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How To Find Newborn Black Holes Kazumi Kashiyama (UCB) Eliot Quataert and Rodrigo Fernandez (UCB) 1 2 3 4 IBIS IBIS/SPI/JEM-X IBIS/SPI/JEM-X IBIS/JEM-X IBIS/SPI/JEM-X (date yy/mm/dd) 02/11/25–02/12/15 02/12/09–02/12/11 03/06/07–03/06/11 03/03/24–04/09/10 04/11/22 (ks) Type d.o.f. 810 583 582 581 staring, 5 × 5a , hexb584 365/365/31 5×5 Notes. The assumed5stellar 292/296/275 × 5 temperature is Teff = 31,000 K. Ropt is the stellar radius derived from the models. Rdist is the stellar radius derive c measured assumed temperature. Vrot sin i = 95 ± 6 km s−1 is the projected rotational velocity of the O-star derived from the model 269/35parallax and GPS assumes orbit and synchronous rotation. Model B assumes a circular orbit and nonsynchronous rotation. Model C assumes an eccentri 8/8/6a circularcalibration pseudosynchronous rotation. Model D assumes an eccentric orbit and nonsynchronous rotation. The adopted parameters are the weighted aver values for Model D derived for each temperature in the range of 30,000 K ! Teff ! 32,000 K. Stellar-Mass Black Holes Notes: a 5×5 dither pattern around the nominal target location. b Hexagonal pattern around the nominal target location. c Individual exposures separated by 6◦ along the scan path, shifted by 27.5◦ in galactic longitude. (Observations indicated on the first line also used, together with epochs 1–4, for Figs. 2 and 3.) U X-ray (1.5-12 keV) B tion of the Binary Mass Function Eric Addison Fig. 1. RXTE/ASM daily average (1.5–12 keV)Bel+06 light curve Cadolle of Cygnus X-1 from 2002 November to 2004 November (MJD = JD − 2 400 000.5) with the periods of our INTEGRAL observations (see text and Tables 1 and 2 for epoch definitions). were active. For the IBIS/ISGRI spectral extraction however, we implemented the most recent module (prepared for the OSA 5.0 delivery) which is based on the least squares fit done on background and efficiency corrected data, using coded source zones only. This option minimizes spurious features in the extracted spectra, which appear in particular when the Orosz+11 sources are weak, partially coded and the background poorly corrected (A. Gros, private communication). For the PICsIT spectral extraction, we took the flux and error values in the mosaic image at the best-fit position found for the source. We used the response matrices officially released with OSA 4.2, rebinned to the 8 energy channels of the imaging output. The SPI data were preprocessed with OSA 4.2 using the standard energy calibration gain coefficients per orbit and excluding bad quality pointings which have anomalous exposure and dead time values (or with a high final χ2 during imaging). The spiros 9.2 release (Skinner & Connell 2003) was used to extract the spectra of Cygnus X-1, Cygnus X-3 and EXO 2030+375, with a background model proportional to the saturating event count rates in the Ge detectors. Concerning the instrumental response, version 15 of the IRF (Image Response Files) and version 2 of the RMF (Redistribution Matrix Files) were used for epoch 1 and 2, e.g., prior to detector losses, while Credit: Chandra X-Ray Observatory, NASA V The Astrophysical Journal, 785:28 (6pp), 2014 April 10 Fig. 2. The 20–200 keV IBIS/ISGRI light curve of Cygnus X-1 from 2002 November 25 until 2004 November 22 and corresponding HR between the 40–100 and the 20–30 keV energy bands (see text and Tables 1 and 2 for epoch definitions). versions 17 and 4 respectively were taken for epoch 4, e.g., after the failure of two detectors. Figure 3. Schematic diagram of Cygnus X-1, shown as it wo the sky plane. The offsets are in milliarcseconds (mas), assum of 1.86 kpc. The orbital phase is φ = 0.5, which corresponds conjunction of the O-star. The orbit of the black hole is indicated where the major and minor axes have been drawn in for clarity dashed line, respectively). The direction of the orbital motion as determined by the radio observations (Reid et al. 2011). T represents the local effective temperature. The star is much c inner Lagrangian point because of the well-known effect of “grav (Orosz & Hauschildt 2000). The temperatures referred to in Figure 1 and Table 1 refer to intensity-weighted average values. (A color version of this figure is available in the online journal.) , f (m1 ) is a piece of information constructed from observables of a Resultsorbital of the analysis period P Assuming we have values for3.the orb and the maximum As shown in Fig. 1, during the epoch 2 INTEGRAL observa3 tions, the 1.5–12 keV ASM average countquantity rate of Cygnus X-1 rs, say V2 , we can compute the value for the m sin i through 1 (∼1.3 Crab) was larger than during epoch 1 (∼290 mCrab) by a factor of 4.5. derived IBIS/ISGRI 20–200 keV light Figure 2. Top: the The optical light curves and best-fitting models assuming an eccentric with e Ratio = 0.018 D, leftX-1 panels) and a recircular orbit curves andorbit Hardness (HR)(Model of Cygnus are shown (Model A, in right Noteoverview how muchofbetter thePV-Phase unequal maxima of the spectively Fig.panels). 2 (general part of and of the recent work considers circular orbits and s light curves are accommodated by the model that includes eccentricity. Bottom: epochs 1 to 4) and Fig. 3 (specific zooms on part of PV-Phase, the radial velocity measurements binned into 50 bins (filled circles) and the rotation (e.g., Caballero-Nieves et al. 2009). While epochs 1 and 2). From 1 toorbit epoch 2, while thecircular ASM orbit aver-(right). best-fitting model for theepoch eccentric (left) and the tricity we find is small (e = 0.018 ± 0.002 for age count rate increased, the 20–200 keV IBIS/ISGRI one deTeff = 31,000 K), it is highly significant. Allowi creased from ∼910 to ∼670 mCrab as shown in Fig. 3 (where, Ozel+12 −1 in the 20–200 keV range, 1 Crab = 205 cts s ). This proba5 bly indicates a state transition between epochs 1 and 2, as also 0 2 4 6 8 10 suggested by the decrease in the IBIS HR (Fig. 3). Similar transition, with a change in the ASM light curves and an evolving IBIS HR, occurred again during GPS data (epoch 3). Figu Figure (200 Figure 2 (bottom) shows the IBIS HR behaviour over the whole1. Observed masses of neutron stars (filled triangles) and black holes (filled squares) from Özel et al. (2010, 2012). The thick solid line at 2.25 M⊙ rapi 2002–2004 period indicated in Table 1. Porb V22 m1 sin3 i = f (m1 ) ≡ 2 (1 + q) 2πG (1) rst component of the binary, i is the inclination angle of the orbit, of the system, and G is the gravitational constant. Which progenitors produce BHs not NSs? Supernova shock is stalled or not? How much material fallback on protoNS? The key will be inner density structure within r ⇠ 1000 km, M r ⇠ 2-3 M Red supergiant O’Connor & Ott 2011; Ugliano et al. 2012; K. Kashiyama, R. Fernandez, and E. Quataert (RSG) Horiuchi et al. 2014; Pejcha & Thompson 2015 2 12 13 15 17 20 25 30 35 40 45 50 55 60 70 80 100 Density [g cm ] 105 100 10 0.8 1052 RSG 0 6 10 10 WR 0.6 0.2 -10 10 53 BH? BSG 0.4 Blue supergiant (BSG) -5 Z = Zsun Z = 0.01 Zsun 1 ξ2.5 10 10 10 7 8 10 9 10 10 10 10 Radius [cm] 11 10 12 Walf-Rayet star (WR) 10 13 10 14 10 20 30 40 50 60 70 80 100 ZAMS mass [Msun] Fig. 3.