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Repository of works by Caltech published authors.

Group = IPTF

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  1. iPTF16fnl: A Faint and Fast Tidal Disruption Event in an E+A Galaxy

    Blagorodnova, N.; Kulkarni, S. R.; Yan, L.; Bue, B. D.; Ho, A. Y. Q.; Kasliwal, M. M.; Laher, R. R.; Lunnan, R.; Masci, F. J.; Neill, J. D.; Walters, R.
    We present ground-based and Swift observations of iPTF16fnl, a likely tidal disruption event (TDE) discovered by the intermediate Palomar Transient Factory (iPTF) survey at 66.6 Mpc. The light curve of the object peaked at an absolute mag M_g =- 17.2. The maximum bolometric luminosity (from optical and UV) was L_p ≃ (1.0 ± 0.15) x 10^(43) erg s^(−1), an order of magnitude fainter than any other optical TDE discovered so far. The luminosity in the first 60 days is consistent with an exponential decay, with L ∝ e^(-(t-t_0)/τ, where t_0 = 57631.0 (MJD) and τ ≃ 15 days. The X-ray...

  2. Revisiting Optical Tidal Disruption Events with iPTF16axa

    Hung, T.; Gezari, S.; Blagorodnova, N.; Roth, N.; Cenko, S. B.; Kulkarni, S. R.; Horesh, A.; Arcavi, I.; McCully, C.; Yan, Lin; Lunnan, R.; Fremling, C.; Cao, Y.; Nugent, P. E.; Wozniak, P.
    We report the discovery by the intermediate Palomar Transient Factory (iPTF) of a candidate tidal disruption event (TDE) iPTF16axa at z = 0.108 and present its broadband photometric and spectroscopic evolution from three months of follow-up observations with ground-based telescopes and Swift. The light curve is well fitted with a t^(−5/3) decay, and we constrain the rise time to peak to be <49 rest-frame days after disruption, which is roughly consistent with the fallback timescale expected for the ~5 × 10^6 M_⊙ black hole inferred from the stellar velocity dispersion of the host galaxy. The UV and optical spectral energy...

  3. Revisiting Optical Tidal Disruption Events with iPTF16axa

    Hung, T.; Gezari, S.; Blagorodnova, N.; Roth, N.; Cenko, S. B.; Kulkarni, S. R.; Horesh, A.; Arcavi, I.; McCully, C.; Yan, Lin; Lunnan, R.; Fremling, C.; Cao, Y.; Nugent, P. E.; Wozniak, P.
    We report the discovery by the intermediate Palomar Transient Factory (iPTF) of a candidate tidal disruption event (TDE) iPTF16axa at z = 0.108 and present its broadband photometric and spectroscopic evolution from three months of follow-up observations with ground-based telescopes and Swift. The light curve is well fitted with a t^(−5/3) decay, and we constrain the rise time to peak to be <49 rest-frame days after disruption, which is roughly consistent with the fallback timescale expected for the ~5 × 10^6 M_⊙ black hole inferred from the stellar velocity dispersion of the host galaxy. The UV and optical spectral energy...

  4. Revisiting Optical Tidal Disruption Events with iPTF16axa

    Hung, T.; Gezari, S.; Blagorodnova, N.; Roth, N.; Cenko, S. B.; Kulkarni, S. R.; Horesh, A.; Arcavi, I.; McCully, C.; Yan, Lin; Lunnan, R.; Fremling, C.; Cao, Y.; Nugent, P. E.; Wozniak, P.
    We report the discovery by the intermediate Palomar Transient Factory (iPTF) of a candidate tidal disruption event (TDE) iPTF16axa at z = 0.108 and present its broadband photometric and spectroscopic evolution from three months of follow-up observations with ground-based telescopes and Swift. The light curve is well fitted with a t^(−5/3) decay, and we constrain the rise time to peak to be <49 rest-frame days after disruption, which is roughly consistent with the fallback timescale expected for the ~5 × 10^6 M_⊙ black hole inferred from the stellar velocity dispersion of the host galaxy. The UV and optical spectral energy...

