PS1-12sk is a Type Ibn supernova (SN) found in a host environment showing no obvious ongoing star formation, which challenges the massive star explosion scenario. We use the ejecta-circumstellar medium (CSM) interaction (CSI) and the CSI plus Ni-56 models in the context of double white dwarf (WD) merger to fit the bolometric light curve (LC) of PS1-12sk, since the He emission lines at the photospheric phases indicated the interaction between the SN ejecta and He-rich CSM. We find that the CSI model failed to explain the LC, but the CSI plus Ni-56 model can account for the bolometric LC. The derived masses of the two WDs and Ni-56 are similar to 0.70, similar to 0.40, and similar to 0.09 M-circle dot, respectively. The facts that the ejecta mass (similar to 0.984M(circle dot)) is well below the Chandrasekhar limit (similar to 1.4M(circle dot)) and that the Ni-56 mass is comparable to the Ni-56 yields of the explosions of some sub-Chandrasekhar explosion models support the scenario that PS1-12sk might be from a sub-Chandrasekhar explosion induced by the merger of two low-mass WDs. The derived innermost radius (similar to 13.81 & times; 10 (12) cm) and the mass of the CSM (similar to 0.116 M-circle dot) disfavour the possibility that the CSM was formed in the merger phase. We suggest that the flybys before the merger can account for the position and mass of the CSM.

It is known that there is an association between long gamma-ray bursts and supernovae (SNe), and study of these SNe is important for exploring the death of massive stars. Here, we investigate GRB 171205A/SN 2017iuk (at redshift z = 0.0368) by fitting multiband light curves and modeling the SN 2017iuk spectra with SYNAPPS. The light curve of GRB 171205A/SN 2017iuk shows a long plateau, not only in X-rays but also in optical bands. This plateau may be from the late-time contribution of a magnetar central engine. We use a magnetar spindown model, 56Ni model, and cooling model to fit the multiband light curves. The best-fitting results reveal the total SN ejected mass Mej=4.60-0.70+1.20M circle dot , Ni mass MNi=0.31-0.03+0.05M circle dot , and total kinetic energy EK approximate to 3.14 x 1052 erg, consistent with the average values inferred for other gamma-ray burst-SNe. The best-fitting photospheric velocities are 14,700 and 11,400 km s-1, and the photospheric temperatures are 9900 and 11,800 K, at +7.2 and +13.2 days (respectively). From our light curves and spectral analysis, we suggest that the central engine of GRB 171205A/SN 2017iuk is likely to be a magnetar, with initial spin period P0=70.61-0.97+0.62ms and surface magnetic field at the pole Bp=3.84-0.61+0.33x1015G .

SN 2014av is a type Ibn supernova (SN) characterized by the interaction between the SN ejecta and a helium-rich circumstellar medium (CSM). We use the Ni-56 model, the ejecta-CSM interaction (CSI) model, and the CSI plus Ni-56 model to fit the multiband light curves (LCs) of SN 2014av. For the CSI and CSI plus Ni-56 models, we assume that the CSM is a constant density shell ("shell") or a steady-state stellar wind ("wind") with density proportional to r(-2). We find that both the Ni-56 and CSI models fail to fit the multiband LCs of SN 2014av, while the CSI plus Ni-56 model can account for the LCs. In the last scenario, the LCs around the peaks were mainly powered by the CSI, while the flattening of the LCs was mainly powered by the radioactive decay of Ni-56. For the wind case, the derived mass-loss rate of the progenitor is approximate to 20.5-205.5 M-circle dot yr(-1), whose lower limit is significantly larger than the upper limit of normal stellar winds, and comparable the upper limit of hyper-winds. Hence, we suggest that the wind case is disfavored. For the shell case, the best-fitting values of the ejecta, Ni-56, and the CSM are 2.29 M-circle dot, 0.09 M-circle dot, and 5.00 M-circle dot, respectively. Provided the velocity of the CSM shell is 100-1000 km s(-1), we infer that the shell might be expelled approximate to 0.49-5.20 yr before the SN exploded.

