Y. Jimenez-Teja - Academia.edu (original) (raw)

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Papers by Y. Jimenez-Teja

Astronomy & Astrophysics, 2014

ABSTRACT Context. Rings have recently been discovered around the Centaur 10199 Chariklo. Aims. In... more ABSTRACT Context. Rings have recently been discovered around the Centaur 10199 Chariklo. Aims. In this paper we present new photometric data, obtained at the 4.2 m SOAR Telescope, aiming to investigate Chariklo's absolute magnitude and rotational period, which is still unknown, and to look for potential cometary activity. Methods. The field background of the images was very crowded so several approaches were used for the extraction of Chariklo fluxes. The background sources were subtracted using difference image analysis and then aperture photometry was applied. A Fourier polynomial fit was used to determine the period. Results. We find a synodic rotation period of 7.004 +/- 0.036 h. The visual absolute magnitude derived from the SOAR data is H-upsilon = 7.03 +/- 0.10. We model the rings' contribution to the flux, and find that the derived H-upsilon is consistent with the predicted ring system aspect angle. We also revised the Chariklo system albedo (4.2%) and effective radius (119 + 5 km) from a re-analysis of Herschel and WISE thermal data obtained during 2010 with the correct H-upsilon value. No coma is detected from the SOAR data, nor in previous VLT images acquired in 2007-2008, where the rings' aspect angle was close to zero. The upper limit to the dust production rate is 2.5 kg/s.

Astronomy & Astrophysics, 2014

Geodetic Research on Deception Island and its Environment (South Shetland Islands, Bransfield Sea... more Geodetic Research on Deception Island and its Environment (South Shetland Islands, Bransfield Sea and Antarctic Peninsula) During Spanish Antarctic Campaigns (1987-2007) M. Berrocoso, A. Fernández-Ros, ME Ramírez, JM Salamanca, C. Torrecillas, A. ...

The Astrophysical Journal, 2012

Monthly Notices of the Royal Astronomical Society, 2015

ABSTRACT Photometric redshifts, which have become the cornerstone of several of the largest astro... more ABSTRACT Photometric redshifts, which have become the cornerstone of several of the largest astronomical surveys like PanStarrs, DES, J-PAS or the LSST, require precise measurements of galaxy photometry in different bands using a consistent physical aperture. This is not trivial, due to the variation in the shape and width of the Point Spread Function (PSF) introduced by wavelength differences, instrument positions and atmospheric conditions. Current methods to correct for this effect rely on a detailed knowledge of the PSF characteristics as a function of the survey coordinates, which can be difficult due to the relative paucity of stars tracking the PSF behaviour. Here we show that it is possible to measure accurate, consistent multicolour photometry without knowing the shape of PSF. The Chebyshev-Fourier Functions (CHEFs) can fit the observed profile of each object and produce high signal-to-noise integrated flux measurements unaffected by the PSF. These total fluxes, which encompass all the galaxy populations, are much more useful for Galaxy Evolution studies than aperture photometry. We compare the total magnitudes and colours obtained using our software to traditional photometry with SExtractor, using real data from the COSMOS survey and the Hubble Ultra Deep Field. We also apply the CHEFs technique to the recently published Extreme Deep Field and compare the results to those from ColorPro on the HUDF. We produce a photometric catalogue with 35732 sources (10823 with S/N>5), reaching a photometric redshift precision of 2% due to the extraordinary depth and wavelength coverage of the XDF images.

Monthly Notices of the Royal Astronomical Society, 2015

The Astrophysical Journal, 2014

Monthly Notices of the Royal Astronomical Society, 2014

Abell 2744 is a galaxy cluster merger similar to the Bullet Cluster but more massive and somewhat... more Abell 2744 is a galaxy cluster merger similar to the Bullet Cluster but more massive and somewhat more complex. A2744 exhibits an even larger (the largest observed) projected separation between dark matter and the stripped, shocked cluster gas ( 54" 240 kpc). We may even be witnessing a triple merger similar to "The Cosmic Train Wreck" (Abell 520) as evidenced

The Astrophysical Journal, 2014

ABSTRACT Growing observational evidence now indicates that nebular line emission has a significan... more ABSTRACT Growing observational evidence now indicates that nebular line emission has a significant impact on the rest-frame optical fluxes of z~5-7 galaxies observed with Spitzer. This line emission makes z~5-7 galaxies appear more massive, with lower specific star formation rates. However, corrections for this line emission have been very difficult to perform reliably due to huge uncertainties on the overall strength of such emission at z>~5.5. Here, we present the most direct observational evidence yet for ubiquitous high-EW [OIII]+Hbeta line emission in Lyman-break galaxies at z~7, while also presenting a strategy for an improved measurement of the sSFR at z~7. We accomplish this through the selection of bright galaxies in the narrow redshift window z~6.6-7.0 where the IRAC 4.5 micron flux provides a clean measurement of the stellar continuum light. Observed 4.5 micron fluxes in this window contrast with the 3.6 micron fluxes which are contaminated by the prominent [OIII]+Hbeta lines. To ensure a high S/N for our IRAC flux measurements, we consider only the brightest (H_{160}<26 mag) magnified galaxies we have identified in CLASH and other programs targeting galaxy clusters. Remarkably, the mean rest-frame optical color for our bright seven-source sample is very blue, [3.6]-[4.5]=-0.9+/-0.3. Such blue colors cannot be explained by the stellar continuum light and require that the rest-frame EW of [OIII]+Hbeta be greater than 637 Angstroms for the average source. The bluest four sources from our seven-source sample require an even more extreme EW of 1582 Angstroms. Our derived lower limit for the mean [OIII]+Hbeta EW could underestimate the true EW by ~2x based on a simple modeling of the redshift distribution of our sources. We can also set a robust lower limit of >~4 Gyr^-1 on the specific star formation rates based on the mean SED for our seven-source sample. (abridged)