  5. Revisiting Optical Tidal Disruption Events with iPTF16axa

    Hung, T.; Gezari, S.; Blagorodnova, N.; Roth, N.; Cenko, S. B.; Kulkarni, S. R.; Horesh, A.; Arcavi, I.; McCully, C.; Yan, Lin; Lunnan, R.; Fremling, C.; Cao, Y.; Nugent, P. E.; Wozniak, P.
    We report the discovery by the intermediate Palomar Transient Factory (iPTF) of a candidate tidal disruption event (TDE) iPTF16axa at z = 0.108 and present its broadband photometric and spectroscopic evolution from three months of follow-up observations with ground-based telescopes and Swift. The light curve is well fitted with a t^(−5/3) decay, and we constrain the rise time to peak to be <49 rest-frame days after disruption, which is roughly consistent with the fallback timescale expected for the ~5 × 10^6 M_⊙ black hole inferred from the stellar velocity dispersion of the host galaxy. The UV and optical spectral energy...

  6. Color Me Intrigued: the Discovery of iPTF 16fnm, a Supernova 2002cx-like Object

    Miller, A. A.; Kasliwal, M. M.; Cao, Y.; Adams, S. M.; Goobar, A.; Knežević, S.; Laher, R. R.; Lunnan, R.; Masci, F. J.; Nugent, P. E.; Perley, D. A.; Petrushevska, T.; Quimby, R. M.; Rebbapragada, U. D.; Sollerman, J .; Taddia, F.; Kulkarni, S. R.
    Modern wide-field, optical time-domain surveys must solve a basic optimization problem: maximize the number of transient discoveries or minimize the follow-up needed for the new discoveries. Here, we describe the Color Me Intrigued experiment, the first from the intermediate Palomar Transient Factory (iPTF) to search for transients simultaneously in the g_(PTF) and R_(PTF) bands. During the course of this experiment, we discovered iPTF 16fnm, a new member of the 02cx-like subclass of Type Ia supernovae (SNe). iPTF 16fnm peaked at M_(gPTF) = -15.09 ± 0.17 mag, making it the second-least-luminous known SN Ia. iPTF 16fnm exhibits all the hallmarks of...

  7. Color Me Intrigued: the Discovery of iPTF 16fnm, a Supernova 2002cx-like Object

    Miller, A. A.; Kasliwal, M. M.; Cao, Y.; Adams, S. M.; Goobar, A.; Knežević, S.; Laher, R. R.; Lunnan, R.; Masci, F. J.; Nugent, P. E.; Perley, D. A.; Petrushevska, T.; Quimby, R. M.; Rebbapragada, U. D.; Sollerman, J.; Taddia, F.; Kulkarni, S. R.
    Modern wide-field, optical time-domain surveys must solve a basic optimization problem: maximize the number of transient discoveries or minimize the follow-up needed for the new discoveries. Here, we describe the Color Me Intrigued experiment, the first from the intermediate Palomar Transient Factory (iPTF) to search for transients simultaneously in the g_(PTF) and R_(PTF) bands. During the course of this experiment, we discovered iPTF 16fnm, a new member of the 02cx-like subclass of Type Ia supernovae (SNe). iPTF 16fnm peaked at M_(gPTF) = -15.09 ± 0.17 mag, making it the second-least-luminous known SN Ia. iPTF 16fnm exhibits all the hallmarks of...