In this paper, we determine the photosphere evolution of PTF11rka which is a type Ic supernova (SN) by fitting its spectral energy distributions at different epochs. We find that the photosphere of PTF11rka expanded at a constant velocity at early epochs, and the photosphere temperature increased slightly after reaching a minimum. These features are reminiscent of those of SN 2017dio. Based on the photosphere module that can describe the photosphere evolution of PTF11rka, we use the Ni-56 cascade decay model to fit its multiband light curves (LCs), finding that the model can well fit the photometric data. The derived ejecta mass and Ni-56 mass are respectively 8.76 M(circle dot)and 0.29-0.41 M-circle dot; the derived peak luminosity and the rise time of the theoretical bolometric LC of PTF11rka are similar to 8.24 x 10(42) erg s(-1) and similar to 35 days, respectively. Moreover, we find that the theoretical multiband LCs and the theoretical bolometric LC of PTF11rka do not show early-time excesses proposed in the literature. This indicates that additional energy sources (e.g., the interaction between the ejecta and the circumstellar material) suggested to be responsible for the early-time excess can be neglected.

High-cadence, multiwavelength observations have continuously revealed the diversity of tidal disruption events (TDEs), thus greatly advancing our knowledge and understanding of TDEs. In this work, we conducted an intensive optical-UV and X-ray follow-up campaign of TDE AT2023lli, and found a remarkable month-long bump in its UV/optical light curve nearly two months prior to maximum brightness. The bump represents the longest separation time from the main peak among known TDEs to date. The main UV/optical outburst declines as t^-4.10, making it one of the fastest decaying optically selected TDEs. Furthermore, we detected sporadic X-ray emission 30 days after the UV/optical peak, accompanied by a reduction in the period of inactivity. It is proposed that the UV/optical bump could be caused by the self-intersection of the stream debris, whereas the primary peak is generated by the reprocessed emission of the accretion process. In addition, our results suggest that episodic X-ray radiation during the initial phase of decline may be due to the patched obscurer surrounding the accretion disk, a phenomenon associated with the inhomogeneous reprocessing process. The double TDE scenario, in which two stars are disrupted in sequence, is also a possible explanation for producing the observed early bump and main peak. We anticipate that the multicolor light curves of TDEs, especially in the very early stages, and the underlying physics can be better understood in the near future with the assistance of dedicated surveys such as the deep high-cadence survey of the 2.5-meter Wide Field Survey Telescope (WFST).

We study the energy sources, the physical properties of the ejecta and the circumstellar medium (CSM), and the mass-loss history of the progenitor of SN 2017dio, which is a broad-lined Ic (Ic-BL) supernova (SN) having unusual light curves (LCs) and signatures of hydrogen-rich CSM in its early spectrum. We find that the temperature of SN 2017dio began to increase linearly about 20 days after the explosion. We use the ^56 Ni plus the ejecta–CSM interaction model to fit the LCs of SN 2017dio, finding that the masses of the ejecta, the ^56 Ni, and the CSM are ∼12.41 M _⊙ , ∼0.17 M _⊙ , and ∼5.82 M _⊙ , respectively. The early-time photosphere velocity and the kinetic energy of the SN are, respectively, ∼1.89 × 10 ^4 km s ^−1 and ∼2.66 × 10 ^52 erg, which are comparable to those of SNe Ic-BL and hypernovae (HNe), respectively. We suggest that the CSM of SN 2017dio might be from a luminous blue variable–like outburst or pulsational pair instability ∼1.2−11.4 yr prior to the SN explosion or binary mass transfer. Moreover, we find that its ejecta mass is larger than those of many SNe Ic-BL and that its ^56 Ni mass ( M _Ni ) is approximately equal to the mean (or median) value of M _Ni of SNe Ic-BL in the literature but lower than M _Ni of prototype HNe (e.g., SN 1998bw and SN 2003dh).

In this paper, we perform the detailed modeling for the light curves (LCs) of PTF 10iuv which is a calcium-rich (Ca-rich) supernova (SN) to constrain the physical properties of its ejecta and the energy sources, as well as the explosion mechanism. We find that the Ni-56 model and the Ni-56 plus circumstellar interaction model fail to explain the LCs, while the four-element (Ni-56, Cr-48, Fe-52, and Ti-44) model can account for the LCs. The ejecta mass of PTF 10iuv derived by the model (1.52-0.25+0.34M(circle dot)) is consistent with that of the merger of a sub-Chandrasekhar mass white dwarf. The early-time LCs were mainly powered by Ni-56 whose mass is similar to 0.03 M-circle dot, while the contributions of Cr-48 and Fe-52 can be neglected. The derived Ti-44 mass (similar to 0.25 M-circle dot) is similar to 1.8 times the upper limit of the derived Ti-44 mass of Ca-rich SN 2005E. We suggest that subtracting the contributions of the host-galaxy, which are unknown, and including the flux from other long-lived elements (e.g., Co-57, Fe-55, Co-60) can reduce the amount of Ti-44, and that this value can be regarded as an upper limit.

