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D. B. Sanders

Publications and source records attributed to D. B. Sanders.

At least 181 records · Page 10Linked to original sources
arXiv2004

An IRAS High Resolution Image Restoration (HIRES) Atlas of All Interacting Galaxies in the IRAS Revised Bright Galaxy Sample

We present high-resolution (30"-1') 12, 25, 60, and 100 micron images of 106 interacting galaxy systems contained in the IRAS Revised Bright Galaxy Sample (RBGS, Sanders et al. 2003), a complete sample of all galaxies having a 60 micron flux density greater than 5.24 Jy. These systems were selected to have at least two distinguishable galaxies separated by less than three average galactic diameters, and thus we have excluded very widely separated systems and very advanced mergers. The new complete survey has the same properties as the prototype survey of Surace et al. 1993. We find no increased tendency for infrared-bright galaxies to be associated with other infrared bright galaxies among the widely separated pairs studied here. We find small enhancements in far-infrared activity in multiple galaxy systems relative to RBGS non-interacting galaxies with the same blue luminosity distribution. We also find no differences in infrared activity (as measured by infrared color and luminosity) between late and early-type spiral galaxies.

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arXiv2003

A deep 6.7um survey in the SSA13 field with ISO

We present results of a deep mid-infrared survey in the SSA13 field with the Infrared Space Observatory (ISO). In order to probe the near-infrared light at high redshifts, we surveyed the field with the broad band LW2 (5-8.5um) filter of the mid-infrared camera ISOCAM. Adopting a highly redundant imaging strategy for the 23 hour observation and carefully treating gradual changes in the detector responsivity caused by a very high rate of cosmic ray impacts, we succeeded in reaching an 80% completeness limit of 16uJy in the central 7 arcmin2 region. Utilizing the signal-to-noise ratio map, we detected 65 sources down to 6uJy in the 16 arcmin2 field. Integral galaxy number counts at 6.7um are then derived, reaching 1.3e4/deg2 at the faint limit with a slope of -1.6 between 13uJy and 130uJy. Integrating individual sources in this flux range, the resolved fraction of the extragalactic background light at 6.7um is estimated to be 0.56nW/m2/sr. These results, which reach a flux limit three times fainter than those in the Hubble Deep Fields, are in fairly good agreement with a model prediction by Franceschini et al. (1997). Finally, we discuss the relation of distant massive E/S0 galaxies to the faint 6.7um galaxy population.

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arXiv2003

The IRAS Revised Bright Galaxy Sample (RBGS)

IRAS flux densities, redshifts, and infrared luminosities are reported for all sources identified in the IRAS Revised Bright Galaxy Sample (RBGS), a complete flux-limited survey of all extragalactic objects with total 60 micron flux density greater than 5.24 Jy, covering the entire sky surveyed by IRAS at Galactic latitude |b| > 5 degrees. The RBGS includes 629 objects, with a median (mean) sample redshift of 0.0082 (0.0126) and a maximum redshift of 0.0876. The RBGS supersedes the previous two-part IRAS Bright Galaxy Samples, which were compiled before the final ("Pass 3") calibration of the IRAS Level 1 Archive in May 1990. The RBGS also makes use of more accurate and consistent automated methods to measure the flux of objects with extended emission. Basic properties of the RBGS sources are summarized, including estimated total infrared luminosities, as well as updates to cross-identifications with sources from optical galaxy catalogs established using the NASA/IPAC Extragalactic Database (NED). In addition, an atlas of images from the Digitized Sky Survey with overlays of the IRAS position uncertainty ellipse and annotated scale bars is provided for ease in visualizing the optical morphology in context with the angular and metric size of each object. The revised bolometric infrared luminosity function, phi(L_ir), for infrared bright galaxies in the local Universe remains best fit by a double power law, phi(L_ir) ~ L_ir^alpha, with alpha = -0.6 (+/- 0.1), and alpha = -2.2 (+/- 0.1) below and above the "characteristic" infrared luminosity L_ir ~ 10^{10.5} L_solar, respectively. (Abridged)

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arXiv2003

Optical and Near-Infrared Imaging of the IRAS 1-Jy Sample of Ultraluminous Infrared Galaxies: I. The Atlas

An imaging survey of the {\em IRAS} 1-Jy sample of 118 ultraluminous infrared galaxies was conducted at optical (R) and near-infrared (K') wavelengths using the University of Hawaii 2.2m telescope. The methods of observation and data reduction are described. An R and K' atlas of the entire sample is presented along with some of the basic astrometric and photometric parameters derived from these images. A more detailed analysis of these data is presented in a companion paper (Veilleux, Kim, & Sanders 2002; astro-ph/0207401).

