- ID:
- ivo://CDS.VizieR/J/ApJ/716/530
- Title:
- Mid-IR variability from the SDWFS
- Short Name:
- J/ApJ/716/530
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the multi-epoch, mid-infrared Spitzer Deep Wide-Field Survey (SDWFS; Ashby et al. 2009, Cat. J/ApJ/701/428) to investigate the variability of objects in 8.1deg^2^ of the NOAO Deep Wide Field Survey Bootes field (NDWFS; Jannuzi & Dey 1999ASPC..191..111J). We perform a Difference Image Analysis of the four available epochs between 2004 and 2008, focusing on the deeper 3.6 and 4.5um bands. Out of 474, 179 analyzed sources, 1.1% meet our standard variability selection criteria that the two light curves are strongly correlated (r>0.8) and that their joint variance ({sigma}_12_) exceeds that for all sources with the same magnitude by 2{sigma}. We then examine the mid-IR colors of the variable sources and match them with X-ray sources from the XBootes survey (Murray et al. 2005ApJS..161....1M), radio catalogs (FIRST (Becker et al., Cat. VIII/71) and WSRT (de Vries et al. 2002, Cat. J/AJ/123/1784)), 24um selected active galactic nucleus (AGN) candidates (see Houck et al. 2005ApJ...622L.105H), and spectroscopically identified AGNs from the AGN and Galaxy Evolution Survey (AGES; C. S. Kochanek et al. 2010, in prep). Based on their mid-IR colors, most of the variable sources are AGNs (76%), with smaller contributions from stars (11%), galaxies (6%), and unclassified objects, although most of the stellar, galaxy, and unclassified sources are false positives. For our standard selection criteria, 11%-12% of the mid-IR counterparts to X-ray sources, 24um AGN candidates, and spectroscopically identified AGNs show variability.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/649/A83
- Title:
- Milky Way nuclear disk KMOS survey
- Short Name:
- J/A+A/649/A83
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In the central few degrees of the bulge of the Milky Way there is a flattened structure of gas, dust, and stars, known as the central molecular zone, that is similar to nuclear disks in other galaxies. As a result of extreme foreground extinction, we possess only sparse information about the (mostly old) stellar population of the nuclear disk. In this work we present our KMOS spectroscopic survey of the stars in the nuclear disk reaching the old populations. To obtain an unbiased data set, we sampled stars in the full extinction range along each line of sight. We also observed reference fields in neighboring regions of the Galactic bulge. We describe the design and execution of the survey and present first results. We obtain spectra and five spectral indices of 3113 stars with a median S/N of 67 and measure radial velocities for 3051 stars. Of those, 2735 sources have sufficient S/N to estimate temperatures and metallicities from indices. We derive metallicities using the CO 2-0 and Na I K-band spectral features, where we derive our own empirical calibration using metallicities obtained with higher-resolution observations.We use 183 giant stars for calibration spanning in metallicity from -2.5 to 0.6dex and covering temperatures of up to 5500K. The derived index based metallicities deviate from the calibration values with a scatter of 0.32dex. The internal uncertainty of our metallicities is likely smaller. We use these metallicity measurements, together with the CO index, to derive effective temperatures using literature relations. We publish the catalog in this paper. Our data set complements Galactic surveys such as Gaia and APOGEE for the inner 200pc radius of the Milky Way, which is not readily accessible by those surveys owing to extinction. We will use the derived properties in future papers for further analysis of the nuclear disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/719/763
- Title:
- Millimeter-wave sources in the SPT survey
- Short Name:
- J/ApJ/719/763
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of an 87deg^2^ point-source survey centered at R.A. 5h30m, decl. -55{deg} taken with the South Pole Telescope at 1.4 and 2.0mm wavelengths with arcminute resolution and milli-Jansky depth. Based on the ratio of flux in the two bands, we separate the detected sources into two populations, one consistent with synchrotron emission from active galactic nuclei and the other consistent with thermal emission from dust. We present source counts for each population from 11 to 640mJy at 1.4mm and from 4.4 to 800mJy at 2.0mm. The 2.0mm counts are dominated by synchrotron-dominated sources across our reported flux range; the 1.4mm counts are dominated by synchrotron-dominated sources above ~15mJy and by dust-dominated sources below that flux level. We detect 141 synchrotron-dominated sources and 47 dust-dominated sources at signal-to-noise ratio S/N>4.5 in at least one band. All of the most significantly detected members of the synchrotron-dominated population are associated with sources in previously published radio catalogs. Some of the dust-dominated sources are associated with nearby (z<<1) galaxies whose dust emission is also detected by the Infrared Astronomy Satellite. However, most of the bright, dust-dominated sources have no counterparts in any existing catalogs. We argue that these sources represent the rarest and brightest members of the population commonly referred to as submillimeter galaxies (SMGs).
