Recursos de colección

Caltech Authors (155.447 recursos)

Repository of works by Caltech published authors.

Group = Space Astrophysics Laboratory

Mostrando recursos 1 - 14 de 14

  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. 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...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. Classical Novae in Andromeda: Light Curves from the Palomar Transient Factory and GALEX

    Cao, Yi; Kasliwal, Mansi M.; Neill, James D.; Kulkarni, S. R.; Lou, Yu-Qing; Ben-Ami, Sagi; Bloom, Joshua S.; Cenko, S. Bradley; Law, Nicholas M.; Nugent, Peter E.; Ofek, Eran O.; Poznanski, Dovi; Quimby, Robert M.
    We present optical light curves of 29 novae in M31 during the 2009 and 2010 observing seasons of the Palomar Transient Factory (PTF). The dynamic and rapid cadences in PTF monitoring of M31, from one day to ten minutes, provide excellent temporal coverage of nova light curves, enabling us to record the photometric evolution of M31 novae in unprecedented detail. We also detect eight of these novae in the near-ultraviolet (UV) band with the Galaxy Evolution Explorer (GALEX) satellite. Novae M31N 2009-10b and M31N 2010-11a show prominent UV emission peaking a few days prior to their optical maxima, possibly implying...

  9. Identifying Variations to the IMF at High-z Through Deep Radio Surveys

    Murphy, Eric J.
    In this article I briefly describe how deep radio surveys may provide a means to identify variations in the upper end of the initial mass function (IMF) in star-forming galaxies at high redshifts (i.e., z ≳ 3). At such high redshifts, I argue that deep radio continuum observations at frequencies ≳10 GHz using next generation facilities (e.g., EVLA, MeerKAT, SKA/NAA) will likely provide the most accurate measurements for the ionizing photon rates (star formation rates; SFRs) of normal galaxies since their non-thermal emission should be highly suppressed due to the increased inverse Compton (IC) losses from the cosmic microwave background (CMB), leaving only thermal (free-free) emission detectable. Thus,...

  10. PTF 10fqs: A Luminous Red Nova in the Spiral Galaxy Messier 99

    Kasliwal, Mansi M.; Kulkarni, Shri R.; Arcavi, I.; Quimby, Robert M.; Ofek, Eran O.; Nugent, Peter E.; Jacobsen, Janet; Gal-Yam, Avishay; Green, Yoav; Yaron, Ofer; Fox, Derek B.; Howell, Jacob L.; Cenko, S. Bradley; Kleiser, Io K. W.; Bloom, Joshua S.; Miller, Adam; Li, Weidong; Filippenko, Alexei V.; Starr, Dan; Poznanski, Dovi; Law, Nicholas M.; Helou, George; Frail, Dale A.; Neill, James D.; Forster, Karl; Martin, Christopher; Tendulkar, Shriharsh P.; Gehrels, Neil; Kennea, Jamie; Sullivan, Mark; Bildsten, Lars; Dekany, Richard; Rahmer, Gustavo; Hale, David; Smith, Roger; Zolkower, Jeff; Velur, Viswa; Walters, Richard; Henning, John; Bui, Khanh; McKenna, Dan; Blake, Cullen
    The Palomar Transient Factory (PTF) is systematically charting the optical transient and variable sky. A primary science driver of PTF is building a complete inventory of transients in the local universe (distance less than 200 Mpc). Here, we report the discovery of PTF 10fqs, a transient in the luminosity “gap” between novae and supernovae. Located on a spiral arm of Messier 99, PTF 10fqs has a peak luminosity of M_r = −12.3, red color (g − r = 1.0), and is slowly evolving (decayed by 1 mag in 68 days). It has a spectrum dominated by intermediate-width Hα (≈930 km s^(−1)) and...

  11. PTF 10fqs: A Luminous Red Nova in the Spiral Galaxy Messier 99

    Kasliwal, Mansi M.; Kulkarni, Shri R.; Arcavi, I.; Quimby, Robert M.; Ofek, Eran O.; Nugent, Peter E.; Jacobsen, Janet; Gal-Yam, Avishay; Green, Yoav; Yaron, Ofer; Fox, Derek B.; Howell, Jacob L.; Cenko, S. Bradley; Kleiser, Io K. W.; Bloom, Joshua S.; Miller, Adam; Li, Weidong; Filippenko, Alexei V.; Starr, Dan; Poznanski, Dovi; Law, Nicholas M.; Helou, George; Frail, Dale A.; Neill, James D.; Forster, Karl; Martin, Christopher; Tendulkar, Shriharsh P.; Gehrels, Neil; Kennea, Jamie; Sullivan, Mark; Bildsten, Lars; Dekany, Richard; Rahmer, Gustavo; Hale, David; Smith, Roger; Zolkower, Jeff; Velur, Viswa; Walters, Richard; Henning, John; Bui, Khanh; McKenna, Dan; Blake, Cullen
    The Palomar Transient Factory (PTF) is systematically charting the optical transient and variable sky. A primary science driver of PTF is building a complete inventory of transients in the local universe (distance less than 200 Mpc). Here, we report the discovery of PTF 10fqs, a transient in the luminosity “gap” between novae and supernovae. Located on a spiral arm of Messier 99, PTF 10fqs has a peak luminosity of M_r = −12.3, red color (g − r = 1.0), and is slowly evolving (decayed by 1 mag in 68 days). It has a spectrum dominated by intermediate-width Hα (≈930 km s^(−1)) and...