  8. iPTF16geu: A multiply imaged, gravitationally lensed type Ia supernova

    Goobar, A.; Amanullah, R.; Kulkarni, S. R.; Nugent, P. E.; Johansson, J.; Steidel, C.; Lawrence, D.; Mörtsell, E.; Quimby, R.; Blagorodnova, N.; Brandeker, A.; Cao, Y.; Cooray, A.; Ferretti, R.; Fremling, C.; Hangard, L.; Kasliwal, M.; Kupfer, T.; Lunnan, R.; Masci, F.; Miller, A. A.; Nayyeri, H.; Neill, J. D.; Ofek, E. O.; Papadogiannakis, S.; Petrushevska, T.; Ravi, V.; Sollerman, J.; Sullivan, M.; Taddia, F.; Walters, R.; Wilson, D.; Yan, L.; Yaron, O.
    We report the discovery of a multiply imaged, gravitationally lensed type Ia supernova, iPTF16geu (SN 2016geu), at redshift z = 0.409. This phenomenon was identified because the light from the stellar explosion was magnified more than 50 times by the curvature of space around matter in an intervening galaxy. We used high-spatial-resolution observations to resolve four images of the lensed supernova, approximately 0.3 arc seconds from the center of the foreground galaxy. The observations probe a physical scale of ~1 kiloparsec, smaller than is typical in other studies of extragalactic gravitational lensing. The large magnification and symmetric image configuration imply...

  9. iPTF16geu: A multiply imaged, gravitationally lensed type Ia supernova

    Goobar, A.; Amanullah, R.; Kulkarni, S. R.; Nugent, P. E.; Johansson, J.; Steidel, C.; Lawrence, D.; Mörtsell, E.; Quimby, R.; Blagorodnova, N.; Brandeker, A.; Cao, Y.; Cooray, A.; Ferretti, R.; Fremling, C.; Hangard, L.; Kasliwal, M.; Kupfer, T.; Lunnan, R.; Masci, F.; Miller, A. A.; Nayyeri, H.; Neill, J. D.; Ofek, E. O.; Papadogiannakis, S.; Petrushevska, T.; Ravi, V.; Sollerman, J.; Sullivan, M.; Taddia, F.; Walters, R.; Wilson, D. M.; Yan, L.; Yaron, O.
    We report the discovery of a multiply imaged, gravitationally lensed type Ia supernova, iPTF16geu (SN 2016geu), at redshift z = 0.409. This phenomenon was identified because the light from the stellar explosion was magnified more than 50 times by the curvature of space around matter in an intervening galaxy. We used high-spatial-resolution observations to resolve four images of the lensed supernova, approximately 0.3 arc seconds from the center of the foreground galaxy. The observations probe a physical scale of ~1 kiloparsec, smaller than is typical in other studies of extragalactic gravitational lensing. The large magnification and symmetric image configuration imply...

  10. iPTF16geu: A multiply imaged, gravitationally lensed type Ia supernova

    Goobar, A.; Amanullah, R.; Kulkarni, S. R.; Nugent, P. E.; Johansson, J.; Steidel, C.; Lawrence, D.; Mörtsell, E.; Quimby, R.; Blagorodnova, N.; Brandeker, A.; Cao, Y.; Cooray, A.; Ferretti, R.; Fremling, C.; Hangard, L.; Kasliwal, M.; Kupfer, T.; Lunnan, R.; Masci, F.; Miller, A. A.; Nayyeri, H.; Neill, J. D.; Ofek, E. O.; Papadogiannakis, S.; Petrushevska, T.; Ravi, V.; Sollerman, J.; Sullivan, M.; Taddia, F.; Walters, R.; Wilson, D. M.; Yan, L.; Yaron, O.
    We report the discovery of a multiply imaged, gravitationally lensed type Ia supernova, iPTF16geu (SN 2016geu), at redshift z = 0.409. This phenomenon was identified because the light from the stellar explosion was magnified more than 50 times by the curvature of space around matter in an intervening galaxy. We used high-spatial-resolution observations to resolve four images of the lensed supernova, approximately 0.3 arc seconds from the center of the foreground galaxy. The observations probe a physical scale of ~1 kiloparsec, smaller than is typical in other studies of extragalactic gravitational lensing. The large magnification and symmetric image configuration imply...

