J/ApJ/925/218 Nature of PAH in PG quasars from Spitzer/IRS sp. (Xie+, 2022)
The ionization and destruction of polycyclic aromatic hydrocarbons in powerful
quasars.
Xie Y., Ho L.C.
<Astrophys. J., 925, 218 (2022)>
=2022ApJ...925..218X 2022ApJ...925..218X
ADC_Keywords: QSOs; Spectra, infrared; Redshifts; Interstellar medium;
Active gal. nuclei
Keywords: Interstellar medium ; Star formation ; Infrared astronomy ;
AGN host galaxies
Abstract:
We reanalyze the mid-infrared (5-40µm) Spitzer spectra of
86 low-redshift (z<0.5) Palomar-Green quasars to investigate the
nature of polycyclic aromatic hydrocarbon (PAH) emission and its
utility as a star formation rate (SFR) indicator for the host galaxies
of luminous active galactic nuclei (AGNs). We decompose the spectra
with our recently developed template-fitting technique to measure PAH
fluxes and upper limits, which we interpret using mock spectra that
simulate the effects of AGN dilution. While luminous quasars can
severely dilute and affect the detectability of emission lines, PAHs
are intrinsically weak in some sources that are otherwise gas-rich and
vigorously forming stars, conclusively demonstrating that powerful
AGNs destroy PAH molecules. Comparing PAH-based SFRs with independent
SFRs derived from the mid-infrared fine-structure neon lines and the
total infrared luminosity reveals that PAHs can trace star formation
activity in quasars with bolometric luminosities ≤1046erg/s, but
increasingly underestimate the SFR for more powerful quasars,
typically by ∼0.5dex. Relative to star-forming galaxies and
low-luminosity AGNs, quasars have a comparable PAH 11.3µm/7.7µm
ratio but characteristically lower ratios of 6.2µm/7.7µm,
8.6µm/7.7µm, and 11.3µm/17.0µm. We suggest that these
trends indicate that powerful AGNs preferentially destroy small grains
and enhance the PAH ionization fraction.
Description:
We study the 87 low-redshift (z<0.5) optical/UV-selected quasars
from the Palomar-Green (PG) survey (Schmidt & Green 1983, J/ApJ/269/352),
as summarized in Boroson & Green (1992ApJS...80..109B 1992ApJS...80..109B).
Our final sample contains 86 quasars with low-resolution spectra from
the Spitzer Infrared Spectrograph (IRS) acquired by
Shi+ (2014, J/ApJS/214/23).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 218 86 Physical properties and measurements of PG quasars
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See also:
VII/157 : The Extended 12um galaxy sample (Rush+ 1993)
J/ApJ/269/352 : Quasar evolution (Schmidt+, 1983)
J/A+A/357/839 : AGN 2.5-11um spectroscopy (Clavel+, 2000)
J/ApJ/653/127 : 9.7um silicate features in AGNs (Shi+, 2006)
J/ApJ/656/770 : Mid-IR spectrum of star-forming galaxies (Smith+, 2007)
J/ApJ/705/885 : PAH in galaxies at z∼0.1 (O'Dowd+, 2009)
J/ApJ/719/1191 : Mid-IR indicators of SF and AGN in galaxies (Treyer+, 2010)
J/ApJ/723/895 : IR luminosities and aromatic features of 5MUSES (Wu+, 2010)
J/ApJ/758/1 : SDSS-Spitzer AGN properties (LaMassa+, 2012)
J/ApJS/214/23 : IR spectra and photometry of z<0.5 quasars (Shi+, 2014)
J/ApJ/790/124 : Dust and gas physics of the GOALS sample (Stierwalt+, 2014)
J/A+A/578/A74 : Nuclear obscuration in LINERs (Gonzalez-Martin+, 2015)
J/ApJS/219/18 : LIRAS: LoCuSS IR AGN survey (Xu+, 2015)
J/ApJ/819/L27 : Stellar masses of optical & IR QSO hosts (Zhang+, 2016)
J/MNRAS/470/3071 : PAH features of AGN (Jensen+, 2017)
J/ApJ/854/158 : z<0.5 PG quasars IR energy distributions (Shangguan+, 2018)
J/ApJ/884/136 : PAH features of star-forming gal. using Spitzer (Xie+, 2019)
