Results for "Rongmon Bordoloi"

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Photo-z Performance for Precision CosmologyOct 30 2009Current and future weak lensing surveys will rely on photometrically estimated redshifts of very large numbers of galaxies. In this paper, we address several different aspects of the demanding photo-z performance that will be required for future experiments, ... More
On the CGM Fundamental Plane: The Halo Mass Dependency of Circumgalactic HIDec 06 2017Aug 07 2018We analyze the equivalent widths of HI Ly-$\alpha$ ($W_{Ly\alpha}$) absorption from the inner (R < 160 kpc) circumgalactic medium (CGM) of 85 galaxies at $z \sim 0$ with stellar masses $M*$ ranging $\rm{8 \leq log M* / M_{\odot} \leq 11.6}$. Across three ... More
The COS-AGN survey: Revealing the nature of circum-galactic gas around hosts of active galactic nucleiMay 14 2018May 30 2018Active galactic nuclei (AGN) are thought to play a critical role in shaping galaxies, but their effect on the circumgalactic medium (CGM) is not well studied. We present results from the COS-AGN survey: 19 quasar sightlines that probe the CGM of 20 optically-selected ... More
A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: II. Program Design, Absorption-line Measurements, and Absorber StatisticsOct 05 2015To investigate the evolution of metal-enriched gas over recent cosmic epochs as well as to characterize the diffuse, ionized, metal-enriched circumgalactic medium (CGM), we have conducted a blind survey for C IV absorption systems in 89 QSO sightlines ... More
A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: III. The Mass- and Environment-dependent Circumgalactic MediumDec 02 2015Sep 15 2016Using Hubble Space Telescope Cosmic Origins Spectrograph observations of 89 QSO sightlines through the Sloan Digital Sky Survey footprint, we study the relationships between C IV absorption systems and the properties of nearby galaxies as well as large-scale ... More
Nuclear Outflow of the Milky Way: Studying the Kinematics and Spatial Extent of the Northern Fermi BubbleDec 05 2016We report new observations from a systematic, spectroscopic, ultraviolet absorption-line survey that maps the spatial and kinematic properties of the high-velocity gas in the Galactic Center region. We examine the hypothesis that this gas traces the biconical ... More
Probing the Outflowing Multiphase Gas ~1 kpc Below the Galactic CenterJul 21 2017Nov 01 2017Comparison of ISM absorption in the UV spectrum of LS 4825, a B1 Ib-II star d=21+/-5 kpc from the Sun toward l = 1.67 deg and b = -6.63 deg, with ISM absorption toward an aligned foreground star at d < 7.0+/-1.7 kpc, allows us to isolate and study gas ... More
The production and escape of ionizing photons from galaxies over cosmic time (Astro2020 Science White Paper)May 14 2019The ionizing photons produced by massive stars are key actors in galaxy evolution. Ionizing photon production and escape is poorly understood. Improved space-based, spatially-resolved, multiplexed spectroscopic capabilities covering observed wavelengths ... More
The formation and physical origin of highly ionized cooling gasMay 23 2016Jul 28 2016We present a physically clear cooling flow theory that explains the origin of warm diffuse gas seen primarily as highly ionized absorption line systems in the spectra of background sources. We predict the observed column densities of several highly ionized ... More
Spectroscopic Observations of the Fermi BubblesMar 12 2019Two giant plasma lobes, known as the Fermi Bubbles, extend 10 kpc above and below the Galactic Center. Since their discovery in X-rays in 2003 (and in gamma-rays in 2010), the Bubbles have been recognized as a new morphological feature of our Galaxy and ... More
Astro2020 Science White Paper: Spatially Resolved UV Nebular Diagnostics in Star-Forming GalaxiesMar 15 2019Diagnosing the physical and chemical conditions within star-forming galaxies (SFGs) is of paramount importance to understanding key components of galaxy formation and evolution: star-formation, gas enrichment, outflows, and accretion. Well established ... More
