LB-1 Is Inconsistent with the X-Ray Source Population and Pulsar-Black Hole Binary Searches in the Milky Way
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LB-1 Is Inconsistent with the X-Ray Source Population and Pulsar-Black Hole Binary Searches in the Milky Way. / Safarzadeh, Mohammadtaher; Ramirez-Ruiz, Enrico; Kilpatrick, Charles.
I: Astrophysical Journal, Bind 901, Nr. 2, 116, 01.10.2020.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - LB-1 Is Inconsistent with the X-Ray Source Population and Pulsar-Black Hole Binary Searches in the Milky Way
AU - Safarzadeh, Mohammadtaher
AU - Ramirez-Ruiz, Enrico
AU - Kilpatrick, Charles
PY - 2020/10/1
Y1 - 2020/10/1
N2 - If confirmed, a wide binary system consisting of a 70Mblack hole (BH) and an 8Mmain-sequence star (LB-1) is observed to reside in the Milky Way (MW). While we remain agnostic about the nature of LB-1, we show that long-term evolution of an 8Mstar around a BH with mass between 5 and 70Mmakes them visible as ultraluminous X-ray (ULX) sources in the sky. Given the expected ULX phase lifetime (0.1 Myr) and their lack of detection in the MW, we conclude that the frequency of an 8-20Mstar to be in binary around a stellar mass BH should be less (f <4 x 10(-3)). This is in tension with Liu et al., who claimed the detection frequency of an LB-1-like system to be around 8-20Mstars (f 3 x 10(-2)). Moreover, the 8Mstar is likely to end as a neutron star (NS) born with a very small kick from an electron-capture supernova (ECSN), leaving behind a wide NS-BH binary. So far, less than 1% of all the detectable pulsars in the MW have been mapped and there has been no detection of any pulsars in binary systems around BHs, which sets an upper bound of about 100 possible pulsar-BH systems in the MW. We show whether the NS is born from ECSN, a frequency upper limit of (f 10(-3)) for stars with masses 8-20Min the MW to have a BH companion. The rate discrepancy will further increase as more pulsars are mapped in the MW, yet these searches would not be able to rule out the Liu et al. detection frequency if NSs are instead born in core collapse SNe with the commonly inferred high kick velocities.
AB - If confirmed, a wide binary system consisting of a 70Mblack hole (BH) and an 8Mmain-sequence star (LB-1) is observed to reside in the Milky Way (MW). While we remain agnostic about the nature of LB-1, we show that long-term evolution of an 8Mstar around a BH with mass between 5 and 70Mmakes them visible as ultraluminous X-ray (ULX) sources in the sky. Given the expected ULX phase lifetime (0.1 Myr) and their lack of detection in the MW, we conclude that the frequency of an 8-20Mstar to be in binary around a stellar mass BH should be less (f <4 x 10(-3)). This is in tension with Liu et al., who claimed the detection frequency of an LB-1-like system to be around 8-20Mstars (f 3 x 10(-2)). Moreover, the 8Mstar is likely to end as a neutron star (NS) born with a very small kick from an electron-capture supernova (ECSN), leaving behind a wide NS-BH binary. So far, less than 1% of all the detectable pulsars in the MW have been mapped and there has been no detection of any pulsars in binary systems around BHs, which sets an upper bound of about 100 possible pulsar-BH systems in the MW. We show whether the NS is born from ECSN, a frequency upper limit of (f 10(-3)) for stars with masses 8-20Min the MW to have a BH companion. The rate discrepancy will further increase as more pulsars are mapped in the MW, yet these searches would not be able to rule out the Liu et al. detection frequency if NSs are instead born in core collapse SNe with the commonly inferred high kick velocities.
KW - Astrophysical black holes
KW - Pulsars
KW - Binary stars
KW - Common envelope binary stars
KW - Interstellar dust extinction
KW - MASS
KW - LUMINOSITY
KW - SUPERNOVAE
KW - STAR
U2 - 10.3847/1538-4357/abb0e8
DO - 10.3847/1538-4357/abb0e8
M3 - Journal article
VL - 901
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 116
ER -
ID: 252155641