- ID:
- ivo://CDS.VizieR/J/ApJS/191/212
- Title:
- MIPS sources near the South Ecliptic Pole
- Short Name:
- J/ApJS/191/212
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have imaged an 11.5deg^2^ region of sky toward the South Ecliptic Pole (SEP; J0443-5340) at 24 and 70um with MIPS, the Multiband Imaging Photometer for Spitzer. This region is coincident with a field mapped at longer wavelengths by AKARI and BLAST. We discuss our data reduction and source extraction procedures. The median 1{sigma} depths of the maps are 47uJy/beam at 24um and 4.3mJy/beam at 70um. At 24um, we identify 93098 point sources with signal-to-noise ratio (S/N)>=5 and an additional 63 resolved galaxies; at 70um we identify 891 point sources with S/N>=6. From simulations, we determine a false detection rate of 1.8% (1.1%) for the 24um (70um) catalog. The 24 and 70um point-source catalogs are 80% complete at 230uJy and 11mJy, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/671/470
- Title:
- MIPS survey of YSOs in Vela Molecular Ridge-D
- Short Name:
- J/ApJ/671/470
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new, unbiased Spitzer MIPS imaging survey (~1.8deg^2^) of the young stellar content of the Vela Molecular Ridge-D (VMR-D) is presented. The survey is complete down to 5 and 250mJy at 24 and 70{mu}m, respectively. A total of 849 sources are detected at 24{mu}m, and 52 of them also have a 70{mu}m counterpart. The VMR-D region is one that we have already partially mapped in dust and gas millimeter emission, and we discuss the correlation between the Spitzer compact sources and the millimeter contours. About half of the 24{mu}m sources are located inside the region delimited by the ^12^CO(1-0) contours, corresponding to only one-third of the full area mapped with MIPS. Therefore, the 24{mu}m source density increases by about 100% moving from outside to inside the CO contours. For the 70{mu}m sources, the corresponding density increase is a factor of 4. About 400 sources of these have a 2MASS counterpart, and we have used this to construct a Ks versus Ks-[24] diagram and to identify the protostellar population inside the cloud.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/1403
- Title:
- M31 IRAC 3.6/4.5um extended survey
- Short Name:
- J/MNRAS/459/1403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from an extended survey of the Andromeda galaxy (M31) using 41.1h of observations by Spitzer-IRAC at 3.6 and 4.5{mu}m. This survey extends previous observations to the outer disc and halo, covering total lengths of 44 and 66 along the minor and major axes, respectively. We have produced surface brightness profiles by combining the integrated light from background-corrected maps with stellar counts from a new catalogue of point sources. Using auxiliary catalogues, we have carried out a statistical analysis in colour-magnitude space to discriminate M31 objects from foreground Milky Way stars and background galaxies. The catalogue includes 426 529 sources, of which 66 per cent have been assigned probability values to identify M31 objects with magnitude depths of [3.6]=19.0+/-0.2, [4.5]=18.7+/-0.2. We discuss applications of our data for constraining the stellar mass and characterizing point sources in the outer radii.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/44
- Title:
- Mira-like variables from the KELT survey
- Short Name:
- J/ApJS/247/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 4132 Mira-like variables (red variables with long periods and high amplitudes) in the Kilodegree Extremely Little Telescope (KELT) survey. Of these, 376 are new Mira-like detections. We used Two Micron All Sky Survey (2MASS) colors to identify candidate asymptotic giant branch stars. We searched for photometric variability among the candidate asymptotic giant branch stars and identified stars that show periodic variability. We selected variables with high amplitudes and strong periodic behavior using a Random Forest classifier. Of the sample of 4132 Mira-like variables, we estimate that 70% are Miras and 30% are semiregular (SR) variables. We also adopt the method of using (W_RP_-W_Ks_) versus (J-Ks) colors in distinguishing between O-rich and C-rich Miras and find it to be an improvement over 2MASS colors.
