Recursos de colección

Caltech Authors (160.010 recursos)

Repository of works by Caltech published authors.

Group = Space Astrophysics Laboratory

Mostrando recursos 1 - 20 de 54

  1. Quenching or Bursting: Star Formation Acceleration—A New Methodology for Tracing Galaxy Evolution

    Martin, D. Christopher; Gonçalves, Thiago S.; Darvish, Behnam; Seibert, Mark; Schiminovich, David
    We introduce a new methodology for the direct extraction of galaxy physical parameters from multiwavelength photometry and spectroscopy. We use semianalytic models that describe galaxy evolution in the context of large-scale cosmological simulation to provide a catalog of galaxies, star formation histories, and physical parameters. We then apply models of stellar population synthesis and a simple extinction model to calculate the observable broadband fluxes and spectral indices for these galaxies. We use a linear regression analysis to relate physical parameters to observed colors and spectral indices. The result is a set of coefficients that can be used to translate observed...

  2. High Efficiency UV/Optical/NIR Detectors for Large Aperture Telescopes and UV Explorer Missions: Development of and Field Observations with Delta-doped Arrays

    Nikzad, Shouleh; Jewell, April D.; Hoenk, Michael E.; Jones, Todd; Hennessy, John; Goodsall, Tim; Carver, Alexander; Shapiro, Charles; Cheng, Samuel R.; Hamden, Erika; Kyne, Gillian; Martin, D. Christopher; Schiminovich, David; Scowen, Paul; France, Kevin; McCandliss, Stephan; Lupu, Roxana E.
    A number of exciting concepts are under development for Flagship, Probe class, Explorer class, and Suborbital class NASA missions in the ultraviolet/optical spectral ranges. These missions will depend on high performance silicon detector arrays being delivered affordably and in high numbers. In a focused effort we have advanced delta-doping technology to high throughput and high yield wafer-scale processing, encompassing a multitude of state-of-the-art silicon-based detector formats and designs. As part of this technology advancement and in preparation for upcoming missions, we have embarked on a number of field observations, instrument integrations, and independent evaluations of delta-doped arrays. In this paper,...

  3. A Hubble Space Telescope Survey for Novae in M87. II. Snuffing out the Maximum Magnitude–Rate of Decline Relation for Novae as a Non-standard Candle, and a Prediction of the Existence of Ultrafast Novae

    Shara, Michael M.; Doyle, Trisha; Lauer, Tod R.; Zurek, David; Baltz, Edward A.; Kovetz, Attay; Madrid, Juan P.; Mikołajewska, Joanna; Neill, J. D.; Prialnik, Dina; Welch, D. L.; Yaron, Ofer
    The extensive grid of numerical simulations of nova eruptions from the work of Yaron et al. first predicted that some classical novae might significantly deviate from the Maximum Magnitude–Rate of Decline (MMRD) relation, which purports to characterize novae as standard candles. Kasliwal et al. have announced the observational detection of a new class of faint, fast classical novae in the Andromeda galaxy. These objects deviate strongly from the MMRD relationship, as predicted by Yaron et al. Recently, Shara et al. reported the first detections of faint, fast novae in M87. These previously overlooked objects are as common in the giant...

  4. Discovery of an Enormous Lyα Nebula in a Massive Galaxy Overdensity at z = 2.3

    Cai, Zheng; Fan, Xiaohui; Yang, Yujin; Bian, Fuyan; Prochaska, J. Xavier; Zabludoff, Ann; McGreer, Ian; Zheng, Zhen-Ya; Greenberg, Richard; Cantalupo, Sebastiano; Frye, Brenda; Hamden, Erika; Jiang, Linhua; Kashikawa, Nobunari; Wang, Ran
    Enormous Lyα nebulae (ELANe), unique tracers of galaxy density peaks, are predicted to lie at the nodes and intersections of cosmic filamentary structures. Previous successful searches for ELANe have focused on wide-field narrowband surveys or have targeted known sources such as ultraluminous quasi-stellar objects (QSOs) or radio galaxies. Utilizing groups of coherently strong Lyα absorptions, we have developed a new method to identify high-redshift galaxy overdensities and have identified an extremely massive overdensity, BOSS1441, at z = 2-3. In its density peak, we discover an ELAN that is associated with a relatively faint continuum. To date, this object has the...

