.106I);
L10 = Lehmer et al. (2010ApJ...724..559L 2010ApJ...724..559L);
P11 = Pereira-Santaella et al. (2011A&A...535A..93P 2011A&A...535A..93P);
W09 = Winter et al. (2009ApJ...690.1322W 2009ApJ...690.1322W);
XRT = Swift X-ray Telescope.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 06-Nov-2014