1,139 research outputs found
Letter from P. B. Van Trump to John Muir, 1910 Jul 18.
[1]Yelm, Wash, July 18th, 1910.John Muir,Martinez, Cal.My Dear Friend:Your Kind, friendly and esteemed letter of 12th came duly to hand, and I thank you for it. Your acceptance and commendation of Tahoma will, I am sure, be very helpful in this matter. It is principally the Rotary Clubs and their friends, so far, that have publicly agreed to the compromise name, but they are large and influential organizations in both cities. The editors of the papers of the rival cities do not wrangle as much as they048332used to over the mountain name. The new comers to the state - and their number is on the increase - will naturally prefer the expressive and poetic native name, Altogether, the existing conditions seem to favor the movement for a change.Excuse my use of a pencil. In my old age I find writing with a pen difficult and [irksome.?]Most faithfully yours,P. B. Van Trump.P.S. Since writing the above yours of 14th has come.Yes, the mountain book sent is beautiful, and the mountain is thoroughly pictured nowadays. The views taken by Warner when04833 we visited and ascended the mountain with the Ingraham party were for some time the standards on Puget Sound, but since then five photographers ga[illegible]e have taken the mountain from many view points, and a perfect ar[illegible]y of amateur and of Kodak friends have taken shots at the old giant. That Warner turned out a bad but . He promised me duplicates of the views but never sent me one. Old man S[illegible] gave him money in advance for pictures, but never got one.P. B. V. T
C IV BAL disappearance in a large SDSS QSO sample
Broad absorption lines (BALs) in the spectra of quasi-stellar objects (QSOs)
originate from outflowing winds along our line of sight; winds are thought to
originate from the inner regions of the QSO accretion disk, close to the
central supermassive black hole (SMBH). Winds likely play a role in galaxy
evolution and aid the accretion mechanism onto the SMBH. BAL equivalent widths
can change on typical timescales from months to years; such variability is
generally attributed to changes in the covering factor and/or in the ionization
level of the gas. We investigate BAL variability, focusing on BAL
disappearance. We analyze multi-epoch spectra of more than 1500 QSOs -the
largest sample ever used for such a study- observed by different programs from
the Sloan Digital Sky Survey-I/II/III (SDSS), and search for disappearing C IV
BALs. The spectra rest-frame time baseline ranges from 0.28 to 4.9 yr; the
source redshifts range from 1.68 to 4.27. We detect 73 disappearing BALs in the
spectra of 67 sources. This corresponds to 3.9% of disappearing BALs, and 5.1%
of our BAL QSOs exhibit at least one disappearing BAL. We estimate the average
lifetime of a BAL along our line of sight (~ 80-100 yr), which appears
consistent with the accretion disk orbital time at distances where winds are
thought to originate. We inspect properties of the disappearing BALs and
compare them to the properties of our main sample. We also investigate the
existence of a correlation in the variability of multiple troughs in the same
spectrum, and find it persistent at large velocity offsets between BAL pairs,
suggesting that a mechanism extending on a global scale is necessary to explain
the phenomenon. We select a more reliable sample of disappearing BALs following
Filiz Ak et al. (2012), where a subset of our sample was analyzed, and compare
the findings from the two works, obtaining generally consistent results.Comment: 22 pages, 9 figures. Accepted for publication in A&
The Sloan Digital Sky Survey Reverberation Mapping Project: Post-Starburst Signatures in Quasar Host Galaxies at z < 1
Quasar host galaxies are key for understanding the relation between galaxies
and the supermassive black holes (SMBHs) at their centers. We present a study
of 191 broad-line quasars and their host galaxies at z < 1, using high
signal-to-noise ratio (SNR) spectra produced by the Sloan Digital Sky Survey
Reverberation Mapping project. Clear detection of stellar absorption lines
allows a reliable decomposition of the observed spectra into nuclear and host
components, using spectral models of quasar and stellar radiations as well as
emission lines from the interstellar medium. We estimate age, mass (M*), and
velocity dispersion (sigma*) of the host stars, the star formation rate (SFR),
quasar luminosity, and SMBH mass (Mbh), for each object. The quasars are
preferentially hosted by massive galaxies with M* ~ 10^{11} Msun characterized
by stellar ages around a billion years, which coincides with the transition
phase of normal galaxies from the blue cloud to the red sequence. The host
galaxies have relatively low SFRs and fall below the main sequence of
star-forming galaxies at similar redshifts. These facts suggest that the hosts
have experienced an episode of major star formation sometime in the past
billion years, which was subsequently quenched or suppressed. The derived Mbh -