— Compactness of the progenitors. The magenta and cyan points to the cases instar Figs. can 1 andform 2, respectively. Allcorrespond types of massive BHs. lations, the necessary condition for successful SN explosion is ⇠2.5 . 0.2 0.3. In the following sections, we What is observational signature? Stellar type (RSG, BSG, or WR) * Rotation profile (disk or not) * Magnetic field (jet or not) Possible Outcomes in a BH Formation No. 2, 2008 DO SUPERGIANTS VANISH? 1339 Kochanek+08 Fig. 3.— Possible outcomes in forming a BH. The optical signatures of the ‘‘no explosion’’ scenarios are little explored. significantly less luminous than before it died. Other known sources galaxies (axis ratios <0.3). Only 40 galaxies need to be observed # 5 Possible Outcomes in a BH Formation No. 2, 2008 DO SUPERGIANTS VANISH? 1339 Gamma-ray bursts? Hypernovae? Super-luminous supernovae? luminous, but rare Fig. 3.— Possible outcomes in forming a BH. The optical signatures of the ‘‘no explosion’’ scenarios are little explored. significantly less luminous than before it died. Other known sources galaxies (axis ratios <0.3). Only 40 galaxies need to be observed # 5 Possible Outcomes in a BH Formation No. 2, 2008 DO SUPERGIANTS VANISH? 1339 “Unnovae” probably not rare Fig. 3.— Possible outcomes in forming a BH. The optical signatures of the ‘‘no explosion’’ scenarios are little explored. significantly less luminous than before it died. Other known sources galaxies (axis ratios <0.3). Only 40 galaxies need to be observed # 5 Very low energy supernovae from neutrino mass loss Even if the SN shock is stalled, 10.— Shock modeled by CASTRO in RSG15 (TOV = 2.5, aFig. weak shockmapped can into be KEPLER. driven by full neutrino losses) neutrino mass loss of the PNS. Fig. 11.— Velocity of the hydrogen envelope at 5×107 s after core collapse in RSG15, TOV = 2.5, full neutrino loss model, evolved further in KEPLER. “Luminous red novae” then continued to evolve them. Figures 10 and 11 show the KEPLER results RSG15, TOV = 2.5; 13 Figure 10 Nadezhin 80,for Lovegrove & Woosley 5 shows the imported shock, and Figure 11 shows the final 7 velocity of the hydrogen envelope at t = 5 × 10 s. The shock has decreased significantly in strength by the time it reaches the base of the hydrogen envelope; however, this envelope is very tenuously bound in both RSG15 and RSG25. For each model we tested six choices of TOV limit (2.0 - 2.5 M⊙ , in 0.1 M⊙ increments) and evaluated the strength of the shock that reached the hydrogen envelope. Using the full neutrino loss model, we found in every case tested for RSG15 and in 3 of 6 tested for RSG25 that the shock produced was larger than 1×1047 ergs, the approximate binding energy of the envelope (see Table 3). We can therefore realistically expect the envelope to be ejected in these cases. However, the highest kinetic energy achieved was only of the order of 6×1047 ergs, and most models fell well below that number. The envelope is therefore ejected with a very low velocity (50 - 100 km/s). It emits most of its energy Fig. 12.— KEPLER light curve for a transient from RSG15, via hydrogen recombination. Optically this transient has A significant part of the energy TOV = 2.5. The transient is low luminosity but lasts for around 39 40 a low luminosity ∼ 10 − 10 ergs/s, but maintains this a year. 47 48model comes frominH Fig. 6.— Collapse offor the in the maximum neutrino RSG15 model the recombination. fully-modeled neuluminosity ofRSG15 order a year. The color temperature of Fig. 7.— Collapse of the mass loss case, showing a shock forming due to the effective core trino mass loss case, showing a shock forming due to the such effective sh the transient is very red, of order 3000 K. An example explosion would leave a black hole. A survey as that mass decrement. Positive velocities are outwards, negative are incore mass decrement. Positive velocities are outwards, negative light curve can be Figure 12 for RSG15, TOV =are inwards. proposed byare Kochanek al. (2008), monitoring red suwards. Curves are purple for seen early in times, shading to red for late. Curves purple foretearly times, shading to red for 2.5.has the TOV limit set to 2.5, resulting in a mass decrepergiants forthe anomalous might This model late. This model has TOV limittransients set to 2.5, that resulting in asignal mass the Ecalculated of H envelope of RSG ment of 0.525 . Bind. The shock propagates out ofare the helium core muchdecrement of 0.523 M⊙ . The shock is smaller in strength than theThey TheM⊙transients here obviously birth of a black hole, should catch these events. 10 cm). Time shock reaches 1010 cm: 38 s. Time to casevisible and reaches edge of the simulation with “star” a (r = 3.568×10 fainter and less energetic than standard core-collapse su-maximum-loss would be as a the sudden brightening of the 11 cm: 577 s. lower velocity. Time shock reaches 1010 cm: 40 s. Time to end of end of helium core: 196 s. Time to 10 pernova, but they do bear some similarity to a class ofhelium for of207 order a year, bys.a gradual but complete 11 cm: 620 core: s. Time to 10followed recently-observed transients: “luminous novae,” disappearance. corresponds to MGh as given by Eq. the 4. This model red takes such as V838 Mon (Munari 2002). Luminous red novae In RSG25 a TOV limit of 2.2 M⊙ or lower resulted into account the thermal mass loss and ties the cessation E ⇠ 10 & erg T ⇠ 3000 K No Data No Data 4589 4652 4795 4915 Searching for vanishing supergiants • Monitoring ~106 RSGs in ~25 Gal. within ~10 Mpc with ~0.5 yr cadence for ~5 yrs using the Large Binocular Telescope • Examine sources with (⌫L⌫ ) Figure 14. Select V and Rc band observations for Candidate 1 in NGC all. The selected observations give a clear picture of the source’s variabi July 2008 (3 May 2008) and the “Last” observation is on 20 November 2 Kochanek+08, Gerke+15 104 L • 3 core collapse supernovae • 1 candidate of vanishing RSG • Continuous obs. will 14give J. R. Gerke et al. meaningful constraints on failed SN rate. REF RMS First 52 Figure 13. The B, V and Rc band differential light curves for Candidate 1 in NGC 6946. The open circle in the V band light curve was an observation that fell just outside our quality criteria No Data band that was later added as a check on the measurements. The V vertical axis is in units of 104 L⊙ (νLν ) and has been normalized to 20080503 20080705 20081125 20090325 20100318 20110923 20120612 20130610difference 20141120 between Last the first observation so that the luminosity the first and last observations can be easily seen. A change in lumiNo Data No Data R band nosity by 104 L⊙ in either direction, as indicated by the horizontal lines, would lead to the source being selected as a candidate. The 4589 4652 4795 4915 5273 6090 bottom two panels are5827 the 3.6µm and6453 4.5µm 6981 SST archival light curves normalized to the first epoch and on a different y-axis scale. F H se ob 1 fo m 14 in ob sh ca an a th fr de un w If va Possible Outcomes in a BH Formation No. 2, 2008 DO SUPERGIANTS VANISH? 1339 BH + super Eddington disk maybe not rare Fig. 3.— Possible outcomes in forming a BH. The optical signatures of the ‘‘no explosion’’ scenarios are little explored. significantly less luminous than before it died. Other known sources galaxies (axis ratios <0.3). Only 40 galaxies need to be observed # 5 Fall back disk may be ubiquitous Woosley & Heger 12, Perna+14 The Astrophysical Journal, 752:32 (11pp), 2012 June 10 Woosley & Heger BSG WR in binary Figure 1. Distribution Journal, of angular752:32 momentum with respect angular momentum The Astrophysical (11pp), 2012 June to 10 mass in the pre-supernova models for V24 and V36. The smooth curves show the Woosley & Heger required to form a stable disk at the last stable orbit of a Schwarzschild black hole (lower curve) or Kerr black hole (upper curve) including the given mass. The intermediate curve that follows the Schwarzschild curve until far out in the star uses the integrated angular momentum in the model to determine the last stable orbit. Where the irregular dark line showing the actual angular momentum on the star intersects this line a disk can form. The outer 9 M⊙ of Model V24 and the outer 10 M⊙ of Model V36 will form a disk. The edge of the helium cores of the two models is apparent in the sharp inflection in the angular momentum at 8.3 M⊙ and 15.0 M⊙ . Mass loss was included in the calculation, but due to the low metallicity, only 0.05 M⊙ and 0.15 M⊙ was lost in V24 and V36, respectively. Note that, if all the surface material accreted here, the black hole would rotate at nearly its maximum allowed value (i.e., the red line intersects the green one at the end). for massive main-sequence stars depends upon some fractional power of the metallicity (Kudritzki 2002). More important and less certain is the dependence of mass lost as a red or blue supergiant on metallicity. It is thought that mass loss from cool giants is more dependent upon pulsations and grain formation (Reimers 1977; Smith et al. 2011). One might expect therefore a rapid falloff in mass loss below some value necessary for significant grain production. It has been estimated that red giant mass loss will be significantly less below 0.1 Z⊙ (Bowen & Willson 1991; Zijlstra 2004). If stars do not lose mass then they conserve angular momentum. Since the natural course of evolution leads to the contraction and spin up of the inner star, shear instabilities and magnetic torques will concentrate an increasing amount of angular momentum in the outer regions of the star. While the Outer layers of up to ~ a few M angular momentum distributions as shown in Figure 1. While the lack of sufficient angular momentum within the helium core precludes making a disk around a black hole within that mass, there is ample rotation in the outer part of the hydrogen envelope to do so. This could be a very common occurrence. From the survey of A. Heger & S. E. Woosley (2012, in preparation), the total angular momentum of a massive star at birth that has an equatorial rotation speed of about 20% Keplerian on the main sequence is ! " M 1.8 52 Jtot = I ω ≈ 2 × 10 erg s. (1) M⊙ can “naturally” have sufficient j If the star does not lose mass, most of this angular momentum becomes concentrated, in the pre-supernova star, in a nearly rigidly 13 v r0 ≈ fr × for ∼ 3& ×ionized 10 cm helium, . (1) min (MRI). Proga Begelman (2003a,b) simulated accre′ a steady The density be des ctronity scattering singly fully ionized inner dis (MRI). Proga accre-structure ρby≈wind. ρsimulated . 2 canmost (8) c2 rate, ṀEdd =ity4πGM 10 BH /cκ 10 M 0−2 the fallback material. Eddington accretion ∼ ⊙1 & × Begelman ρ(2003a,b) " ! ! t v acc out,min ≈gas ρ0quali(r/r ,disk where ρqualiṀ the /4πr , energy or 0 ≈ 3/2 nuclear energy released 0 v̄out ium10tion and hydrogen, respectively. Theof accretion rate nuclear low angular momentum gas in ara-isscenario −15 −1 −1 tion angular momentum in 0The a) scenario accretes once out angular momentum fṀ Mof (κ/0.2 cm2cases g−1 )in (M ). Note that f ⊙ son marginal BH /10M ⊙ r ′ −12 −3 We focus which the low circularization ! " ! " We determine the normalization of the density by mass confectively transported by e.g., magnetorotational inim ρ ∼ 4 × 10 g cm −3/2 2 −1 dynamically o below the accretion rate at which there is significant dynamically importan 0showed tatively analogous toorbit thatThey considered showed # rmaxhere.2 They tatively to0.4that here. the opacity ∼ 0.1,larger 0.2 and cm g considered corresponds to f&r Begelman f(2003a,b) −3 dius is notκanalogous much than the innermost circular Ṁ 10 0.1 ity (MRI). Proga simulated servation, 4πr ρdr ≈ fṀ Md ,the which yields At t " ta ρ0 ∼ 60 g cm rmomentum the MRI redistributes during min utrino (Chen 2007). this electron scattering for& singly ionized helium, fullyIn ionized At t 0.1 " tinacc the 10 that MRI redistributes angular momentum during the of cooling the the BH (f −Beloborodov 100); wethat show below (Fig. 4) case, that angular " ! ! tion of ! low angular momentum gas" a ,scenario r ∼ 10 −9/2 " ! " ! and the outflo 3/2 helium and hydrogen, respectively. The accretion rate is circularization, leading to dissipation which powers both R M " ! " ! "M ! ∗ d e cancircularization, expect a strong radiation-driven from the ′ powers both tatively analogous that considered here. essen They s −3/2 −3 fṀoutflow larger circularization radii likely to leaddissipation