The COS Absorption Survey of Baryon Harbors (CASBaH): Warm-hot Circumgalactic Gas Reservoirs Traced by Ne VIII AbsorptionOct 15 2018We present a sample of 30 galaxies at 0.49 < z(gal) < 1.44 probed by Ne VIII absorption to study the highly ionized circumgalactic medium (CGM) based on high-S/N ultraviolet spectra of z > 1 QSOs and the galaxy database from the COS Absorption Survey ... More
The First Distance Constraint on the Renegade High Velocity Cloud Complex WDJul 21 2016We present medium-resolution, near-ultraviolet VLT/FLAMES observations of the star USNO-A0600-15865535. We adapt a standard method of stellar typing to our measurement of the shape of the Balmer epsilon absorption line to demonstrates that USNO-A0600-15865535 ... More
The Sunburst Arc: Direct Lyman α escape observed in the brightest known lensed galaxyOct 25 2017Nov 19 2017We present rest-frame ultraviolet and optical spectroscopy of the brightest lensed galaxy yet discovered, at redshift z = 2.4. This source reveals a characteristic, triple-peaked Lyman {\alpha} profile which has been predicted by various theoretical works ... More
Spatially Resolved Galactic Wind in Lensed Galaxy RCSGA 032727-132609Feb 24 2016We probe the spatial distribution of outflowing gas along four lines of sight separated by up to 6 kpc in a gravitationally-lensed star-forming galaxy at z=1.70. Using MgII and FeII emission and absorption as tracers, we find that the clumps of star formation ... More
Ultraviolet Perspectives on Diffuse Gas in the Largest Cosmic StructuresMar 14 2019The past decade has seen an explosion of discoveries and new insights into the diffuse gas within galaxies, galaxy clusters, and the filaments composing the Cosmic Web. A new decade will bring fresh opportunities to further this progress towards developing ... More
Connection Between the Circumgalactic Medium and the Interstellar Medium of Galaxies: Results from the COS-GASS SurveyApr 06 2015Sep 15 2015We present a study exploring the nature and properties of the Circum-Galactic Medium (CGM) and its connection to the atomic gas content in the interstellar medium (ISM) of galaxies as traced by the HI 21cm line. Our sample includes 45 low-z (0.026-0.049) ... More
The Properties of the Circumgalactic Medium in Red and Blue Galaxies: Results from the COS-GASS+COS-Halos SurveysSep 20 2016We use the combined data from the COS-GASS and COS-Halos surveys to characterize the Circum-Galactic Medium (CGM) surrounding typical low-redshift galaxies in the mass range $\rm~M_*\sim~10^{9.5-11.5}~M_{\odot} $, and over a range of impact parameters ... More
Spatially Resolved Patchy Lyman-$α$ Emission Within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8Aug 01 2017We report the detection of extended Lyman-$\alpha$ emission from the host galaxy of SDSS~J2222+2745, a strongly lensed quasar at $z = 2.8$. Spectroscopic follow-up clearly reveals extended Lyman-$\alpha$ in emission between two images of the central active ... More
The High-Ion Content and Kinematics of Low-Redshift Lyman Limit SystemsOct 23 2013Nov 05 2013We study the high-ionization phase and kinematics of the circumgalactic medium around low-redshift galaxies using a sample of 23 Lyman Limit Systems (LLSs) at 0.08<z<0.93 observed with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope. ... More
The COS-Dwarfs Survey: The Carbon Reservoir Around sub-L* GalaxiesJun 02 2014Nov 20 2014We report new observations of circumgalactic gas from the COS-Dwarfs survey, a systematic investigation of the gaseous halos around 43 low-mass z $\leq$ 0.1 galaxies using background QSOs observed with the Cosmic Origins Spectrograph. From the projected ... More
Baryon Cycling in the Low-Redshift Circumgalactic Medium: A Comparison of Simulations to the COS-Halos SurveyMar 06 2015We analyze the low-redshift (z~0.2) circumgalactic medium by comparing absorption-line data from the COS-Halos Survey to absorption around a matched galaxy sample from two cosmological hydrodynamic simulations. The models include different prescriptions ... More