sigma* and Mbh - M* relations agree with our past measurements and are
consistent with no evolution from the local Universe. The present analysis
demonstrates that reliable measurements of stellar properties of quasar host
galaxies are possible with high-SNR fiber spectra, which will be acquired in
large numbers with future powerful instruments such as the Subaru Prime Focus
Spectrograph.Comment: ApJ in pres
The XMM-Newton wide-field survey in the COSMOS field. IV: X-ray spectral properties of Active Galactic Nuclei
We present a detailed spectral analysis of point-like X-ray sources in the
XMM-COSMOS field. Our sample of 135 sources only includes those that have more
than 100 net counts in the 0.3-10 keV energy band and have been identified
through optical spectroscopy. The majority of the sources are well described by
a simple power-law model with either no absorption (76%) or a significant
intrinsic, absorbing column (20%).As expected, the distribution of intrinsic
absorbing column densities is markedly different between AGN with or without
broad optical emission lines. We find within our sample four Type-2 QSOs
candidates (L_X > 10^44 erg/s, N_H > 10^22 cm^-2), with a spectral energy
distribution well reproduced by a composite Seyfert-2 spectrum, that
demonstrates the strength of the wide field XMM/COSMOS survey to detect these
rare and underrepresented sources.Comment: 16 pages, ApJS COSMOS Special Issue, 2007 in press. The
full-resolution version is available at
http://www.mpe.mpg.de/XMMCosmos/PAPERS/mainieri_cosmos.ps.g
Bayesian High-Redshift Quasar Classification from Optical and Mid-IR Photometry
We identify 885,503 type 1 quasar candidates to i<22 using the combination of
optical and mid-IR photometry. Optical photometry is taken from the Sloan
Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey
(SDSS-III/BOSS), while mid-IR photometry comes from a combination of data from
the Wide-Field Infrared Survey Explorer (WISE) "ALLWISE" data release and
several large-area Spitzer Space Telescope fields. Selection is based on a
Bayesian kernel density algorithm with a training sample of 157,701
spectroscopically-confirmed type-1 quasars with both optical and mid-IR data.
Of the quasar candidates, 733,713 lack spectroscopic confirmation (and 305,623
are objects that we have not previously classified as photometric quasar
candidates). These candidates include 7874 objects targeted as high probability
potential quasars with 3.5<z<5 (of which 6779 are new photometric candidates).
Our algorithm is more complete to z>3.5 than the traditional mid-IR selection
"wedges" and to 2.2<z<3.5 quasars than the SDSS-III/BOSS project. Number counts
and luminosity function analysis suggests that the resulting catalog is
relatively complete to known quasars and is identifying new high-z quasars at
z>3. This catalog paves the way for luminosity-dependent clustering
investigations of large numbers of faint, high-redshift quasars and for further
machine learning quasar selection using Spitzer and WISE data combined with
other large-area optical imaging surveys.Comment: 54 pages, 17 figures; accepted by ApJS Data for tables 1 and 2
available at
http://www.physics.drexel.edu/~gtr/outgoing/optirqsos/data/master_quasar_catalogs.011414.fits.bz2
and
http://www.physics.drexel.edu/~gtr/outgoing/optirqsos/data/optical_ir_quasar_candidates.052015.fits.bz
A wide angle tail radio galaxy in the COSMOS field: evidence for cluster formation
We have identified a complex galaxy cluster system in the COSMOS field via a
wide angle tail (WAT) radio galaxy consistent with the idea that WAT galaxies
can be used as tracers of clusters. The WAT galaxy, CWAT-01, is coincident with
an elliptical galaxy resolved in the HST-ACS image. Using the COSMOS
multiwavelength data set, we derive the radio properties of CWAT-01 and use the
optical and X-ray data to investigate its host environment. The cluster hosting
CWAT-01 is part of a larger assembly consisting of a minimum of four X-ray
luminous clusters within ~2 Mpc distance. We apply hydrodynamical models that
combine ram pressure and buoyancy forces on CWAT-01. These models explain the
shape of the radio jets only if the galaxy's velocity relative to the
intra-cluster medium (ICM) is in the range of about 300-550 km/s which is
higher than expected for brightest cluster galaxies (BCGs) in relaxed systems.
This indicates that the CWAT-01 host cluster is not relaxed, but is possibly
dynamically young. We argue that such a velocity could have been induced
through subcluster merger within the CWAT-01 parent cluster and/or
cluster-cluster interactions. Our results strongly indicate that we are
witnessing the formation of a large cluster from an assembly of multiple
clusters, consistent with the hierarchical scenario of structure formation. We
estimate the total mass of the final cluster to be approximately 20% of the
mass of the Coma cluster.Comment: 18 pages, 13 figures; accepted for publication in ApJS, COSMOS
special issue; added color figure (Fig. 13) which was previously unavailabl
- âŠ