J/ApJ/922/155 [FeX]λ6374 em. in SDSS dwarf galaxies (Molina+, 2021)
A sample of massive black holes in dwarf galaxies detected via [FeX] coronal
line emission: active galactic nuclei and/or tidal disruption events.
Molina M., Reines A.E., Latimer C.J., Baldassare V., Salehirad S.
<Astrophys. J., 922, 155 (2021)>
=2021ApJ...922..155M 2021ApJ...922..155M
ADC_Keywords: Galaxies, dwarf; Active gal. nuclei; Black holes; Spectra, optical
Keywords: Black holes ; Active galaxies ; Active galactic nuclei ;
Low-luminosity active galactic nuclei ; Dwarf galaxies ;
Tidal disruption
Abstract:
The massive black hole (BH) population in dwarf galaxies
(MBH≲105M☉) can provide strong constraints on the origin of
BH seeds. However, traditional optical searches for active galactic
nuclei (AGNs) only reliably detect high-accretion, relatively
high-mass BHs in dwarf galaxies with low amounts of star formation,
leaving a large portion of the overall BH population in dwarf galaxies
relatively unexplored. Here, we present a sample of 81 dwarf galaxies
(M*≤3x109M☉) with detectable [FeX]λ6374 coronal line
emission indicative of accretion onto massive BHs, only two of which
were previously identified as optical AGNs. We analyze optical
spectroscopy from the Sloan Digital Sky Survey and find
[FeX]λ6374 luminosities in the range L[FeX]∼1036-1039erg/s,
with a median value of 1.6x1038erg/s. The [FeX]λ6374
luminosities are generally much too high to be produced by stellar
sources, including luminous Type IIn supernovae (SNe). Moreover, based
on known SNe rates, we expect at most eight Type IIn SNe in our
sample. That said, the [FeX]λ6374 luminosities are consistent
with accretion onto massive BHs from AGNs or tidal disruption events
(TDEs). We find additional indicators of BH accretion in some cases
using other emission line diagnostics, optical variability, and X-ray
and radio emission (or some combination of these). However, many of
the galaxies in our sample only have evidence for a massive BH based
on their [FeX]λ6374 luminosities. This work highlights the
power of coronal line emission to find BHs in dwarf galaxies missed by
other selection techniques and to probe the BH population in bluer,
lower-mass dwarf galaxies.
Description:
We selected our sample of dwarf galaxies from version v101 of the
NASA-Sloan Atlas (NSA; Blanton+ 2011AJ....142...31B 2011AJ....142...31B).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 92 81 Sample of 81 [FeX]6374-emitting dwarf galaxies
table2.dat 42 81 [FeX]6374 measurements
table3.dat 103 81 Emission line fluxes
--------------------------------------------------------------------------------
See also:
V/154 : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
J/AcA/50/421 : OGLE-II DIA BUL_SC1 field (Wozniak, 2000)
J/ApJ/703/370 : Radio SNRs in nearby galaxies (Chomiuk+, 2009)
J/MNRAS/398/1165 : AGN in nearby galaxies (Goulding+, 2009)
J/ApJ/698/895 : Variations in QSOs optical flux (Kelly+, 2009)
J/MNRAS/412/1419 : Nearby supernova rates (Leaman+, 2011)
J/MNRAS/410/166 : Morphological types from Galaxy Zoo 1 (Lintott+, 2011)
J/ApJ/733/60 : Accretion rate of AGNs from COSMOS surveys (Trump+, 2011)
J/MNRAS/421/1043 : Emission-line galaxies from SDSS DR7 (Shirazi+, 2012)
J/ApJ/775/116 : z<0.06 active BH galaxies from SDSS-DR8 (Reines+, 2013)
J/MNRAS/450/905 : New SNe in SDSS DR9 (Graur+, 2015)
J/ApJ/813/82 : z<0.06 broad-line AGN emission-line measures (Reines+, 2015)
J/MNRAS/454/3722 : AGN in nearby low-mass galaxies (Sartori+, 2015)
J/MNRAS/467/540 : BASS. IV. NIR lines & X-ray (Lamperti+, 2017)