  5. iPTF Discovery of the Rapid “Turn-on” of a Luminous Quasar

    Gezari, S.; Hung, T.; Cenko, S. B.; Blagorodnova, N.; Yan, Lin; Kulkarni, S. R.; Mooley, K.; Kong, A. K. H.; Cantwell, T. M.; Yu, P. C.; Cao, Y.; Fremling, C.; Neill, J. D.; Ngeow, C.-C.; Nugent, P. E.; Wozniak, P.
    We present a radio-quiet quasar at z = 0.237 discovered "turning on" by the intermediate Palomar Transient Factory (iPTF). The transient, iPTF 16bco, was detected by iPTF in the nucleus of a galaxy with an archival Sloan Digital Sky Survey spectrum with weak narrow-line emission characteristic of a low-ionization nuclear emission-line region (LINER). Our follow-up spectra show the dramatic appearance of broad Balmer lines and a power-law continuum characteristic of a luminous (L_(bol) ≈ 10^(45) erg s^(−1)) type 1 quasar 12 yr later. Our photometric monitoring with PTF from 2009–2012 and serendipitous X-ray observations from the XMM-Newton Slew Survey in...

  6. iPTF Discovery of the Rapid “Turn-on” of a Luminous Quasar

    Gezari, S.; Hung, T.; Cenko, S. B.; Blagorodnova, N.; Yan, Lin; Kulkarni, S. R.; Mooley, K.; Kong, A. K. H.; Cantwell, T. M.; Yu, P. C.; Cao, Y.; Fremling, C.; Neill, J. D.; Ngeow, C.-C.; Nugent, P. E.; Wozniak, P.
    We present a radio-quiet quasar at z = 0.237 discovered "turning on" by the intermediate Palomar Transient Factory (iPTF). The transient, iPTF 16bco, was detected by iPTF in the nucleus of a galaxy with an archival Sloan Digital Sky Survey spectrum with weak narrow-line emission characteristic of a low-ionization nuclear emission-line region (LINER). Our follow-up spectra show the dramatic appearance of broad Balmer lines and a power-law continuum characteristic of a luminous (L_(bol) ≈ 10^(45) erg s^(−1)) type 1 quasar 12 yr later. Our photometric monitoring with PTF from 2009–2012 and serendipitous X-ray observations from the XMM-Newton Slew Survey in...

  7. A Hubble Space Telescope Survey for Novae in M87. I. Light and Color Curves, Spatial Distributions, and the Nova Rate

    Shara, Michael M.; Doyle, Trisha F.; Lauer, Tod R.; Zurek, David; Neill, J. D.; Madrid, Juan P.; Mikołajewska, Joanna; Welch, D. L.; Baltz, Edward A.
    The Hubble Space Telescope has imaged the central part of M87 over a 10 week span, leading to the discovery of 32 classical novae (CNe) and nine fainter, likely very slow, and/or symbiotic novae. In this first paper of a series, we present the M87 nova finder charts, and the light and color curves of the novae. We demonstrate that the rise and decline times, and the colors of M87 novae are uncorrelated with each other and with position in the galaxy. The spatial distribution of the M87 novae follows the light of the galaxy, suggesting that novae accreted by...