We perform a comprehensive study of the physical properties of SN 2018gk, which is a luminous Type IIb supernova (SN). We find that the early-time photospheric velocity varies from a larger value to a smaller one before the photosphere reaches a temperature floor. We generalize the photosphere modulus and fit the multiband light curves (LCs) of SN 2018gk. We find that the Ni-56 mass model requires similar to 0.90 M (circle dot) of Ni-56, which is larger than the derived ejecta mass (similar to 0.10 M (circle dot)). Alternatively, we use the magnetar plus Ni-56 and the fallback plus Ni-56 models to fit the LCs of SN 2018gk, finding that the two models can fit the LCs. We favor the magnetar plus Ni-56 model since the parameters are rather reasonable (M (ej) = 1.65 M (circle dot), M (Ni) = 0.05 M (circle dot), which is smaller than the upper limit of the Ni-56 mass that can by synthesized by neutrino-powered core-collapse SNe, B = 6.52 x 10(14) G, which is comparable to magnetic fields in luminous and superluminous SNe studied in the literature, and P (0) = 10.42 ms, which is comparable to initial periods for luminous SNe), while the validity of the fallback plus Ni-56 model depends on the accretion efficiency (eta). Therefore, we suggest that SN 2018gk might be an SN IIb powered mainly by a central engine. Finally, we confirm the near-IR excesses of the spectral energy distributions of SN 2018gk at some epochs and constrain the physical properties of the putative dust using the blackbody plus dust emission model.

In this paper, we study five luminous supernovae (LSNe) Ibc (SN 2009ca, ASASSN-15mj, SN 2019omd, SN 2002ued, and SN 2021bmf) whose peak absolute magnitudes M peak are ≈ −19.5 to −21 mag by fitting their multi-band light curves (LCs) with different energy source models. We find that SN 2009ca might be powered by the 56 Ni model since the required 56 Ni mass (0.56 M ⊙ ) is comparable to those of energetic SNe Ic, while the rest four SNe cannot be accounted for the 56 Ni model since their derived 56 Ni masses are ≳1 M ⊙ or the ratios of the 56 Ni mass to the ejecta mass are larger than 0.2. This indicates that some LSNe might be powered by 56 Ni decay, while most of them need additional energy sources. We then use the magnetar plus 56 Ni model and the fallback plus 56 Ni model to fit the LCs of the four LSNe that cannot be explained by the 56 Ni model, finding that the two models can account for the four SNe, and the derived parameters are comparable to those of LSNe or superluminous SNe in the literature, if they were (mainly) powered by magnetars or fallback. We suggest that the magnetar plus 56 Ni model is more reasonable than the fallback plus 56 Ni model, since the validity of the fallback plus 56 Ni model depends on the value of accretion efficiency ( η ) and favors a large η value, and the magnetar plus 56 Ni model yields smaller χ 2 /dof values. It should be pointed out that, however, the fallback plus 56 Ni model is still a promising model that can account for the four SNe in our sample as well as other LSNe.

Long-duration gamma-ray bursts (GRBs) associated with supernovae (SNe) are believed to originate from massive star core-collapse events, whereas short-duration GRBs that are related to compact star mergers are expected to be accompanied by kilonovae. GRB 211227A, which lasted about 84 s, had an initial short/hard spike followed by a series of soft gamma-ray extended emission at redshift z = 0.228. We performed follow-up observations of the optical emission using BOOTES, LCOGT, and the Lijiang 2.4 m telescope, but we detected no associated supernova signature, even down to very stringent limits at such a low redshift. We observed the host galaxy within a large error circle and roughly estimated the physical offset of GRB 211227A as 20.47 ± 14.47 kpc from the galaxy center. These properties are similar to those of GRB 060614, and suggest that the progenitor of GRB 211227A is not favored to be associated with the death of massive stars. Hence, we propose that GRB 211227A originates from a compact star merger. Calculating pseudo-kilonova emission for this case by adopting the typical parameters, we find that any associated pseudo-kilonova is too faint to be detected. If this is the case, it explains naturally the characteristics of the prompt emission, the lack of SN and kilonova emission, and the large physical offset from the galaxy center.