to outflow fainter more slowly frto R and the −12 × M −3 leading which M ∗ BH d ρ ∼ 4 × 10 g cm also below the accretion rate at which there is significant the outflow e 0 that the MRI redistributes angular momentum durin 12 andestimated outflow. In our scenario, viscous × 1the M⊙ 10 0.1cm ejecta 10 k. Such outflows haveThe been alsoaccretion confirmed byannumerievolving transients. fallback rate can be as 10 12outflow the wid 1 M 10 10 M⊙ accretion outflow. In our scenario, the viscous circularization, leading tocm dissipation powers neutrino coolingand (Chen an & Beloborodov 2007). In this case, ⊙ r/t"which ≈ v. The time of the disk is much shorter than the fallback time " ! " ! ! −9/2 3/2 Ṁ ≈ M /t , or acc d d (Ohsuga simulations etradiation-driven al. 2005; Sa̧dowski et al. accretion outflow. InM our scenario, the p v R M ∗an one can expect a strong outflow from the2014; Here, rdmax of ≈and vout,max tacc ≈ Since r/t ≈ v. min as time of the disk is much shorter than the fallback time scale. Thus, the accretion rateisis given bymuch the the density the outflow at, The rrBH =described rdensity the .vout,mi (9) ×essentially 0 . the −5 −1 time of the disk is shorter than fallback 12 ng, disk. Stone 1M 10 cm 10 M outflows have alsofrom confirmed by numeri⊙ , and ⊙ ṀLuminous ∼& Davis 3 × Blue 10 2014). M s ⊙ been d Such v̄the vdescribed = fessentially v̄outgiven . Inb v,max out out,min v,min Fastscale. Transients Newborn BHs 3 isftypically initially highly optically thick, the temperatur fallback rate (Eq. 2), which is larger than the scale. Thus, the accretion rate isas Thus, the accretion rate is essentially given by ! " ! " ! " cal simulations (Ohsuga et al. 2005; Sa̧dowski et al. 2014; −3/2 1/2 We model the fallback disk outflow as follows. First, 1/3 −2/3 Luminous Blue Transients BHs 3 Here, rmax vout,max tacc ,(Eq. ≈ tacc = ! fallback is,! typically larger choose fv,max " 1, f1which 1,, v#and > adiabatically, Trate ∝ ρrmin rvout,min thus Tout,max ≈ ξT0tha (r Md(Eq. from R∗ Newborn MBH Eddington accretion rate, ṀEdd =≈4πGM /cκ ∼2),∝ × v,min BH fallback rate 2), which is typically larger than the Jiang, Stone & Davis 2014). × , (2) rmax accretion rate, Ṁ −15is isotropic, raction fṀFinally, < 1 we ofM the accreting is⊙ loaded on cm the v̄−1 , and venergy f/8πar v̄02out . Edd In this4πGM paper, we∼ ′(4π BH /cκ out out,min v,min assume that outflow although in 2fv,max Kasen 12the TEddington ≈ (Ṁout v=Note )1/4 , or= 0 /10M 10mass M10 s−1 g−1 )where (M that isfy the conservation 1 10 cm M BH ⊙ ). ⊙ ⊙ (κ/0.2 −15 −1out 2 −1 −1 i.e., ρ r≈ ρ0 We model the fallback disk outflow as follows. First, Finally, we assume that outflowrate, is isotropic, although in 4πGMBH s (κ/0.2 g ξ )> (M /10M Not min ⊙ ).satEddington accretion Ṁ =∼ /cκ ∼ 2101 × We determine choose fv,max " −1 1,Mf⊙v,min ! 1,"cm so as to Edd reality it will bethe bipolar. tflow, Ṁout =f fbeṀ × Ṁ or, ! !0.4 22cm "BH dmoderately # rm #and 2 −1 2corresponds the opacity κ 0.1, 0.2 and 0.4 cm g to −5/8 1/4 r 2 max 3 1/2 reality it will moderately bipolar. the opacity κ ∼ 0.1, 0.2 and g correspon a fraction < 1 of the accreting mass is loaded on the −15taccṀ −1 2 −1 fenergy v̄conservation that the en fṀ out /2. fnote the (4πr × internal ρv /2)dr r≈ Next, let describe density and)−1 temperature profile isfy he pror where ≈ π(R /8GM )the ,"or servation, 8 Wei.e., Ṁ Mdthat ∗ us BH ! 10 M s (κ/0.2 cm g (M /10M ). Note rmin ionized ⊙ BH ⊙ T ∼ 8 × 10 K m Next, let us describe the density and temperature profile electron scattering for singly helium, fully i electron scattering for singly ionized helium, fully ionized 0 outflow,inṀthe = fṀ × which Ṁd!or,are fcrucial out outflow, 2subdominant at for ! quantifying the electrors have We determine the norm " " is r ≈ r due to adiab 10 0.1 2 −1 −6 −1 min f M v̄ /2. We note that the internal energy of the shell Ṁ 3/2 −1/2 out d in for quantifying electrohelium and hydrogen, respectively. accretion r # rThe Ṁ ! the opacity κare 0.1, and the 0.4 cm expands g (4) corresponds to ∼the 3outflow, × 10 which M scrucial helium and hydrogen, respectively. The accretion rate is Rf∗0.2 M ut ⊙ BH max 2" 4∼ magnetic emission. After the" launch, the outflow l torus " ! " ! ! Super-Eddington accretion! 1/4 −3/8 is subdominant at r ≈ r due to adiabatic cooling. To ′ obtain f , f , and ξ consistently magnetic emission. After the launch, the outflow expands t ∼ 3 × 10 s (3) also below the accretion rate at which there is sign −6 −1 min servation, 4πr 0.1 Ṁ acc out,max out,min RDecember M 12 cm ρr0min ×ρ 1 (4) Ṁ ∼ 3the × 10 M⊙ s 10 ∗ Therate Astrophysical Journal, 796:106 (14pp), 2014 1 ∼ M4BH d significant also below the accretion at which there is out into surrounding medium. For t ! t , the accretion 10 M electron scattering for singly ionized helium, fully ionized acc ⊙ into the surrounding For0.1 t"! tacc , ! the accretion cooling (Chen & Beloborodov 2007). In this obtain fform ,× fout,min , and ξ consistently, one the has to per"medium. ! "1/2 ! out,maxneutrino numerical simulations, but basic 12 −3/2 " 1 expect MIn 10 cm 10 M! rate isM almost and the ! outflow is"approximately neutrino cooling (Chenaccretion &form Beloborodov 2007). case, ⊙ this ⊙ rate is almost and the approximately one can abut strong outflow fro M "constant, ! R !constant, dtimescale, numerical simulations, theradiation-driven basic characteristics of helium hydrogen, rate is 1/2 The −3/2is is the free and fall R∗∗ outflow is"respectively. the radius ofBH the outermost . (1) R M M . × the optical emission are not so sensitive t steadyThe wind. The12 density structure can be described as ∗ BH ddensity a steadya wind. structure can be described as disk. Such outflows have been also confirmed by nu ′ −12 one can expect a. strong radiation-driven outflow from the × We note that the gas temperature in the disk the optical emission are not so sensitive to these paramelayer, and M is the total mass of the disk. The torus is op−2 2 1 M 10 cm 10 M ρ ∼ 4 × 10 g c × −2 2 ⊙ also below rate which there is significant 0 =et0.7, ρ ≈0 )ρ0 (r/r where ρcm v̄M or ρ ≈ ρ0 (r/r ,dwhere ≈10 Ṁ12 /4πr v̄out , or10 cal simulations (Ohsuga al. 2005; Sa̧dowski et al.1 0 )⊙ ρ,0accretion 0 ≈ Ṁ out 1⊙the M out out /4πr 0at −1/4 ⊙,outflows 0disk. 9numeriters. We take f 1.4, v,min v,max Such have been also confirmed by ters. We take f = 0.7, f = this 1.4, f and ξ heavy == 3.75 as Outflows! f T ! a few 10 K. In case, nuc v,min v,max 0 ion ra-tically and geometrically thick, trapping the heat generated ! " ! " Jiang, Stone & Davis 2014). ! " ! " Ṁ −3/2 −3/2 neutrino cooling (Chen & Beloborodov 2007). In this case, cond, the outflow velocity is approximately the escape vefṀ cal fsimulations fr −3 isfrapproximately Second, the outflow velocity the escape vefiducial choices. As long as the is≈! a (Ohsuga et al. at 2005; et al. 2014; fiducial choices. long as the thefallback ejecta issynthesized almost adiabatic, " ! ejecta −3material. r orbit mostSa̧dowski O,As Ne, and Mg can bedisk inside Ṁ We model outflow asrmax follows. Here, ρby ∼ ρfallback 60 0 the 0 g∼cm 60 g cm 1/2 1/2 M 10/r 0.1 Jiang, locity, v̄can ≈ (2GM ,10 or expect radiation-driven outflow from the 0.1 Stone profile described as out BH 0 ) strong 4) & Davisis2014). ity,that v̄one ≈ (2GM /r ," or aFe fraction <be 1 of theHence, accreting mass loaded the temperature profile can bethere described ao out The BH 0 )a but not groupfcan elements. isisv̄dno radi disk accretes once the angular momentum ef- the temperature Ṁ fv,max out , an × " ! " ! −3/2 ! −3/2 " ! " ! " ! ! " ! " " ! −3/2 −3/2 outflow, Ṁ = f × Ṁ or, slowly out −1Ṁ First, d −ξ/3 −1/2model Md outflows ∗ BH We the fallback disk outflow as The follows. !nuclear !1 M "− " !fMrbeen in the outflow. burning only occu disk. Such have also by numeriR M MdR10 fectively× transported by e.g., instabil∗ magnetorotational BH −1 −1/2 choose f⊙v,max t above v " , (6)confirmed ′ −1 " ! 12 , (6) × ated as t v f M⊙ cmcm s12 M T ≈ Tdisk, (10) v̄1out ∼ 1 ×10 10 . fM < 1(5)of the accreting r⊙ ′thethe 10 0is loaded fṀ is. likely larger a10 fraction mass on enthalpy −6 −1 ity (MRI). Proga &M Begelman (2003a,b) simulated accre⊙ cm10 Ṁ 10 vMout,min isfy the energ Twhere ≈10T v̄out ∼ 1 × 110 s−1cm . ⊙ Sa̧dowski (5) etinner cal simulations (Ohsuga et al. 10 2005; al. most 2014; Ṁout ∼tacc 3× ⊙ s 0 Here, r the0.1nuclear ≈vout,min vout,max is the of density ofangular the outflow at r = r0 . gas Sinceinthe outflow =the fṀoutflow × Ṁd or, nuclear energy released, so tthat reaction acc max out tion scenario quali2 is low the density of momentum the outflow outflow, at10 r = r0Ṁ .a Since Then, what will happen? "! "f−3/2 !d v̄out " ! M /2. Jiang, &000, Davis 1/ is initially Stone highly optically thick, 2014). the temperature evolves ṀMetzger " ! f v̄ , and R Mv M ctatively dynamically important (Fernández & 201 ⃝ 2015 RAS, MNRAS 1–7 ∗ BH d v,max out out,m analogous to that considered here. They showed is initially highly optically thick, the temperature evolves 1/3 −2/3 −2/3 × adiabatically, T ∝ ρ ∝ r 1/3 , thus−2/3 T ≈ T0 (r/r0 ) , −6 −2/3 −1 fṀ First, subdominan We model the disk outflow as follows. 1M 1012 rate cm isdecreases 10 M⊙sign ⊙ 2 ρ1/4fallback At t " t , the accretion adiabatically, T ∝ ∝ r , thus T ≈ T (r/r ) , (4) Ṁ ∼ 3 × 10 M s 2015 where RAS,the MNRAS 000, 1–7 acc 0 0 that MRI redistributes angular momentum during the out ⊙ choose f " 1, f T ≈ ( Ṁ v /8πar ) , or v,max 0 out out 0 , (2) obtain f 2 1/4 0.1 out,ma where T ≈ ( Ṁ v /8πar ) , or the essentially outflow velocity is approximately the esca out out and theSecond, outflow decouples from the dis 0 1/4 accreting acircularization, fraction 0fṀ 1to!offdissipation the the ! < "−5/8 " leading which powers isfy the conser "is! loaded"on ! v̄out ≈ (2GM "1/2 !massboth 1/2 energy fr form numerica −3/2 8 Ṁ−5/8 ! ! " " locity, /r ) , or BH 0 1/4 T ∼ 8 × and 10 Kan = ejecta 0 R∗ the outflow M accretion In ourfṀscenario, theMviscous BH will expand in a homologous d outflow, Ṁ out 10outflow. r0.1Ṁd or, 8 fṀ f× 2 the ! "optical . × em −1/2 T0 the 8× 10 K fṀ Mof v̄out−1 /2. 12 cm r/t ≈ v. The10density profile homologous ejec d fr We not "1/4 "−3/8 ! 0.1 "−3/8fallback !∼ disk time of is !much shorter than!the 10 the 1 M M 10 ⊙time 10 ⊙ " v̄out ∼ 1 × 10 cm s ters. We . take R∗ MBH Md 10 " ! "−3/8 f ! given !accretion described as .(7) "−3/8 × the is essentially by the 1/4 rate is subdominant at r (3)scale. Thus, −6 −1 12 Ṁ 1 M 10 cm 10 M R M M ⊙ ⊙ ∗ BH d Second, the outflow velocity is approximately the escape ve! " ! " fiducial choice (4) Ṁ ∼ 3 × 10 M s −3 −ξ out ⊙ .(7) 1/2 × fallback rate (Eq. 2), which is typically larger than the 12 t v obtain fout,max , fout,m c 2015 RAS, MNRAS ⃝ 000, 1–7 1M 10 inlocity, cm M≈⊙ BH /r0 ) We note that the gas temperature the disk is 10 Td(2GM ⊙ v̄out0.1 ≈ , or the temperatu ρ ≈ ρ′0 . ermost −1/4 9 Eddington accretion rate, Ṁ = 4πGM /cκ ∼ 1 × BH Edd fṀ T0We ! anote few that 10 ! K. In this case, heavy nuclei up to t v " ! " ! " acc out,min form numerical simula ! "−1/2 1/2 −3/2 the gas in the disk is Td ≈ 2 temperature s is op-10−15 M s−1 (κ/0.2 Jiang+14 cm g−1 )−1 (Minside /10M ). Note that Figure 3. Snapshot of disk structures for density (left) and radiation energy ⊙Ne, and Mg can BH at most O, be the ⊙ disk, −1/4 R M M 9d synthesized f ∗ BH r 10 fṀ T0 !×a few 10 K. In this case, heavy nuclei to We the theρ0density nerated 2 radioactivity −1 v̄out ∼ 1 up × 10 s−1atdetermine . 1.13 the optical am densitycm (right) time 10.4 ts normalization . Units for (5) ρ and Eof and ar T04byT # r× r are emission but Fe group elements. Hence, there iscm no the not opacity κ ∼ 0.1, 0.2 and 0.4 g corresponds to 12 max 2 10 at most O, Ne, and Mg can be synthesized inside the disk, M⊙burning10 cm in the 10 M⊙ servation, r respectively. 4πr ρdr ≈ fṀ Md , which yields in the outflow. The above1 nuclear only occurs Fast Luminous Blue Transients 2 K. Kashiyama, E. Quataert KK & Quataert 15 Fast Luminous Blue Transient Fallback Disk Outflow Absolute AB magnitude 6 The Inner core is directly swallowed by the central black hole. ! The outermost layers have sufficient angular momentum to form a disk. ! K. Kashiyama, E. Quataert 4 -18 -17.5 2 WR BSG DISCUSSION Figure 1. Schematic picture of failed supernova model for fast luminous blue transients. DIVERSITY OF BLACK HOLE FORMATION -17 Stellar-mass BHs are predominately formed in the core -16.5 of massive stars. For stars NUVwith zero-age-mainR collapse sequence (ZAMS) masses of ! 