  8. CHIMERA: a wide-field, multi-colour, high-speed photometer at the prime focus of the Hale telescope

    Harding, L. K.; Hallinan, G.; Milburn, J.; Gardner, P.; Konidaris, N.; Singh, N.; Shao, M.; Sandhu, J.; Kyne, G.; Schlichting, H. E.
    The Caltech HIgh-speed Multi-colour camERA (CHIMERA) is a new instrument that has been developed for use at the prime focus of the Hale 200-inch telescope. Simultaneous optical imaging in two bands is enabled by a dichroic beam splitter centred at 567 nm, with Sloan u′ and g′ bands available on the blue arm and Sloan r′, i′ and z_s bands available on the red arm. Additional narrow-band filters will also become available as required. An electron multiplying CCD (EMCCD) detector is employed for both optical channels, each capable of simultaneously delivering sub-electron effective read noise under multiplication gain and frame...

  9. The detection rate of early UV emission from supernovae: A dedicated GALEX/PTF survey and calibrated theoretical estimates

    Ganot, Noam; Gal-Yam, Avishay; Ofek, Eran O.; Sagiv, Ilan; Waxman, Eli; Lapid, Ofer; Kulkarni, Shrinivas R.; Ben-Ami, Sagi; Kasliwal, Mansi M.; Chelouche, Doron; Rafter, Stephen; Behar, Ehud; Laor, Ari; Poznanski, Dovi; Nakar, Udi; Maoz, Dan; Trakhtenbrot, Benny; Neill, James D.; Barlow, Thomas A.; Martin, D. Christopher; Gezari, Suvi; Arcavi, Iair; Bloom, Joshua S.; Nugent, Peter E.; Sullivan, Mark
    The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early UV observations of core collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early UV emission from SNe. Six Type II SNe and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX NUV data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that...

  10. The detection rate of early UV emission from supernovae: A dedicated GALEX/PTF survey and calibrated theoretical estimates

    Ganot, Noam; Gal-Yam, Avishay; Ofek, Eran O.; Sagiv, Ilan; Waxman, Eli; Lapid, Ofer; Kulkarni, Shrinivas R.; Ben-Ami, Sagi; Kasliwal, Mansi M.; Chelouche, Doron; Rafter, Stephen; Behar, Ehud; Laor, Ari; Poznanski, Dovi; Nakar, Udi; Maoz, Dan; Trakhtenbrot, Benny; Neill, James D.; Barlow, Thomas A.; Martin, D. Christopher; Gezari, Suvi; Arcavi, Iair; Bloom, Joshua S.; Nugent, Peter E.; Sullivan, Mark
    The radius and surface composition of an exploding massive star, as well as the explosion energy per unit mass, can be measured using early UV observations of core collapse supernovae (SNe). We present the first results from a simultaneous GALEX/PTF search for early UV emission from SNe. Six Type II SNe and one Type II superluminous SN (SLSN-II) are clearly detected in the GALEX NUV data. We compare our detection rate with theoretical estimates based on early, shock-cooling UV light curves calculated from models that fit existing Swift and GALEX observations well, combined with volumetric SN rates. We find that...

  11. A Giant Protogalactic Disk Linked to the Cosmic Web

    Martin, D. Christopher; Matuszewski, Mateusz; Morrissey, Patrick; Neill, James D.; Moore, Anna; Cantalupo, Sebastiano; Prochaska, J. Xavier; Chang, Daphne
    The specifics of how galaxies form from, and are fuelled by, gas from the intergalactic medium remain uncertain. Hydrodynamic simulations suggest that ‘cold accretion flows’—relatively cool (temperatures of the order of 10^4 kelvin), unshocked gas streaming along filaments of the cosmic web into dark-matter halos—are important. These flows are thought to deposit gas and angular momentum into the circumgalactic medium, creating disk- or ring-like structures that eventually coalesce into galaxies that form at filamentary intersections. Recently, a large and luminous filament, consistent with such a cold accretion flow, was discovered near the quasi-stellar object QSO UM287 at redshift 2.279 using...