There are some dozen supernovae (SNe) associated with long Gamma-ray bursts (GRBs) have been confirmed. Most of previous studies derive the physical properties of the GRB-SNe by fitting the constructed (psuedo-)bolometric light curves. However, many GRB-SNe have only a few filter data, for which the (psuedo-)bolometric light curves are very difficult to be constructed. Additionally, constructing (psuedo-)bolometric light curves rely on some assumptions. In this paper, we use the multi-band broken power-law plus ^56Ni model to fit the multi-band light curves of the afterglows and the SNe (SN 2001ke, SN 2013dx, and SN 2016jca) associated with three GRBs (GRB 011121, GRB 130702A, and GRB 161219B). We find our model can account for the multi-band light curves of the three GRB-SNe (except for the late-time z-band light curves of two events), indicating that the model is a reliable model. The ^56Ni masses we derive are higher than that in the literature. This might be due to the fact that the ^56Ni masses in the literature are usually obtained by fitting the psuedo-bolometric light curves whose luminosities are usually (significantly) underestimated. We suggest that the multi-band model can not only be used to fit the multi-band light curves of GRB-SNe that have many filter observations, but also fit those having sparse data.

We present BVRI and unfiltered Clear light curves of 70 stripped-envelope supernovae (SESNe), observed between 2003 and 2020, from the Lick Observatory Supernova Search (LOSS) follow-up program. Our SESN sample consists of 19 spectroscopically normal SNe Ib, two peculiar SNe Ib, six SN Ibn, 14 normal SNe Ic, one peculiar SN Ic, ten SNe Ic-BL, 15 SNe IIb, one ambiguous SN IIb/Ib/c, and two superluminous SNe. Our follow-up photometry has (on a per-SN basis) a mean coverage of 81 photometric points (median of 58 points) and a mean cadence of 3.6d (median of 1.2d). From our full sample, a subset of 38 SNe have pre-maximum coverage in at least one passband, allowing for the peak brightness of each SN in this subset to be quantitatively determined. We describe our data collection and processing techniques, with emphasis toward our automated photometry pipeline, from which we derive publicly available data products to enable and encourage further study by the community. Using these data products, we derive host-galaxy extinction values through the empirical colour evolution relationship and, for the first time, produce accurate rise-time measurements for a large sample of SESNe in both optical and infrared passbands. By modeling multiband light curves, we find that SNe Ic tend to have lower ejecta masses and lower ejecta velocities than SNe Ib and IIb, but higher ^56Ni masses.

Supernovae (SNe), kilonovae (KNe), tidal disruption events (TDEs), optical afterglows of gamma ray bursts (GRBs), and many other optical transients are important phenomena in time-domain astronomy. Fitting the multi-band light curves (LCs) or the synthesized (pseudo-)bolometric LCs can be used to constrain the physical properties of optical transients. The (UV absorbed) blackbody module is one of the most important modules used to fit the multi-band LCs of optical transients having (UV absorbed) blackbody spectral energy distributions (SEDs). We find, however, that the SEDs of some SNe show UV excesses, which cannot be fitted by the model including a (UV absorbed) blackbody module. We construct the bolometric LCs and employ the (cooling plus) \Ni model to fit the constructed bolometric LCs, obtaining decent fits. Our results demonstrate that the optical transients showing UV excesses cannot be fitted by the multi-band models that include (UV-absorbed) blackbody module, but can be well modeled by constructing and fitting their bolometric LCs.