  11. Type Ibn Supernovae Show Photometric Homogeneity and Spectral Diversity at Maximum Light

    Hosseinzadeh, Griffin; Cao, Yi; Duggan, Gina; Horesh, Assaf; Kasliwal, Mansi; Laher, Russ; Masci, Frank; Surace, Jason
    Type Ibn supernovae (SNe) are a small yet intriguing class of explosions whose spectra are characterized by low-velocity helium emission lines with little to no evidence for hydrogen. The prevailing theory has been that these are the core-collapse explosions of very massive stars embedded in helium-rich circumstellar material (CSM). We report optical observations of six new SNe Ibn: PTF11rfh, PTF12ldy, iPTF14aki, iPTF15ul, SN 2015G, and iPTF15akq. This brings the sample size of such objects in the literature to 22. We also report new data, including a near-infrared spectrum, on the Type Ibn SN 2015U. In order to characterize the class...

  12. Confined dense circumstellar material surrounding a regular type II supernova

    Yaron, O.; Perley, D. A.; Gal-Yam, A.; Groh, J. H.; Horesh, A.; Ofek, E. O.; Kulkarni, S. R.; Sollerman, J.; Fransson, C.; Rubin, A.; Szabo, P.; Sapir, N.; Taddia, F.; Cenko, S. B.; Valenti, S.; Arcavi, I.; Howell, D. A.; Kasliwal, M. M.; Vreeswijk, P. M.; Khazov, D.; Fox, O. D.; Cao, Y.; Gnat, O.; Kelly, P. L.; Nugent, P. E.; Filippenko, A. V.; Laher, R. R.; Wozniak, P. R.; Lee, W. H.; Rebbapragada, U. D.; Maguire, K.; Sullivan, M.; Soumagnac, M. T.
    With the advent of new wide-field, high-cadence optical transient surveys, our understanding of the diversity of core-collapse supernovae has grown tremendously in the last decade. However, the pre-supernova evolution of massive stars, which sets the physical backdrop to these violent events, is theoretically not well understood and difficult to probe observationally. Here we report the discovery of the supernova iPTF 13dqy = SN 2013fs  a mere ~3 h after explosion. Our rapid follow-up observations, which include multiwavelength photometry and extremely early (beginning at ~6 h post-explosion) spectra, map the distribution of material in the immediate environment (≲10^(15) cm) of the exploding star and establish that...

  13. Confined dense circumstellar material surrounding a regular type II supernova

    Yaron, O.; Perley, D. A.; Gal-Yam, A.; Groh, J. H.; Horesh, A.; Ofek, E. O.; Kulkarni, S. R.; Sollerman, J.; Fransson, C.; Rubin, A.; Szabo, P.; Sapir, N.; Taddia, F.; Cenko, S. B.; Valenti, S.; Arcavi, I.; Howell, D. A.; Kasliwal, M. M.; Vreeswijk, P. M.; Khazov, D.; Fox, O. D.; Cao, Y.; Gnat, O.; Kelly, P. L.; Nugent, P. E.; Filippenko, A. V.; Laher, R. R.; Wozniak, P. R.; Lee, W. H.; Rebbapragada, U. D.; Maguire, K.; Sullivan, M.; Soumagnac, M. T.
    With the advent of new wide-field, high-cadence optical transient surveys, our understanding of the diversity of core-collapse supernovae has grown tremendously in the last decade. However, the pre-supernova evolution of massive stars, which sets the physical backdrop to these violent events, is theoretically not well understood and difficult to probe observationally. Here we report the discovery of the supernova iPTF 13dqy = SN 2013fs  a mere ~3 h after explosion. Our rapid follow-up observations, which include multiwavelength photometry and extremely early (beginning at ~6 h post-explosion) spectra, map the distribution of material in the immediate environment (≲10^(15) cm) of the exploding star and establish that...