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arXiv2003

Optical and Near-Infrared Imaging of the IRAS 1-Jy Sample of Ultraluminous Infrared Galaxies: II. The Analysis

The present paper discusses the results from an analysis of the images presented in Paper I (astro-ph/0207373) supplemented with new spectroscopic data obtained at Keck. All but one object in the 1-Jy sample show signs of a strong tidal interaction/merger. Multiple mergers involving more than two galaxies are seen in no more than 5 of the 118 (< 5%) systems. None of the 1-Jy sources is in the first-approach stage of the interaction, and most (56%) of them harbor a single disturbed nucleus and are therefore in the later stages of a merger. Seyfert galaxies (especially those of type 1), warm ULIGs (f_{25}/f_{60} > 0.2) and the more luminous systems (> 10^{12.5} L_sun) all show a strong tendency to be advanced mergers with a single nucleus. An analysis of the surface brightness profiles of the host galaxies in single-nucleus sources reveals that about 73% of the R and K' surface brightness profiles are fit adequately by an elliptical-like R^{1/4}-law. These elliptical-like 1-Jy systems have luminosities, half-light radii, and R-band axial ratio distribution that are similar to those of normal (inactive) intermediate-luminosity ellipticals and follow with some scatter the same mu_e - r_e relation. These elliptical-like hosts are most common among merger remnants with Seyfert 1 nuclei (83%), Seyfert 2 optical characteristics (69%) or mid-infrared (ISO) AGN signatures (80%). In general, the results from the present study are consistent with the merger-driven evolutionary sequence ``cool ULIGs --> warm ULIGs --> quasars,'' although there are many exceptions. (abridged)

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arXiv2003

Imaging Large Scale Structure in the X-ray Sky

We present the first results from a wide solid angle, moderately deep {\it Chandra} survey of the Lockman Hole North-West region. Our 9 ACIS-I fields cover an effective solid angle of 0.4 deg$^{2}$ and reach a depth of $3 \times 10^{-16}$ \ergpcmsqps in the 0.4--2 keV band and $3 \times 10^{-15}$ \ergpcmsqps in the 2--8 keV band. The best fit logN-logS for the entire field, the largest contiguous {\it Chandra} field yet observed, matches well onto that of the {\it Chandra} Deep Field North. We show that the full range of the `cosmic variance' previously seen in different {\it Chandra} fields is reproduced in this small region of the sky. Counts-in-cells analysis shows that the hard band sources are more strongly correlated than the soft band sources.

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arXiv2003

The Discovery of a Very Narrow-Line Star Forming Obat a Redshift of 5.66ject

We report on the discovery of a very narrow-line star forming object beyond redshift of 5. Using the prime-focus camera, Suprime-Cam, on the 8.2 m Subaru telescope together with a narrow-passband filter centered at $λ_{\rm c}$ = 8150 Åwith passband of $Δλ$ = 120 Å, we have obtained a very deep image of the field surrounding the quasar SDSSp J104433.04$-$012502.2 at a redshift of 5.74. Comparing this image with optical broad-band images, we have found an object with a very strong emission line. Our follow-up optical spectroscopy has revealed that this source is at a redshift of $z=5.655\pm0.002$, forming stars at a rate $\sim 13 ~ h_{0.7}^{-2} ~ M_\odot$ yr$^{-1}$. Remarkably, the velocity dispersion of Ly$α$-emitting gas is only 22 km s$^{-1}$. Since a blue half of the Ly$α$ emission could be absorbed by neutral hydrogen gas, perhaps in the system, a modest estimate of the velocity dispersion may be $\gtrsim$ 44 km s$^{-1}$. Together with a linear size of 7.7 $h_{0.7}^{-1}$ kpc, we estimate a lower limit of the dynamical mass of this object to be $\sim 2 \times 10^9 M_\odot$. It is thus suggested that LAE J1044$-$0123 is a star-forming dwarf galaxy (i.e., a subgalactic object or a building block) beyond redshift 5 although we cannot exclude a possibility that most Ly$α$ emission is absorbed by the red damping wing of neutral intergalactic matter.

