On the minimum mass of neutron stars Yudai Suwa （ Kyoto Sangyo University ） collaboration with T. Yoshida (Tokyo), M. Shibata (Kyoto/AEI), H. Umeda (Tokyo), K. Takahashi (Bonn)
Yudai Suwa @ Stellar deaths and their diversity, NAOJ Kyoto Sangyo University （京都産業大学） Kyoto Sangyo University ~10km (~40min w/ metro & bus) Kyoto University Long-term workshop “Multi-messenger astrophysics in the GW era” (24 Sep.-25 Oct. 2019) incl. YKIS conference (7 Oct.-11 Oct. 2019) Kyoto Station 2 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ Pulsar number is increasing pulsar millisecond pulsar pulsar w/ precise mass compiled data from ATNF pulsar catalog and P. Freire’s table 3 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ Mass measurements of NSs Özel & Freie 2016 6 J0453+1559c J1756-2251c J0737-3039B J1906+0746 J1906+0746c B1534+12 5 J0737-3039A Double J1756-2251 B1534+12c Double neutron stars B2127+11Cc neutron stars B2127+11C B1913+16c 4 B1913+16 Likelihood J0453+1559 J1518+4904c J1811-1736c J1930-1852 J1829+2456c 3 J1829+2456 J1930-1852c J1811-1736 J1518+4904 J1750-37A J2222-0137 2 Recycled B1802-07 pulsars J1802-2124 J1910-5958A J1713+0747 J1824-2452C Slow 1 J1807-2500B J0024-7204H pulsars J2234+0611 J0337+1715 J0437-4715 Recycled J0514-4002A 0 pulsars J1909-3744 J1738+0333 0.8 1.0 1.2 1.4 1.6 1.8 2.0 J0621+1002 B1855+09 J1903+0327 Mass (M ☉ ) J0751+1807 J1748-2446J J1012+5307 J1748-2446I J1946+3417 J1614-2230 >2600 pulsars have been found B1516+02B J0348+0432 J1748-2021B Cyg X-2 in the Galaxy 4U 1608-52 KS 1731-260 Bursters EXO 1745-248 4U 1820-30 SAX J1748.9-2021 4U 1724-207 10% in the binary system 4U1538-52 Her X-1 SMC X-1 J1141-6545 B2303+46 → mass measurement possible Slow XTE J1855-026 LMC X-4 pulsars SAX J1802.7-2017 Cen X-3 OAO 1657-415 EXO 1722-363 Vela X-1 15 double NSs so far [Tauris+ 2017] 0.0 1.0 2.0 3.0 Mass (M ☉ ) http://www3.mpifr-bonn.mpg.de/sta fg /pfreire/NS_masses.html 4 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ Massive NSs tell us nuclear physics Demorest+ 2010 GR MS0 MPA1 2.5 P < ∞ AP3 PAL1 Causality ENG AP4 MS2 ← 1.97±0.04M ⊙ 2.0 J1614-2230 SQM3 MS1 NB) mass estimation was FSU J1903+0327 Mass ( M ( ) SQM1 updated by Arzoumanian+ 2018 GM3 PAL6 1.5 J1909-3744 as 1.908±0.016M ⊙ GS1 Double neutron s Double neutron star sy systems sy 1.0 Another massive NS was Rotation 0.5 reported by Antoniadis+ (2013), J0348+0432, 2.01±0.04M ⊙ 0.0 7 8 9 10 11 12 13 14 15 Radius (km) 5 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ So, what does a small NS tell? 6 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ Double NSs J0453+1559c J1756-2251c J0737-3039B J1906+0746 concentrating within a small range J1906+0746c B1534+12 J0737-3039A J1756-2251 B1534+12c Double B2127+11Cc neutron stars B2127+11C B1913+16c B1913+16 J0453+1559 J1518+4904c J1811-1736c J1930-1852 J1829+2456c J1829+2456 J1930-1852c J1811-1736 Vela X-1 J1518+4904 J1750-37A 0.0 1.0 2.0 3.0 Mass (M ☉ ) 7 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ First asymmetric DNS system Martinez+ 2015 M p =1.559±0.005M ⊙ M c =1.174±0.004M ⊙ 8 w 23/1/2019 /16 w > � w = = D = = �
