Normalized to: R.
[1]
oai:arXiv.org:1203.0026 [pdf] - 493624
Ultra Long Period Cepheids: a primary standard candle out to the Hubble
flow
Submitted: 2012-02-29
The cosmological distance ladder crucially depends on classical Cepheids
(with P=3-80 days), which are primary distance indicators up to 33 Mpc. Within
this volume, very few SNe Ia have been calibrated through classical Cepheids,
with uncertainty related to the non-linearity and the metallicity dependence of
their period-luminosity (PL) relation. Although a general consensus on these
effects is still not achieved, classical Cepheids remain the most used primary
distance indicators. A possible extension of these standard candles to further
distances would be important. In this context, a very promising new tool is
represented by the ultra-long period (ULP) Cepheids (P \geq 80 days), recently
identified in star-forming galaxies. Only a small number of ULP Cepheids have
been discovered so far. Here we present and analyse the properties of an
updated sample of 37 ULP Cepheids observed in galaxies within a very large
metallicity range of 12+log(O/H) from ~7.2 to 9.2 dex. We find that their
location in the colour(V-I)-magnitude diagram as well as their Wesenheit (V-I)
index-period (WP) relation suggests that they are the counterparts at high
luminosity of the shorter-period (P \leq 80 days) classical Cepheids. However,
a complete pulsation and evolutionary theoretical scenario is needed to
properly interpret the true nature of these objects. We do not confirm the
flattening in the studied WP relation suggested by Bird et al. (2009). Using
the whole sample, we find that ULP Cepheids lie around a relation similar to
that of the LMC, although with a large spread (~0.4 mag).
[2]
oai:arXiv.org:0912.0201 [pdf] - 554126
LSST Science Book, Version 2.0
LSST Science Collaboration;
Abell, Paul A.;
Allison, Julius;
Anderson, Scott F.;
Andrew, John R.;
Angel, J. Roger P.;
Armus, Lee;
Arnett, David;
Asztalos, S. J.;
Axelrod, Tim S.;
Bailey, Stephen;
Ballantyne, D. R.;
Bankert, Justin R.;
Barkhouse, Wayne A.;
Barr, Jeffrey D.;
Barrientos, L. Felipe;
Barth, Aaron J.;
Bartlett, James G.;
Becker, Andrew C.;
Becla, Jacek;
Beers, Timothy C.;
Bernstein, Joseph P.;
Biswas, Rahul;
Blanton, Michael R.;
Bloom, Joshua S.;
Bochanski, John J.;
Boeshaar, Pat;
Borne, Kirk D.;
Bradac, Marusa;
Brandt, W. N.;
Bridge, Carrie R.;
Brown, Michael E.;
Brunner, Robert J.;
Bullock, James S.;
Burgasser, Adam J.;
Burge, James H.;
Burke, David L.;
Cargile, Phillip A.;
Chandrasekharan, Srinivasan;
Chartas, George;
Chesley, Steven R.;
Chu, You-Hua;
Cinabro, David;
Claire, Mark W.;
Claver, Charles F.;
Clowe, Douglas;
Connolly, A. J.;
Cook, Kem H.;
Cooke, Jeff;
Cooray, Asantha;
Covey, Kevin R.;
Culliton, Christopher S.;
de Jong, Roelof;
de Vries, Willem H.;
Debattista, Victor P.;
Delgado, Francisco;
Dell'Antonio, Ian P.;
Dhital, Saurav;
Di Stefano, Rosanne;
Dickinson, Mark;
Dilday, Benjamin;
Djorgovski, S. G.;
Dobler, Gregory;
Donalek, Ciro;
Dubois-Felsmann, Gregory;
Durech, Josef;
Eliasdottir, Ardis;
Eracleous, Michael;
Eyer, Laurent;
Falco, Emilio E.;
Fan, Xiaohui;
Fassnacht, Christopher D.;
Ferguson, Harry C.;
Fernandez, Yanga R.;
Fields, Brian D.;
Finkbeiner, Douglas;
Figueroa, Eduardo E.;
Fox, Derek B.;
Francke, Harold;
Frank, James S.;
Frieman, Josh;
Fromenteau, Sebastien;
Furqan, Muhammad;
Galaz, Gaspar;
Gal-Yam, A.;
Garnavich, Peter;
Gawiser, Eric;
Geary, John;
Gee, Perry;
Gibson, Robert R.;
Gilmore, Kirk;
Grace, Emily A.;
Green, Richard F.;
Gressler, William J.;
Grillmair, Carl J.;
Habib, Salman;
Haggerty, J. S.;
Hamuy, Mario;
Harris, Alan W.;
Hawley, Suzanne L.;
Heavens, Alan F.;
Hebb, Leslie;
Henry, Todd J.;
Hileman, Edward;
Hilton, Eric J.;
Hoadley, Keri;
Holberg, J. B.;
Holman, Matt J.;
Howell, Steve B.;
Infante, Leopoldo;
Ivezic, Zeljko;
Jacoby, Suzanne H.;
Jain, Bhuvnesh;
R;
Jedicke;
Jee, M. James;
Jernigan, J. Garrett;
Jha, Saurabh W.;
Johnston, Kathryn V.;
Jones, R. Lynne;
Juric, Mario;
Kaasalainen, Mikko;
Styliani;