10M⊙ , the iron core collapses -16once its mass exceeds the Chandrasekhar limit, forming a proto-NS. The proto-NS cools via intense neutrino emission of ∼ 1053 erg, which is believed to ultimately -15.5 power the SN explosion, at least in some progenitors (e.g., O’Connor & Ott 2011; Ugliano et al. 2012; Horiuchi et al. -15 2014; Pejcha & Thompson 2015). If, however, the accretion -3 the -2 proto-NS -1 0stalls1 and2never 3 reverses 4 5to un6 shock onto bind the stellar envelope, the t continued [day]accretion eventually leads the proto-NS to collapse into a BH. We are interested latter case this paper. of Even in thisdisk case, however, Figurein3.the Absolute ABinmagnitude fallback outflow emisif the progenitor is a RSG, the change in core mass asso- Using a simple analytic model, we have calculated the fal back disk outflow emission from the formation of BHs in oth emi erwise failed supernova explosions. disks power ou plosions (e.g., Woosley & Bloom 2006). It Fallback is not guaranteed, however, every,can or be evenobserved the majority of, flows whose that emission as a rapidly-evolvin 42−43 momenWR (∼ or BSG progenitors with significant angular a few days)41-43 luminous (∼ 10 erg s−1 ) blue (T -1 tum produce successful GRBs. For example, the power104bol K) transient. This outflow can be observed only when ful jets that produce GRBs may require large-scale magnotinenshrouded a quasi-spherical explosion. This like neticisflux the stellar by progenitor as well as rapid rorequires compact progenitors, and tation (Tchekhovskoy & Giannios 2014). like SinceWRs large-scale 4 BSGs, whic magnetic tendsbound to slowenvelopes down the rotation theneutrino core haveflux tightly so that ofthe radiatio during stellar evolution, it could be that the combination of of the proto-NS binding energy would not lead to significan conditions required to produce luminous GRBs is somewhat mass ejection. Our simplified treatments of e.g., the fallbac rare. In this paper, we argue that an alternative electrodisk counterpart formation,associated the (thermo-)dynamics the outflow, an magnetic with BH formation of during the transfer of the cooling radiation, need tois be the collapse of rapidly rotating WR or BSG progenitors a followed u by moreUV-optical detailed numerical studies. fast luminous transient broadly similar to some ü t ~ Days to 10 days ü L ~ 10 erg s ü blue continua with T ~10 K events discovered by Pan-STARRs and PTF in the last ∼ 5 The PS1-MDS Transients Pan-STARRS1 Medium Deep Survey (PS1-MDS) for Rapidly Evolving and Luminous Transients Drout+14 The Astrophysical Journal, 794:23 (23pp), 2014 October 10 Drout et al. ü t1/2 < 12 day --- rapidly evolving than any SN type ü Lpeak ~ 1042-43 erg s-1 --- luminous as bright SNe ü Tpeak ~ a few 104 K --- blue ü No line blanketing --- not powered by the radioactive decay ü Host Gal. = star forming Gal. --- related to massive stars Figure 1. PS1 absolute magnitude, rest-frame, light curves for gold sample transients. Circles represent griz detections and triangles represent 3σ upper limits. Vertical dashed indicate epochs when spectroscopic acquired. The gray shaded region the R-band Typerare Ibc template from Drout et al. (2011), ülinesEvent rate ~ 4-7observations % of were core-collapse SNis --not normalized to the peak magnitude of the PS1-MDS transient. P1 (A color version of this figure is available in the online journal.) Summary and Discussion How to find newborn black holes • Vanishing supergiants • Luminous red novae • Fast blue transients üa day to 10 day depending on progenitor structure üLbol ~ 1041-43 erg s-1 üBlue continua with T ~ 104 K üThe PS1-MDS transients are from WRs and BSGs? ümay not be rare (~5% of CCSNe). • Multi-Messenger Approach üRadio üGravitational wave Back up Now is the good timing Annu. Rev. Astro. Astrophys. 2006.44:49-92. Downloaded from www.annualreviews.org Access provided by University of Nevada - Las Vegas on 10/05/15. For personal use only. Figure 1 Scale drawings of 16 black-hole binaries in the Milky Way (courtesy of J. Orosz). The Sun–Mercury distance (0.4 AU) is shown at the top. The estimated binary inclination is indicated by the tilt of the accretion disk. The color of the companion star roughly indicates its surface temperature. Optical Transients 383 Transients in the local Universe −24 45 SCP06F6 SN2005ap SN2008es PTF09cnd SN2006gy PTF09cwl PTF09atu PTF10cwr −22 Thermonuclear Supernovae 43 10 SN2002bj −18 Core−Collapse Supernovae PTF10bhp .Ia Explosions −16 PTF11bij PTF09dav PTF10iuv SN2005E 42 10 SN2008ha −14 Ca−rich Transients 41 10 SN2008S PTF10acbp Peak Luminosity [erg s−1] V 44 10 SN2007bi −20 Peak Luminosity [M ] 10 Luminous Supernovae NGC300OT −12 PTF10fqs P60−M82OT−081119 −10 40 10 M85 OT V838 Mon Classical Novae −8 Luminous Red Novae M31 RV 39 10 P60−M81OT−071213 38 −6 10 0 10 1 10 Characteristic Timescale [day] 2 10 Kasliwal 11 Figure 4. Framework of Cosmic Explosions in the Year 2011 (Kasliwal 2011). Note that until 2005 (Fig. 1), we only knew about three classes (denoted by gray bands). In the past six years, systematic searches, serendipitous discoveries and archival searches have uncovered a plethora of novel, rare transients. Discov- Possible Outcomes in a BH Formation No. 2, 2008 DO SUPERGIANTS VANISH? 1339 Dimer class of SNe ? (e.g., 1987A) probably not rare Fig. 3.— Possible outcomes in forming a BH. The optical signatures of the ‘‘no explosion’’ scenarios are little explored. significantly less luminous than before it died. Other known sources galaxies (axis ratios <0.3). Only 40 galaxies need to be observed # 5 10 The PS1-MDS Transients Drout et al. Figure 7. Phase space of SNe: peak luminosity vs. rest-frame time above halfmaximum for a variety of SNe. The PS1-MDS transients described in this paper are shown as red stars. They span an order of magnitude in peak luminosity and significantly increase the number of known transients with short characteristic Drout+14 The PS1-MDS Transients The Astrophysical Journal, 794:23 (23pp), 2014 October 10 Figure 11. Best-fit blackbody temperatures (top panel) and radii (bottom panel) as a function of time. In general, temperatures evolve from around 20,000 K near maximum to 7000 K at later times. Exceptions include PS1-12brf (whose initial temperature is around 50,000 K), PS1-10ah (whose temperature rise to Drout+14 Figure 12. Left panel: p The PS1-MDS Transients The Astrophysical Journal, 794:23 (23pp), 2014 October 10 Drout et al. Blue Continua No Line Blanketing Figure 14. Mg ii absorption in the spectrum of PS1-12bv. Left: vertical lines mark the systemic velocities of the host galaxy as measured from [O ii] λ3727 and Hβ in emission. The red line signifies the extent of the resolved blue “shelf,” which may be due to absorption in the CSM surrounding the progenitor. Right: an example multiple component fit to the absorption feature. The green (blue) components are blue shifted ∼700 km s−1 (1500 km s−1 ) with respect to the host galaxy and have a FWHM of 550 km s−1 (900 km s−1 ). The galaxy [O ii] λ 3727 feature has a FWHM of 300 km s−1 . (A color version of this figure is available in the online journal.) 