- ID:
- ivo://CDS.VizieR/J/ApJ/886/33
- Title:
- MIR reverberation mapping analysis of 87 z<0.5 PG AGNs
- Short Name:
- J/ApJ/886/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The continued operation of the Wide-field Infrared Survey Explorer (WISE), combined with several ground-based optical transient surveys (e.g., CRTS, ASAS-SN, and PTF), offers an unprecedented opportunity to explore the dust structures in luminous active galactic nuclei (AGNs). We use these data for a mid-IR dust reverberation mapping (RM) study of 87 archetypal Palomar-Green quasars at z<~0.5. To cope with various contaminations of the photometry data and the sparse time sampling of the light curves, procedures to combine these data sets and retrieve the dust RM signals have been developed. We find that ~70% of the sample (with a completeness correction up to 95%) has convincing mid-IR time lags in the WISE W1 (~3.4{mu}m) and W2 (~4.5{mu}m) bands, and they are proportional to the square root of the AGN luminosity. Combined with previous K-band (~2.2{mu}m) RM results in the literature, the inferred dust emission size ratios are R_K_:R_W1_:R_W2_=0.6:1:1.2. Under simple assumptions, we put preliminary constraints on the projected dust surface density at these bands and reveal the possibly different torus structures among hot-dust-deficient, warm-dust-deficient, and normal quasars from the reverberation signals. With multi-epoch Spitzer data and later WISE photometry, we also explore AGN IR variability at 10-24{mu}m over a 5yr timescale. Except for blazars and flat-spectrum radio sources, the majority of AGNs have typical variation amplitudes at 24{mu}m of no more than 10% of that in the W1 band, indicating that the dust reverberation signals damp out quickly at longer wavelengths. In particular, steep-spectrum radio quasars also lack strong 24{mu}m variability, consistent with the unification picture of radio-loud AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/231
- Title:
- MISFITS survey: HCO+ obs. of Spitzer YSOs
- Short Name:
- J/ApJ/806/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an HCO^+^ J=3->2 survey of Class 0+I and Flat SED young stellar objects (YSOs) found in the Gould Belt clouds by surveys with Spitzer. Our goal is to provide a uniform Stage 0+I source indicator for these embedded protostar candidates. We made single point HCO^+^ J=3->2 measurements toward the source positions at the CSO and APEX of 546 YSOs (89% of the Class 0+I + Flat SED sample). Using the criteria from van Kempen et al. (2009, J/A+A/498/167), we classify sources as Stage 0+I or bona fide protostars and find that 84% of detected sources meet the criteria. We recommend a timescale for the evolution of Stage 0+I (embedded protostars) of 0.54Myr. We find significant correlations of HCO^+^ integrated intensity with {alpha} and T_bol_ but not with L_bol_. The detection fraction increases smoothly as a function of {alpha} and L_bol_, while decreasing smoothly with T_bol_. Using the Stage 0+I sources tightens the relation between protostars and high extinction regions of the cloud; 89% of Stage I sources lie in regions with A_V_>8mag. Class 0+I and Flat SED YSOs that are not detected in HCO^+^ have, on average, a factor of ~2 higher T_bol_ and a factor of ~5 lower L_bol_than YSOs with HCO^+^ detections. We find less YSO contamination, defined as the number of undetected YSOs divided by the total number surveyed, for sources with T_bol_<~600K and L_bol_>~1L_{sun}_. The contamination percentage is >90% at A_V_<4mag and decreases as A_V_ increases.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/140
- Title:
- M81, LMC and 3C 273/Coma 17-60keV obs.
- Short Name:
- J/MNRAS/459/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a deep survey of three extragalactic fields, M81 (exposure of 9.7Ms), Large Magellanic Cloud (6.8 Ms) and 3C 273/Coma (9.3Ms), in the hard X-ray (17-60keV) energy band with the IBIS telescope onboard the INTEGRAL observatory, based on 12 years of observations (2003-2015). The combined survey reaches a 4{sigma} peak sensitivity of 0.18mCrab (2.6x10^-12^erg/s/cm^2^) and sensitivity better than 0.25 and 0.87mCrab over 10 per cent and 90 per cent of its full area of 4900 deg^2^, respectively. We have detected in total 147 sources at S/N>4{sigma}, including 37 sources observed in hard X-rays for the first time. The survey is dominated by extragalactic sources, mostly active galactic nuclei (AGN). The sample of identified sources contains 98 AGN (including 64 Seyfert galaxies, seven low-ionization nuclear emission-line region galaxies, three X-ray bright optically normal galaxies, 16 blazars and eight AGN of unclear optical class), two galaxy clusters (Coma and Abell 3266), 17 objects located in the Large and Small Magellanic Clouds (13 high- and two low-mass X-ray binaries and two X-ray pulsars), three Galactic cataclysmic variables, one ultraluminous X-ray source (M82 X-1) and one blended source (SWIFT J1105.7+5854). The nature of 25 sources remains unknown, so that the survey's identification is currently complete at 83 per cent. We have constructed AGN number-flux relations (log N-log S) and calculated AGN number densities in the local Universe for the entire survey and for each of the three extragalactic fields.