  14. Confined dense circumstellar material surrounding a regular type II supernova

    Yaron, O.; Perley, D. A.; Gal-Yam, A.; Groh, J. H.; Horesh, A.; Ofek, E. O.; Kulkarni, S. R.; Sollerman, J.; Fransson, C.; Rubin, A.; Szabo, P.; Sapir, N.; Taddia, F.; Cenko, S. B.; Valenti, S.; Arcavi, I.; Howell, D. A.; Kasliwal, M. M.; Vreeswijk, P. M.; Khazov, D.; Fox, O. D.; Cao, Y.; Gnat, O.; Kelly, P. L.; Nugent, P. E.; Filippenko, A. V.; Laher, R. R.; Wozniak, P. R.; Lee, W. H.; Rebbapragada, U. D.; Maguire, K.; Sullivan, M.; Soumagnac, M. T.
    With the advent of new wide-field, high-cadence optical transient surveys, our understanding of the diversity of core-collapse supernovae has grown tremendously in the last decade. However, the pre-supernova evolution of massive stars, which sets the physical backdrop to these violent events, is theoretically not well understood and difficult to probe observationally. Here we report the discovery of the supernova iPTF 13dqy = SN 2013fs  a mere ~3 h after explosion. Our rapid follow-up observations, which include multiwavelength photometry and extremely early (beginning at ~6 h post-explosion) spectra, map the distribution of material in the immediate environment (≲10^(15) cm) of the exploding star and establish that...

  15. Small Near-Earth Asteroids in the Palomar Transient Factory Survey: a Real-Time Streak-detection System

    Waszczak, Adam; Prince, Thomas A.; Laher, Russ; Masci, Frank; Bue, Brian; Rebbapragada, Umaa; Barlow, Tom; Surace, Jason; Helou, George; Kulkarni, Shrinivas
    Near-Earth asteroids (NEAs) in the 1–100 meter size range are estimated to be ~1,000 times more numerous than the ~15,000 currently cataloged NEAs, most of which are in the 0.5–10 kilometer size range. Impacts from 10–100 meter size NEAs are not statistically life-threatening, but may cause significant regional damage, while 1–10 meter size NEAs with low velocities relative to Earth are compelling targets for space missions. We describe the implementation and initial results of a real-time NEA-discovery system specialized for the detection of small, high angular rate (visually streaked) NEAs in Palomar Transient Factory (PTF) images. PTF is a 1.2-m...

  16. Small Near-Earth Asteroids in the Palomar Transient Factory Survey: a Real-Time Streak-detection System

    Waszczak, Adam; Prince, Thomas A.; Laher, Russ; Masci, Frank; Bue, Brian; Rebbapragada, Umaa; Barlow, Tom; Surace, Jason; Helou, George; Kulkarni, Shrinivas
    Near-Earth asteroids (NEAs) in the 1–100 meter size range are estimated to be ~1,000 times more numerous than the ~15,000 currently cataloged NEAs, most of which are in the 0.5–10 kilometer size range. Impacts from 10–100 meter size NEAs are not statistically life-threatening, but may cause significant regional damage, while 1–10 meter size NEAs with low velocities relative to Earth are compelling targets for space missions. We describe the implementation and initial results of a real-time NEA-discovery system specialized for the detection of small, high angular rate (visually streaked) NEAs in Palomar Transient Factory (PTF) images. PTF is a 1.2-m...

  17. Preparing for Advanced LIGO: A Star–Galaxy Separation Catalog for the Palomar Transient Factory

    Miller, A. A.; Kulkarni, M. K.; Cao, Y.; Laher, R. R.; Masci, F. J.; Surace, J. A.
    The search for fast optical transients, such as the expected electromagnetic counterparts to binary neutron star mergers, is riddled with false positives (FPs) ranging from asteroids to stellar flares. While moving objects are readily rejected via image pairs separated by ~1 hr, stellar flares represent a challenging foreground, significantly outnumbering rapidly evolving explosions. Identifying stellar sources close to and fainter than the transient detection limit can eliminate these FPs. Here, we present a method to reliably identify stars in deep co-adds of Palomar Transient Factory (PTF) imaging. Our machine-learning methodology utilizes the random forest (RF) algorithm, which is trained using...