5.2. Lack of Nebular Features in PS1-12bb Figure 13. Explosion spectra for five PS1-MDS transients (colored) in comparison to events from the literature (black). With the exception of PS1-12bb our events are dominated by a blue continuum, with a lack of strong P Cygni fea- We obtained two spectra for PS1-12bb. At the time of the second epoch (+33 days) the i-band light curve of PS1-12bb had declined by ∼3 mag. Similar to the spectrum obtained near maximum light, this spectrum is dominated by continuum (with some contribution from its host galaxy’s light). This is in contrast to any other “late time” spectra of a rapidly declining SN that has been obtained to date. Both SN 2005ek (Drout et al. 2013) and SN 2010X (Kasliwal et al. 2010) were observed between 10 and 35 days post-maximum. Both events (Type Ic) displayed Drout+14 a growing emission component in the Ca ii NIR triplet. By +23 days the spectrum of SN 2010X was dominated by the Ca ii NIR triplet between 8000 and 9000 Å. This is not the case r 10 The PS1-MDS Transients Drout et al. Table 5 Host Galaxy Properties Methodb PP04N2 PP04N2 PP04N2 Z94 PP04N2 ··· KD02 KD02 PP04N2 log(Mgal /M⊙ ) SFR (M⊙ yr−1 ) Figure 16. Cumulative distributions of various host galaxy properties: stellar mass, metallicity, star formation rate, and specific star formation rate. In all panels the red line(s) represents the rapid evolving SNe presented in this work. In panels 3 and 4 the solid red line represents the six gold/silver objects with host galaxy spectra and the dashed red line includes lower limits based on the explosion spectra of the remaining four objects. Also shown are distributions from LGRBs and core-collapse (black and green Norm. lines, respectively; see text for references). The dashed green line in panel 2 is the untargeted Type Ibc SN from Sanders et al. (2012). The sSFR SNe Offset Offset Offsetc vertical dashed line in panel 2 signifies solar metallicity. −1 (Gyr ) (arcsec) (kpc) (A color version of this figure is available in the online journal.) ∼0.9 0.42 0.68 0.21 9.12+0.18 −0.21 Journal,∼1.2 The Astrophysical 794:23 (23pp), 2014 October 10 9.12+0.18 ∼2.1 ∼1.6 0.95 −0.24 10.17+0.20 ∼4.3 ∼0.3 1.54 −0.37 >0.3 >2.4 0.47 8.01+0.61 −0.70 10.54+0.43 ∼2.3 ∼0.06 4.93 −0.12 9.89+0.62 >0.3 >0.03 0.97 −0.52 8.73+0.20 >0.3 >0.5 0.42 −0.17 8.78+0.15 >0.1 >0.2 0.33 −0.12 8.96+0.27 ∼1.9 ∼2.0 1.40 −0.01 +0.07 8.68−0.13 ∼4.5 ∼9.3 0.14 2.39 0.85 2.90 0.69 Drout et al. test yields a 14% (37%) probability that the rapidly evolving 12.58 0.98 transients hosts are drawn from the same population as the 8.81 1.05 CC-SN (LGRB) hosts. Thus, while our host galaxies skew 10.99 lower masses, 1.92 slightly toward there is no statistical evidence for 0.50 a different10.29 parent population from either LGRBs or CC-SNe. 2.16 6.2. 0.44 Metallicity the8.28 Markov 0.82 Chain Using Monte Carlo method described in 1.04(2012) 0.32 Sanders et al. we measure the emission line fluxes and metallicities of nine of the host galaxies. Due to the varying wavelength coverage and quality of our spectra, it was not Diagnostics utilized varied between objects. possible to use the same strong line diagnostic for all of the Pettini & Pagel (2004); Z94 = Zaritsky et al. (1994); KD02 = Kewley & Dopita (2002); M91 galaxies. In Table 5 we list both the measured value and the Figure 4. Gold and silver sample explosion environments. Images areutilized. from PS1 templates. explosion sitesof are comparison, marked with red crosses. diagnostic For Transient the purposes we then s of the host galaxy. (A color version of thisall figure available in the online journal.) convert ofis the values to the R23 system of Kewley & Dopita The Astrophysical Journal, 794:23 (23pp), 2014 October 10 selection criteria listed in Section 2.2. The absolute& magnitude, an aperture to encompass all of the visible light.(2002) Cross-checks using the calibration relations from Kewley Ellison Figure 17. Mass–metallicity relation for nine gold/silver transients (red stars). rest-frame, light curves for these events are shown in Figure 1. show the PS1 and SDSS magnitudes are consistent. In Figures 4 g to accelerate (2008). Our silver sample is composed of four objects. These are and 6 we show the environments immediately surrounding the Also plotted are contours representing the 53,000 SDSS star-forming galaxies follow-up our spectroscopic m s−1 ) to these Many of the host haveasmetallicities aretheroughly eventsgalaxies that were noted rapidly evolvingthat during normal transients. from Tremonti et al. (2004) (shaded region, lines represent discovered the 2.5, 16, 50, 84, PS1-MDS in the s due to CSM operations of the PS1-MDS but that possess lightIn curves solar, with a median value of log (O/H) + 12sparser = 8.8. the and 97.5 percentile of the distribution in each bin) and the long-duration GRBtimescale i Because their 2.6. Optical Spectroscopy 2).16 In we all cases the observed light curves are sufficient diative driving hosts from Levesque et al. (2010b). Unlike the LGRB hosts,due which are offset to or maint second panel of (Figure Figure plot their cumulative distribution. to poor weather to characterize them as rapidly evolving, but sparse enough lower metallicities, our sample is consistent with being drawn from the greater peed found for Spectroscopic follow-up for the PS1-MDS is carried out on aare offset to a significantly higher metallicity than Our hosts such that they fail the systematic selection criteria described on the efficiency with which number of telescopes, with the MMT, Magellan and Gemini SDSS population. eas the speeds above.