This paper investigates eleven (UV-)optical-infrared (IR) spectral energy distributions (SEDs) of six tidal disruption events (TDEs), which are ASASSN-14li, ASASSN-15lh, ASASSN-18ul, ASASSN18zj, PS18kh, and ZTF18acaqdaa. We find that all the SEDs show evident IR excesses. We invoke the blackbody plus dust emission model to fit the SEDs, and find that the model can account for the SEDs. The derived masses of the dust surrounding ASASSN-14li, ASASSN-15lh, ASASSN-18ul, ASASSN18zj, PS18kh, and ZTF18acaqdaa are respectively ∼ 0 . 7 − 1 . 0 (1 . 5 − 2 . 2) × 10 − 4 M (cid:12) , ∼ 0 . 6 − 3 . 1 (1 . 4 − 6 . 3) × 10 − 2 M (cid:12) , ∼ 1 . 0 (2 . 8) × 10 − 4 M (cid:12) , ∼ 0 . 1 − 1 . 6 (0 . 3 − 3 . 3) × 10 − 3 M (cid:12) , ∼ 1 . 0 (2 . 0) × 10 − 3 M (cid:12) , and ∼ 1 . 1 (2 . 9) × 10 − 3 M (cid:12) , if the dust is graphite (silicate). The temperature of the graphite (silicate) dust of the six TDEs are respectively ∼ 1140 − 1430 (1210 − 1520) K, ∼ 1030 − 1380 (1100 − 1460) K, ∼ 1530 (1540) K, ∼ 960 − 1380 (1020 − 1420) K, ∼ 900 (950) K, and ∼ 1600 (1610) K. By comparing the derived temperatures to the vaporization temperature of graphite ( ∼ 1900 K) and silicate ( ∼ 1100 − 1500 K), we suggest that the IR excesses of PS18kh can be explained by both the graphite and silicate dust, the rest five TDEs favor the graphite dust while the silicate dust model cannot be excluded. Moreover, we demonstrate the lower limits of the radii of the dust shells surrounding the six TDEs are significantly larger than those of the radii of the photospheres at the first epochs of SEDs, indicating that the dust might exist before the the TDEs occurred.

In this paper, we searched for the dust formation evidence of 66 supernovae (SNe) by using the blackbody model and the blackbody plus dust emission model to fit their early-time optical–near-infrared (NIR) spectral energy distributions (SEDs). We find that, while the blackbody model can fit most SEDs of the SNe in our sample, the model cannot fit the SEDs of some SNe in which the SEDs of two SNe (SNe 2010bq and 2012ca) show NIR excesses which can be attributed to the emission from the heated dust. We use the blackbody plus dust emission model to fit the SEDs showing NIR excesses, finding that both the graphite and silicate dust models can fit the SEDs, and the graphite model gets reasonable temperatures or better fits. Assuming that the dust is graphite, the best-fitting temperatures (masses) of the dust of SNe 2010bq and 2012ca are ∼1300–1800 K (∼0.1–3.4 ×10 −4 M ⊙ ) and ∼600–1000 K (∼0.6–7.5 × 10 −3 M ⊙ ), respectively. We compare the vaporization radii and the blackbody radii of the dust shells of the two SNe with the upper limits of the ejecta radii of the SNe at the first epochs, and demonstrate that the NIR excesses of the SEDs of the two SNe might be caused by the pre-existing dust.

In this paper, we fit the spectral energy distributions of iPTF 16asu, which has so far been classified as a luminous rapidly evolving broad-lined Ic supernova (SN Ic-BL), and reconstruct its postpeak bolometric light curve. We find that the luminosity of the postpeak bolometric light curve of iPTF 16asu is about 3 times that of the pseudobolometric light curve derived in the literature, and the extrapolated peak luminosity exceeds ∼1044 erg s−1, which is higher than the threshold of superluminous supernovae (SLSNe). We then use the 56Ni model and the magnetar plus 56Ni model to fit the multiband light curves of iPTF 16asu, and construct the theoretical bolometric light curve using the best-fitting theoretical multiband light curves. We find that the magnetar plus 56Ni model can account for the photometry of iPTF 16asu, and the peak luminosity of its theoretical bolometric light curve is ∼1.06 × 1044 erg s−1. We suggest that iPTF 16asu and similar SNe (e.g., SN 2018gep) constitute the class of rapidly evolving SLSNe Ic-BL.