J/ApJ/872/148 : 2MASX/NVSS gal. brighter than K20fe=12.25 (Condon+, 2019)
J/ApJ/871/193 : Chandra & LAMOST study of stellar activity (He+, 2019)
J/A+A/623/A173 : SNe/SNRs in starburst galaxy Arp 220 (Varenius+, 2019)
J/ApJ/896/10 : NSA galaxies with long-term PTF obs. (Baldassare+, 2020)
J/ApJ/888/36 : SDSS/FIRST galaxies with VLA high res. obs. (Reines+, 2020)
J/ApJ/907/17 : HMXB-dominant galaxy sample and properties (Lehmer+, 2021)
http://www.nsatlas.org/ : NASA-Sloan Atlas home page
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- NSAID [50/670127] NASA-Sloan Atlas (NSA)
identification number (1)
8- 16 F9.5 deg RAdeg [8/343.2] Right Ascension of galaxy center
(J2000) (1)
18- 26 F9.5 deg DEdeg [-11.2/68.2] Declination of galaxy center
(J2000) (1)
28- 36 F9.5 deg RASdeg [8/343.2] Right Ascension of SDSS fiber
(J2000) (1)
38- 46 F9.5 deg DESdeg [-11.2/68.2] Declination of SDSS fiber (J2000)
(1)
48- 51 F4.2 arcsec Sep [0.02/3] Distance between galaxy center and
SDSS fiber
53- 59 F7.5 --- z [0.002/0.15] Redshift (1)
61- 63 F3.1 [Msun] Mass [7.5/9.7] Log of the stellar mass (1) (2)
65- 68 F4.2 Msun/yr SFR [0.01/7.6]? Star Formation Rate (3)
70- 72 F3.1 --- Metal [7.7/8.6] Metallicity (4)
74- 82 A9 --- Ref Reference of previous study (5)
84- 92 A9 --- Class Classification from previous study (6)
--------------------------------------------------------------------------------
Note (1): All values are from the v101 version of the NSA and assume h=0.73.
Note (2): The mass for NSA 533731 (Mrk 709S) is taken from
Reines+ (2014ApJ...787L..30R 2014ApJ...787L..30R).
Note (3): The total SFR in the galaxy calculated using the GALEX FUV values
from the NSA and WISE W4 magnitudes, assuming equations from
Kennicutt & Evans (2012ARA&A..50..531K 2012ARA&A..50..531K).
Note (4): 12+log([O/H]) calculated using the [NII]/Halpha measurements
calculated in this work and assuming the equation from
Pettini & Pagel (2004MNRAS.348L..59P 2004MNRAS.348L..59P).
Note (5): Inclusion of object in previous studies as follows:
BGG20 = Baldassare et al. (2020, J/ApJ/896/10);
Reines+20 = Reines et al. (2020, J/ApJ/888/36);
Kimbro+21 = Kimbro et al. (2021ApJ...912...89K 2021ApJ...912...89K);
Reines+13 = Reines et al. (2013, J/ApJ/775/116);
BWA20 = Birchall et al. (2020MNRAS.492.2268B 2020MNRAS.492.2268B);
Note (6): Classification Key as follows:
AGN = AGN-like in BPT diagram (5 occurrences);
Composite = Composite in BPT diagram (1 occurrence);
SF+BHa = star-forming in BPT with a broad Hα detection (1 occurrence);
SF = radio consistent with star formation (1 occurrence);
Sne = supernova candidate (1 occurrence).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- NSAID [50/670127] NSA Identification Number
8- 11 F4.1 10-20W/m2 FFeX [2.4/40] Emission-line [FeX]6374Å flux;
in 10-17erg/s/cm2
13- 16 F4.1 10-20W/m2 e_FFeX [1/10.4] Error on FeX-flx
18- 22 F5.2 [10-7W] LFeX [36/39.6] Log of emission-line
[FeX]6374Å luminosity in erg/s
24- 27 F4.2 [10-7W] e_LFeX [0.3/1] Error on FeX-lum
29- 32 F4.1 --- sigPk [2/11.1] Comparison of [FeX] peak to
residual continuum, σpeak
34- 36 F3.1 --- S/N [2/9.5] Signal-to-noise of the
emission-line flux, S/Nline
38- 42 F5.1 --- FeXg/sn [0.1/165.4] Comparison of [FeX]
emission in galaxy to SN2005ip,
L([FeX])gal/L([FeX])SN2005ip) (7)
--------------------------------------------------------------------------------
Note (7): We assume the SN2005ip's peak luminosity of ∼2x1037erg/s that
occurred within 100 days of its discovery, Smith+ (2009ApJ...695.1334S 2009ApJ...695.1334S).