  12. The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star

    Howell, D. Andrew; Sullivan, Mark; Nugent, Peter E.; Ellis, Richard S.; Conley, Alexander J.; Le Borgne, Damien; Carlberg, Raymond G.; Guy, Julien; Balam, David; Basa, Stephane; Fouchez, Dominique; Hook, Isobel M.; Hsiao, Eric Y.; Neill, James D.; Pain, Reynald; Perrett, Kathryn M.; Pritchet, Christopher J.
    The accelerating expansion of the Universe, and the need for dark energy, were inferred from observations of type Ia supernovae. There is a consensus that type Ia supernovae are thermonuclear explosions that destroy carbon–oxygen white dwarf stars that have accreted matter from a companion star, although the nature of this companion remains uncertain. These supernovae are thought to be reliable distance indicators because they have a standard amount of fuel and a uniform trigger: they are predicted to explode when the mass of the white dwarf nears the Chandrasekhar mass of 1.4 solar masses (M_☉). Here we show that the...

  13. Probing the Intergalactic Medium with Fast Radio Bursts

    Zheng, Z.; Ofek, E. O.; Kulkarni, S. R.; Neill, J. D.; Juric, M.
    The recently discovered fast radio bursts (FRBs), presumably of extragalactic origin, have the potential to become a powerful probe of the intergalactic medium (IGM). We point out a few such potential applications. We provide expressions for the dispersion measure and rotation measure as a function of redshift, and we discuss the sensitivity of these measures to the He II reionization and the IGM magnetic field. Finally, we calculate the microlensing effect from an isolated, extragalactic stellar-mass compact object on the FRB spectrum. The time delays between the two lensing images will induce constructive and destructive interference, leaving a specific imprint...

  14. Probing the Intergalactic Medium with Fast Radio Bursts

    Zheng, Z.; Ofek, E. O.; Kulkarni, S. R.; Neill, J. D.; Juric, M.
    The recently discovered fast radio bursts (FRBs), presumably of extragalactic origin, have the potential to become a powerful probe of the intergalactic medium (IGM). We point out a few such potential applications. We provide expressions for the dispersion measure and rotation measure as a function of redshift, and we discuss the sensitivity of these measures to the He II reionization and the IGM magnetic field. Finally, we calculate the microlensing effect from an isolated, extragalactic stellar-mass compact object on the FRB spectrum. The time delays between the two lensing images will induce constructive and destructive interference, leaving a specific imprint...

  15. From Spitzer Galaxy photometry to Tully–Fisher distances

    Sorce, J. G.; Tully, R. B.; Courtois, H. M.; Jarrett, T. H.; Neill, J. D.; Shaya, E. J.
    This paper involves a data release of the observational campaign: Cosmicflows with Spitzer (CFS). Surface photometry of the 1270 galaxies constituting the survey is presented. An additional ∼400 galaxies from various other Spitzer surveys are also analysed. CFS complements the Spitzer Survey of Stellar Structure in Galaxies, that provides photometry for an additional 2352 galaxies, by extending observations to low galactic latitudes (|b| < 30°). Among these galaxies are calibrators, selected in the K band, of the Tully–Fisher relation. The addition of new calibrators demonstrates the robustness of the previously released calibration. Our estimate of the Hubble constant using supernova...

  16. The Calibration of the WISE W1 and W2 Tully-Fisher Relation

    Neill, J. D.; Seibert, Mark; Tully, R. Brent; Courtois, Hélène; Sorce, Jenny G.; Jarrett, T. H.; Scowcroft, Victoria; Masci, Frank J.
    In order to explore local large-scale structures and velocity fields, accurate galaxy distance measures are needed. We now extend the well-tested recipe for calibrating the correlation between galaxy rotation rates and luminosities—capable of providing such distance measures—to the all-sky, space-based imaging data from the Wide-field Infrared Survey Explorer (WISE) W1 (3.4 μm) and W2 (4.6 μm) filters. We find a correlation of line width to absolute magnitude (known as the Tully-Fisher relation, TFR) of M^(b,i,k,ɑ)_(W1) = -20.35 - 9.56(log W^i_(mx) - 2.5) (0.54 mag rms) and M^(b,i,k,ɑ)_(W2) = -19.76 - 9.74 (log W^i_(mx)-2.5)(0.56 mag rms) from 310 galaxies in 13...