Kafka;
Kahn, Steven M.;
Kaib, Nathan A.;
Kalirai, Jason;
Kantor, Jeff;
Kasliwal, Mansi M.;
Keeton, Charles R.;
Kessler, Richard;
Knezevic, Zoran;
Kowalski, Adam;
Krabbendam, Victor L.;
Krughoff, K. Simon;
Kulkarni, Shrinivas;
Kuhlman, Stephen;
Lacy, Mark;
Lepine, Sebastien;
Liang, Ming;
Lien, Amy;
Lira, Paulina;
Long, Knox S.;
Lorenz, Suzanne;
Lotz, Jennifer M.;
Lupton, R. H.;
Lutz, Julie;
Macri, Lucas M.;
Mahabal, Ashish A.;
Mandelbaum, Rachel;
Marshall, Phil;
May, Morgan;
McGehee, Peregrine M.;
Meadows, Brian T.;
Meert, Alan;
Milani, Andrea;
Miller, Christopher J.;
Miller, Michelle;
Mills, David;
Minniti, Dante;
Monet, David;
Mukadam, Anjum S.;
Nakar, Ehud;
Neill, Douglas R.;
Newman, Jeffrey A.;
Nikolaev, Sergei;
Nordby, Martin;
O'Connor, Paul;
Oguri, Masamune;
Oliver, John;
Olivier, Scot S.;
Olsen, Julia K.;
Olsen, Knut;
Olszewski, Edward W.;
Oluseyi, Hakeem;
Padilla, Nelson D.;
Parker, Alex;
Pepper, Joshua;
Peterson, John R.;
Petry, Catherine;
Pinto, Philip A.;
Pizagno, James L.;
Popescu, Bogdan;
Prsa, Andrej;
Radcka, Veljko;
Raddick, M. Jordan;
Rasmussen, Andrew;
Rau, Arne;
Rho, Jeonghee;
Rhoads, James E.;
Richards, Gordon T.;
Ridgway, Stephen T.;
Robertson, Brant E.;
Roskar, Rok;
Saha, Abhijit;
Sarajedini, Ata;
Scannapieco, Evan;
Schalk, Terry;
Schindler, Rafe;
Schmidt, Samuel;
Schmidt, Sarah;
Schneider, Donald P.;
Schumacher, German;
Scranton, Ryan;
Sebag, Jacques;
Seppala, Lynn G.;
Shemmer, Ohad;
Simon, Joshua D.;
Sivertz, M.;
Smith, Howard A.;
Smith, J. Allyn;
Smith, Nathan;
Spitz, Anna H.;
Stanford, Adam;
Stassun, Keivan G.;
Strader, Jay;
Strauss, Michael A.;
Stubbs, Christopher W.;
Sweeney, Donald W.;
Szalay, Alex;
Szkody, Paula;
Takada, Masahiro;
Thorman, Paul;
Trilling, David E.;
Trimble, Virginia;
Tyson, Anthony;
Van Berg, Richard;
Berk, Daniel Vanden;
VanderPlas, Jake;
Verde, Licia;
Vrsnak, Bojan;
Walkowicz, Lucianne M.;
Wandelt, Benjamin D.;
Wang, Sheng;
Wang, Yun;
Warner, Michael;
Wechsler, Risa H.;
West, Andrew A.;
Wiecha, Oliver;
Williams, Benjamin F.;
Willman, Beth;
Wittman, David;
Wolff, Sidney C.;
Wood-Vasey, W. Michael;
Wozniak, Przemek;
Young, Patrick;
Zentner, Andrew;
Zhan, Hu
Submitted: 2009-12-01
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.
[3]
oai:arXiv.org:astro-ph/9905323 [pdf] - 106649
X-ray spectral complexity in narrow-line Seyfert 1 galaxies
Submitted: 1999-05-25
We present a systematic analysis of the X-ray spectral properties of a sample
of 22 ``narrow-line'' Seyfert 1 galaxies for which data are available from the
ASCA public archive. Many of these sources, which were selected on the basis of
their relatively narrow H-beta line width (FWHM <= 2000 km/s), show significant
spectral complexity in the X-ray band. Their measured hard power-law continua
have photon indices spanning the range 1.6 - 2.5 with a mean of 2.1, which is
only slightly steeper than the norm for ``broad-line'' Seyfert 1s. All but four
of the sources exhibit a soft excess, which can be modelled as blackbody
emission (T_{bb} ~ 100 - 300 eV) superposed on the underlying power-law. This
soft component is often so strong that, even in the relatively hard bandpass of
ASCA, it contains a significant fraction, if not the bulk, of the X-ray
luminosity, apparently ruling out models in which the soft excess is produced
entirely through reprocessing of the hard continuum.
Most notably, 6 of the 22 objects show evidence for a broad absorption
feature centred in the energy range 1.1 - 1.4 keV, which could be the signature
of resonance absorption in highly ionized material. A further 3 sources exhibit
``warm absorption'' edges in the 0.7 - 0.9 keV bandpass. Remarkably, all 9
``absorbed'' sources have H-beta line widths below 1000 km/s, which is less
than the median value for the sample taken as a whole. This tendency for very
narrow line widths to correlate with the presence of ionized absorption
features in the soft X-ray spectra of NLS1s, if confirmed in larger samples,
may provide a further clue in the puzzle of active galactic nuclei.