J/ApJ/905/55 : Bright-PAH gal. from AKARI & Spitzer (ASESS) (Lai+, 2020)
J/ApJ/910/124 : Star formation rates of low-z QSOs from 1-500um (Xie+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [PG]
4- 11 A8 --- PG QSO name (HHMM+DDd; B1950)
13- 17 F5.3 --- zsp [0.025/0.472] Spectroscopic redshift
19- 22 I4 Mpc Dist [113/2723] Luminosity distance
24- 27 F4.2 [Msun] logMBH [6.62/9.9] Log of black hole mass (1)
29- 33 F5.2 [10-7W] logLbol [44.6/47.2] Log of AGN bolometric
luminosity, in erg/s (1)
35- 39 F5.2 [Msun] logMs [9.7/12.1] Stellar mass of the quasar
host galaxy
41 A1 --- l_logMs [* ] Flag on source of logMs (2)
43- 47 F5.1 --- fAGN [1/110]? AGN fraction
50 A1 --- l_logLPAH6 Limit flag on logLPAH6
52- 56 F5.2 [10-7W] logLPAH6 [39.3/43.33]? PAH luminosity at 6.2 um
58- 61 F4.2 [10-7W] e_logLPAH6 [0.02/0.14]? Lower uncertainty on logLPAH6
63- 66 F4.2 [10-7W] E_logLPAH6 [0.02/0.14]? Upper uncertainty on logLPAH6
68 A1 --- l_logLPAH7 Limit flag on logLPAH7
70- 74 F5.2 [10-7W] logLPAH7 [41.38/44] PAH luminosity at 7.7 um
76- 79 F4.2 [10-7W] e_logLPAH7 [0.01/0.14]? Lower uncertainty on logLPAH7
81- 84 F4.2 [10-7W] E_logLPAH7 [0.01/0.14]? Upper uncertainty on logLPAH7
86 A1 --- l_logLPAH8 Limit flag on logLPAH8
88- 92 F5.2 [10-7W] logLPAH8 [40.23/43.65] PAH luminosity at 8.6 um
94- 97 F4.2 [10-7W] e_logLPAH8 [0.05/0.14]? Lower uncertainty on logLPAH8
99- 102 F4.2 [10-7W] E_logLPAH8 [0.05/0.14]? Upper uncertainty on logLPAH8
104 A1 --- l_logLPAH11 Limit flag on logLPAH11
106- 110 F5.2 [10-7W] logLPAH11 [40.98/43.77] PAH luminosity at 11.3 um
112- 115 F4.2 [10-7W] e_logLPAH11 [0.03/0.14]? Lower uncertainty on
logLPAH11
117- 120 F4.2 [10-7W] E_logLPAH11 [0.03/0.14]? Upper uncertainty on
logLPAH11
122 A1 --- l_logLPAH17 Limit flag on logLPAH17
124- 128 F5.2 [10-7W] logLPAH17 [40.9/44] PAH luminosity at 17.0 um
130- 133 F4.2 [10-7W] e_logLPAH17 [0.02/0.14]? Lower uncertainty on
logLPAH17
135- 138 F4.2 [10-7W] E_logLPAH17 [0.02/0.14]? Upper uncertainty on
logLPAH17
140 A1 --- l_logLPAHt Limit flag on logLPAHt
142- 146 F5.2 [10-7W] logLPAHt [41.8/44.4] PAH luminosity within 5-15um
148- 151 F4.2 [10-7W] e_logLPAHt [0.01/0.14]? Lower uncertainty on logLPAHt
153- 156 F4.2 [10-7W] E_logLPAHt [0.01/0.14]? Upper uncertainty on logLPAHt
158 A1 --- l_logSFRPAH Limit flag on logSFRPAH
160- 164 F5.2 [Msun/yr] logSFRPAH [-0.5/2.1] Log, SFR derived from the PAH
luminosity within 5-15um
166- 169 F4.2 [Msun/yr] e_logSFRPAH [0.03/0.2]? Lower uncertainty on logSFRPAH
171- 174 F4.2 [Msun/yr] E_logSFRPAH [0.03/0.2]? Upper uncertainty on logSFRPAH
176- 180 F5.2 [Msun/yr] b_logSFRNe [-0.13/1.25]? Lower bound on logSFRNe
182- 185 F4.2 [Msun/yr] B_logSFRNe [0.47/1.51]? Upper bound on logSFRNe
187- 190 F4.2 [Msun/yr] logSFRNe [0.19/2.4]? Log, SFR derived from the
neon line luminosity
192- 195 F4.2 [Msun/yr] e_logSFRNe [0.14/0.81]? Lower uncertainty on logSFRNe
197- 200 F4.2 [Msun/yr] E_logSFRNe [0.14/0.81]? Upper uncertainty on logSFRNe
202 A1 --- l_logSFRIR Limit flag on logSFRIR
204- 208 F5.2 [Msun/yr] logSFRIR [-0.7/2.5] Log, SFR derived from the
total IR luminosity
210- 213 F4.2 [Msun/yr] e_logSFRIR [0.01/0.16]? Lower uncertainty on logSFRIR
215- 218 F4.2 [Msun/yr] E_logSFRIR [0.01/0.2]? Upper uncertainty on logSFRIR
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Note (1): From Shangguan et al. (2018, J/ApJ/854/158)
Note (2): Stellar mass of the quasar host galaxy from
Zhang+ (2016, J/ApJ/819/L27) or (*) derived from the MBH-Ms relation
of Greene+ (2020ARA&A..58..257G 2020ARA&A..58..257G)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 11-Sep-2023