Yudai Suwa @ Stellar deaths and their diversity, NAOJ A low-mass NS M NS =1.174M ⊙ ! (NB, it ‘s gravitational mass, baryonic mass is ~1.28M ⊙ ) Is it a white dwarf? Maybe no a large eccentricity (e=0.112) is di ffj cult to explain by slow evolution into a WD Sukhbold+ 2018 1 . 9 How to make it? 1 . 8 Iron Core Mass [M � ] a small iron core of massive star? 1 . 7 (typically M Fe ~1.4–1.8M ⊙ ) 1 . 6 getting rid of mass from a NS? 1 . 5 1 . 4 ˙ M N ˙ M N / 2 1 . 3 15 20 25 30 35 40 M ZAMS [M � ] 9 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ A path toward a low mass NS?: Ultra-stripped SN [Suwa+, MNRAS, 454 , 3073 (2015); Yoshida+, MNRAS, 471 , 4275 (2017)] Tauris+ 2017 lower M C/O - - ´ ´ M C/O =1.45M ⊙ - - ´ ´ � M C/O =2.0M ⊙ t � ¥ -17 CO145 - 10 42 CO15 -16 CO145: Ye-B Luminosity [erg s -1 ] Absolute Magnitude SN2005ek -15 = R -14 10 41 -13 -12 10 40 -11 0 5 10 15 20 25 30 35 40 Days since explosion 10 23/1/2019 /16 � ~ �
Yudai Suwa @ Stellar deaths and their diversity, NAOJ When does a core collapse? Mass M Chandra collapse! M core Time till collapse 11 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ Modified Chandrasekhar mass Chandrasekhar mass without temperature correction M Ch0 ( Y e ) = 1.46 M ⊙ ( 2 0.5 ) Y e Chandrasekhar mass with temperature correction M Ch ( T ) = M Ch0 ( Y e ) [ 1 + ( ] s e = 0.5 ρ − 1/3 2 π Y 2 ) s e 10 ( Y e /0.42) 2/3 T MeV Baron+ 1990; Timmes+ 1996 To make a small core, low Y e and low entropy are necessary 12 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ M ch vs. M core [Suwa, Yoshida, Shibata, Umeda, Takahashi, MNRAS, 481 , 3305 (2018)] 2 2 2 1.8 1.8 1.8 M Ch 1.6 1.6 1.6 Mass [M ⊙ ] Mass [M ⊙ ] Mass [M ⊙ ] 1.4 1.4 1.4 M Ch0 1.2 1.2 1.2 1 1 1 M Fe 0.8 0.8 0.8 CO138 CO138 CO138 CO145 CO145 CO145 0.6 0.6 0.6 15M ⊙ 15M ⊙ 15M ⊙ 10 2 10 2 10 2 10 1 10 1 10 1 10 0 10 0 10 0 10 -1 10 -1 10 -1 10 -2 10 -2 10 -2 10 -3 10 -3 10 -3 10 -4 10 -4 10 -4 10 -5 10 -5 10 -5 10 -6 10 -6 10 -6 10 -7 10 -7 10 -7 Time until ρ c =10 10 g cm -3 [year] Time until ρ c =10 10 g cm -3 [year] Time until ρ c =10 10 g cm -3 [year] 13 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ Explosion simulations and NS masses [Suwa, Yoshida, Shibata, Umeda, Takahashi, MNRAS, 481 , 3305 (2018)] Model M CO (M ⊙ ) M ZAMS (M ⊙ ) M Fe (M ⊙ ) M NS,b (M ⊙ ) M NS,g (M ⊙ ) CO137 1.37 9.35 1.280 1.289 1.174 CO138 1.38 9.4 1.274 1.296 1.179 CO139 1.39 9.45 1.258 1.302 1.184 CO140 1.4 9.5 1.296 1.298 1.181 CO142 1.42 9.6 1.265 1.287 1.172 CO144 1.44 9.7 1.234 1.319 1.198 CO145 1.45 9.75 1.277 1.376 1.245 M NS,b -M NS,g =0.084M ⊙ (M NS,g /M ⊙ ) 2 (Lattimer & Prakash 2001) 14 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ Discussion [Suwa, Yoshida, Shibata, Umeda, Takahashi, MNRAS, 481 , 3305 (2018)] M NS,b M NS,g (M ⊙ ) (M ⊙ ) ONeMg core -> electron-capture SN ~1.32 ~1.20 ~1.28 ~1.17 Fe core -> core-collapse SN ~1.37 ~1.42 M CO (M ⊙ ) 15 23/1/2019 /16
Yudai Suwa @ Stellar deaths and their diversity, NAOJ Summary A low-mass NS of M NS,g =1.174M ⊙ was found Q: Is it possible to make such a low-mass NS with standard modeling of SN? A: Yes, it is. The minimum mass is ~1.17M ⊙ . If a new observation fj nds even lower mass NS, we cannot make it. Something wrong. 16 23/1/2019 /16
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