Probing the Fermi Bubbles in Ultraviolet Absorption: A Spectroscopic Signature of the Milky Way's Biconical Nuclear OutflowDec 03 2014Dec 19 2014Giant lobes of plasma extend 55 degrees above and below the Galactic Center, glowing in emission from gamma rays (the Fermi Bubbles) to microwaves (the WMAP haze) and polarized radio waves. We use ultraviolet absorption-line spectra from the Hubble Space ... More
Probing the Southern Fermi Bubble in Ultraviolet Absorption using Distant AGNsApr 27 2018The Fermi Bubbles are two giant gamma-ray emitting lobes extending 55$^{\circ}$ above and below the Galactic Center. While the Northern Bubble has been extensively studied in ultraviolet (UV) absorption, little is known about the gas kinematics of the ... More
Form Factors and charge radii of heavy flavored mesons in a potential modelAug 24 2016We report the results for charge radii of heavy flavored mesons ($D^+, D^0, D^+_s, B^+, B^0, B^0_s$) in a QCD model with the potential $V(r)=-4\frac{\alpha_s}{3r}+br+c$ by incorporating two scales $r^{short}$ and $r^{long}$ as an integration limit so ... More
Leptonic decay of Heavy-light Mesons in a QCD Potential ModelJul 08 2012Jan 22 2013We study the masses and decay constants of heavy-light flavour mesons D, Ds, B and Bs in a QCD Potential model. The mesonic wavefunction is used to compute the masses of D and B mesons in the ground state and the wavefunction is transformed to momentum ... More
Isgur-Wise function within a QCD quark model with Airy's function as the wave function of heavy-light mesonsSep 27 2012We report some improved wave function for mesons taking linear confinement term in standard QCD potential as parent and Coulombic term as perturbation while applying quantum mechanical perturbation technique in solving Schrodinger equation with such a ... More
A model of mesons in finite extra-dimensionJan 24 2017Feb 06 2019Recently,problem of stability of H-atom has been reported in extra-finite dimension,and found out that it is stable in extra-finite dimension of size,$R\leq\frac{a_0}{4}$,where,$a_0$ is the Bohr radius.Assuming that,the heavy flavoured mesons have also ... More
Understanding the circumgalactic medium is critical for understanding galaxy evolutionMar 13 2019Galaxies evolve under the influence of gas flows between their interstellar medium and their surrounding gaseous halos known as the circumgalactic medium (CGM). The CGM is a major reservoir of galactic baryons and metals, and plays a key role in the long ... More
The COS-Halos Survey: Physical Conditions and Baryonic Mass in the Low-Redshift Circumgalactic MediumMar 04 2014Aug 07 2014We analyze the physical conditions of the cool, photoionized (T $\sim 10^4$ K) circumgalactic medium (CGM) using the COS-Halos suite of gas column density measurements for 44 gaseous halos within 160 kpc of $L \sim L^*$ galaxies at $z \sim 0.2$. These ... More
Charge radii of heavy flavored mesons in a potential modelAug 24 2016Oct 17 2017We report the results for charge radii of heavy flavored mesons ($D^+, D^0, D^+_s, B^+, B^0, B^0_s$) in an improved QCD potential model. To enhance the effectiveness of short range and long range effect of the potential $V(r)=-4\frac{\alpha_s}{3r}+br+c$ ... More
Modeling the distribution of Mg II absorbers around galaxies using Background Galaxies & QuasarsNov 15 2012Feb 24 2014We present joint constraints on the distribution of MgII absorption around galaxies, by combining the MgII absorption seen in stacked background galaxy spectra and the distribution of host galaxies of strong MgII systems from the spectra of background ... More
The confinement energy of quantum dotsDec 11 2012One of the most significant research interests in the field of electronics is that on quantum dot, because such materials have electronic properties intermediate between those of bulk semiconductors and those of discrete molecules. Confinement energy ... More