  17. PTF1 J191905.19+481506.2--A Partially Eclipsing AM CVn System Discovered in the Palomar Transient Factory

    Levitan, David; Kupfer, Thomas; Groot, Paul J.; Margon, Bruce; Prince, Thomas A.; Kulkarni, Shrinivas R.; Hallinan, Gregg; Harding, Leon K.; Kyne, Gillian; Laher, Russ; Ofek, Eran O.; Rutten, René G. M.; Sesar, Branimir; Surace, Jason
    We report on PTF1 J191905.19+481506.2, a newly discovered, partially eclipsing, outbursting AM CVn system found in the Palomar Transient Factory synoptic survey. This is only the second known eclipsing AM CVn system. We use high-speed photometric observations and phase-resolved spectroscopy to establish an orbital period of 22.4559(3) minutes. We also present a long-term light curve and report on the normal and super-outbursts regularly seen in this system, including a super-outburst recurrence time of 36.8(4) days. We use the presence of the eclipse to place upper and lower limits on the inclination of the system and discuss the number of known...

  18. Giant Sparks at Cosmological Distances?

    Kulkarni, S. R.; Ofek, E. O.; Neill, J. D.; Zheng, Z.; Juric, M.
    Millisecond-duration bright radio pulses at 1.4 GHz with high dispersion measures (DMs) were reported by Lorimer et al., Keane et al., and Thornton et al. Their all-sky rate is ≈10^4 day^(–1) above ~1 Jy. Related events are "Perytons"—similar pulsed, dispersed sources, but most certainly local. Suggested models of fast radio bursts (FRBs) can originate in Earth's atmosphere, in stellar coronae, in other galaxies, and even at cosmological distances. Using physically motivated assumptions combined with observed properties, we explore these models. In our analysis, we focus on the Lorimer event: a 30 Jy, 5 ms duration burst with DM = 375...

  19. Giant Sparks at Cosmological Distances?

    Kulkarni, S. R.; Ofek, E. O.; Neill, J. D.; Zheng, Z.; Juric, M.
    Millisecond-duration bright radio pulses at 1.4 GHz with high dispersion measures (DMs) were reported by Lorimer et al., Keane et al., and Thornton et al. Their all-sky rate is ≈10^4 day^(–1) above ~1 Jy. Related events are "Perytons"—similar pulsed, dispersed sources, but most certainly local. Suggested models of fast radio bursts (FRBs) can originate in Earth's atmosphere, in stellar coronae, in other galaxies, and even at cosmological distances. Using physically motivated assumptions combined with observed properties, we explore these models. In our analysis, we focus on the Lorimer event: a 30 Jy, 5 ms duration burst with DM = 375...

  20. UV-bright Nearby Early-type Galaxies Observed in the Mid-infrared: Evidence for a Multi-stage Formation History by Way of WISE and GALEX Imaging

    Petty, S. M.; Neill, J. D.; Jarrett, T. H.; Blain, A. W.; Farrah, D. G.; Rich, R. M.; Tsai, C.-W.; Benford, D. J.; Bridge, C. R.; Lake, S. E.; Masci, F. J.; Wright, E. L.
    In the local universe, 10% of massive elliptical galaxies are observed to exhibit a peculiar property: a substantial excess of ultraviolet emission than what is expected from their old, red stellar populations. Several origins for this ultraviolet excess (UVX) have been proposed including a population of hot young stars and a population of old, blue horizontal branch or extended horizontal branch (BHB or EHB) stars that have undergone substantial mass loss from their outer atmospheres. We explore the radial distribution of UVX in a selection of 49 nearby E/S0-type galaxies by measuring their extended photometry in the UV through mid-infrared...

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