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arXiv2003

Are the hosts of Gamma-Ray Bursts sub-luminous and blue galaxies?

We present K-band imaging observations of ten Gamma-Ray Burst (GRB) host galaxies. We compare their observed and absolute K magnitudes as well as their R-K colours with those of other distant sources detected in various optical, near-infrared, mid-infrared and submillimeter deep surveys. We find that the GRB host galaxies, most of them lying at 0.5<z<1.5, exhibit very blue colours, comparable to those of the faint blue star-forming sources at high redshift. They are sub-luminous in the K-band, suggesting a low stellar mass content. We do not find any GRB hosts harbouring R- and K-band properties similar to those characterizing the luminous infrared/submillimeter sources and the extremely red starbursts. Should GRBs be regarded as an unbiased probe of star-forming activity, this lack of luminous and/or reddened objects among the GRB host sample might reveal that the detection of GRB optical afterglows is likely biased toward unobscured galaxies. It would moreover support the idea that a large fraction of the optically-dark GRBs occur within dust-enshrouded regions of star formation. On the other hand, our result might also simply reflect intrinsic properties of GRB host galaxies experiencing a first episode of very massive star formation and characterized by a rather weak underlying stellar population. Finally, we compute the absolute B magnitudes for the whole sample of GRB host galaxies with known redshifts and detected at optical wavelengths. We find that the latter appear statistically even less luminous than the sub-luminous blue sources which mostly contributed to the B-band light emitted at high redshift. This indicates that the formation of GRBs could be favoured in particular systems with very low luminosities and, therefore, low metallicities. (Abridged)

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arXiv2002

VLT and HST Observations of the Host Galaxy of GRB990705

We present VLT spectroscopic observations of Gamma-Ray Burst (GRB) 990705 host galaxy and highlight the benefits provided by the prompt-phase features of GRBs to derive the redshifts of the latter. In the host spectrum, we indeed detect an emission feature which we attribute to the [OII] 3726/3729 Angstrom doublet and derive an unambiguous redshift z=0.8424+/-0.0002 for this galaxy. This is in full agreement with the value z~0.86+/-0.17 previously derived using a transient absorption edge discovered in the X-ray spectrum of GRB990705. This burst is therefore the first GRB for which a reliable redshift was derived from the prompt phase emission itself, as opposed to redshift determinations performed using putative host galaxy emission lines or intestellar absorption lines in the GRB afterglows. Deep and high resolution images of the host of GRB990705 with the HST/STIS camera reveal that the burst occured in a nearly face-on Sc spiral galaxy typical of disk-dominated systems at 0.75<z<1. Assuming a cosmology with Ho=65km/s/Mpc, Omega_m=0.3 and Omega_lambda=0.7, we derive an absolute B magnitude M_B=-21.75 for this galaxy and a star formation rate SFR ~ 5-8~Msol/yr. Finally, we discuss the implications of using X-ray transient features to derive GRB redshifts with larger burst samples, and especially examine the case of short and dark-long GRBs.