The Magellan Evolution of Galaxies Spectroscopic and Ultraviolet Reference Atlas (MEGaSaURA) II: Stacked SpectraOct 20 2017We stack the rest-frame ultraviolet spectra of N=14 highly magnified gravitationally lensed galaxies at redshifts 1.6<z<3.6. The resulting new composite spans $900< \lambda_{rest} < 3000$ \AA, with a peak signal-to-noise ratio of 103 per spectral resolution ... More
Heavy Element Absorption Systems at $5.0<z<6.8$: Metal-Poor Neutral Gas and a Diminishing Signature of Highly Ionized Circumgalactic MatterJan 17 2019Ratios of different ions of the same element encode ionization information independently from relative abundances in quasar absorption line systems, crucial for understanding the multiphase nature and origin of absorbing gas, particularly at $z>6$ where ... More
Photo-z Performance for Precision Cosmology II : Empirical VerificationJan 04 2012The success of future large scale weak lensing surveys will critically depend on the accurate estimation of photometric redshifts of very large samples of galaxies. This in turn depends on both the quality of the photometric data and the photo-z estimators. ... More
Obscured AGN at 1.5 < z < 3.0 from the zCOSMOS-deep Survey I. Properties of the emitting gas in the Narrow Line RegionMar 26 2019Apr 12 2019We select a sample of 90 obscured (type2) AGN with 1.45<z<3.05 from the zCOSMOS-deep galaxy sample by 5 sigma-detection of the high-ionization CIV {\lambda}1549 narrow emission line. The presence of this feature in a galaxy spectrum is often associated ... More
Obscured AGN at 1.5 < z < 3.0 from the zCOSMOS-deep Survey I. Properties of the emitting gas in the Narrow Line RegionMar 26 2019We select a sample of 90 obscured (type2) AGN with 1.45<z<3.05 from the zCOSMOS-deep galaxy sample by 5 sigma-detection of the high-ionization CIV {\lambda}1549 narrow emission line. The presence of this feature in a galaxy spectrum is often associated ... More
Obscured AGN at z~1 from the zCOSMOS-Bright Survey I. Selection and Optical Properties of a [Ne v]-selected sampleMay 27 2013A sample of 94 narrow line AGN with 0.65<z<1.20 has been selected from the 20k-Bright zCOSMOS galaxy sample by detection of the high-ionization [NeV]3426 line. Taking advantage of the large amount of data available in the COSMOS field, the properties ... More
A group-galaxy cross-correlation function analysis in zCOSMOSJun 29 2012Oct 23 2012We present a group-galaxy cross-correlation analysis using a group catalog produced from the 16,500 spectra from the optical zCOSMOS galaxy survey. Our aim is to perform a consistency test in the redshift range 0.2 < z < 0.8 between the clustering strength ... More
The dependence of Galactic outflows on the properties and orientation of zCOSMOS galaxies at z ~ 1Jul 24 2013We present an analysis of cool outflowing gas around galaxies, traced by MgII absorption lines in the co-added spectra of a sample of 486 zCOSMOS galaxies at 1 < z < 1.5. These galaxies span a range of stellar masses (9.45< log[M*/Msun]<10.7) and star ... More
Spot the difference. Impact of different selection criteria on observed properties of passive galaxies in zCOSMOS 20-k sampleMay 06 2013Sep 11 2013We present the analysis of photometric, spectroscopic, and morphological properties for differently selected samples of passive galaxies up to z=1 extracted from the zCOSMOS-20k spectroscopic survey. This analysis intends to explore the dependence of ... More
The radial and azimuthal profiles of Mg II absorption around 0.5 < z < 0.9 zCOSMOS galaxies of different colors, masses and environmentsJun 03 2011Aug 25 2011We map the radial and azimuthal distribution of Mg II gas within 200 kpc (physical) of 4000 galaxies at redshifts 0.5 < z < 0.9 using co-added spectra of more than 5000 background galaxies at z > 1. We investigate the variation of Mg II rest frame equivalent ... More
The dominant role of mergers in the size evolution of massive early-type galaxies since z ~ 1Feb 21 2012Nov 05 2012In this paper we measure the merger fraction and rate, both minor and major, of massive early-type galaxies (M_star >= 10^11 M_Sun) in the COSMOS field, and study their role in mass and size evolution. We use the 30-band photometric catalogue in COSMOS, ... More