(Svensson For instance,et PS1-13ess onlySavaglio has one band deep either LGRB hosts al. 2010; etwith al. a2009; We therefore use a Monte Ca bearing most of the load. Spectra are acquired for roughly (A color version of this figure is available in the online journal.) limit in the 9 days prior to observed maximum (as opposed to of a wind from in Quimby et al. (2012, 201 10% of the transients identified by the photpipeLevesque pipeline, withet al. 2010a; Levesque et al. 2010b; Graham & the requisite two). For a majority of this manuscript, the silver spectra of five is one offinal ourselections left to the observer. We obtainedFruchter which each PS1-MDS field 2013) objects or thewill untargeted Ibc hosts from Sanders be analyzed Type with our gold sample, as they further transients while they were active, including two observations hotometrically function of distance. inform theand properties of rapidly evolving transients. However, et al. (2012) (black line dashed green line, respectively) with of PS1-12bb. The epochs on which these spectra were taken 6.4. Star Formation Rates in Section 7 when calculating volumetric rates, only objects that We begin by constructing uj (which are was indicated by a dashed vertical line in the appropriate panels a !0.5% probability of being drawn from the same population. pass the well defined set of selection criteria outlined above will lution templates based on t of Figures 1 and 2. Host galaxy spectra were also obtained for m an optically The entire CC-SN sample from Kelly & Kirshner (2012) (solid be considered. We estimate host galaxy SFRs for the six events for whicha luminosity six transients. A summary of our spectroscopic data is given in then construct ′ ′ may therefore In Figure 4 we show the 25 × 25 region surrounding the green line) is shifted to even higher metallicities than our sample, Table 3. we possess galaxy spectra (Figure 15) by measuring their Hαdistribution trinsic Gaussian gold and silver transients, all of which have an associated host. g wind in the Initial reduction (overscan correction, flat fielding, extraction, although we caution fraction these events Narrowaemission andof absorption lines werewere used todiscovered measure the line fluxes and applying the relation of Kennicutt (1998). tion to accountInfor host gal wavelength calibration) of all long slit spectra was carried out by targeted surveys (which toward higher redshift to each bias host. These range from z metallicities). = 0.074 (PS1-10ah) Quimby fraction et al. (2013) we ad each case we apply a rough correction for the covering using the standard packages in IRAF. Flux calibration and d by either a to z = 0.646 (PS1-11bbq) with a median redshift of z = 0.275. telluric correction were performed using a set of custom idl (Hatano et al. 1998) for the h of our spectra by scaling to our PS1 photometry of the hosts. In Table 1 we list the redshift, Relation luminosity distance, and Milky system along 6.3. Mass–Metallicity scripts (see, e.g., Matheson et al. 2008; Blondin et al. 2012) point for thecases intrinsic distrib Way reddening in the direction of each transient (Schlafly & We do not correct for intrinsic extinction. In the three andto standard star observations obtained the same night as the xy. In order same mean and variance as Finkbeinertransients. 2011). Throughout this paper we correct only for Figure 15. Host galaxy for six of the 17 gold/silver Nebular where both Hα and Hβ are detected the decrement is reasonably science exposures. Spectra obtained withspectra the Hectospec multiIn Figure we plot the stellar mass versus metallicity for Figure 18.a Projected host offsets for our sample (red) in comparison to λλ 2796,2803) Milky Way extinction. All calculations in this paper assume of our gold sample after pe fiber spectrograph (Fabricant et al.labeled 2005) by were reduced emission lines are dashed vertical lines.flat ΛCDM −1 astronomical consistent withphysical zero extinction. SFRs range from nine of using the transients (redcosmology stars) versus ∼53,000 SDSS other transients. Left panel: offsets. Right The panel:resulting offsets with H0the = 71 km s−1 Mpc , Ωstarm = o this portion the Malmquist bias. As a c the IRAF package “hectospec” and the CfA pipeline designed −1 normalized by the g-band half-light radiiand of theare hosts. Our sample most closely 0.27,from and ΩΛSDSS = 0.73. (Tremonti et al. 2004, 1–5 M yr listed in Table 5. For the four forming galaxies shaded ⊙ for this instrument. he right panel Carlo remaining simulations distributin distribution of core-collapse SN offsets. In Figure 5 we plot peak absolute magnitude traces versusthe redobjects we may place lower limits on the SFR by measuring thein space. Th regions). Also shown are the low redshift LGRB hosts from explosion site offsets of the host galaxies in comparison to the tribution evenly shift in grizP1 for the gold/silver transients. Stars represent dividual Mg ii (A color version of this figure is available in the online journal.) 3. SAMPLE OVERVIEW Levesque et al. (2010b, black). The hosts of the PS1-MDS Hβ emission line flux from the explosion spectra (Figure 13) hosts of other classes of transients. our observed magnitudes corrected for distance and MW ex>1.5 mag above the nomina s their sum. In magnitudes been The 14 rapidly evolving transients we identify in the PS1and assuming zero extinction. We do not attempt correct foragree well rapidly evolvingtinction. SNe Circles appearrepresent to be absolute consistent with that thehave bulk of forto detectability) hat were both k-corrected to the rest-frame grizP1 bandpasses based on best- we can draw, there is no statistical evidence that the conclusions MDS can be usefully split into three groupsstar-forming based on (1) galaxies 6.1. Mass the covering fraction in these cases. The lower limits range fromdistance. Th in SDSS. This is in contrast to the hosts luminosity and fit blackbodies (see Section 4). We see that our sample spans aare drawn from different M absorptions the quality of their observed light curves and (2) constraints samples −1progenitor populations. The (i-band) Gaussian 0.1–0.3 M yr . In the second and third panels of Figure 16 we distribu of LGRBs and Type I SLSNe, both which have shown wide range of absolute peakof magnitude (−17 > been M > −20). ⊙ available on their After distances. For the rest of the manuscript these SFRs measured for our hosts are clustered around the median correcting the host griz-band photometry for Milky M91 Host Gal. = SF Gal. Drout+14 The PS1-MDS Transients The Astrophysical Journal, 794:23 (23pp), 2014 October 10 Figure 19. PS1-MDS rapid-transient detection efficiencies for our rate calculation. Solid lines indicate detection efficiencies for individual PS1-MDS fields as a function of redshift (bottom axis) or luminosity distance (top axis). A black solid line indicates the detection efficiencies for the survey as a whole, which peak around 11% at z = 0.1. The dashed black line indicates the distance at which we expect our detections to be located. This peaks at z = 0.2. The actual 4%-7% of CCSN@z =0.2 reasonable agre derived rates to decrease. In addition, examine every p events. As a by transients will will be missed i timescales. It is this factor, but derived rates. Finally, we a that no objects SN 2005ek and Only PS1-12bb but its spectra Ca ii NIR featur events. Using th curve and temp through a simila Gaussian lumin Drout+14 find that, due to SN 2005ek, the similar transien