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arXiv2002

Molecular Gas and Nuclear Activity in Ultraluminous Infrared Galaxies with Double Nuclei

High-resolution CO(1-0) observations of five ultraluminous infrared galaxies (ULIGs: L_IR [8-1000um] >~ 10^12 L_sun) with double nuclei are analyzed. These sources constitute a complete subset of local ULIGs expected to be in an intermediate stage of merging and selected with projected nuclear separations of 2.0-5.4 (3-5 kpc) so they could be resolved with the Owens Valley Radio Observatory Millimeter Array. The observed pairs include two mergers with cool far-infrared colors (25um to 60um flux density ratio f_25um/f_60um < 0.2) from the Infrared Astronomical Satellite (IRAS) Bright Galaxy Sample (IRAS 12112+0305 and IRAS 14348-1447) and three mergers with warm infrared dust temperatures f_25um/f_60um >~ 0.2) selected from the IRAS Warm Galaxy Sample (IRAS 08572+3915, IRAS 13451+1232 = PKS 1345+12, and IRAS 13536+1836 = Mrk 463). These ULIGs are further distinguished by the presence of pairs of active nuclei; among the ten nuclei, nine have Seyfert or LINER classifications and one is unclassified. Molecular gas is detected only on the redder, more radio-luminous nucleus of the warm objects, whereas both nuclei of the cool ULIGs are detected in CO. The inferred molecular gas masses for the detected nuclei are 0.1-1.2x10^10 M_sun, and the undetected nuclei have molecular gas masses at least 1.2--2.8 times less than that of their CO-luminous companions. Upper limits on the extent of the CO emitting regions of each detected nucleus range from 2--4 kpc, which is about 3-6 times smaller than the average effective CO diameter of nearby spiral galaxies...

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arXiv2002

A New High-Redshift Lyman alpha Emitter: Possible Superwind Galaxy at z = 5.69

During the course of our deep optical imaging survey for Ly alpha emitters at z approximately 5.7 in the field around the z=5.74 quasar SDSSp J104433.04-012502.2, we have found a candidate strong emission-line source. Follow-up optical spectroscopy shows that the emission line profile of this object is asymmetric, showing excess red-wing emission. These properties are consistent with an identification of Ly alpha emission at a redshift of z=5.687 +/- 0.002. The observed broad line width, Delta V_{FWHM} ~= 340 km s^{-1} and excess red-wing emission also suggest that this object hosts a galactic superwind.

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arXiv2002

Keck Absorption-Line Spectroscopy of Galactic Winds in Ultraluminous Infrared Galaxies

In this paper, we present moderately-high resolution (~65 km/s) spectroscopy, acquired with ESI on Keck II, of 11 ultraluminous infrared galaxies at z < 0.3 from the IRAS 1 Jy sample. The targets were chosen as good candidates to host galaxy-scale outflows, and most have infrared luminosities dominated by star formation. We use a chi-squared minimization to fit one- to three-component profiles to the NaI D interstellar absorption doublet in each object. Assuming that gas blueshifted by more than 70 km/s relative to the systemic velocity of the host is outflowing, we detect outflows in 73% of these objects. We adopt a simple model of a mass-conserving free wind to infer mass outflow rates in the range (dM/dt)_tot(H) = 13-133 M_sun/yr for galaxies hosting a wind. These values of (dM/dt)_tot, normalized to the corresponding global star formation rates inferred from infrared luminosities, are in the range eta = (dM/dt)_tot / SFR = 0.1-0.7. This is on average a factor of only 10 less than eta from recent measurements of nearby dwarfs, edge-on spirals, and lower-luminosity infrared galaxies. Within our sample, we conclude that eta has no dependence on the mass of the host (parameterized by host galaxy kinematics and absolute R- and K'-band magnitudes). We also attempt to estimate the average escape fraction = Sum(dM/dt_esc^i) / Sum(dM/dt_tot^i) and ``ejection efficiency'' = Sum(dM/dt_esc^i) / Sum(SFR^i) for our sample, which we find to be \~0.4-0.5 and ~0.1, respectively. The complex absorption-line properties of Mrk 231, an ultraluminous infrared galaxy which is optically classified as a Seyfert 1, are discussed separately in an appendix.