In this paper, we investigate the early-time optical–near-infrared (NIR) spectral energy distributions (SEDs) of four Type Ibn supernovae (SNe). We find that the SEDs of SN 2010al, LSQ13ddu, and SN 2015G can be well explained by the single-component blackbody model, while the SEDs of OGLE-2012-SN-006 cannot. We invoke the double-component model assuming that the SEDs were produced by the SN photosphere and the heated dust to fit the optical−NIR SEDs of the four SNe Ibn, finding that the derived temperatures of the dust associated with OGLE-2012-SN-006 favor the scenario that the dust consists of the graphite grains, and the mass and temperature of dust are ∼0.5–2.0 × 10−3 M ⊙ and ∼1200–1300 K, respectively. Moreover, our fits for SN 2010al, LSQ13ddu, and SN 2015G show that the upper limits of the masses of the dust associated with the three SNe Ibn are respectively 1.45 × 10−5 M ⊙, 5.9 × 10−7 M ⊙, and 2.4 × 10−7 M ⊙. A further analysis demonstrates that the inferred radius of the dust shell surrounding OGLE-2012-SN-006 is significantly larger than that of the SN ejecta at early epochs, indicating that the NIR excesses of the SEDs of OGLE-2012-SN-006 were produced by a preexisting dust shell. Our study for the early-time SEDs of four SNe Ibn, together with the previous studies and the fact that some SNe showed evidence of dust formation at the late-time SEDs, indicates that at least ∼1/3 of SNe Ibn show evidence for dust formation.

ABSTRACT Assuming that the shallow-decaying phase in the early X-ray light curves of gamma-ray bursts (GRBs) is attributed to the dipole radiations (DRs) of a newborn magnetar, we present a comparative analysis for the magnetars born in death of massive stars and merger of compact binaries with long and short GRB (lGRB and sGRB) data observed with the Swift mission. We show that the typical braking index (n) of the magnetars is ∼3 in the sGRB sample, and it is ∼4 for the magnetars in the lGRB sample. Selecting a sub-sample of the magnetars whose spin-down is dominated by DRs (n ≲ 3) and adopting a universal radiation efficiency of 0.3, we find that the typical magnetic field strength (Bp) is 1016 G versus 1015 G and the typical initial period (P0) is ∼20 ms versus 2 ms for the magnetars in the sGRBs versus lGRBs. They follow the same relation between P0 and the isotropic GRB energy as $P_0\propto E_{\rm jet}^{-0.4}$. We also extend our comparison analysis to superluminous supernovae (SLSNe) and stable pulsars. Our results show that a magnetar born in merger of compact stars tends to have a stronger Bp and a longer P0 by about one order of magnitude than that born in collapse of massive stars. Its spin-down is dominated by the magnetic DRs as old pulsars, being due to its strong magnetic field strength, whereas the early spin-down of magnetars born in massive star collapse is governed by both the DRs and gravitational wave (GW) emission. A magnetar with a faster rotation speed should power a more energetic jet, being independent of its formation approach.

In this paper, we use (broken) power-law plus Ni models to fit the multi-band light curves of the optical and near-infrared (NIR) counterparts of four gamma-ray bursts (GRBs 011121, 100316D, 130702A, and GRB 161219B). We find that the models can account for the light curves of the optical– NIR counterparts which can be divided into the GRB afterglows and their associated supernovae (SNe 2001ke, 2010bh, 2013dx, and 2016jca, respectively). The most parameters we derive are consistent with previous studies. However, the Ni masses we derive are higher than that in the literatures (except for that of GRB 100316D/SN 2010bh). The difference of the Ni masses might be due to the fact that the Ni masses in the literatures are obtained by fitting the quasi-bolometric light curves which are usually (significantly) underestimated, and dimmer than the theoretical bolometric light curves reproduced by the best-fitting parameters we derive. Our results demonstrate that the spectral energy distributions (SEDs) of SNe associated with GRBs can be well described by the blackbody model, and the Ni model can account for their multi-band light curves. We suggest that the Ni masses of a fraction of GRB-SNe have been underestimated.

The study on stellar mass black holes is an important issue in astrophysics. Over the past decades, astronomers have confirmed some stellar mass black holes and determined their physical properties via the observations of the X-ray binaries and the gravitational waves emitted from the mergers of binary black holes. Recently, a research team remeasured the precise distance of Cygnus X-1 (an X-ray binary) and subsequently derived the values of the mass, spin, and other properties of the black hole V1357 Cyg in Cygnus X-1. The results show that the mass of Cygnus X-1 is (21.2 +/- 2.2) M-circle dot, indicating that V1357 is the most massive stellar mass black hole in X-ray binaries, thus challenging the existing models of massive stellar binary evolution. The future precise measurements of similar black holes in X-ray binaries would further deepen our understanding of the stellar evolution models as well as the physical properties of stellar mass black holes.