TY - JOUR
T1 - Gravitational Waves from Supermassive Black Hole Binaries in Ultraluminous Infrared Galaxies
AU - Inayoshi, Kohei
AU - Ichikawa, Kohei
AU - Haiman, Zoltán
N1 - Funding Information:
We thank Jeremiah Ostriker, Alberto Sesana, and Yoshiki Toba for useful discussions and comments. This work is partially supported by the Simons Foundation through the Simons Society of Fellows (K.I.), by JSPS KAKENHI 18K13584 and JST grant “Building of Consortia for the Development of Human Resources in Science and Technology” K.I.), and by NASA grant NNX17AL82G and NSF grant 1715661 (Z.H.).
Funding Information:
This work is partially supported by the Simons Foundation through the Simons Society of Fellows (K.I.), by JSPS KAKENHI 18K13584 and JST grant Building of Consortia for the Development of Human Resources in Science and Technology K.I.), and by NASA grant NNX17AL82G and NSF grant 1715661 (Z.H.).
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved..
PY - 2018/8/20
Y1 - 2018/8/20
N2 - Gravitational waves (GWs) in the nanohertz band are great tools for understanding the cosmological evolution of supermassive black holes (SMBHs) in galactic nuclei. We consider SMBH binaries in high-z ultraluminous infrared galaxies (ULIRGs) as sources of a stochastic GW background (GWB). ULIRGs are likely associated with gas-rich galaxy mergers containing SMBHs that possibly occur at most once in the life of galaxies, unlike multiple dry mergers at low redshift. Adopting a well-established sample of ULIRGs, we study the properties of the GWB due to coalescing binary SMBHs in these galaxies. Since the ULIRG population peaks at z > 1.5, the amplitude of the GWB is not affected even if BH mergers are delayed by as long as ∼10 Gyr. Despite the rarity of the high-z ULIRGs, we find a tension with the upper limits from pulsar timing array experiments. This result suggests that if a fraction of ULIRGs are associated with SMBH binaries, then no more than of the binary SMBHs in ULIRGs can merge within a Hubble time, for plausible values of the Eddington ratio of ULIRGs (λ Edd) and their lifetime (t life).
AB - Gravitational waves (GWs) in the nanohertz band are great tools for understanding the cosmological evolution of supermassive black holes (SMBHs) in galactic nuclei. We consider SMBH binaries in high-z ultraluminous infrared galaxies (ULIRGs) as sources of a stochastic GW background (GWB). ULIRGs are likely associated with gas-rich galaxy mergers containing SMBHs that possibly occur at most once in the life of galaxies, unlike multiple dry mergers at low redshift. Adopting a well-established sample of ULIRGs, we study the properties of the GWB due to coalescing binary SMBHs in these galaxies. Since the ULIRG population peaks at z > 1.5, the amplitude of the GWB is not affected even if BH mergers are delayed by as long as ∼10 Gyr. Despite the rarity of the high-z ULIRGs, we find a tension with the upper limits from pulsar timing array experiments. This result suggests that if a fraction of ULIRGs are associated with SMBH binaries, then no more than of the binary SMBHs in ULIRGs can merge within a Hubble time, for plausible values of the Eddington ratio of ULIRGs (λ Edd) and their lifetime (t life).
KW - gravitational waves
KW - infrared: galaxies
KW - quasars: supermassive black holes
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U2 - 10.3847/2041-8213/aad8ad
DO - 10.3847/2041-8213/aad8ad
M3 - Article
AN - SCOPUS:85052385281
VL - 863
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
SN - 2041-8205
IS - 2
M1 - L36
ER -