  18. PTF1 J082340.04+081936.5: A Hot Subdwarf B Star with a Low-mass White Dwarf Companion in an 87-minute Orbit

    Kupfer, Thomas; van Roestel, Jan; Brooks, Jared; Geier, Stephan; Marsh, Tom R.; Groot, Paul J.; Bloemen, Steven; Prince, Thomas A.; Bellm, Eric; Heber, Ulrich; Bildsten, Lars; Miller, Adam A.; Dyer, Martin J.; Dhillon, Vik S.; Green, Matthew; Irawati, Puji; Laher, Russ; Littlefair, Stuart P.; Shupe, David L.; Steidel, Charles C.; Rattansoon, Somsawat; Pettini, Max
    We present the discovery of the hot subdwarf B star (sdB) binary PTF1 J082340.04+081936.5. The system has an orbital period of P_(orb) = 87.49668(1) minutes (0.060761584(10) days), making it the second-most compact sdB binary known. The light curve shows ellipsoidal variations. Under the assumption that the sdB primary is synchronized with the orbit, we find a mass of M_(sdB) = 0.45_(-0.07)^(+0.09) M_⊙, a companion white dwarf mass of M_(WD) = 0.46_(-0.09)^(+0.12) M_⊙, and a mass ratio of q = M_(WD)/M_(sdB) = 1.03_(-0.08)^(+0.10). The future evolution was calculated using the MESA stellar evolution code. Adopting a canonical sdB mass of M_(sdB)...

  19. PTF1 J082340.04+081936.5: A Hot Subdwarf B Star with a Low-mass White Dwarf Companion in an 87-minute Orbit

    Kupfer, Thomas; van Roestel, Jan; Brooks, Jared; Geier, Stephan; Marsh, Tom R.; Groot, Paul J.; Bloemen, Steven; Prince, Thomas A.; Bellm, Eric; Heber, Ulrich; Bildsten, Lars; Miller, Adam A.; Dyer, Martin J.; Dhillon, Vik S.; Green, Matthew; Irawati, Puji; Laher, Russ; Littlefair, Stuart P.; Shupe, David L.; Steidel, Charles C.; Rattansoon, Somsawat; Pettini, Max
    We present the discovery of the hot subdwarf B star (sdB) binary PTF1 J082340.04+081936.5. The system has an orbital period of P_(orb) = 87.49668(1) minutes (0.060761584(10) days), making it the second-most compact sdB binary known. The light curve shows ellipsoidal variations. Under the assumption that the sdB primary is synchronized with the orbit, we find a mass of M_(sdB) = 0.45_(-0.07)^(+0.09) M_⊙, a companion white dwarf mass of M_(WD) = 0.46_(-0.09)^(+0.12) M_⊙, and a mass ratio of q = M_(WD)/M_(sdB) = 1.03_(-0.08)^(+0.10). The future evolution was calculated using the MESA stellar evolution code. Adopting a canonical sdB mass of M_(sdB)...

  20. PTF1 J082340.04+081936.5: A Hot Subdwarf B Star with a Low-mass White Dwarf Companion in an 87-minute Orbit

    Kupfer, Thomas; van Roestel, Jan; Brooks, Jared; Geier, Stephan; Marsh, Tom R.; Groot, Paul J.; Bloemen, Steven; Prince, Thomas A.; Bellm, Eric; Heber, Ulrich; Bildsten, Lars; Miller, Adam A.; Dyer, Martin J.; Dhillon, Vik S.; Green, Matthew; Irawati, Puji; Laher, Russ; Littlefair, Stuart P.; Shupe, David L.; Steidel, Charles C.; Rattansoon, Somsawat; Pettini, Max
    We present the discovery of the hot subdwarf B star (sdB) binary PTF1 J082340.04+081936.5. The system has an orbital period of P_(orb) = 87.49668(1) minutes (0.060761584(10) days), making it the second-most compact sdB binary known. The light curve shows ellipsoidal variations. Under the assumption that the sdB primary is synchronized with the orbit, we find a mass of M_(sdB) = 0.45_(-0.07)^(+0.09) M_⊙, a companion white dwarf mass of M_(WD) = 0.46_(-0.09)^(+0.12) M_⊙, and a mass ratio of q = M_(WD)/M_(sdB) = 1.03_(-0.08)^(+0.10). The future evolution was calculated using the MESA stellar evolution code. Adopting a canonical sdB mass of M_(sdB)...

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