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 I6 --- NSAID [50/670127] NSA Identification Number
8- 10 I3 10-20W/m2 FHeII4686 [4/100]? HeII4686Å emission-line flux
(8)
12- 13 I2 10-20W/m2 e_FHeII4686 [2/10]? Error on HeII4686-flx
15- 18 I4 10-20W/m2 FHbeta-n [6/7270] Hβ 4861Å narrow
emission-line flux (8)
20- 22 I3 10-20W/m2 e_FHbeta-n [1/100] Error on Hbeta-n-flx
24- 26 I3 10-20W/m2 FHbeta-b [360/360]? Hβ 4861Å broad
emission-line flux (8)
28- 29 I2 10-20W/m2 e_FHbeta-b [30/30]? Error on Hbeta-b-flx
31- 35 I5 10-20W/m2 FOIII5007 [8/38100] Forbidden [OIII]5007Å
emission-line flux (8)
37- 41 I5 10-20W/m2 e_FOIII5007 [2/10000] Error on OIII5007-flx
43- 45 I3 10-20W/m2 FOI6300 [5/460] Forbidden [OI]6300Å
emission-line flux (8)
47- 48 I2 10-20W/m2 e_FOI6300 [1/30] Error on OI6300-flx
50- 54 I5 10-20W/m2 FHalpha-n [19/29400] Hα 6563 narrow
emission-line flux (8)
56- 59 I4 10-20W/m2 e_FHalpha-n [1/2000] Error on Halpha-n-flx
61- 64 I4 10-20W/m2 FHalpha-b [30/2520]? Hα 6563 broad
emission-line flux (8)
66- 67 I2 10-20W/m2 e_FHalpha-b [10/50]? Error on Halpha-b-flx
69- 72 I4 10-20W/m2 FNII6583 [2/2613] Forbidden [NII]6583Å
emission-line flux (8)
74- 75 I2 10-20W/m2 e_FNII6583 [1/10] Error on NII6583-flx
77- 80 I4 10-20W/m2 FSII6716 [4/1660] Forbidden [SII]6716Å
emission-line flux (8)
82- 83 I2 10-20W/m2 e_FSII6716 [1/80] Error on SII6716-flx
85- 88 I4 10-20W/m2 FSII6731 [6/1380] Forbidden [SII]6731Å
emission-line flux (8)
90- 91 I2 10-20W/m2 e_FSII6731 [1/80] Error on SII6731-flx
93- 95 I3 10-20W/m2 FOII7320 [4/200]? Forbidden [OII]7320Å
emission-line flux (8)
97 I1 10-20W/m2 e_FOII7320 [2/9]? Error on OII7320-flx
99- 101 I3 10-20W/m2 FOIII7330 [3/161]? Forbidden [OII]7330Å
emission-line flux (8)
103 I1 10-20W/m2 e_FOIII7330 [1/8]? Error on OII7330-flx
--------------------------------------------------------------------------------
Note (8): All fluxes are not corrected for reddening. While the weaker lines
in the [OIII] and [NII] doublets were simultaneously fit with the
stronger doublet line, we do not list their fluxes as they are weaker
by a fixed factor of 3. The [OI] doublet is fit as described in
Section 2.1. The Halpha and Hbeta fluxes are split into the narrow (n)
and broad (b) components, where applicable.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 27-Mar-2023