Environmental effects in the interaction and merging of galaxies in zCOSMOSDec 20 2011(Abridged) We analyze the environments and galactic properties (morphologies and star-formation histories) of a sample of 153 close kinematic pairs in the redshift range 0.2 < z < 1 identified in the zCOSMOS-bright 10k spectroscopic sample of galaxies. ... More
The Colors of Central and Satellite Galaxies in zCOSMOS out to z ~ 0.8 and Implications for QuenchingNov 23 2012May 02 2013We examine the red fraction of central and satellite galaxies in the large zCOSMOS group catalog out to z ~ 0.8 correcting for both the incompleteness in stellar mass and for the less than perfect purities of the central and satellite samples. We show ... More
Investigating the relationship between AGN activity and stellar mass in zCOSMOS galaxies at 0<z<1 using emission line diagnostic diagramsApr 09 2013We investigate the link between AGN activity, star-formation and stellar mass of the host galaxy at 0<z<1, looking for spectroscopic traces of AGN and aging of the host. This work provides an extension of the existing studies at z<0.1 and contributes ... More
Improved constraints on the expansion rate of the Universe up to z~1.1 from the spectroscopic evolution of cosmic chronometersJan 17 2012Feb 05 2013We present new improved constraints on the Hubble parameter H(z) in the redshift range 0.15 < z < 1.1, obtained from the differential spectroscopic evolution of early-type galaxies as a function of redshift. We extract a large sample of early-type galaxies ... More
The zCOSMOS 20k Group CatalogJun 29 2012Oct 23 2012We present an optical group catalog between 0.1 < z < 1 based on 16,500 high-quality spectroscopic redshifts in the completed zCOSMOS-bright survey. The catalog published herein contains 1498 groups in total and 192 groups with more than five observed ... More
The COSMOS Density Field: A Reconstruction Using Both Weak Lensing and Galaxy DistributionsMay 04 2012The COSMOS field has been the subject of a wide range of observations, with a number of studies focusing on reconstructing the 3D dark matter density field. Typically, these studies have focused on one given method or tracer. In this paper, we reconstruct ... More
The zCOSMOS Redshift Survey: evolution of the light in bulges and discs since z~0.8Mar 27 2014We studied the chronology of galactic bulge and disc formation by analysing the relative contributions of these components to the B-band rest-frame luminosity density at different epochs. We present the first estimate of the evolution of the fraction ... More
Proto-groups at 1.8<z<3 in the zCOSMOS-deep sampleOct 09 2012Oct 14 2013We identify 42 candidate groups lying between 1.8<z<3.0 from a sample of 3502 galaxies with spectroscopic redshifts in the zCOSMOS-deep redshift survey within the same redshift interval. These systems contain three to five spectroscopic galaxies that ... More
A journey from the outskirts to the cores of groups I: Color- and mass-segregation in 20K-zCOSMOS groupsJan 09 2012Using the group catalog obtained from zCOSMOS spectroscopic data and the complementary photometric data from the COSMOS survey, we explore segregation effects occurring in groups of galaxies at intermediate/high redshifts. We built two composite groups ... More
Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter functionMar 24 2010Sep 27 2010We explore the inter-relationships between mass, star-formation rate and environment in the SDSS, zCOSMOS and other surveys. The differential effects of mass and environment are completely separable to z ~ 1, indicating that two distinct processes are ... More
X-ray Groups of Galaxies at 0.5<z<1 in zCOSMOS: Increased AGN Activities in High Redshift GroupsOct 05 2011We present a photometric and spectroscopic study of galaxies at 0.5<z<1 as a function of environment based on data from the zCOSMOS survey. There is a fair amount of evidence that galaxy properties depend on mass of groups and clusters, in the sense that ... More