  12. Gattini 2010: Cutting Edge Science at the Bottom of the World

    Moore, Anna M.; Ahmed, Sara; Ashley, Michael C. B.; Barreto, Max K.; Cui, Xiangqun; Delacroix, Alex; Feng, LongLong; Gong, Xuefei; Lawrence, Jon; Luong-van, Daniel M.; Martin, D. Christopher; Riddle, Reed; Rowley, Nicole; Shang, Zhaohui; Storey, John W. V.; Tothill, Nick F. H.; Travouillon, Tony; Wang, Lifan; Yang, Huigen; Yang, Ji; Zhou, Xu; Zhu, Zhengxi
    The high altitude Antarctic sites of Dome A and the South Pole offer intriguing locations for future large scale optical astronomical Observatories. The Gattini project was created to measure the optical sky brightness, large area cloud cover and aurora of the winter-time sky above such high altitude Antarctic sites. The Gattini-DomeA camera was installed on the PLATO instrument module as part of the Chinese-led traverse to the highest point on the Antarctic plateau in January 2008. This single automated wide field camera contains a suite of Bessel photometric filters (B, V, R) and a long-pass red filter for the detection...

  13. An Ultraviolet-to-Radio Broadband Spectral Atlas of Nearby Galaxies

    Dale, D. A.; Gil de Paz, A.; Gordon, K. D.; Hanson, H. M.; Armus, L.; Bendo, G. J.; Bianchi, L.; Block, M.; Boissier, S.; Boselli, A.; Buckalew, B. A.; Buat, V.; Burgarella, D.; Calzetti, D.; Cannon, J. M.; Engelbracht, C. W.; Helou, G.; Hollenbach, D. J.; Jarrett, T. H.; Kennicutt, R. C.; Leitherer, C.; Li, A.; Madore, B. F.; Martin, D. C.; Meyer, M. J.; Murphy, E. J.; Regan, M. W.; Roussel, H.; Smith, J. D. T.; Sosey, M. L.; Thilker, D. A.; Walter, F.
    The ultraviolet-to-radio continuum spectral energy distributions are presented for all 75 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS). A principal component analysis of the sample shows that most of the sample's spectral variations stem from two underlying components, one representative of a galaxy with a low infrared-to-ultraviolet ratio and one representative of a galaxy with a high infrared-to-ultraviolet ratio. The influence of several parameters on the infrared-to-ultraviolet ratio is studied (e.g., optical morphology, disk inclination, far-infrared color, ultraviolet spectral slope, and star formation history). Consistent with our understanding of normal star-forming galaxies, the SINGS sample of galaxies in...

  14. Ultraviolet and Infrared Diagnostics of Star Formation and Dust in NGC 7331

    Thilker, David A.; Boissier, Samuel; Bianchi, Luciana; Calzetti, Daniela; Boselli, Alessandro; Dale, Daniel A.; Seibert, Mark; Braun, Robert; Burgarella, Denis; Gil de Paz, Armando; Helou, George; Walter, Fabian; Kennicutt, R. C., Jr.; Madore, Barry F.; Martin, D. Christopher; Barlow, Tom A.; Forster, Karl; Friedman, Peter G.; Morrissey, Patrick; Neff, Susan G.; Schiminovich, David; Small, Todd; Wyder, Ted K.; Donas, José; Heckman, Timothy M.; Lee, Young-Wook; Milliard, Bruno; Rich, R. Michael; Szalay, Alex S.; Welsh, Barry Y.; Yi, Sukyoung K.
    We present images of NGC 7331 obtained with GALEX and Spitzer, tracing UV and IR signatures of star formation. NGC 7331's morphology at 8-850 μm is dominated by a central dust ring. This structure is a vigorous site of star formation (hosting one-third of the present activity) but remains inconspicuous in our GALEX UV imagery. Radial profile analysis and photometry for discrete UV- and UV+IR-selected substructures indicate a decline in UV extinction with increasing galactocentric distance, although highly attenuated star-forming regions can be found throughout the disk. UV-optical surface brightness profiles suggest a recent birthrate parameter (b_8) that is highest...

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