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arXiv2002

A Multi-band Photometric Study of Tidal Debris in A Compact Group of Galaxies: Seyfert's Sextet

In order to investigate the properties of the prominent tidal debris feature extending to the northeast of the compact group of galaxies Seyfert's Sextet, we analyzed multi-band (U, B, V, VR, R, I, J, H and K') photometric imaging data and obtained the following results: 1) The radial surface brightness distribution of this tidal debris in Seyfert's Sextet (TDSS) in each band appears to be well approximated by an exponential profile. 2) The observed B-V color of TDSS is similar to those of dwarf elliptical galaxies in nearby clusters. 3) Comparing the spectral energy distribution (SED) of TDSS with theoretical photometric evolution models and with the SED of the stars in the outer part of HCG 79b, we find that its SED is comparable to that of a $\sim$ 10 Gyr-old stellar population with solar metallicity, similar to the stellar population in the outer part of HCG 79b. This suggests that TDSS consists of stars that may have been liberated from HCG 79b by strong galaxy interactions, not a pre-existing dwarf galaxy previously thought.

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arXiv2001

Far-Infrared Galaxies in the Far-Ultraviolet

In an effort to better understand the UV properties of ultraluminous infrared galaxies (ULIGs), and compare them to the rest-frame UV properties of high redshift sub-mm and Lyman-break galaxies, we have obtained far- and near-UV imaging observations (lambda_{eff}=1457Å, lambda_{eff}=2364Å, respectively) of two luminous infrared galaxies (LIGs--VV 114 and IC 883) and five ULIGs (IRAS 08572+3915, Mrk 273, IRAS 15250+3609, Arp 220, and IRAS 19254--7245) using the Hubble Space Telescope. All the galaxies were detected in both channels. UV light, both diffuse and from star clusters, can be traced to within the inner kpc of the dominant near-IR nuclei. However, in general, the brightest UV sources are clearly displaced from the $I$-band and near-IR peaks by at least hundreds of pc. Further, only 0.07%-7.3% of the total near-UV light is projected within the inner 500 pc radius, even though this is the same region wherein most of the bolometric energy is generated. All nuclei are highly obscured by dust. (Abridged)

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arXiv2001

Ultraluminous Infrared Galaxies and the Origin of QSOs

We review the evidence which suggests that ultraluminous infrared galaxies (ULIGs) are the precursors of optically selected quasi-stellar objects (QSOs) and discuss additional data that suggests that the majority, if not all QSOs, may begin their lives in an intense infrared phase. Implications for the host galaxies of QSOs are discussed.

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arXiv2001

The QSO - Ultraluminous Infrared Galaxies Connection

For the past several years, our group has pursued a vigorous ground-based program aimed at understanding the nature of ultraluminous infrared galaxies. We recently published the results from a optical/near-infrared spectroscopic survey of a large statistically complete sample of ultraluminous infrared galaxies (the "IRAS 1-Jy sample"). We now present the results from our recently completed optical/near-infrared imaging survey of the 1-Jy sample. These data provide detailed morphological information on both large scale (e.g., intensity and color profiles, intensity and size of tidal tails and bridges, etc) and small scale (e.g., nuclear separation, presence of bars, etc) that helps us constrain the initial conditions necessary to produce galaxies with such high level of star formation and/or AGN activity. The nature of the interdependence between some key spectroscopic and morphological parameters in our objects (e.g., dominant energy source: super-starburst versus quasar, nuclear separation, merger phase, star formation rate, and infrared luminosity and color) is used to clarify the connection between starbursts, ultraluminous infrared galaxies, and quasars.

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arXiv2001

A Molecular Gas of z<0.2 Infrared-Excess, Optical QSOs

Millimeter-wave (CO) observations of optically-selected QSOs are potentially a powerful tool for studying the properties of both the QSOs and their host galaxies. We summarize here a recent molecular gas survey of z<0.17 optical QSOs with infrared (IR) excess, L_IR (8-1000 um) / L_bbb (0.1-1.0 um) > 0.36. Eight of these QSOs have been detected to date in CO(1-0), and the derived molecular gas masses are in the range 1.7-35x10^9 M_sun. The high L_IR / L'_CO of QSOs relative to the bulk of the local (z<0.2) IR luminous galaxy merger population is indicative of significant heating of dust (L_IR) by the QSO nucleus and/or by massive stars created in the host galaxy with high efficiency (i.e., per unit molecular gas, L'_CO).

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